Patent Application
20120135016
The present invention relates to methods and compositions, in particular using Copolymer 1, for induction and/or enhancement of endogenous neurogenesis and/or oligodendrogenesis and for stem cell therapy in injuries, diseases, disorders or conditions, in particular those associated with the central nervous system (CNS) or peripheral nervous system (PNS).
Abbreviations: Aβ, β-amyloid; AD, Alzheimer's disease; BDNF, brain-derived neurotrophic factor; BMS, Basso motor score; BrdU, 5-bromo-2′-deoxyuridine; CFA, complete Freund's adjuvant; CNS, central nervous system; Cop 1, Copolymer 1, same as GA; DCX, doublecortin; DG, dentate gyrus; EAE, experimental autoimmune encephalomyelitis; EGF, epidermal growth factor; FCS, fetal calf serum; FGF, fibroblast growth factor; i.c.v., intracerebroventricular; GA, glatiramer acetate; GFAP, glial fibrillary acidic protein; GFP, green fluorescent protein; IB4, isolectin B4; IFA, incomplete Freund's adjuvant; IGF-I, insulin-like growth factor 1; IFN, interferon; IL, interleukin; LPS, lipopolysaccharide; MBP, myelin basic protein; MG, microglia; MHC-II, class II major histocompatibility complex molecules; MOG, myelin oligodendrocyte glycoprotein; MS, multiple sclerosis; MWM, Morris water maze; NeuN, neuronal nuclear antigen; NPC, neural stem/progenitor cell; OB, olfactory bulb; PBS, phosphate-buffered saline; PDL, poly-D-lysine; PNS, peripheral nervous system; RMS, rostral migratory stream; SCI, spinal cord injury; SGZ, subgranular zone; SVZ, subventricular zone; TGF-β, transforming growth factor-β; TNF, tumor necrosis factor.
The central nervous system (CNS) is particularly vulnerable to insults that result in cell death or damage in part because cells of the CNS have a limited capacity for repair. Since damaged brain tissue does not regenerate, recovery must come from the remaining intact brain.
Poor recovery from acute insults or chronic degenerative disorders in the CNS has been attributed to lack of neurogenesis, limited regeneration of injured nerves, and extreme vulnerability to degenerative conditions. The absence of neurogenesis was explained by the assumption that soon after birth the CNS reaches a permanently stable state, needed to maintain the equilibrium of the brain's complex tissue network. Research during the last decade showed, however, that the brain is capable of neurogenesis throughout life, albeit to a limited extent (Morshead et al., 1994). In the inflamed brain, neurogenesis is blocked (Ekdahl et al., 2003; Monje et al., 2003). This latter finding strengthened the traditional view that local immune cells in the CNS have an adverse effect on neurogenesis. Likewise, the limited regeneration and excessive vulnerability of CNS neurons under inflammatory conditions or after an acute insult were put down to the poor ability of the CNS to tolerate the immune-derived defensive activity that is often associated with local inflammation and cytotoxicity mediated, for example, by tumor necrosis factor (TNF)-α or nitric oxide (Merrill et al., 1993). More recent studies have shown, however, that although an uncontrolled local immune response indeed impairs neuronal survival and blocks repair processes, a local immune response that is properly controlled can support survival and promote recovery (Hauben and Schwartz, 2003; Schwartz et al., 2003). It was further shown that after an injury to the CNS, a local immune response that is well controlled in time, space, and intensity by peripheral adaptive immune processes (in which CD4+ helper T cells are directed against self-antigens residing at the site of the lesion) is a critical requirement for post-traumatic neuronal survival and repair (Moalem et al., 1999; Butovsky et al., 2001; Schwartz et al., 2003; Shaked et al., 2004). These and other results led the inventor M Schwartz and colleagues to formulate the concept of ‘protective autoimmunity’ (Moalem et al., 1999).
Neurogenesis occurs throughout life in adult individuals, albeit to a limited extent. Most of the newly formed cells die within the first 2-3 weeks after proliferation and only a few survive as mature neurons. Little is known about the mechanism(s) underlying the existence of neural stem/progenitor cells (NPCs) in an adult brain and why these cells are restricted in amount and limited to certain areas. Moreover, very little is known about how neurogenesis from an endogenous NPC pool can be physiologically increased. Knowledge of the factors allowing such stem cells to exist, proliferate, and differentiate in the adult individual is a prerequisite for understanding and promoting the conditions conducive to CNS repair. This in turn can be expected to lead to the development of interventions aimed at boosting neural cell renewal from the endogenous stem-cell pool or from exogenously applied stem cells.
Experiments with rat and mouse models in our laboratory have shown that well-controlled implantation of specifically activated blood-borne macrophages (Rapalino et al., 1998) or dendritic cells (Hauben et al., 2003) promotes recovery from spinal cord injury (SCI). Other studies showed that the well-controlled activity of autoimmune T cells reactive to CNS antigens residing in the lesioned site can promote recovery from axonal insults (Hauben et al., 2000; Moalem et al., 1999). It was also shown that neuroprotection, mediated by T cells directed specifically to CNS-related autoantigens, is the body's physiological response to CNS injury (Yoles et al., 2001a, 2001b).
Under normal conditions in the adult brain, new neurons are formed in the neurogenic niches of the subventricular zone of the lateral ventricles and the subgranular zone of the hippocampal dentate gyrus (Kempermann et al., 2004). Under pathological conditions some neurogenesis can also be induced in non-neurogenic brain areas. Several studies have demonstrated, for example, that injury to the CNS in animals is followed by recruitment of endogenous NPCs, which can undergo differentiation to neurons and glia at the injured site (Nakatomi et al., 2002; Imitola et al., 2004a). However, this injury-triggered cell renewal from endogenous progenitors is limited in extent and is not sufficient for full replacement of the damaged tissue. To overcome the deficit, scientists are currently seeking ways to promote recovery by transplanting cultured adult NPCs (aNPCs) (McDonald et al., 2004). Exogenous aNPCs might contribute to recovery by acting as a source of new neurons and glia in the injured CNS (Cummings et al., 2005; Lepore and Fischer, 2005) or by secreting factors that directly or indirectly promote neuroprotection (Lu et al., 2005) and neurogenesis from endogenous stem-cell pools (Enzmann et al., 2005).
Current opinions concur that neurogenesis persists in the adult brain, where it may contribute to repair and recovery after injury. Brain insults such as cerebral ischemia (Jin et al., 2003), apoptosis (Magavi et al., 2000) or autoimmune inflammatory demyelination (Picard-Riera et al., 2002) enhance neurogenesis. Hence, multipotent cells located in the hippocampus hilus and the subventricular zone (SVZ) of the lateral ventricle manifest increased proliferation and migration in pathological situations. Moreover, progenitor cells from the SVZ that migrate through the rostral migratory stream (RMS) to the olfactory bulb (OB) can be triggered to differentiate into astrocytes and neurons (Picard-Riera et al., 2004). Nevertheless, the therapeutic significance of self-neurogenesis in CNS pathology is limited, as it fails to regenerate functional neurons that compensate the damage.
In multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), the immune system provokes the detrimental process via autoimmune inflammatory mechanisms (Hellings et al., 2002; Behi et al., 2005). Still, neuronal and axonal degeneration, initiated at disease onset and revealed when compensatory CNS resources are exhausted, are the major determinant of the irreversible neurological disability (Bjartmar et al., 2003), particularly in the myelin oligodendrocyte glycoprotein (MOG) induced model (Hobom et al., 2003). Current treatments for MS are effective in ameliorating the immune inflammatory process, but their ability to enhance the intrinsic CNS repair mechanism and to induce effective neuroprotection and neurogenesis has not been shown.
A potential approach for treatment of CNS damage includes the use of adult neural stem cells or any type of stem cells. The adult neural stem cells are progenitor cells present in the mature mammalian brain that have the ability of self-renewal and, given the appropriate stimulation, can differentiate into brain neurons, astrocytes and oligodendrocytes. Stem cells (from other tissues) have classically been defined as pluripotent and having the ability to self-renew, to proliferate, and to differentiate into multiple different phenotype lineages. Hematopoietic stem cells are defined as stem cells that can give rise to cells of at least one of the major hematopoietic lineages in addition to producing daughter cells of equivalent potential. Three major lineages of blood cells include the lymphoid lineage, e.g. B-cells and T-cells, the myeloid lineage, e.g. monocytes, granulocytes and megakaryocytes, and the erythroid lineage, e.g. red blood cells. Certain hematopoietic stem cells are capable of differentiating to other cell types, including brain cells.
Transplantation of multipotent (stem) precursor cells is a promising strategy for the therapy of various disorders caused by loss or malfunction of single or few cell types. These include neurological disorders such as spinal cord injury, subcortical neurodegeneration e.g. Huntington and Parkinson, and demyelinatindg diseases e.g. MS, as well as other pathological conditions such as diabetes, myocardial infarction of cardiac failure, tissue injury and insufficient wound healing. Particularly in MS and its animal model EAE, stem cells differentiating into oligodendrocytes and neurons may lead to repair of myelin damage and replace degenerating neurons. However, hitherto stem cell transplantation in these systems resulted in poor therapeutic outcome. Thus, stem cells transplanted as such into EAE mice were found mainly around the injection site (in cases of local administration) or in perivascular position (when systemic administration was employed), and their proliferation, migration and differentiation were insufficient to compensate for the damage inflicted by the disease (Goldman, 2005; Pluchino and Martini, 2005). A clinical trial in which stem cells were transplanted into demyelinating brain areas of MS patients was discontinued in 2003, as no evidence of stem cell survival was found in the implanted patients (Pluchino and Martini, 2005). These outcomes were related to the chronic inflammatory processes that destroy the transplanted as well as the resident cells. It has been suggested that stem cell-based therapeutic strategies, especially those intended for MS, will require disease modification adjuncts to cell delivery. Stem cell therapy is also considered for many other medical applications, not related to neurological disorders.
Separation and cloning of neural stem cell lines from both the murine and human brain have been reported. Human CNS neural stem cells, like their rodent homologues, when maintained in a mitogen-containing (typically epidermal growth factor or epidermal growth factor plus basic fibroblast growth factor), serum-free culture medium, grow in suspension culture to form aggregates of cells known as neurospheres. Upon removal of the mitogens and provision of a substrate, the stem cells differentiate into neurons, astrocytes and oligodendrocytes. When such stem cells are reintroduced into the developing or mature brain, they can undergo through division, migration and growth processes, and assume neural phenotypes, including expression of neurotransmitters and growth factors normally elaborated by neurons. Thus, use of neural stem cells may be advantageous for CNS damage recovery in at least two ways: (1) by the stem cells partially repopulating dead areas and reestablishing neural connections lost by CNS damage, and (2) by secretion of important neurotransmitters and growth factors required by the brain to rewire after CNS damage.
Recently, a renewable source of neural stem cells was discovered in the adult human brain. These cells may be a candidate for cell-replacement therapy for nervous system disorders. The ability to isolate these cells from the adult human brain raises the possibility of performing autologous neural stem cell transplantation. It has been reported that clinical trials with adult human neural stem cells have been initiated for treatment of Parkinson's disease patients. If adult neural stem cells are to be used in clinical trials they must be amenable to expansion into clinically significant quantities. Unfortunately, these cells seem to have a limited life-span in the culture dish and it remains to be determined whether they are stable at later passages and capable of generating useful numbers of neurons.
The brain has long been viewed as an immune-privileged site. However, autoimmune T cells (controlled with respect to the onset, duration, and intensity of their activity) were recently shown to exert a beneficial effect on neuronal survival after CNS injury (Schwartz et al., 2003), as well as in cases of mental dysfunction (Kipnis et al., 2004). Moreover, in-depth understanding of the mechanisms underlying the beneficial effect of T cells for degenerative neural tissue has has pointed out that the T cells instruct the microglia, at the injured area, to acquire a phenotype supportive of neural tissue. In addition, it appeared that several immune-based intervention can boost this protective response, all of which converts to microglial activation (Shaked et al., 2004). The type of damage does not determine the choice of the approach, it is the site which determines it. Some antigens cross-react with numerous antigens and thus can overcome tissue specificity barrier. According to the present invention, we show that the same manipulation that leads to neuronal survival leads to neurogenesis and oligodendrogenesis. It appears that the same microglia, activated by T cells or by their cytokines, not only support neuronal survival but also support oligodendrogenesis and neurogenesis. These results indicate that T-cell-based manipulation will create conditions in damaged neural tissue that favor cell renewal not only from endogenous stem cell resources but also from exogenously applied stem cells.
Copolymer 1 or Cop 1, a non-pathogenic synthetic random copolymer composed of the four amino acids: L-Glu, L-Lys, L-Ala, and L-Tyr. Glatiramer acetate (GA), one form of Cop 1, is currently an approved drug for the treatment of multiple sclerosis under the name of Copaxone® (a trademark of Teva Pharmaceutical Industries Ltd., Petach Tikva, Israel). It exerts a marked suppressive effect on EAE induced by various encephalitogens, in several species (Arnon and Sela, 2003).
Cop 1 is a very well tolerated agent with only minor adverse reactions and high safety profile. Treatment with Cop 1 by ingestion or inhalation is disclosed in U.S. Pat. No. 6,214,791.
Recently it was found that in animal models Cop 1 provides a beneficial effect for several additional disorders. Thus, Cop 1 suppresses the immune rejection manifested in graft-versus-host disease (GVHD) in case of bone marrow transplantation (Schlegel et al., 1996; Aharoni et al., 1997; U.S. Pat. No. 5,858,964), as well as in graft rejection in case of solid organ transplantation (Aharoni et al., 2001, 2004) and in the applicant's patent applications WO 00/27417 and WO/009333A2)
WO 01/52878 and WO 01/93893 of the same applicants disclose that Cop 1, Cop 1-related peptides and polypeptides and T cells activated therewith protect CNS cells from glutamate toxicity and prevent or inhibit neuronal degeneration or promote nerve regeneration in the CNS and in the PNS. Thus, for example, Cop 1 is under evaluation as a therapeutic vaccine for neurodegenerative diseases such as optic neuropathies and glaucoma (Kipnis and Schwartz, 2002).
Cop 1 has been shown to act as a low-affinity antigen that activates a wide range of self-reacting T cells, resulting in neuroprotective autoimmunity that is effective against both CNS white matter and grey matter degeneration (Schwartz and Kipnis, 2002). The neuroprotective effect of Cop 1 vaccination was demonstrated in animal models of acute and chronic neurological disorders such as optic nerve injury (Kipnis et al., 2000), head trauma (Kipnis et al., 2003), glaucoma (Schori et al., 2001; Bakalash et al., 2003), amyotrophic lateral sclerosis (Angelov et al., 2003) and in the applicant's patent applications WO 01/52878, WO 01/93893 and WO 03/047500.
The use of Copolymer 1 for treatment of prion-related diseases is disclosed in WO 01/97785. Gendelman and co-workers disclose that passive immunization with splenocytes of mice immunized with Cop 1 confers dopaminergic neuroprotection in MPTP-treated mice (Benner et al., 2004).
Cop 1 and related copolymers and peptides have been disclosed in WO 00/05250 (Aharoni et al., 2000) for treating autoimmune diseases and in WO 2004/064717 for treatment of Inflammatory Bowel Diseases (Aharoni et al, 2004).
The immunomodulatory effect of GA was attributed to its ability to induce Th2/3 cells that secrete high levels of anti-inflammatory cytokines (Aharoni et al., 1998; Duda et al., 2000). These cells cross the blood brain barrier (BBB), accumulate in the CNS (Aharoni et al., 2000, 2002), and express in situ interleukin-10 (IL-10), transforming growth factor-β (TGF-β), as well as Brain Derived Neurotrophic Factor (BDNF) (Aharoni et al., 2003). Furthermore, the GA-specific cells induce bystander effect on neighboring CNS cells to express these beneficial factors and reduce interferon (IFN)-γ expression. A key issue in the capability of GA to counteract the pathological process is its effect on the neuronal system, which is the actual target of the pathological process.
None of the above-mentioned references discloses specifically that GA induces neurogenesis in the CNS and no data nor protocol is disclosed for testing GA effect in the induction of neurogenesis in the CNS.
The present invention relates to a method for inducing and enhancing neurogenesis and/or oligodendrogenesis from endogenous as well as from exogenously administered stem cells, which comprises administering to an individual in need thereof an agent selected from the group consisting of Copolymer 1, a Copolymer 1-related polypeptide, a Copolymer 1-related peptide, and activated T cells which have been activated by Copolymer 1, a Copolymer 1-related polypeptide, or a Copolymer 1-related peptide.
The invention further relates to a method of stem cell therapy comprising transplantation of stem cells in combination with a neuroprotective agent to an individual in need thereof, wherein said neuroprotective agent is selected from the group consisting of Copolymer 1, a Copolymer 1-related polypeptide, a Copolymer 1-related peptide, and activated T cells which have been activated by Copolymer 1, a Copolymer 1-related polypeptide, or a Copolymer 1-related peptide.
The invention also relates to the use of a neuroprotective agent selected from the group consisting of Copolymer 1, a Copolymer I-related polypeptide, a Copolymer 1-related peptide, and activated T cells which have been activated by Copolymer 1, a Copolymer 1-related polypeptide, or a Copolymer 1-related peptide, for the preparation of a pharmaceutical composition for inducing and enhancing neurogenesis and/or oligodendrogenesis from endogenous as well as from exogenous stem cells administered to a patient.
In a preferred embodiment, the agent is Copolymer 1 for use in combination with stem cell therapy.
While trying to elucidate the effect of EAE induction on neurogenesis and differentiation towards the neural lineage and to investigate whether peripheral immunomodulatory treatment with GA injection in various stages of disease has any effect on neurogenesis and neuroprotective processes, it was found by some of the inventors that in EAE mice neuroproliferation was elevated following disease appearance, but subsequently declined below that of naive mice. In contrast, GA treatment led to sustained reduction in the neuronal/axonal damage and augmented neuroprogenitor proliferation and mobilization. The newborn neuroprogenitors manifested massive migration through exciting and dormant migration pathways, into injury sites in brain regions, which do not normally undergo neurogenesis, and differentiated to mature neuronal phenotype, endorsing a direct linkage between immunomodulation, neurogenesis and therapeutic consequence in the CNS.
Research during the last decade has disclosed that the brain is potentially capable of cell renewal throughout life, albeit to a limited extent (Morshead et al., 1994). However, the mechanisms that might restrict or favor the renewal of adult neural cells are not known. Recent studies from the laboratory of the present inventors have shown that after an injury to the CNS a local immune response that is properly controlled in time, space, and intensity by the peripheral adaptive immunity is a pivotal requirement for posttraumatic neuronal survival (Moalem et al., 1999; Butovsky et al., 2001; Schwartz et al., 2003; Shaked et al., 2004). We therefore envisaged the possibility that the lack of neurogenesis and the restricted recovery might be attributable to a common factor, which might in turn be related to the local immune response.
The present invention is based on the assumption of some of the inventors that well-regulated adaptive immunity is needed for cell renewal in the brain. It was thus postulated that neurogenesis and oligodendrogenesis are induced and supported by microglia that encounter cytokines associated with adaptive immunity, but are not supported by naïve microglia and are blocked by microglia that encounter endotoxin.
In fact, it is shown herein that certain specifically activated microglia can induce and support neural cell renewal. Thus, both neurogenesis and oligodendrogenesis were induced and supported in NPCs co-cultured with microglia activated by the cytokines IL-4 and IFN-γ, both associated with adaptive immunity. In contrast, microglia exposed to LPS blocked both neurogenesis and oligodendrogenesis, in line with previous reports that MG(LPS) block cell renewal (Monje et al., 2003).
Defense mechanisms in the form of activated microglia are often seen in acute and chronic neurodegenerative conditions, and the CNS is poorly equipped to tolerate them (Dijkstra et al., 1992). As a result, activated microglia have generally been viewed as a uniformly hostile cell population that causes inflammation, interferes with cell survival (Popovich et al., 2002), and blocks cell renewal (Monje et al., 2002, 2003).
Recent studies have shown, however, that the type of activation determines microglial activity, and that just as their effects can be inimical to cell survival in some circumstances, they can be protective in others. Thus, for example, microglia that encountered adaptive immunity (CD4+ T cells) were shown to acquire a protective phenotype (Butovsky et al., 2001). Among the cytokines that are produced by such T cells and can endow microglia with a neuroprotective phenotype are IFN-γ and IL-4, characteristic of Th1 and Th2 cells, respectively. Thus, microglia exposed to activated Th1 cells or to IFN-γ show increased uptake of glutamate, a key player in neurodegenerative disorders (Shaked et al., unpublished observation), while their exposure to IL-4 results in down-regulation of TNF-α, a common player in the destructive microglial phenotype, and up-regulation of insulin-like growth factor (IGF-1) (shown herein in the examples), which promotes differentiation of oligodendrocytes from multipotent adult neural progenitor cells (Hsieh et al., 2004). In addition, IGF-I prevents the acute destructive effect of glutamate-mediated toxicity on oligodendrocytes in vitro (Ness et al., 2002) and inhibits apoptosis of mature oligodendrocytes during primary demyelination (Mason et al., 2000). These and other findings strongly suggest that the outcome of the local immune response (in terms of its effect on the microglia) in the damaged CNS will be either beneficial or harmful, depending on how the microglia interpret the threat.
In general, tissue repair is a process that is well synchronized in time and space, and in which immune activity is needed to clear the site of the lesion and create the conditions for migration, proliferation, and differentiation of progenitor cells for renewal. In light of the well-known fact that constitutive cell renewal is limited in the CNS, as well as the reported observations that treatment with MG(LPS) causes neuronal loss (Boje et al., 1992) and interferes with the homing and differentiation of NPCs (Monje et al., 2003), and that adaptively activated microglia can support neuronal survival, it is not surprising to discover that immune conditions favoring neuronal survival will also support cell renewal. MG(LPS) produce excessive amounts of NO (causing oxidative stress) and TNF-α, as well as other cytotoxic elements, leading to a spiral of worsening neurotoxicity (Boje et al., 1992). NO was found to act as an important negative regulator of cell proliferation and neurogenesis in the adult mammalian brain (Packer et al., 2003), and TNF-α has an inhibitory effect on oligodendrogenesis (Cammer et al., 1999).
The results of the present invention show that MG(LPS) are indeed detrimental to NPC survival and differentiation, but that when microglia are activated by cells or cytokines possessing adaptive immune function, not only are they not cytotoxic but they even exert a positive effect on NPC proliferation, inducing and supporting their differentiation into neurons or oligodendrocytes. In vivo, injection of MG(IL-4) into rat brain lateral ventricles resulted in no neuronal loss, minimal migration of microglia to the CNS parenchyma, and the appearance of new neurons and oligodendrocytes (indicated by the double-staining of BrdU+ cells with markers of neurons or oligodendrocytes). Staining for microglia revealed significant invasion of the healthy CNS by MG(LPS), with consequent massive tissue loss, unlike in the case of MG(IL-4) or MG(−). Interestingly, in the non-injected hippocampus, resident microglia were found adjacent to the subventricular zone. It is tempting to speculate that these might be the cells responsible for controlling neurogenesis, restraining it when in their resting state (as found in the present work using MG(−)), but inducing and supporting it when suitably activated.
Our findings are supported by the observation that in mice with experimental autoimmune encephalomyelitis (EAE), NPCs migrate to sites of CNS damage (Pluchino et al., 2003). They are also in line with the common experience that cell renewal is favored by injury, since they imply that in the absence of injury the conditions that might favor renewal do not exist.
Renewal of cells and their replenishment by new growth is the common procedure for tissue repair in most tissues of the body. It was thought that in the brain those processes do not occur, and therefore that any loss of neurons, being irreplaceable, results in functional deficits that range from minor to devastating. Since an insult to the CNS, whether acute or chronic, is often followed by the postinjury spread of neuronal damage, much research has been devoted to finding ways to minimize this secondary degeneration by rescuing as many neurons as possible.
The results of the present invention lead us to an intriguing conclusion. First, under pathological conditions (when cell renewal is critical), not only do the microglia not favor cell renewal, but they interfere with it. Secondly, this paradoxical situation can be remedied by well-controlled adaptive immunity, which shapes the microglia in such a way that their activity is not cytotoxic but is both protective and conducive to renewal. This indicates that in those cases in which protective autoimmunity leads to improved recovery, both neurogenesis and gliogenesis are likely to occur. These data can also explain the lack of cell renewal in autoimmune diseases; in such cases, it is likely that the quantity of circulating autoimmune T cells exceeds the threshold above which TNF-α production, due to an excess of IFN-γ, does not allow the microglia to acquire a protective phenotype. They can also explain why steroids are not helpful, as their anti-inflammatory activity masks not only the destructive but also the beneficial adaptive immunity. The therapy of choice for both autoimmune diseases and neurodegenerative conditions would therefore appear to be immunomodulation in which, after the acute phase of disease, the surviving tissue can be maintained by relatively small quantities of T cells.
The findings of the present invention indicate that the limitation of spontaneous, endogenous neurogenesis and oligodendrogenesis in the adult brain is, at least in part, an outcome of the local immune activity, and that harnessing of adaptive immunity rather than immunosuppression is the path to choose in designing ways to promote cell renewal in the CNS.
Cell renewal in the adult mammalian CNS is limited. Recent studies suggest that it is arrested by inflammation. That view is challenged by the findings of the present invention that microglia, depending on environmental stimulation, can either induce and support or block such renewal. In vitro, neurogenesis and oligodendrogenesis from neural progenitor cells were shown herein to be promoted by mouse microglia that encountered T-cell-associated cytokines (IFN-γ, IL-4), but were blocked by microglia that encountered endotoxin. Anti-IGF-1 antibodies neutralized the IL-4 effect, while anti-TNF-α antibodies augmented the effect of IFN-γ. Injection of IL-4-activated microglia into cerebral ventricles of adult rats induced significant hippocampal neurogenesis and cortical oligodendrogenesis, whereas endotoxin-activated microglia caused neuronal loss and blocked neurogenesis and oligodendrogenesis. These results strengthen our assumption that controlled adaptive immunity, unlike uncontrolled (e.g. endotoxin-induced) inflammation, activates microglia to induce and support neuronal and oligodendrocyte survival and renewal. Thus, to promote cell renewal in the CNS, well-controlled immunity is needed and should not be suppressed.
It has been reported that the controlled activity of T cells directed to auto-antigens in the CNS is needed for postinjury survival and repair (Moalem et al., 1999; Yoles et al., 2001; Kipnis et al., 2002). These results led us to suspect that a fundamental role of autoimmune T cells, known to be present in healthy individuals, is to help maintain the integrity of the CNS, and that their remedial effect in a neurodegenerative environment is a manifestation of the same restorative role under extreme conditions. Moreover, accumulating evidence attesting to the participation of such autoimmune T cells in postinjury neuronal survival led us to postulate that if they have a similar role in the healthy CNS, it might well have to do with neurogenesis in adult life, possibly by maintaining the conditions needed for such cell renewal.
According to the present invention, we examined how the nature of microglial activation affects neurogenesis in the adult rat hippocampus under physiological and pathological conditions associated with brain inflammation. Transient inflammatory conditions associated with transient accumulation of myelin-specific Th1 cells promoted neurogenesis. Injection of microglia (MG) activated by IFN-γ (MG(IFN-γ)) or by IL-4 (MG(IL-4)) into the lateral ventricles of the brains of healthy rats promoted neurogenesis. In rats that developed monophasic (transient) EAE, the induced neurogenesis was further promoted by MG(IL-4). Our results in vitro showed that MG(IFN-γ) supported neurogenesis from adult rat NPCs as long as the IFN-γ concentration was low. The impediment to neurogenesis imposed by high-dose IFN-γ could be counteracted by IL-4. Neurogenesis induced by IL-4 was weaker, however, than that induced by low-dose IFN-γ or by high-dose IFN-γ administered in combination with IL-4.
We, have identified herein cellular elements in the CNS that can respond to local environmental changes and needs, and consequently can support the formation of new cells from adult aNPCs. We demonstrated that once the microglia become suitably activated by circulating T cell-derived cytokines, they can induce neuronal and oligodendroglial differentiation from aNPCs. In view of that observation, and our previous demonstration in rodents that a T cell-based vaccination promotes recovery from contusive spinal cord injury (SCI), we postulated that translation of those findings into a therapeutic approach might benefit the repair process by creating a niche-like neurogenic/gliogenic environment at the injured site. Thus, we expected to find that supplementing the vaccination by transplantation of homologous aNPCs would further promote functional recovery after SCI. In the present invention we in fact demonstrated, using a mouse model, synergistic interaction between T cell-based immune activation and transplanted aNPCs in promoting functional motor recovery after contusive injury of the spinal cord.
Previous studies by the inventor M. Schwartz have shown that systemic manipulations of the immune system, based on increasing the numbers of T cells directed to weak agonists of autoantigens, beneficially affect neurodegenerative conditions by promoting neuronal survival (Moslem et al., 1999; Hauben et al., 2001; Schwartz and Kipnis, 2002). The same manipulations, for example, T cell-based vaccination, is proposed here for increasing neurogenesis, yielding novel ways to maintain the integrity of the aging brain and the diseased mind.
It thus seems that maintenance and repair of brain cells necessitate a dialog between CNS-autoreactive T cells and brain-resident microglia. This dialog cannot take place, however, unless the microglia are able to act as APCs, presenting the relevant antigens to the homing T cells. We therefore postulated that in order to halt the progression of Alzheimer disease (AD), T cells that recognize CNS-specific antigens other than aggregated amyloid-β (Aβ) must target sites of aggregated Aβ plaques in the brain. On reaching these sites they become activated by the encounter with their specific antigens, presented to them by microglia acting as APCs. Such activation enables these T cells to offset the negative effect of aggregated Aβ on locally resident microglia, thus preventing the latter from becoming cytotoxic to neurons and blocking neurogenesis. We tested this hypothesis by vaccinating AD mice with glatiramer acetate (GA, also known as copolymer 1 or Cop-1), a synthetic copolymer approved by the FDA for treatment of multiple sclerosis, and capable of weakly cross-reacting with a wide range of CNS-resident autoantigens (Kipnis et al., 2000). GA-activated T cells, after infiltrating the CNS, have the potential to become locally activated without risk of the overwhelming proliferation that is likely to cause an autoimmune disease. Studies by the present inventors and others have shown that GA can simulate the protective and reparative effects of autoreactive T cells (Kipnis et al., 2000; Benner et al., 2004).
In the present invention, APP/PS1 double-transgenic AD mice (which coexpress mutated human presenilin 1 and amyloid-β precursor protein) suffering from decline in cognition and accumulation of Aβ plaques, a T cell-based vaccination, by altering the microglial phenotype, ameliorated cognitive performance, reduced plaque formation, rescued cortical and hippocampal neurons, and induced hippocampal neurogenesis.
We show here that vaccination of Tg mice with GA reduced plaque formation, and prevented and even partially reversed cognitive decline, even if the vaccination was given after some loss of cognition and some plaque formation had already occurred. It should be noted that vaccination with GA was effective not only in preventing disease progression but also—when administered after onset of the clinical symptoms of learning/memory loss and pathological appearance of plaques—in promoting tissue repair. The above findings are in line with our observation that in mice deficient in CNS-autoreactive T cells the expression of brain-derived neurotrophic factor (BDNF), known to be associated with both cognitive activity and cell renewal, is impaired. They are also in accord with our observation that T cells are needed for the maintenance of cognitive functioning in the healthy as well as in the diseased brain (Kipnis et al., 2004). Since aggregated Aβ evidently interferes with the ability of microglia to engage in dialog with T cells, its presence in the brain can be expected to cause loss of cognitive ability and impairment of neurogenesis. Homing of CNS-autoreactive T cells to the site of disease or damage in such cases is critical, but will be effective only if those T cells can counterbalance the destructive activity of the aggregated Aβ. Myelin-presenting microglia, with which myelin-specific T cells can readily hold a dialog, are likely to be present in abundance. Myelin-related antigens, or antigens (such as GA) that are weakly cross-reactive with myelin, are therefore likely to be the antigens of choice for the therapeutic vaccination. Myelin-specific T cells will then home to the CNS and, upon encountering their relevant APCs there, will become locally activated to supply the cytokines and growth factors needed for appropriate modulation of harmful microglia like those activated by aggregated A13. The resulting synapse between T cells and microglia will create a supportive niche for cell renewal by promoting neurogenesis from the pool of adult stem cells, thereby overcoming the age-related impairment induced in the inflammatory brain.
The known features of glatiramer acetate (GA, Copolymer 1) are also of essence in relation to stem cell transplantation for the treatment of neurological and other disorders. It is therefore proposed to use GA to improve the therapeutic outcome of stem cell transplantation for various disorders including neurological diseases, especially MS. The rationale for GA usage is for this purpose is based on previous results of the inventors R. Aharoni and R. Arnon concerning its mechanism of action as well on their findings of its efficacy in reducing graft and bone marrow rejection and self-neurogenerating effects. It is thus envisioned that GA will be effective not only in augmenting endogenous neurogenesis of self-neuroprogenitor cells but also exogenous neurogenesis of transplanted multipotent (stem) progenitor cells. These manifestations of GA function taken together with its very high safety profile, support its application in combination therapy for the improvement of progenitor stem cell transplantation for many clinical applications, in addition to those specifically related to neurological disorders.
The present invention thus relates, in one aspect, to a method for inducing and enhancing neurogenesis and/or oligodendrogenesis from endogenous as well as from exogenously administered stem cells, which comprises administering to an individual in need thereof an agent selected from the group consisting of Copolymer 1, a Copolymer 1-related polypeptide, a Copolymer 1-related peptide, and activated T cells which have been activated by Copolymer 1, a Copolymer 1-related polypeptide, or a Copolymer 1-related peptide.
The method of the invention further includes proliferation, differentiation and survival of newly formed neurons or oligodendrocytes, and includes neuronal progenitor proliferation, neuronal migration, and/or neuronal differentiation of newly formed neurons into mature neurons.
In one embodiment, the present invention relates to a method for inducing and enhancing neurogenesis from endogenous or exogenously applied stem cells. In another embodiment, the method is for inducing and augmenting self-neurogenesis in damaged or injured brain regions, both in brain regions that normally undergo neurogenesis and in brain regions that normally do not undergo neurogenesis such as striatum, nucleus accumbens and/or cortex.
In another embodiment, the invention relates to a method for inducing and augmenting self-neurogenesis including neuronal progenitor proliferation, neuronal migration, and/or neuronal differentiation of newly formed neurons into mature neurons, in the central nervous system (CNS), which comprises administering to an individual in need an agent selected from the group consisting of Copolymer 1, a Copolymer 1-related polypeptide and a Copolymer 1-related peptide.
In another embodiment, the invention relates to a method for inducing and enhancing oligodendrogenesis from endogenous or exogenously applied stem cells.
In another embodiment, the present invention relates to a method for inducing and enhancing oligodendrogenesis from endogenous or exogenously applied stem cells, by immune modulation, which comprises administering to an individual in need a neuroprotective agent selected from the group consisting of Copolymer 1, a Copolymer 1-related polypeptide, a Copolymer 1-related peptide, and activated T cells which have been activated by Copolymer 1, a Copolymer 1-related polypeptide, or a Copolymer 1-related peptide.
In another embodiment, the agent for use in the invention are T cells which have been activated by Copolymer 1, a Copolymer 1-related polypeptide, or a Copolymer 1-related peptide. The T cells can be endogenous and activated in vivo by administration of the antigen or peptide, thereby producing a population of T cells that accumulate at a site of injury or disease of the CNS or PNS, or the T cells are prepared from T lymphocytes isolated from the blood and then sensitized to the antigen. The T cells are preferably autologous, most preferably of the CD4 and/or CD8 phenotypes, but they may also be allogeneic T cells from related donors, e.g., siblings, parents, children, or HLA-matched or partially matched, semi-allogeneic or hilly allogeneic donors. Methods for the preparation of said T cells are described in the above-mentioned WO 99/60021.
The methods of the invention are useful for inducing and enhancing neurogenesis and/or oligodendrogenesis both from endogenous and exogenously administered stem cells and may assist in solving the problems found today with the poor results of stem cell transplantation, particularly in the cases of injuries, diseases, disorders and conditions of the nervous system, both the CNS and PNS.
In one embodiment, the method of the invention is applied to induce and enhance neurogenesis and/or oligodendrogenesis from endogenous pools of neural stem/progenitor cells. Thus, Copolymer 1, a Copolymer 1-related polypeptide, a Copolymer 1-related peptide, and T cells activated therewith will by themselves boost endogenous neurogenesis and oligodendrogenesis in damaged tissues, supporting also the survival of the new neurons and oligodendrocytes.
In another embodiment, the method of the invention is applied to induce and enhance neurogenesis and/or oligodendrogenesis from both endogenous and exogenous stem cells administered to the patient. The administration of said neuroprotective agent will assist to enhance the successful engraftment of the implanted stem cells, cell renewal and differentiation of the stem cells into neurons and/or oligodendrocytes, while at the same time inducing the endogenous neurogenesis and oligodendrogenesis in the damaged tissues and supporting the survival of the new neurons and oligodendrocytes.
Thus, in another aspect, the present invention provides a method of stem cell therapy comprising transplantation of stem cells in combination with a neuroprotective agent to an individual in need thereof, wherein said neuroprotective agent is selected from the group consisting of Copolymer 1, a Copolymer 1-related polypeptide, a Copolymer I-related peptide, and activated T cells which have been activated by Copolymer 1, a Copolymer 1-related polypeptide, or a Copolymer 1-related peptide.
In one embodiment, the methods of the invention are applied to individuals suffering from an injury, disease, disorder or condition of the central nervous system (CNS) or peripheral nervous system (PNS).
The CNS or PNS njury to be treated according to the methods of the invention, preferably by stem cell therapy, include spinal cord injury, closed head injury, blunt trauma, penetrating trauma, hemorrhagic stroke, ischemic stroke, cerebral ischemia, optic nerve injury, myocardial infarction or injury caused by tumor excision. The transplanted stem cells will migrate to the region of the injury where cells had died (for example, due to ischaemia) and will differentiate into neurons and/or oligodendrocytes.
The CNS or PNS diseases, disorders or conditions to be treated according to the methods of the invention, preferably by stem cell therapy, include Parkinson's disease and Parkinsonian disorders, Huntington's disease, Alzheimer's disease, multiple sclerosis, or amyotrophic lateral sclerosis (ALS). Other diseases, disorders or conditions include facial nerve (Bell's) palsy, glaucoma, Alper's disease, Batten disease, Cockayne syndrome, Guillain-Barré syndrome, Lewy body disease, Creutzfeldt-Jakob disease, or a peripheral neuropathy such as a mononeuropathy or polyneuropathy selected from the group consisting of adrenomyeloneuropathy, alcoholic neuropathy, amyloid neuropathy or polyneuropathy, axonal neuropathy, chronic sensory ataxic neuropathy associated with Sjogren's syndrome, diabetic neuropathy, an entrapment neuropathy nerve compression syndrome, carpal tunnel syndrome, a nerve root compression that may follow cervical or lumbar intervertebral disc herniation, giant axonal neuropathy, hepatic neuropathy, ischemic neuropathy, nutritional polyneuropathy due to vitamin deficiency, malabsorption syndromes or alcoholism, porphyric polyneuropathy, a toxic neuropathy caused by organophosphates, uremic polyneuropathy, a neuropathy associated with a disease or disorder selected from the group consisting of acromegaly, ataxia telangiectasia, Charcot-Marie-Tooth disease, chronic obstructive pulmonary diseases, Fabry's disease, Friedreich ataxia, Guillain-Barré syndrome, hypoglycemia, IgG or IgA monoclonal gammopathy (non-malignant or associated with multiple myeloma or with osteosclerotic myeloma), lipoproteinemia, polycythemia vera, Refsum's syndrome, Reye's syndrome, and Sjogren-Larsson syndrome, a polyneuropathy associated with various drugs, with hypoglycemia, with infections such as HIV infection, or with cancer; epilepsy, amnesia, anxiety, hyperalgesia, psychosis, seizures, oxidative stress, opiate tolerance and dependence, and for the treatment of a psychosis or psychiatric disorder selected from the group consisting of an anxiety disorder, a mood disorder, schizophrenia or a schizophrenia-related disorder, drug use and dependence and withdrawal, and a memory loss or cognitive disorder.
In another embodiment, the method of cell therapy of the present invention is applied to injuries, diseases, disorders or conditions unrelated to the nervous system. In one preferred embodiment, the method is suitable for bone marrow-derived stem cell transplantation for treatment of an injury, disease, disorder or condition selected from diabetes, failure of tissue repair, myocardial infarction, kidney failure, liver cirrhosis, muscular dystrophy, skin burn, leukemia, arthritis injury, or osteoporosis injury.
The stem cells for use in the methods of the invention include, but are not limited to, adult stem cells, embryonic stem cells, umbilical cord blood stem cells, hematopoietic stem cells, peripheral blood stem cells, mesenchimal stem cells, multipotent stem cells, neural stem cells, neural progenitor cells, stromal stem cells, progenitor cells, or precursors thereof, and genetically-engineered stem cells, and any other stem cells that may be found suitable for the purpose of the present invention. Examples of such cells include the CNS neural stems cells disclosed in U.S. Pat. No. 6,777,233 and U.S. Pat. No. 6,680,198; the neural stern cells and hematopoietic cells disclosed in U.S. Pat. No. 6,749,850 for administration with neural stimulants; and the stromal cells disclosed in U.S. Pat. No. 6,653,134 for treatment of CNS diseases.
As used herein, the term “neural stem cell” is used to describe a single cell derived from tissue of the central nervous system, or the developing nervous system, that can give rise in vitro and/or in vivo to at least one of the following fundamental neural lineages: neurons (of multiple types), oligodendroglia and astroglia as well as new neural stem cells with similar potential. “Multipotent” or “pluripotent” neural stem cells are capable of giving rise to all of the above neural lineages as well as cells of equivalent developmental potential.
In a more preferred embodiment, the neural stem cells are human neural stem cells that can be isolated from both the developing and adult CNS, and can be successfully grown in culture, are self-renewable, and can generate mature neuronal and glial progeny. Embryonic human neural stem cells can be induced to differentiate into specific neuronal phenotypes. Human neural stem cells integrate into the host environment after transplantation into the developing or adult CNS. Human neural stem cells transplanted into animal models of Parkinson's disease and spinal cord injury have induced functional recovery. However, there are still problems with the engraftment of said cells and the present invention will enhance the successful engraftment, survival and further differentiation of the implanted cells. In a most preferred embodiment, the neural stem cells are autologous.
As used herein, the term “hematopoietic stem cells” refer to stem cells that can give rise to cells of at least one of the major hematopoietic lineages in addition to producing daughter cells of equivalent potential. Certain hematopoietic stem cells are capable of giving rise to many other cell types including brain cells.
The stem cells, once isolated, are cultured by methods known in the art, for example as described in U.S. Pat. No. 5,958,767, U.S. Pat. No. 5,270,191, U.S. Pat. No. 5,753,506, all of these patents being herewith incorporated by reference as if fully disclosed herein.
The treatment regimen according to the invention is carried out, in terms of administration mode, timing of the administration, and dosage, depending on the type and severity of the injury, disease or disorder and the age and condition of the patient. The immunomodulator may be administered concomitanly with, before or after the injection or implantation of the cells.
The administration of the cells may be carried out by various methods. In certain embodiments, the cells are preferably administered directly into the stroke cavity, the spinal fluid, e.g., intraventricularly, intrathecally, or intracisternally. The stem cells can be formulated in a pharmaceutically acceptable liquid medium, which can contain the Copolymer 1 or the T cells as well. Cells may also be injected into the region of the brain surrounding the areas of damage, and cells may be given systemically, given the ability of certain stern cells to migrate to the appropriate position in the brain.
In one preferred embodiment, the method of the invention comprises stem cell therapy by administration of stem cells in combination with Copolymer 1. In one embodiment, the stem cells are injected/transplanted to the patient, followed by vaccination with Copolymer 1. In another embodiment, a combination of the stem cells with the Copolymer 1 is injected/transplanted to the patient. In a further embodiment, the stem cells can be cultured in vitro (artificially) with the Copolymer 1 and differentiated prior to transplantation
As used herein in the application, the terms “Cop 1”, “Copolymer 1”, “glatiramer acetate” and “GA” are used interchangeably.
For the purpose of the present invention, “Copolymer 1 or a Copolymer 1-related peptide or polypeptide” is intended to include any peptide or polypeptide, including a random copolymer that cross-reacts functionally with MBP and is able to compete with MBP on the MHC class II in the antigen presentation.
The composition for use in the invention may comprise as active agent a Cop 1 or a Cop 1-related peptide or polypeptide represented by a random copolymer consisting of a suitable ratio of a positively charged amino acid such as lysine or arginine, in combination with a negatively charged amino acid (preferably in a lesser quantity) such as glutamic acid or aspartic acid, optionally in combination with a non-charged neutral amino acid such as alanine or glycine, serving as a filler, and optionally with an amino acid adapted to confer on the copolymer immunogenic properties, such as an aromatic amino acid like tyrosine or tryptophan. Such compositions may include any of those copolymers disclosed in WO 00/05250, the entire contents of which are herewith incorporated herein by reference.
More specifically, the composition for use in the present invention comprises at least one copolymer selected from the group consisting of random copolymers comprising one amino acid selected from each of at least three of the following groups: (a) lysine and arginine; (b) glutamic acid and aspartic acid; (c) alanine and glycine; and (d) tyrosine and tryptophan.
The copolymers for use in the present invention can be composed of or D-amino acids or mixtures thereof. As is known by those of skill in the art, L-amino acids occur in most natural proteins. However, D-am no acids are commercially available and can be substituted for some or all of the amino acids used to make the copolymers used in the present invention. The present invention contemplates the use of copolymers containing both D- and L-amino acids, as well as copolymers consisting essentially of either L- or D-amino acids.
In one embodiment of the invention, the copolymer contains four different amino acids, each from a different one of the groups (a) to (d).
In a more preferred embodiment, the pharmaceutical composition or vaccine of the invention comprises Copolymer 1, a mixture of random polypeptides consisting essentially of the amino acids L-glutamic acid (E), L-alanine (A), L-tyrosine (Y) and L-lysine (K) in an approximate ratio of 1.5:4.8:1:3.6, having a net overall positive electrical charge and of a molecular weight from about 2 KDa to about 40 KDa.
In one preferred embodiment, the Cop 1 has average molecular weight of about 2 KDa to about 20 KDa, more preferably of about 4.7 KDa to about 13 K Da, still more preferably of about 4 KDa to about 8.6 KDa, of about 5 KDa to 9 KDa, or of about 6.25 KDa to 8.4 KDa. In another preferred embodiment, the Cop 1 has average molecular weight of about 13 KDa to about 20 KDa, more preferably of about 13.5 KDa to about 18 KDa, with an average of about 15 KDa to about 16 KD, preferably of 16 kDa. Other average molecular weights for Cop 1, lower than 40 KDa, are also encompassed by the present invention. Copolymer 1 of said molecular weight ranges can be prepared by methods known in the art, for example by the processes described in U.S. Pat. No. 5,800,808, the entire contents of which are hereby incorporated by reference in the entirety. The Copolymer 1 may be a polypeptide comprising from about 5 to about 100, preferably from about 40 to about 80, amino acids in length.
In one preferred embodiment of the invention, the agent is Cop 1 in the form of its acetate salt known under the generic name glatiramer acetate or its trade name Copaxone® (a trademark of Teva Pharmaceutical Industries Ltd., Petach Tikva, Israel).
The activity of Copolymer 1 for the composition disclosed herein is expected to remain if one or more of the following substitutions is made: aspartic acid for glutamic acid, glycine for alanine, arginine for lysine, and tryptophan for tyrosine.
In another embodiment of the invention, the Cop 1-related peptide or polypeptide is a copolymer of three different amino acids each from a different one of three groups of the groups (a) to (d). These copolymers are herein referred to as terpolymers.
In one embodiment, the Cop 1-related peptide or polypeptide is a terpolymer containing tyrosine, alanine, and lysine, hereinafter designated YAK, in which the average molar fraction of the amino acids can vary: tyrosine can be present in a mole fraction of about 0.05-0.250; alanine in a mole fraction of about 0.3-0.6; and lysine in a mole fraction of about 0.1-0.5. More preferably, the molar ratios of tyrosine, alanine and lysine are about 0.10:0.54:0.35, respectively. It is possible to substitute arginine for lysine, glycine for alanine, and/or tryptophan for tyrosine.
In another embodiment, the Cop 1-related peptide or polypeptide is a terpolymer containing tyrosine, glutamic acid, and lysine, hereinafter designated YEK, in which the average molar fraction of the amino acids can vary: glutamic acid can be present in a mole fraction of about 0.005-0.300, tyrosine can be present in a mole fraction of about 0.005-0.250, and lysine can be present in a mole fraction of about 0.3-0.7. More preferably, the molar ratios of glutamic acid, tyrosine, and lysine are about 0.26:0.16:0.58, respectively. It is possible to substitute aspartic acid for glutamic acid, arginine for lysine, and/or tryptophan for tyrosine.
In another preferred embodiment, the Cop 1-related peptide or polypeptide is a terpolymer containing lysine, glutamic acid, and alanine, hereinafter designated KEA, in which the average molar fraction of the amino acids can vary: glutamic acid can be present in a mole fraction of about 0.005-0.300, alanine in a mole fraction of about 0.005-0.600, and lysine can be present in a mole fraction of about 0.2-0.7. More preferably, the molar ratios of glutamic acid, alanine and lysine are about 0.15:0.48:0.36, respectively. It is possible to substitute aspartic acid for glutamic acid, glycine for alanine, and/or arginine for lysine.
In a preferred embodiment, the Cop 1-related peptide or polypeptide is a terpolymer containing tyrosine, glutamic acid, and alanine, hereinafter designated YEA, in which the average molar fraction of the amino acids can vary: tyrosine can be present in a mole fraction of about 0.005-0.250, glutamic acid in a mole fraction of about 0.005-0.300, and alanine in a mole fraction of about 0.005-0.800. More preferably, the molar ratios of glutamic acid, alanine, and tyrosine are about 0.21:0.65:0.14, respectively. It is possible to substitute tryptophan for tyrosine, aspartic acid for glutamic acid, and/or glycine for alanine.
The average molecular weight of the terpolymers YAK, YEK, KEA and YEA can vary between about 2 KDa to 40 KDa, preferably between about 3 KDa to 35 KDa, more preferably between about 5 KDa to 25 KDa.
Copolymer 1 and related peptides and polypeptides may be prepared by methods known in the art, for example, under condensation conditions using the desired molar ratio of amino acids in solution, or by solid phase synthetic procedures. Condensation conditions include the proper temperature, pH, and solvent conditions for condensing the carboxyl group of one amino acid with the amino group of another amino acid to form a peptide bond. Condensing agents, for example dicyclohexylcarbodiimide, can be used to facilitate the formation of the peptide bond. Blocking groups can be used to protect functional groups, such as the side chain moieties and some of the amino or carboxyl groups against undesired side reactions.
For example, the copolymers can be prepared by the process disclosed in U.S. Pat. No. 3,849,550, wherein the N-carboxyanhydrides of tyrosine, alanine, γ-benzyl glutamate and N ε-trifluoroacetyl-lysine are polymerized at ambient temperatures (20° C.-26° C.) in anhydrous dioxane with diethylamine as an initiator. The γ-carboxyl group of the glutamic acid can be deblocked by hydrogen bromide in glacial acetic acid. The trifluoroacetyl groups are removed from lysine by 1M piperidine. One of skill in the art readily understands that the process can be adjusted to make peptides and polypeptides containing the desired amino acids, that is, three of the four amino acids in Copolymer 1, by selectively eliminating the reactions that relate to any one of glutamic acid, alanine, tyrosine, or lysine.
The molecular weight of the copolymers can be adjusted during polypeptide synthesis or after the copolymers have been made. To adjust the molecular weight during polypeptide synthesis, the synthetic conditions or the amounts of amino acids are adjusted so that synthesis stops when the polypeptide reaches the approximate length that is desired. After synthesis, polypeptides with the desired molecular weight can be obtained by any available size selection procedure, such as chromatography of the polypeptides on a molecular weight sizing column or gel, and collection of the molecular weight ranges desired. The copolymers can also be partially hydrolyzed to remove high molecular weight species, for example, by acid or enzymatic hydrolysis, and then purified to remove the acid or enzymes.
In one embodiment, the copolymers with a desired molecular weight may be prepared by a process, which includes reacting a protected polypeptide with hydrobromic acid to form a trifluoroacetyl-polypeptide having the desired molecular weight profile. The reaction is performed for a time and at a temperature that is predetermined by one or more test reactions. During the test reaction, the time and temperature are varied and the molecular weight range of a given batch of test polypeptides is determined. The test conditions that provide the optimal molecular weight range for that batch of polypeptides are used for the batch. Thus, a trifluoroacetyl-polypeptide having the desired molecular weight profile can be produced by a process, which includes reacting the protected polypeptide with hydrobromic acid for a time and at a temperature predetermined by test reaction. The trifluoroacetyl-polypeptide with the desired molecular weight profile is then further treated with an aqueous piperidine solution to form a low toxicity polypeptide having the desired molecular weight.
In a preferred embodiment, a test sample of protected polypeptide from a given batch is reacted with hydrobromic acid for about 10-50 hours at a temperature of about 20-28° C. The best conditions for that batch are determined by running several test reactions. For example, in one embodiment, the protected polypeptide is reacted with hydrobromic acid for about 17 hours at a temperature of about 26° C.
As binding motifs of Cop 1 to MS-associated HLA-DR molecules are known (Fridkis-Hareli et al, 1999), polypeptides derived from Cop 1 having a defined sequence can readily be prepared and tested for binding to the peptide binding groove of the HLA-DR molecules as described in the Fridkis-Hareli et al (1999) publication. Examples of such peptides are those disclosed in WO 00/05249 and WO 00/05250, the entire contents of which are hereby incorporated herein by reference, and include the peptides of SEQ ID NOs. 1-32 hereinbelow.
Such peptides and other similar peptides derived from Cop 1 would be expected to have similar activity as Cop 1. Such peptides, and other similar peptides, are also considered to be within the definition of Cop 1-related peptides or polypeptides and their use is considered to be part of the present invention.
The definition of “Cop 1-related peptide or polypeptide” according to the invention is meant to encompass other synthetic amino acid copolymers such as the random four-amino acid copolymers described by Fridkis-Hareli et al., 2002 (as candidates for treatment of multiple sclerosis), namely copolymers (14-, 35- and 50-mers) containing the amino acids phenylalanine, glutamic acid, alanine and lysine (poly FEAK), or tyrosine, phenylalanine, alanine and lysine (poly YFAK), and any other similar copolymer to be discovered that can be considered a universal antigen similar to Cop 1.
The dosage of Cop 1 to be administered will be determined by the physician according to the age of the patient and stage of the disease and may be chosen from a range of 1-80 mg, preferably 20 mg, although any other suitable dosage is encompassed by the invention. The treatment should be preferably carried out by administration of repeated doses at suitable time intervals, according to the neurodegenerative disease to be treated, the age and condition of the patient. In one embodiment, Cop 1 may be administered daily. In another embodiment, the administration may be made according to a regimen suitable for immunization, for example, at least once a month or at least once every 2 or 3 months, or less frequently, but any other suitable interval between the immunizations envisaged by the invention according to the condition of the patient.
Pharmaceutical compositions for use in accordance with the present invention may be formulated in conventional manner using one or more physiologically acceptable carriers or excipients. The carrier(s) must be “acceptable” in the sense of being compatible with the other ingredients of the composition and not deleterious to the recipient thereof.
Methods of administration include, but are not limited to, parenteral, e.g., intravenous, intraperitoneal, intramuscular, subcutaneous, mucosal (e.g., oral, intranasal, buccal, vaginal, rectal, intraocular), intrathecal, topical and intradermal routes, with or without adjuvant. Administration can be systemic or local.
The invention will now be illustrated by the following non-limiting examples.
(i) Animals. Tneonatal (P0-P1) C57Bl/6J mice were supplied by the Animal Breeding Center of the Weizmann Institute of Science (Rehovot, Israel). All animals were handled according to the regulations formulated by the Weizmann Institute's Animal Care and Use Committee.
(ii) Reagents. Lipopolysaccharide (LPS) (containing <1% contaminating proteins) was obtained from Escherichia coli 0127:B8 (Sigma-Aldrich, St. Louis, Mo.). Recombinant mouse tumor necrosis factor (TNF)-α and insulin-like growth factor (IGF)-I (both containing endotoxin at a concentration below 1 EU per μg of cytokine), recombinant rat and mouse interferon (IFN)-γ and interleukin (IL)-4 (both containing endotoxin at a concentration below 0.1 ng per μg of cytokine), goat anti-mouse neutralizing anti-TNF-α antibodies (ãTNF-α; containing endotoxin at a concentration below 0.001 EU per μg of Ab), and goat anti-mouse neutralizing anti-IGF-I (ãIGF-I; containing endotoxin at a concentration below 0.1 EU per μg of Ab) were obtained from R&D Systems (Minneapolis, Minn.).
(iii) Neural progenitor cell (NPC) culture. Coronal sections (2 mm thick) of tissue containing the subventricular zone of the lateral ventricle were obtained from the brains of adult C57Bl6/J mice. The tissue was minced and then incubated for digestion at 37° C., 5% CO2 for 45 min in Earle's balanced salt solution containing 0.94 mg/ml papain (Worthington, Lakewood, N.J.) and 0.18 mg/ml of L-cysteine and EDTA. After centrifugation at 110×g for 15 min at room temperature, the tissue was mechanically dissociated by pipette trituration. Cells obtained from single-cell suspensions were plated (3500 cells/cm2) in 75-cm2 Falcon tissue-culture flasks (BD Biosciences, Franklin Lakes, N.J.), in NPC-culturing medium [Dulbecco's modified Eagles's medium (DMEM)/F12 medium (Gibco/Invitrogen, Carlsbad, Calif.) containing 2 mM L-glutamine, 0.6% glucose, 9.6 μg/ml putrescine, 6.3 ng/ml progesterone, 5.2 ng/ml sodium selenite, 0.02 mg/ml insulin, 0.1 mg/ml transferrin, 2 μg/ml heparin (all from Sigma-Aldrich, Rehovot, Israel), fibroblast growth factor-2 (human recombinant, 20 ng/ml), and epidermal growth factor (human recombinant, 20 ng/ml; both from Peprotech, Rocky Hill, N.J.)]. Spheres were passaged every 4-6 days and replated as single cells. Green fluorescent protein (GFP)-expressing neural progenitor cells (NPCs) were obtained as previously described (Pluchino et al., 2003).
(iv) Primary microglial culture. Brains from neonatal (P0-P1) C57Bl/6J mice were stripped of their meninges and minced with scissors under a dissecting microscope (Zeiss, Stemi DV4, Germany) in Leibovitz-15 medium (Biological Industries, Beit Ha-Emek, Israel). After trypsinization (0.5% trypsin, 10 min, 37° C./5% CO2), the tissue was triturated. The cell suspension was washed in culture medium for glial cells [DMEM supplemented with 10% fetal calf serum (FCS; Sigma-Aldrich, Rehovot), L-glutamine (1 mM), sodium pyruvate (1 mM), penicillin (100 U/ml), and streptomycin (100 mg/ml)] and cultured at 37° C./5% CO2 in 75-cm2 Falcon tissue-culture flasks (BD Biosciences) coated with poly-D-lysine (PDL) (10 mg/ml; Sigma-Aldrich, Rehovot) in borate buffer (2.37 g borax and 1.55 g boric acid dissolved in 500 ml sterile water, pH 8.4) for 1 h, then rinsed thoroughly with sterile, glass-distilled water. Half of the medium was changed after 6 h in culture and every 2nd day thereafter, starting on day 2, for a total culture time of 10-14 days. Microglia were shaken off the primary mixed brain glial cell cultures (150 rpm, 37° C., 6 h) with maximum yields between days 10 and 14, seeded (105 cells/ml) onto PDL-pretreated 24-well plates (1 ml/well; Corning, Corning, N.Y.), and grown in culture medium for microglia [RPMI-1640 medium (Sigma-Aldrich, Rehovot) supplemented with 10% FCS, L-glutamine (1 mM), sodium pyruvate (1 mM), β-mercaptoethanol (50 mM), penicillin (100 U/ml), and streptomycin (100 mg/ml)]. The cells were allowed to adhere to the surface of a PDL-coated culture flask (1 h, 37° C./5% CO2), and non-adherent cells were rinsed off.
(v) Co-culturing of neural progenitor cells (NPCs) and mouse microglia. Microglia were treated for 24 h with cytokines (IFN-γ, 20 ng/ml; IL-4, 10 ng/ml) or LPS (100 ng/ml). Cultures of treated or untreated microglia were washed twice with fresh NPC-differentiation medium (same as the culture medium for NPCs but without growth factors and with 2.5% FCS) to remove all traces of the tested reagents, then incubated on ice for 15 min, and shaken at 350 rpm for 20 mM at room temperature. Microglia were removed from the flasks and immediately co-cultured (5×104 cells/well) with NPCs (5×104 cells/well) for 5 or 10 days on cover slips coated with Matrigel (BD Biosciences) in 24-well plates, in the presence of NPC differentiation medium, with or without insulin. The cultures were then fixed with 2.5% paraformaldehyde in PBS for 30 min at room temperature and stained for neuronal and glial markers. Cell proliferation rates and cell survival in vitro were determined by staining with 5-bromo-2′-deoxyuridine (BrdU, 2.5 μM; Sigma-Aldrich, St. Louis). For quantification of live and dead cells, live cultures were stained with 1 μg/ml propidium iodide (Molecular Probes, Invitrogen, Carlsbad, Calif.) and 1 μg/ml Hoechst 33342 (Sigma-Aldrich, St. Louis), and cells were counted using Image-Pro (Media Cybernetics, Silver Spring, Md.), as described (Hsieh et al., 2004)
(vi) Immunocytochemistry. Cover slips from co-cultures of NPCs and mouse microglia were washed with PBS, fixed as described above, treated with a permeabilization/blocking solution containing 10% FCS, 2% bovine serum albumin, 1% glycine, and 0.1% Triton X-100 (Sigma-Aldrich, Rehovot) and stained with a combination of the mouse or rabbit anti-tubulin β-III-isoform C-terminus antibodies (β-III-tubulin; 1:500), rabbit anti-NG2 chondroitin sulfate proteoglycan (NG2; 1:500), mouse anti-RIP (RIP; 1:2000), mouse anti-galactocerebroside (GalC; 1:250), mouse anti-glutamic acid decarboxylase 67 (GAD; 1:1000), mouse anti-nestin (Nestin; 1:1000), rat anti-myelin basic protein (MBP; 1:300) (all from Chemicon, Temecula, Calif.), goat anti-double cortin (DCX; 1:400, Santa Cruz Biotechnology, Santa Cruz, Calif.) and mouse anti-glial fibrillary acidic protein (GFAP; 1:100, Sigma-Aldrich, St. Louis). For labeling of microglia we used either rat andi-CD11b (MAC1; 1:50, BD-Pharmingen, N.J.) or FITC-conjugated Bandeiraea simplicifolia isolectin B4 (IB4; 1:50, Sigma-Aldrich, Rehovot). Expression of IGF-1 was detected by goat anti-IGF-1 (1:20, R&D Systems).
(vii) RNA purification, cDNA synthesis, and reverse-transcription PCR analysis. Cells were lysed with TRI reagent (MRC, Cincinnati, Ohio), and total cellular RNA was purified from lysates using the RNeasy kit (Qiagen, Hilden, Germany) according to the manufacturer's instructions. Residual genomic DNA was removed during the purification process by incubation with RNase-free DNase (Qiagen). RNA was stored in RNase-free water (Qiagen) at −80° C. RNA (1 μg) was converted to cDNA using SuperScript II (Promega, Madison, Wis.), as recommended by the manufacturer. The cDNA mixture was diluted 1:5 with PCR-grade water.
We assayed the expression of specific mRNAs using semi-quantitative reverse transcription PCR (RT-PCR) with selected gene-specific primer pairs, using OLIGO v6.4 (Molecular Biology Insights, Cascade, Colo.).
The primers used were:
The RT-PCR reactions were carried out using 1 μg of cDNA, 35 nmol of each primer, and ReadyMix PCR Master Mix (Aβgene, Epsom, UK) in 30-μl reactions. PCR reactions were carried out in an Eppendorf PCR system with cycles (usually 25-30) of 95° C. for 30 s, 60° C. for 1 min, 72° C. for 1 min, and 72° C. for 5 min, and then kept at 4° C. As an internal standard for the amount of cDNA synthesized, we used (β-actin mRNA. PCR products were subjected to agarose gel analysis and visualized by ethidium bromide staining. Signals were quantified using a Gel-Pro analyzer 3.1 (Media Cybernetics). In all cases one product was observed with each primer set, and the observed product had an amplicon size that matched the size predicted from published cDNA sequences.
(viii) Quantification. For microscopic analysis we used a Zeiss LSM 510 confocal laser scanning microscope (40× magnification). For experiments in vitro we scanned fields of 0.053 mm2 (n=8-16 from at least two different coverslips) for each experimental group. For each marker, 500-1000 cells were sampled. Cells co-expressing GFP and β-III-tubulin, NG2, RIP, GalC, and GFAP were counted.
(ix) Statistical analysis. The results were analyzed by the Tukey-Kramer multiple comparisons test (ANOVA) and are expressed as means±SD (unless differently indicated).
Adaptive immunity, in the form of a well-controlled Th1 or a Th2 response to a CNS insult, induces microglia (MG) to adopt a phenotype that facilitates neuronal protection and neuronal tissue repair (Butovsky et al., 2001). Here we examined the ability of adaptive immunity, via activation of microglia, to induce or support the differentiation of NPCs. Neurogenesis is reportedly blocked by the inflammation caused by microglia activated with endotoxin (such as lipopolysaccharide, LPS) (Ekdahl et al., 2003). We therefore compared the effects on NPCs of microglia exposed to LPS (MG(LPS)) with the effects of microglia exposed to the low levels of characteristic Th1 (pro-inflammatory) and Th2 (anti-inflammatory) cytokines, IFN-γ (MG(IFN-γ)) and IL-4 (MG(IL-4γ), respectively, shown herein to be supportive of neural survival. We used NPCs expressing green fluorescent protein (GFP) to verify that any neural cell differentiation seen in the culture was derived from the NPCs rather than from contamination of the primary microglial culture.
Microglia were grown in their optimal growth medium (Zielasek et al., 1992) and were then treated for 24 h with IL-4, IFN-γ (low level), or LPS. Residues of the growth medium and the cytokines were washed off, and each of the treated microglial preparations, as well as a preparation of untreated microglia (MG(−)), was freshly co-cultured with dissociated NPC spheres in the presence of differentiation medium. We examined the effects of both IFN-γ-activated and IL-4-activated microglia. After 5 days in culture, GFP+ cells that expressed the neuronal marker β-III tubulin were identified as neurons.
Since we recently showed that IL-4-activated microglia (MG(IL-4)) produce a high level of IGF-1 (Butovsky et al., 2005), and because IGF-1 is reportedly a key factor in neural cell renewal (O'Kusky et al., 2000), we envisioned a situation in which IGF-1 might be one of the factors in the effect of IL-4-activated microglia. Therefore, the following experiments were carried out both in insulin-free (to allow detection, if exists, of the effect of insulin-related factors secreted by the activated microglia) and in insulin-containing differentiation media.
Quantitative analysis revealed that neurogenesis, in the absence of insulin, was only minimally supported by MG(IFN-γ) and was impaired by MG(LPS), but was almost 3-fold higher in NPCs co-cultured with MG(IL-4) than in controls (
In co-cultures of NPCs with MG(−), however, addition of insulin increased the percentage of GFP+/β-III-tubulin+ cells (
Morphological differences were observed between the newly differentiating neurons in NPCs co-cultured with MG(IFN-γ) and those generated in co-cultures with MG(IL-4) (
Next we examined whether, under the same experimental conditions, microglia would also induce NPCs to differentiate into oligodendrocytes. Under high magnification, we were able to detect newly formed oligodendrocytes. In attempting to detect possible differentiation of NPCs to oligodendrocytes, we first looked for GFP-labeled cells co-expressing oligodendrocyte progenitor marker NG2. Quantitative analysis confirmed that both MG(IL-4) and (to a lesser extent) MG(IFN-γ) induced differentiation of NG2+ cells from co-cultured NPCs (
Addition of insulin to the NPC cultures did not affect the incidence of NG2+ cells in the absence of microglia (control;
In light of the observed early differences between the effects of MG(IL-4) and MG(IFN-γ) on both neurogenesis and oligodendrogenesis, we examined NPCs co-cultured with the cytokine-activated microglia after 10 days in co-culture. As on day 5, few NG2+ cells were seen in the absence of microglia (
In the presence of MG(IL-4), the GFP+/NG2+ cells were more branched at 10 days (
Table 1 records the proliferation of NPCs co-cultured with non-activated, IL-4-activated, or IFN-γ-activated microglia. Cultures of untreated NPCs (control) or NPCs co-cultured with MG(−) or MG(IL-4) or MG(IFN-γ) or MG(LPS), with or without insulin, were analyzed for proliferation and cell death 24, 48, or 72 h after plating. For the proliferation assay, a pulse of BrdU was applied 12 h before each time point. Numbers of BrdU+ cells are expressed as percentages of GFP+ cells (mean±SEM from three independent experiments in duplicate) and analyzed by ANOVA. Cell death with and without insulin was determined by live staining with 1 μg/ml propidium iodide and 1 μg/ml Hoechst 33342 (mean±SEM from two independent experiments in duplicate; * P<0.05; *** P<0.001; ANOVA).
As shown in Table 1, comparisons of proliferation at 24 h and 48 h of culture revealed no differences. After 72 h a slight but non-significant difference was seen between NPCs alone and NPCs co-cultured with MG(−) or MG(LPS), possibly because of decreased proliferation in the culture of NPCs alone rather than any increase in the co-cultures. In the absence of insulin there were no significant differences at any time in culture between NPCs alone and NPCs co-cultured with MG(−) or with MG(IL-4). A reduction in proliferation was observed in NPCs co-cultured with MGLPS, with or without insulin. After 5 days, no proliferation was detectable in any of the co-cultures (data not shown). To identify dead or dying cells we stained live cultures with 1 propidium iodide, which stains dead cells, and 1 μg/ml Hoechst 33342, which stains both live and dead cells (Hsieh et al., 2004). Significant cell death was observed in NPCs co-cultured with MG(LPS), both in the absence and in the presence of insulin, whereas in NPCs cultured alone or with MG(IFN-γ) or MG(IL-4) the percentage of cell death was low and did not differ significantly from that seen in cultures of NPCs alone (Table 1). These results suggested that the primary effect of the cytokine-activated microglia on the fate of NPCs in vitro occurs via a mechanism that is instructive rather than selective.
Insulin-like growth factor (IGF)-I is reportedly a key factor in neurogenesis and oligodendrogenesis (Carson et al., 1993; Aberg et al., 2000; O'Kusky et al., 2000; Hsieh et al., 2004). To determine whether the beneficial effect of the cytokine-activated microglia on the differentiation of NPCs is mediated, at least in part, by the ability of the microglia to produce IGF-I, we added neutralizing antibodies specific to IGF-I (ãIGF-I) to the NPCs co-cultured with activated microglia. ãIGF-I blocked the MG(IL-4)-induced effect on oligodendrogenesis (FIG. 5A), indicating that the effect of IL-4-activated microglia on oligodendrogenesis is dependent on IGF-I. Direct addition of recombinant IGF-I (rIGF-I; 500 ng/ml) to NPCs resulted in their significant differentiation to NG2-expressing cells (
In light of the observed beneficial effect of ãTNF-α on the outcome of MG(IFN-γ)-induced neurogenesis (
Comparative RT-PCR analyses of microglial mRNA disclosed that in the absence of activation the microglia produced both IGF-I and low levels of TNF-α. Analysis of TNF-α and IGF-I production as a function of time revealed that IFN-γ, unlike IL-4, caused a transient increase in TNF-α production and down-regulation of IGF-I (
The results of this study strongly suggest that certain specifically activated microglia can induce neural cell renewal in the adult CNS. The findings showed that microglia can determine the fate of differentiating adult NPCs. Both neurogenesis and oligodendrogenesis were induced in NPCs co-cultured with MG(IL-4), and MG(IFN-γ), whereas both were blocked by MG(LPS), in line with reports that inflammation associated with LPS blocks adult neurogenesis (Ekdahl et al., 2003; Monje et al., 2003). NPCs co-cultured with MG(IL-4) showed a bias towards oligodendrogenesis, whereas NPCs co-cultured with MG(IFN-γ) were biased towards neurogenesis.
Recovery from spinal cord injury evidently necessitates a local immune response that is amenable to well-controlled boosting by immunization with T lymphocytes recognizing myelin-associated antigens at the injury site. The relevant T cells can activate local microglia to express a phenotype supportive of neuronal survival and renewal. We show that recovery of mice from spinal contusion is synergistically promoted by T-cell-based vaccination with a myelin-derived peptide and injection of adult neural stem/progenitor cells (aNPCs) into the cerebrospinal fluid. Significantly more aNPCs targeted the lesion site in vaccinated than in nonvaccinated mice. Synergistic interaction between aNPCs and T cells in vitro was critically dependent on T-cell specificity and phenotype. The results suggest that controlled immune activity underlies efficient regulation of the stem-cell niche, and that stem-cell therapy necessitates autologous or histocompatibility-matched donors instead of the immunosuppressive anti-rejection drugs that would eliminate any beneficial effect of immune cells on spinal cord repair.
(x) Animals. Inbred adult wild-type C57Bl/6J mice were supplied by the Animal Breeding Center of The Weizmann Institute of Science. All animals were handled according to the regulations formulated by the Institutional Animal Care and Use Committee (IACUC).
(xi) Antigens. The following peptides were synthesized by the Synthesis Unit at the Weizmann Institute (Rehovot, Israel): MOG, residues 35-55 MEVGWYRSPFSRVVHLYRNGK (SEQ ID NO:39) and an altered MOG peptide (45D) MEVGWYRSPFDRVVHLYRNGK (SEQ ID NO:40), a peptide analog of MOG 35-55 containing a serine to aspartic acid substitution as shown. OVA was purchased from Sigma.
(xii) Immunization. Adult mice were immunized with MOG, 45D, or OVA (all 100 μg), each emulsified in an equal volume of CFA (Difco, Detroit, Mich.) containing Mycobacterium tuberculosis (5 mg/ml; Difco), or IFA. The emulsion (total volume 0.15 ml) was injected s.c. at one site in the flank. Control mice were injected with PBS.
(xiii) Spinal cord injury. Mice were anesthetized, their spinal cords were exposed by laminectomy at T12, and a force of 200 kdyn was placed for 1 s on the laminectomized cord using the Infinite Horizon spinal cord impactor (Precision Systems and Instrumentation, Lexington, Ky.), a device shown to inflict a well-calibrated contusive injury of the spinal cord.
(xiv) Assessment of functional recovery from spinal cord contusion. Functional recovery from spinal cord contusion in mice was determined by hindlimb locomotor performance. Recovery was scored by the Basso Mouse Scale (BMS) open-field locomotor rating scale, a scale recently developed specifically for mice, with scores ranging from 0 (complete paralysis) to 9 (normal mobility) (Engesser-Cesar et al., 2005). Blind scoring ensured that observers were not aware of the treatment received by each mouse. Twice a week locomotor activities of mice in an open field were monitored by placing the mouse for 4 min in the center of a circular enclosure (90 cm in diameter, 7 cm wall height) made of molded plastic with a smooth, non-slip floor. Before each evaluation the mice were examined carefully for perineal infection, wounds in the hindlimbs, and tail and foot autophagia.
(xv) Stereotaxic injection of neural progenitor cells. Mice were anesthetized and placed in a stereotactic device. The skull was exposed and kept dry and clean. The bregma was identified and marked. The designated point of injection was at a depth of 2 mm from the brain surface, 0.4 mm behind the bregma in the anteroposterior axis, and 1.0 mm lateral to the midline. Neural progenitor cells were applied with a Hamilton syringe (5×105 cells in 3 μl, at a rate of 1 μl/min) and the skin over the wound was sutured.
(xvi) Neural progenitor cell culture. Cultures of adult neural progenitor cells (aNPCs) were obtained as previously described in Example 1.
(xvii) Co-culturing of neural progenitor cells and T cells. CD4+ T cells were purified from lymph nodes of 8-week-old C57Bl6/J mice as previously described (Kipnis et al., 2004). T cells were activated in RPMI medium supplemented with L-glutamine (2 mM), 2-mercaptoethanol (5×10−5M), sodium pyruvate (1 mM), penicillin (100 Mimi), streptomycin (100 μg/ml), nonessential amino acids (1 ml/100 ml), and autologous serum 2% (v/v) in the presence of mouse recombinant IL-2 (mrIL-2; 5 ng/ml) and soluble anti-CD28 and anti-CD3 antibodies (1 ng/ml). T cells were co-cultured (5×104 cells/well) with aNPCs (5×104 cells/well) for 5 d on cover slips coated with Matrigel (BD Biosciences) in 24-well plates. The cultures were then fixed with 2.5% paraformaldehyde in PBS for 30 mM at room temperature and stained for neuronal markers.
(xviii) Immunohistochemistry. Mice subjected to SCI were re-anesthetized 14 or 60 days later and perfused with cold PBS. Their spinal cords were removed, postfixed with Bouin's fixative (75% saturated picric acid, 25% formaldehyde, 5% glacial acetic acid; Sigma-Aldrich) for 48 h, and then transferred to 70% EtOH. The tissues were hydrated through a gradient of 70%, 95%, and 100% EtOH in xylene and paraffin, and were then embedded in paraffin. For each stain, five tissue sections, each 6 μm thick, were taken from each mouse. The paraffin was removed by successive rinsing of slides for 15 mM with each of the following: xylene, EtOH 100%, 95%, 70%, 50%, and PBS. Exposure of the slides to antigen was maximized by heating them to boiling point in 10 mM sodium citrate pH 6.0 in a microwave oven, then heating them at 20% microwave power for a further 10 min. The slides were blocked with 20% normal horse serum for 60 min prior to overnight incubation at room temperature (GFAP, neurofilaments, and BDNF), or for 48 h at 4° C. (CD3), with the monoclonal antibody in 2% horse serum. We used rabbit anti-mouse GFAP (1:200) (DakoCytomation, Glostrup, Denmark) for GFAP; rabbit anti-neurofilament (1:200), low and high molecular weight (Serotec, Oxford, UK) for neurofilaments; and rat anti-human CD3 (1:50) (Serotec) for CD3. For BDNF we used the monoclonal antibody chicken anti-human BDNF (1:100) (Promega, Madison, Wis.) with 0.05% saponin.
After rinsing, sections were incubated for 1 h at room temperature with the secondary antibody Cy3 donkey anti-rat (1:300) (Jackson ImmunoResearch Laboratories, West Grove, Pa.) (staining for CD3), Cy3 donkey anti-chicken (Jackson ImmunoResearch) (1:250) (staining for BDNF), or Cy3 donkey anti-rabbit (Jackson ImmunoResearch) (1:250) (staining for GFAP and neurofilaments). For IB4 staining, sections were blocked for 1 h with 20% horse serum and then incubated for 1 h at room temperature with Cy2-IB4 (1:50) (Sigma-Aldrich). All sections were stained with Hoechst (1:2000) (Molecular Probes—Invitrogen, Carlsbad, Calif.). They were then prepared for examination under a Nicon E-600 fluorescence light microscope. Results were analyzed by counting the cells (CD3-labeled) in the site of injury, or by determination of the density (IB4-labeled or BDNF-labeled), or by measurement of the unstained area (GFAP, neurofilaments). Each of the parameters was measured by an observer who was blinded to the treatment received by the mice.
Our working hypothesis in this study was that the protective immune response evoked at a site of injury by T-cell based immunization creates a niche that supports not only cell survival but also tissue repair. We further suspected that a local T-cell mediated immune response could attract exogenously delivered aNPCs and support their contribution to recovery. To test this hypothesis we vaccinated C57Bl/6J mice, immediately after SCI, with the encephalitogenic peptide pMOG 35-55 (SEQ ID NO: 39) emulsified in CFA containing 0.5% Mycobacterium tuberculosis (MOG/CFA), and 1 week later administered aNPCs via the intracerebroventricular (i.c.v.) route. Mice subjected to this dual treatment protocol (MOG/CFA/aNPC) were compared to a control group of mice that were immunized with the same MOO peptide emulsified in the same adjuvant but were not transplanted with aNPCs and instead were injected i.c.v. with PBS (MOG/CFA/PBS), or to mice that were injected with PBS and CFA (0.5%) and transplanted i.c.v. with aNPCs (PBS/CFA/aNPC) or a control group of mice that were injected with PBS/CFA and then injected i.c.v. with PBS (PBS/CFA/PBS). To assess behavioral outcome after SCI we used the Basso motor score (BMS) rating scale (Engesser-Cesar et al., 2005), in which 0 indicates complete paralysis of the hindlimbs and 9 denotes full mobility. The mean motor recovery (BMS) scores of mice receiving the MOG/CFA/aNPC (4.21±0.45; all values are mean±SEM) were higher than those of mice treated with MOG/CFA/PBS. In mice treated with PBS/CFA/aNPC, recovery was not better than in control mice treated with PBS/CFA/PBS (1.5±0.27). A BMS of 4.21 indicates extensive movement of the ankle and plantar placement of the paw (three animals showed, in addition, occasional weight support and plantar steps), whereas a score of 1.5 indicates ankle movement ranging from slight to extensive. Mice treated with MOG/CFA/PBS scored 2.71±0.5, a, significantly higher score than that of control PBS/CFA/aNPC-treated mice (1.5±0.4) or of control mice treated with PBS/CFA/PBS (
We have previously demonstrated that boosting of the amounts of T cells needed for promoting recovery from SCI does not necessitate the use of encephalitogenic peptides; weak agonists of encephalitogenic peptides are just as effective and do not carry the risk of inducing EAE. To test whether such ‘safe’ vaccination could be utilized in combination with aNPCs transplantation we used a MOG-derived altered peptide ligand (pMOG 35-55 APL; 45D peptide, (SEQ ID NO:40), in which aspartic acid is substituted for serine. Mice were vaccinated with the 45D peptide emulsified in CFA containing 2.5% Mycobacterium tuberculosis. One week later the immunized mice were subjected to contusive SCI, and after another week were transplanted i.c.v. with aNPCs. Increased motor activity (as expressed by the BMS, mean±SEM) was seen in these mice than in control mice treated i.c.v with PBS/CFA/aNPC (4.11±0.27 compared to 1.94±0.22;
To determine the phenotype and specificity of the T cells needed for synergistic interaction with aNPCs we repeated the above experiments using different immunization protocols. Incomplete Freund's adjuvant (LEA), unlike CFA, is free of bacteria and is known to elicit a Th2-like response to encephalitogenic peptides. We found that although immunization with the MOG analog (peptide 45D) emulsified in IFA had some beneficial effect, it showed no synergy with subsequent transplantation of aNPCs (BMS of 3.2±0.76 for MOG/IFA/aNPC-treated mice compared to 2.93±1.03 for MOG/IFA/PBS-treated mice and 2.07±0.53 in the PBS/CFA/PBS-treated mice;
To verify that specificity to CNS-antigens is required for a synergistic effect of vaccination and stem-cell transplantation, mice were immunized with the nonself protein ovalbumin (OVA) emulsified in CFA (containing 2.5% Mycobacterium tuberculosis), and 1 week later were injected i.c.v. with aNPCs or with PBS as control. Immunization with OVA/CFA resulted in a slight, nonsignificant increase in BMS, and implantation of aNPCs did not increase the BMS any further (2.43±1.78 for the OVA/CFA/aNPC-treated mice compared to 2.2±0.68 for OVA/CFA/PBS-treated mice and 1.5±0.29 for PBS/CFA/PBS-treated control group,
Immune activation in the injured CNS, and specifically in the spinal cord, has been a major focus of research attention in recent years (Schwartz and Hauben, 2002). In some of the studies, T cell-based immune responses were shown to be protective only if their intensity and duration were well regulated. Overly strong immunization yielded excessive immune activity, which neutralized the potential benefit of the immune response for the injured spinal cord and even had a detrimental effect. We considered the possibility that if aNPCs home to the site of damage they can offset the negative effect of excessive immune activity and thus contribute to recovery. We therefore set out to determine whether administration of aNPCs can contribute to functional recovery even when the local immune activity is excessive. One week prior to SCI we immunized mice with MOO peptide 35-55 emulsified in CFA containing 2.5% Mycobacterium tuberculosis. Under conditions in which motor recovery from SCI was worse after immunization with MOG/CFA than after injection with PBS/CFA (BMS of 0.35±0.2 and 1.94±0.32, respectively), we found that recovery was improved upon administration of aNPCs (BMS of 2.68±0.51;
In an attempt to gain an insight into the mechanism underlying the apparent synergy between aNPCs and resident immune cells, we examined whether any of the injected aNPCs find their way to the injured spinal cord. We repeated the experiment showed on
One of the morphological features that characterize recovery from SCI is the size of the lesion. To delineate the site of injury we stained longitudinal sections of the spinal cord with antibodies to glial fibrillary acidic protein (GFAP). We assessed the lesion size by measuring the areas that were not stained by GFAP. This analysis disclosed that as early as 7 days after aNPCs were transplanted in the MOG/CFA-vaccinated rats, the averaged size of the site of injury was significantly smaller in mice that had received both vaccination and aNPC transplantation than in mice that had only been vaccinated or had received only aNPCs (
Next we examined whether the observed differences in the extent of recovery could be correlated with local immunological changes. Sections of spinal cord tissue were stained for markers of T cells (CD3) and accumulation of activated microglia/macrophages (IB4) (
Both activated T cells and T cell-activated microglia can serve as sources of growth factors such as brain-derived neurotrophic factor (BDNF). BDNF immunoreactivity was more intense in the spinal cords of mice treated with MOG/CFA/aNPC than in the other groups (
Recent studies have shown that noggin, a bone morphogenesis protein (BMP) inhibitor, can induce neuronal differentiation from aNPCs in the injured spinal cord (Setoguchi et al., 2004). This protein was also shown to be needed to provide a neurogenic environment in the subventricular zone. We therefore assayed noggin immunoreactivity in the various experimental groups, and found that it was significantly increased in mice that received the dual treatment protocol, but was unaffected by MOG immunization alone and was slightly decreased by aNPC transplantation alone (
The above results raised an important question: can a T cell-based vaccination, when given in combination with aNPC transplantation, create conditions favorable for neuronal differentiation of endogenous or exogenous aNPCs? To examine this possibility, we repeated the experiment described in
The above results indicated that cross-talk between immune cells and aNPCs was taking place at the site of injury. We showed hereinabove that microglia pre-activated with the Th1- and Th2-associated cytokines, IFN-γ and IL-4, respectively, can induce neuronal differentiation from aNPCs. We therefore sought to determine whether direct interaction between aNPCs and T cells would also result in an altered pattern of aNPC differentiation. To address this question, we activated CD4+ T cells in vitro by a cognate protocol (with anti-CD3 antibodies, anti-CD28 antibodies, and IL-2) for 24 h and then allowed their activation to continue in co-cultures with aNPCs in a transwell culture system. As controls we used cultures of aNPCs alone (in the presence of anti-CD3 antibodies, anti-CD28 antibodies and IL-2) or aNPCs cultured with CD4+ T cells in a resting state (supplemented with IL-2 only). After 5 days in culture the aNPCs in the lower chamber were fixed and analyzed for the appearance of newly formed neurons. Staining for the early neuronal marker revealed a dramatic effect of T cells on neuronal differentiation (
To exclude the possibility that the T cells had affected NPC differentiation as a consequence of encountering NPC-derived compounds, and to further substantiate our finding that the observed effect was caused by T cell-derived soluble substances, we allowed aNPCs to differentiate in the presence of medium conditioned by activated T cells. After 5 days, staining of these cultures for β-III-tubulin revealed similar results to those obtained in the co-culture system (
We next sought to determine whether the T cell-induced neurogenesis was mediated by cytokines secreted by activated T cells. aNPCs were cultured in the presence of different concentrations of the characteristic T-cell derived cytokines IFN-γ and IL-4. Analysis revealed that IFN-γ, at concentrations as low as 1 ng/ml, could induce an increase in β-III-tubulin expression after 5 days in culture (
These findings suggested that IFN-γ, unlike IL-4, could account in part for the T cell-induced neurogenesis. Even the effect of IFN-γ, however, was limited relative to that of the T cells or to the T cell-derived soluble factors. PCR analysis of expression of the IFN-γ receptor-1 on aNPCs disclosed that this receptor is expressed by aNPCs under all of the conditions examined here (data not shown).
Activation of the Notch pathway is essential for maintenance of aNPCs, and blockage of this pathway and its downstream transcription factors of the Hes gene family underlie the first events in neuronal differentiation. To determine whether T cell-mediated neuronal differentiation induces changes in Notch signaling, we looked for possible changes in expression of Hes genes in aNPCs following their interaction with T cell-derived substances. Real-time PCR disclosed that relative to control cultures, aNPCs cultured for 24 h in the presence of T cell-conditioned medium underwent a five-fold decrease in Hes-5 expression (
Our observation that aNPCs express an IFN-γ receptor, taken together with recent studies showing that these cells express immune-related molecules such as B-7 (Imitola et al., 2004b) and CD44 (Pluchino et al., 2003), known to participate in the dialog between T cells and antigen-presenting cells (APCs), prompted us to examine whether aNPCs could affect T-cell function. First we examined the effects of aNPCs on proliferation of CD4+ T cells by assaying [3H]thymidine incorporation by the T cells. Co-culturing of T cells with aNPCs and APCs (lethally irradiated splenocytes) for 3 days resulted in a significant dose-dependent inhibition of T-cell proliferation (
Local interaction between immune cells and aNPCs underlies functional recovery. In the present study we combined two different therapeutic approaches for SCI: T cell-based vaccination and transplantation of neural progenitor cells into the CSF. Each of these approaches has been shown to be potentially capable of promoting functional recovery from SCI; we show here that when combined, they operate in synergy. Our experiments, both in vivo and in vitro, demonstrated that cross talk between immune cells and aNPCs can take place at the lesion site. The vaccination elicits a local immune response, which, if well controlled, provides the cellular and molecular elements needed to attenuate degeneration and promote repair. The same response also plays a role in recruiting aNPCs to the injured site and creating niche-like compartments that support neurogenesis from endogenous aNPCs. The interaction between aNPCs and immune cells was found to be reciprocal: aNPCs could modulate the postinjury immune activity, ensuring functional recovery even under conditions of excessive immune activity (which, in the absence of aNPCs, have a detrimental effect on recovery).
Accumulation of β-amyloid deposition (Aβ), neuronal loss, cognitive decline, and microglial activation, are characteristic features of Alzheimer's disease (AD). Using AD double-transgenic mice expressing mutant human genes encoding presenilin 1 and chimeric mouse/human amyloid precursor protein, we show that vaccination with glatiramer acetate prevented and restored cognitive decline, assessed by performance in a Morris water maze (MWM). The vaccination modulated microglial activation, eliminated plaque formation, and induced neuronal survival and neurogenesis. In vitro, Aβ-activated microglia impeded neurogenesis from adult neural stem/progenitor cells. This was counteracted by IL-4, and more so when IFN-γ was added, but not by IFN-γ alone.
(xix) Animals. Nineteen adult double-transgenic APPK670N, M671L+PS1ΔE9 mice of the B6C3-Tg (APPswe, PSEN1dE9) 85Dbo/J strain were purchased from The Jackson Laboratory (Bar Harbor, Me.) and were bred and maintained in the Animal Breeding Center of The Weizmann Institute of Science. All animals were handled according to the regulations formulated by the Weizmann Institute's Animal Care and Use Committee. Tg AD mice were produced by co-injection of chimeric mouse/human APPswe (APP695 [humanized Aβ domain] harboring the Swedish [K594M/N595L] mutation) and human PS1dE9 (deletion of exon 9) vectors controlled by independent mouse prion protein promoter (MoPrP) elements, as described (Borchelt et al., 1997).
(xx) Reagents. Recombinant mouse IFN-γ and IL-4 (both containing endotoxin at a concentration below 0.1 ng/μg cytokine) were obtained from R&D Systems (Minneapolis, Minn.). β-amyloid peptides [amyloid protein fragment 1-40 and 1-42 (Aβ1-40/1-42)] were purchased from Sigma-Aldrich, St. Louis, Mo. The Aβ peptides were dissolved in endotoxin-free water, and Aβ aggregates were formed by incubation of Aβ, as described (Ishii et al., 2000).
(xxi) Genotyping. All mice used in this experiment were genotyped for the presence of the transgenes by PCR amplification of genomic DNA extracted from 1-cm tail clippings (Jankowsky et al., 2004). Reactions contained four primers: one anti-sense primer-matching sequence within the vector that is also present in mouse genomic PrP (5′-GTG GAT ACC CCC TCC CCC AGC CTA GAC C) (SEQ ID NO:41); a second sense primer specific for the genomic PrP coding region (which was removed from the MoPrP vector) (5′-CCT CTT TGT GAC TAT GTG GAC TGA TGT CGG) (SEQ ID NO:42); and two sense and anti-sense primers specific for the PS1 transgene cDNA (PS1-a: 5′-AAT AGA GAA CGG CAG GAG CA (SEQ ID NO:43), and PS1-b: 5′-GCC ATG AGG GCA CTA ATC AT) (SEQ ID NO:44). All reactions give a 750-bp product of the endogenous PrP gene as a control for DNA integrity and successful amplification; PS1 transgene-positive samples have an additional band at approximately 608 bp.
(xxii) Glatiramer acetate vaccination. Each mouse was subcutaneously injected five times with a total of 100 μg of glatiramer acetate (GA (TV-5010), MW 13.5-18.5 kDa, average 16 kDa, Teva Pharmaceutical Industries Ltd., Petach Tikva, Israel), emulsified in 200 μl PBS×1, from experimental day 0 until day 24, twice during the first week and once a week thereafter.
(xxiii) Behavioral testing. Spatial learning/memory was assessed by performance on a hippocampus-dependent visuo-spatial learning task in the Morris water maze (MWM) (Morris, 1984). Mice were given four trials per day on 4 consecutive days, during which they were required to find a hidden platform located 1.5 cm below the water surface in a pool 1.4 m in diameter. Within the testing room, only distal visuo-spatial cues for location of the submerged platform were available. The escape latency, i.e., the time required by the mouse to find the platform and climb onto it, was recorded for up to 60 s. Each mouse was allowed to remain on the platform for 30 s and was then moved from the maze to its home cage. If the mouse did not find the platform within 60 s, it was placed manually on the platform and returned to its home cage after 30 s. The interval between trials was 300 s. On day 5 the platform was removed from the pool and each mouse was tested by a probe trial for 60 s. On days 6 and 7 the platform was placed at the quadrant opposite the location chosen on days 1-4, and the mice were then retrained in four sessions per day. Data were recorded using an EthoVision automated tracking system (Noldus).
(xxiv) Administration of BrdU and tissue preparation. BrdU was dissolved by sonication in PBS and injected i.p. into each mouse (50 mg/kg body weight; 1.25 mg BrdU in 200 μl PBS×1). Starting from experimental day 22 after the first GA vaccination, BrdU was injected i.p. twice daily, every 12 h for 2.5 days, to label proliferating cells. Three weeks after the first BrdU injection the mice were deeply anesthetized and perfused transcardially, first with PBS and then with 4% paraformaldehyde. The whole brain was removed, postfixed overnight, and then equilibrated in phosphate-buffered 30% sucrose. Free-floating 30-μm sections were collected on a freezing microtome (Leica SM2000R) and stored at 4° C. prior to immunohistochemistry.
(xxv) Neural progenitor cell culture. Coronal sections (2 mm thick) of tissue containing the subventricular zone of the lateral ventricle were obtained from the brains of adult C57B116J mice. The tissue was minced and then incubated for digestion at 37° C., 5% CO2 for 45 mM in uEarle's balanced salt solution containing 0.94 mg/ml papain (Worthington, Lakewood, N.J.) and 0.18 mg/ml of L-cysteine and EDTA. After centrifugation at 110×g for 15 mM at room temperature, the tissue was mechanically dissociated by pipette trituration. Cells obtained from single-cell suspensions were plated (3500 cells/cm2) in 75-cm2 Falcon tissue-culture flasks (BD Biosciences, San Diego, Calif.), in NPC-culturing medium [Dulbecco's modified Eagles's medium (DMEM)/F12 medium (Gibco/Invitrogen, Carlsbad, Calif.) containing 2 mM L-glutamine, 0.6% glucose, 9.6 μg/ml putrescine, 6.3 ng/ml progesterone, 5.2 ng/ml sodium selenite, 0.02 mg/ml insulin, 0.1 mg/ml transferrin, 2 μg/ml heparin (all from Sigma-Aldrich, Rehovot, Israel), fibroblast growth factor-2 (human recombinant, 20 ng/ml), and epidermal growth factor (human recombinant, 20 ng/ml; both from Peprotech, Rocky Hill, N.J.)]. Spheres were passaged every 4-6 days and replated as single cells. Green fluorescent protein (GFP)-expressing NPCs were obtained as previously described (Pluchino et al., 2003).
(xxvi) Primary microglial culture. Brains from neonatal (P0-P1) C57Bl/6J mice were stripped of their meninges and minced with scissors under a dissecting microscope (Zeiss, Stemi DV4, Germany) in Leibovitz-15 medium (Biological Industries, Kibbutz Beit Ha-Emek, Israel). After trypsinization (0.5% trypsin, 10 min, 37° C./5% CO2), the tissue was triturated. The cell suspension was washed in culture medium for glial cells [DMEM supplemented with 10% fetal calf serum (FCS; Sigma-Aldrich, Rehovot), L-glutamine (1 mM), sodium pyruvate (1 mM), penicillin (10 U/ml), and streptomycin (100 mg/ml)] and cultured at 37° C./5% CO2 in 75-cm2 Falcon tissue-culture flasks (BD Biosciences) coated with poly-D-lysine (PDL) (10 mg/ml; Sigma-Aldrich, Rehovot) in borate buffer (2.37 g borax and 1.55 g boric acid dissolved in 500 ml sterile water, pH 8.4) for 1 h, then rinsed thoroughly with sterile, glass-distilled water. Half of the medium was changed after 6 h in culture and every 2nd day thereafter, starting on day 2, for a total culture time of 10-14 days. Microglia were shaken off the primary mixed brain glial cell cultures (150 rpm, 37° C., 6 h) with maximum yields between days 10 and 14, seeded (105 cells/ml) onto PDL-pretreated 24-well plates (1 ml/well; Corning), and grown in culture medium for microglia [RFMI-1640 medium (Sigma-Aldrich) supplemented with 10% FCS, L-glutamine (1 mM), sodium pyruvate (1 mM), β-mercaptoethanol (50 mM), penicillin (100 U/ml), and streptomycin (100 mg/ml)]. The cells were allowed to adhere to the surface of a PDL-coated culture flask (30 min, 37° C./5% CO2), and non-adherent cells were rinsed off.
(xxvii) Co-culturing of mouse neural progenitor cells and mouse microglia. Cultures of treated or untreated microglia were washed twice with fresh NPC-differentiation medium (same as the culture medium for NPCs but without growth factors and with 2.5% FCS) to remove all traces of the tested reagents, then incubated on ice for 15 min, and shaken at 350 rpm for 20 min at room temperature. Microglia were removed from the flasks and immediately co-cultured (5×104 cells/well) with NPCs (5×104 cells/well) for 10 days on cover slips coated with Matrigel™ (BD Biosciences) in 24-well plates, in the presence of NPC differentiation medium. The cultures were then fixed with 2.5% paraformaldehyde in PBS for 30 min at room temperature and stained for neuronal and glial markers.
(xxviii) Immunocytochemistry and immunohistochemistry. Cover slips from co-cultures of NPCs and mouse microglia were washed with PBS, fixed as described above, treated with a permeabilization/blocking solution containing 10% FCS, 2% bovine serum albumin, 1% glycine, and 0.1% Triton X-100 (Sigma-Aldrich, Rehovot), and stained with a combination of the mouse anti-tubulin β-III-isoform C-terminus antibodies (β-III-tubulin; 1:500; Chemicon, Temecula, Calif.) and CD11b (MAC1; 1:50; BD-Pharmingen, Franklin Lakes, N.J.).
For BrdU staining, sections were washed with PBS and incubated in 2N HCl at 37° C. for 30 min. Sections were blocked for 1 h with blocking solution (PBS containing 20% normal horse serum and 0.1% Triton X-100, or PBS containing mouse immunoglobulin blocking reagent obtained from Vector Laboratories (Burlingame, Calif.)).
For immunohistochemistry, tissue sections were treated with a permeabilization/blocking solution containing 10% FCS, 2% bovine serum albumin, 1% glycine, and 0.05% Triton X-100 (Sigma-Aldrich, St. Louis). Tissue sections were stained overnight at 4° C. with specified combinations of the following primary antibodies: rat anti-BrdU (1:200; Oxford Biotechnology, Kidlington, Oxfordshire, UK), goat anti-DCX [doublecortin] (1:400; Santa Cruz Biotechnology), and mouse anti-NeuN [neuronal nuclear protein] (1:200; Chemicon, Temecula, Calif.). Secondary antibodies were FITC-conjugated donkey anti-goat, Cy-3-conjugated donkey anti-mouse, and Cy-3- or Cy-5-conjugated donkey anti-rat (1:200; Jackson ImmunoResearch, West Grove, Pa.). For labeling of microglia we used either CD11b (MAC1; 1:50; BD-Pharmingen) or FITC-conjugated Bandeiraea simplicifolia isolectin B4 (IB4, 1:50; Sigma-Aldrich, Rehovot). To detect expression of cell-surface MI-IC-II proteins we used anti-MI-IC-II Abs (rat, clone IBL-5/22; 1:50; Chemicon, Temecula, Calif.). To detect expression of human Aβ we used anti-Aβ (human amino-acid residues 1-17) (mouse, clone 6E10, Chemicon, Temecula, Calif.). Expression of IGF-I was detected by goat anti-IGF-I Abs (1:20; R&D Systems). Expression of TNF-α was detected by goat anti-TNF-α Abs (1:100; R&D Systems). T cells were detected with anti-CD3 polyclonal Abs (rabbit, 1:100; DakoCytomation, CA). Propidium iodide (1 μg/ml; Molecular Probes, Invitrogen, Carlsbad, Calif.) was used for nuclear staining.
Control sections (not treated with primary antibody) were used to distinguish specific staining from staining of nonspecific antibodies or autofluorescent components. Sections were then washed with PBS and coverslipped in polyvinyl alcohol with diazabicylo-octane as anti-fading agent.
(xxix) Quantification and stereological counting procedure. For microscopic analysis we used a Zeiss LSM 510 confocal laser-scanning microscope (40× magnification). For experiments in vitro we scanned fields of 0.053 mm2 (n 8-16 from at least two different coverslips) for each experimental group. For each marker, 500-1000 cells were sampled. Cells co-expressing GFP and β-III-tubulin were counted.
For in-vivo experiments, the number of Aβ+ plaques and CD11b+/IB-4+ microglia in the hippocampus were counted at 300-μm intervals from 6-8 coronal sections (30 μm) from each mouse. Neurogenesis in the DG was evaluated by counting of premature neurons (DCX+), proliferating cells (BrdU+), and newly formed mature neurons (BrdU+/NeuN+) in six coronal sections (30 μm) from each mouse. Specificity of BrdU+/NeuN+ co-expression was assayed using the confocal microscope (LSM 510) in optical sections at 1-μm intervals/. Cell counts, numbers of Aβ+ plaques, plaque areas, and intensity of NeuN staining per unit area in the DG were evaluated automatically using Image-Pro Plus 4.5 software (Media Cybernetics).
(xxx) Statistical analysis. MWM behavior scores were analyzed using 3-way ANOVA, with treatment group and trial block as sources of variation, was used to evaluate the significance of differences between mean scores during acquisition trial blocksin the MWM. When the P-value obtained was significant, a pairwise Fisher's least-significant-difference multiple comparison test was run to determine which groups were significantly different.
The in-vitro results were analyzed by the Tukey-Kramer multiple comparisons test (ANOVA) and are expressed as means±SEM. In-vivo results were analyzed by Student's t-test or 1-way ANOVA and are expressed as means SEM.
We examined the effect of GA in AD double-transgenic mice (Tg mice) expressing a mutant human presenilin 1 gene (PS1dE9) and a chimeric mouse/human amyloid precursor protein (APPswe), leading to learning/memory impairment and accumulation of Aβ plaques mainly in the cortex and the hippocampus, both characteristic features of early-onset familial AD (Borchelt et al., 1997). Expression of both transgenes in each mouse was verified by PCR amplification of genomic DNA. APP/PS1 Tg mice aged approximately 8 months were then vaccinated subcutaneously with GA (n=6) twice during the first week and once a week thereafter. Age-matched Tg mice (n=7) and non-Tg littermates that did not carry the transgenes (n=6), were not treated and served as untreated Tg and wild-type non-Tg controls, respectively. Five weeks after the first GA injection all mice were assessed in a Morris water maze (MWM) for cognitive activity, as reflected by performance of a hippocampus-dependent spatial learning/memory task (reviewed in van Praag et al., 2000). The MWM performance of the untreated Tg mice was significantly worse, on average, than that of the age-matched non-Tg littermates (
The above results prompted us to examine the possibility that the observed arrest and reversal of cognitive loss was related to reduction of Aβ plaques and survival of neurons in the hippocampus. Staining of brain cryosections from Tg mice with antibodies specific to human Aβ disclosed numerous plaques in the untreated Tg mice but very few in those vaccinated with GA (
Activated microglia are known to play a role in the pathogenesis of AD. We have shown in the Examples hereinbefore that, unlike microglia seen in association with inflammatory and neurodegenerative diseases, the microglia associated with neural tissue survival express MHC-II, produce IGF-I, and express little or no TNF-α. We therefore examined brain sections from GA-vaccinated and untreated Tg mice for the presence of microglia that stain positively for CD11b or TNF-α (markers of activation associated with a cytotoxic inflammatory phenotype). The presence of plaques was found to be correlated with the appearance of CD11b+ microglia (
In addition, unlike in the untreated Tg mice, in the GA-vaccinated Tg mice numerous T cells (identified by anti-CD3 antibodies) were seen in close proximity to MHC-II+ microglia. Any Aβ-immunoreactivity seen in these mice appeared to be in association with MHC-II+ microglia, creating an immune synapse with CD3+ T cells (
Quantitative analysis confirmed that mice vaccinated with GA showed significantly fewer plaques than untreated Tg mice when examined 6 weeks later (
Because MHC-II-expressing microglia are also associated with neurogenesis in vitro, we examined the same sections for the formation of new neurons in the dentate gyrus (DG) of the hippocampus. This was possible because all mice had been injected with BrdU, a marker of proliferating cells, 3 weeks before tissue excision. Quantitative analysis disclosed significantly more BrdU+ cells in GA-vaccinated Tg mice (
The in-vivo results presented above point to a relationship between arrested neurogenesis, aggregated Aβ, and the phenotype of the activated microglia. To determine whether aggregated Aβ-activated microglia block neurogenesis, and whether T cell-derived cytokines can counteract the inhibitory effect, we co-cultured GFP-expressing NPCs with microglia that had been pre-incubated for 48 h in their optimal growth medium in the presence or absence of aggregated Aβ peptide 1-40/1-42 (Aβ(1-40/1-42); 5 μM) and subsequently treated with IFN-γ (10 ng/ml), or with IL-4 (10 ng/ml) together with IFN-γ (10 ng/ml), for an additional 48 h. Growth media and cytokine residues were then washed off, and each of the treated microglial preparations was freshly co-cultured with dissociated NPC spheres on coverslips coated with Matrigel™ in the presence of differentiation medium (
In this study of APP/PS1 double-transgenic AD mice suffering from decline in cognition and accumulation of Aβ plaques, a T cell-based vaccination, by altering the microglial phenotype, ameliorated cognitive performance, reduced plaque formation, rescued cortical and hippocampal neurons, and induced hippocampal neurogenesis.
(xxxi) Animals. Transgenic mice overexpressing the defective human mutant SOD1 allele containing the Gly93→Ala (G93A) gene (B6SJL-TgN (SOD1-G93A)1Gur (herein “ALS mice”) were purchased from The Jackson Laboratory (Bar Harbor, Me., USA).
(xxxii) Immunization. Adult mice were immunized with Cop-1, 100 μg in 200 μl PBS s.c.
(xxxiii) Neural progenitor cell culture. Cultures of adult neural progenitor cells (aNPCs) were obtained as described in orevious examples
(xxxiv) Stereotaxic injection of neural progenitor cells. Mice were anesthetized a week after the first immunization and placed in a stereotactic device. The skull was exposed and kept dry and clean. The bregma was identified and marked. The designated point of injection was at a depth of 2 mm from the brain surface, 0.4 mm behind the bregma in the anteroposterior axis, and 1.0 mm lateral to the midline. Neural progenitor cells were applied with a Hamilton syringe (5×105 cells in 3 at a rate of 1 μl/min) and the skin over the wound was sutured.
(xxxv) Motor dysfunction. Motor dysfunction of the mice was evaluated using the rotarod task twice a week from 60 d of age onward. Animals were placed on a horizontal accelerating rod [accelerating rotarod (Jones and Roberts) for mice 7650] and time it took for each mouse to fall from the rod was recorded. We performed three trials at each time point for each animal and recorded the longest time taken. A cut-off time point was set to 180 sec and mice remaining on the rod for at least 180 sec were deemed asymptomatic. Onset of disease symptoms was determined as a reduction in rotarod performance between weekly time points. Animals were killed by euthanization when no longer able to right themselves within 30 seconds of being placed on their sides.
The animals were treated with Cop-1 Starting from day 59: in the first two weeks twice a week Cop-1, thereafter they received a weekly injection of Cop-1. The stem cells were given into the CSF: 500,000 cells (single injection of adult neural stem cells).
The experiment was carried out in order to explore whether administration of a combination of Cop-1 vaccination and stem cells has beneficial effect in a mice model of ALS (herein “ALS mice”). For this purpose, 59 days old ALS mice were treated as follows: group 1 (
Mice from each of the groups were weighted (twice a week) and examined routinely for vital signs, and for signs of motor dysfunction. The results obtained in
(xxxvi) Animals. C57BL/6 mice were purchased from Harlan (Jerusalem, Israel). Yellow fluorescent protein (YFP) 2.2 transgenic mice, (originated from C57BL/6 and CBA hybrids), which selectively express YFP on their motor and sensory neuronal population (Feng et al., 2000), were kindly provided by J. R. Sanes (Washington University St. Louis, Mo.). Female mice, 8-10 weeks of age, were used in all experiments.
(xxxvii) EAE. Disease was induced by immunization with the peptide p35-55 of rat MOG (SEQ ID NO:39), (Sigma, St. Louis, Mo.). Mice were injected subcutaneously at the flank, with a 200 μl emulsion containing 300 μg of MOG in CFA and 500 μg of heat-inactivated Mycobacterium tuberculosis (Sigma). An identical booster was given at the other flank one week later. Pertussis toxin (Sigma), 300 μg/mouse, was injected intravenously immediately after the first MOG injection and 48 h later. Mice were examined daily. EAE was scored as follows: 0, no disease; 1, limp tail; 2, hind limb paralysis; 3, paralysis of all four limbs; 4, moribund condition; 5, death.
(xxxviii) Glatiramer acetate (GA, Copaxone®, Copolymer 1) consists of acetate salts of synthetic polypeptides containing four amino acids: L-alanine, L-glutamate, L-lysine, and L-tyrosine. GA from batch 242990599, with an average molecular weight of 7300 kDa, obtained from Teva Pharmaceutical Industries (Petach Tikva, Israel) was used throughout the study. GA treatment was applied by 5-8 consecutive daily subcutaneous injections (2 mg/mouse) in different stages of disease [i.e., (1) starting immediately after EAE induction (prevention treatment), (2) starting after appearance of disease manifestations at day 20 (suppression treatment), or (3) starting during the chronic phase 45 days after induction (delayed suppression).
(xxxix) BrdU. 5-Bromo-2′-deoxyuridine (BrdU, Sigma), a thymidine analog incorporating into the DNA of dividing cells, was injected intraperitoneally (50 mg/kg), either concurrently with GA treatment (once each day), or immediately after completion of GA injections (twice each day).
(xl) Perfusion. Animals were deeply anesthetized with Nembutal and perfused transcardially with 2.5% paraformaldehyde. Brains were removed, postfixed in 1% paraformaldehyde and cryoprotected with 15% sucrose solution in PBS. Free-floating sections (16 μm thick) were cut coronally or sagitaly with a sliding microtome (Leica SM 2000r) through the entire brain and collected serially in PBS.
(xli) Immunohistochemistry. To detect BrdU-incorporated cells, sections were denatured in 2M HCl in PBS at 37° C. for 30 min and then neutralized with 0.1M borate buffer (pH 8.5) for 10 min at room temperature. To detect specific cell types, sections were pre-incubated in PBS solution containing 20% serum and 0.5% Triton-X-100 for 1 h, and then incubated overnight at room temperature with primary antibodies. The following primary antibodies were used: goat anti-doublecortin (DCX) C-18 (1:200, Santa Cruz Biotechnology, Santa Cruz, Calif.), mouse anti-NeuN (1:300, Chemicon, Temecula, Calif.), mouse anti-GFAP (1:100, Pharmingen, San Jose, Calif.), rabbit anti-phospho-histone (1:200, Upstate Biotechnology, Charlottesville, Va.), rat anti-BrdU (1:200, Harlan, Indianapolis, Ind.), rat anti-CD11b (1:50, Pharmingen) and chicken anti-BDNF (1:50, Promega, Madison, Wis.). The second antibody step was performed by labeling with highly cross-absorbed Cy2- or Cy3-conjugated antibodies to rat, mouse, rabbit, goat or chicken (Jackson ImmuneResearch, West Grove, Pa.), to avoid cross-reactivity, (1:200; 20-40 min). Control slides were incubated with secondary antibody alone. In some cases, to enhance the signal, we used biotinylated secondary antibodies for 90 min, followed by Cy2- or Cy3-conjugated Streptavidin (Jackson Immuno-Research). Sections were stained with Hoechst 33258 (Molecular Probes) for nuclear labeling. For detection of apoptosis, we used either rabbit anti-cleaved caspase-3 (1:75, Cell Signaling Technology, Beverly, Mass.) or TUNEL assay (Apoptag Fluorescein Detection Kit, Intergen, Purchase, N.Y.). In addition, we used Fluoro-Jade B derivate (Chemicon), which specifically binds to degenerating neurons.
(xlii) Microscopy. Stained sections were examined and photographed by a confocal microscope (Axiovert 100M; Zeiss, Oberkochen, Germany), or by a fluorescence microscope (E600; Nikon, Tokyo, Japan), equipped with Plan Fluor objectives connected to CCD camera (DMX1200F, Nikon). Digital images were collected and analyzed using Image Pro+software. Images were assembled using Adobe Photoshop (Adobe Systems, San Jose, Calif.).
(xliii) Quantification. Neuronal progenitor cells were quantified by counting the BrdU+ cells (those with BrdU/DCX dual staining) and by counting DCX+ cells (in the SGZ) or by measuring the DCX stained area (in the SVZ and RMS, where density did not permit counting of individual cells). Quantification was performed in coronal sections, in the SVZ starting at the level of the medial septum and 640 μm backward, and in the hippocampal DG (in both blades for BrdU/DCX or in the upper blade for DCX) through its septotemporal axis. Quantification in the RMS was done on sagital sections starting at 1 mm from the median line of the brain and 640 μm laterally. The Results for each brain structure were averaged from 8 unilateral levels per mouse (80 μm apart, 3-4 mice in each treatment group) and are expressed as change fold from naive controls. Quantification of BrdU/NeuN double positive cells in the cortex was performed in areas of 0.15 mm2, selected at random (10 sections counted/mouse, 3 mice in each treatment group).
(xliv) Statistical analysis. For BrdU and DCX analysis, the mean±SEM (averaged from 8 unilateral levels per mouse, 3-4 mice in each treatment group) was subjected to one-way analysis of variance (ANOVA), followed by Fishers' least significant difference (LSD) at comparison-wise error rate of 0.05, where appropriate. Since control values for BrdU incorporation were reduced as a function of time, results were expressed as change fold from naive controls injected concurrently with BrdU. The number of BrdU/NeuN double-positive cells in the cortex was averaged from 10 sections per mouse (3 mice in each treatment group) and expressed as cells per mm3.
(xlv) Preparation of stem cells. ROSA26 mice express lacZ in all tissues of the embryo and in most tissues of the adult mouse. Bone marrow (BM) cells were isolated from ROSA26 mice by flushing the femur and tibias with Hanks balanced salt containing 10% fetal bovine serum. A single cell suspension was prepared for transplantation.
To study the manifestations of EAE as well as GA treatment in the CNS, we used the MOG 35-55 peptide-induced EAE model in two mice strains: the C57BL/6 susceptible strain and the YFP 2.2 transgenic mice, which selectively express YFP (yellow fluorescent protein) on their motor and sensory neuronal population, and thus provide a simple tool to follow axonal/neuronal damage (Feng et al., 2000). YFP 2.2 mice were susceptible to MOG-induced EAE similarly to C57BL/6 mice (
In YFP 2.2 mice, YFP was expressed mainly by axons and dendrites. Partial population in the cerebral cortex and the hippocampus expressed YFP in cell bodies as well. YFP expression in brain sections from mice that had suffered grade 2-4 EAE revealed multiple neuronal malformations manifested in axonal transection, sparse processes and fiber deterioration (
In brains of EAE+GA mice (either prevention or suppression treatment), considerably less damage was detected than in brains of EAE mice, revealing a smaller amount of deteriorating fibers (
Immunostaining for MAC-1 (CD11b, expressed on macrophages and microglia and up-regulated after their activation), correlated with the extent of neuronal injury in EAE mice (shown in the cerebellum,
To evaluate the generation and proliferation of neuronal progenitor cells following the pathological process of EAE, as well as after GA treatment, we used two markers: the immature neuronal marker DCX (associated with migrating and differentiating neurons of fetal and adult brain), and BrdU (thymidine analog incorporating into DNA of dividing cells) that had been injected concurrently with GA treatment. Hence, DCX expression indicated the amount of new neurons generated 10-14 days before animal sacrifice, and the number of BrdU incorporated cells (those with BrdU/DCX dual staining) indicated the number of neuroprogenitors emerging during the BrdU injection period. Neuroproliferation was studied in the neuroproliferative zones—the subventricular zone (SVZ) as well as in the subgranular zone (SGZ) and the granular cell layer (GCL) of the hippocampus. BrdU and DCX manifested overlapping patterns.
In the SVZ of EAE mice, neuroprogenitor proliferation was elevated following disease appearance (25 days after EAE induction, 1 day after last BrdU injection) in comparison to the controls (
In the SGZ of the hippocampus, neuronal proliferation was elevated following disease appearance, but subsequently declined below that of naive control (
GA injection to naive mice (without EAE), either just prior to perfusion or a month earlier, did not result in significant elevation of BrdU or DCX expression, in both the SVZ and the DG (
To study the destiny of the induced progenitor cells, we first followed their mobilization into the route in which SVZ cells normally migrate in adult mice—the rostral migratory stream (RMS, illustrated in
Similar mobilization patterns of neuronal progenitors were found at a later time point (35 days after EAE induction, when GA treatment was given as prevention treatment, i.e., elevated DCX expression in the RMS of EAE vs. control mice, and even more robust migration in EAE+GA mice) (
Treatment of EAE mice with GA led not only to enhanced mobilization of neuronal progenitors through the RMS, but also to their migration into a region corresponding to the lateral cortical stream (LCS) of neuronal migration, naturally found in the developing forebrain (illustrated in
At early time point following GA treatment and BrdU injection (1-10 days), neuronal progenitors that migrated away from the RMS manifested BrdU and DCX co-expression as shown in the striatum (
At later time points (one month after completion of GA treatment), BrdU+ cells co-expressing the neuronal nuclear antigen (NeuN), were found in the striatum (
The newly generated neurons seemed to be attracted to damaged regions. Hence, clusters of DCX/BrdU as well as NeuN/BrdU co-expressing cells, were situated in areas with deteriorating YFP expressing fibers and lesions (
In lesions occupied by DCX+ cells (
The following experiment was carried out in order to assess the effect of the combination of glatiramer acetate (GA) and stem cells administration in an EAE model. We employed the myelin oligodendrocyte glycoprotein (MOG) induced EAE mice model. Neuronal and axonal degeneration are extensively manifested in EAE mice. GA treatment was applied in EAE mice in combination with stem cells by a procedure, which was found to be effective in generating self-neurogenesis, namely by daily subcutaneous injections.
Multipotent stem cells were obtained from bone marrow of ROSA26 transgenic mice, which express Lac-z in most tissues of the adult mouse. Expression of Lac-z gene was detected by enzymatic activity of the gene product beta-galactosidase. These stem cells were transplanted into EAE C57BL/6 mice by local stereotactical inclusion into the lateral ventricle of the brain. Alternatively, rt is possible to administer stem cells systemically by intravenous injection.
The effect of combined GA and stem cells administration was compared to administration of GA and stein cells separately. Untreated EAE mice and naive mice served as controls. After treatment, mice were inspected daily for neuronal symptoms and scored for disease severity and/or clinical improvement. The in situ effect of the treatments was evaluated by characterization of neuronal damage as described in 5(2) above. The fate of the transplanted cells was monitored using immunohistological methods as described in 5(4), 5(5) and 5(6) above. For example, proliferation was assessed by using markers such as BrdU injected concurrently with transplantation and differentiation was monitored by detecting DCX and NeuN markers. We also followed the migration of the transplanted cells and their ability to reach the lesion site.
Preliminary results obtained indicate that combined GA+stem cell treatment augmented the beneficial effect of each treatment separately, as evidenced by the above parameters inspected. The same beneficial effects can be obtained by the combined treatment of GA and stern cells in other experimental models. Thus, the combined treatment of GA and stem cells can be used in therapy of additional neurological diseases and other disorders.
The major finding reported here is that peripheral immunomodulatory treatment of an inflammatory autoimmune neurodegenerative disease induces neuroprotection as well as augmentation of the self-neurogenesis triggered by the pathological process. This results in massive migration of new neurons into injury sites, in brain regions that do not normally undergo neurogenesis, suggesting relevance to the beneficial effect of GA in EAE and MS.
The histopathological manifestations of MOG-induced EAE, in both C57BL/6 and YFP 2.2 strains were deteriorating fibers, axonal loss, widespread lesions, and nucleus margination, indicative of severe damage (
GA treatment resulted not only in decreased neuronal damage but also in increased neuronal proliferation. The combination of two detection markers allowed us to evaluate both the amount of new neurons generated 10-14 days before the animal was killed, by the overall expression of the immature neuronal marker DCX (Bayer et al., 1991) as well as the number of neuroprogenitors emerging during the concurrent BrdU/GA injection period (those that differentiated into the neuronal lineage and thus presented BrdU/DCX dual staining). Both systems gave comparable results as to the effect of the pathological process of EAE and that of GA treatment. Hence, EAE induction triggered increased neuroprogenitor proliferation in the neuroproliferative zones (the SVZ and the SGZ) following disease appearance (
Neuroprogenitors originated in the SVZ were mobilized into the route in which they normally migrate in adults, the RMS. This mobilization was increased in EAE mice, and GA augmented it even further (
At early time points following GA and BrdU injection (1-10 days after their last injection), BrdU+ neuroprogenitors expressed the immature neuronal marker DCX characteristic to migrating and differentiating neurons (Bernier et al., 2002), and displayed migratory morphology, fusiform somata with a leading and a trailing process (O'Rouke et al., 1995) (
These findings establish correlation between GA treatment and generation of neuroprotection and neurogenesis. It is possible that these effects result from suppression of inflammation—the insult initiating the pathological process, and thus the subsequent damage, as demonstrated for anti-inflammatory treatment after endotoxin administration (Monje et al., 2003). The ability of GA to shift cytokine secretion from the Th1 inflammatory to the Th2/3 anti-inflammatory pathway was demonstrated in the periphery of mice and humans (Aharoni et al., 1998; Duda et al., 2000). Moreover, GA induces specific Th2/3-cells that cross the BBB, accumulate in the CNS (Aharoni et al., 2000, 2002) and express in situ the anti-inflammatory cytokines IL-10 and TGF-β (Aharoni et al., 2003). In the present study as well, infiltrating T-cells were found in brains of EAE+GA mice, and in contrast to EAE mice, their location was not associated with damage (
It is of special significance that the newly generated neurons were attracted or recruited to damaged regions, as evidenced by their migration into gliotic scarred areas (
| Number | Date | Country | |
|---|---|---|---|
| 60631163 | Nov 2004 | US | |
| 60690498 | Jun 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11791681 | Jun 2008 | US |
| Child | 13281908 | US |
