Patent Application
20160075995
Throughout this disclosure, various technical and patent publications are referenced to more fully describe the state of the art to which this invention pertains. Some of the references are identified by first author name and date of publication. These publications are incorporated by reference, in their entirety, into this application.
The identification of expandable, self-renewable stem cells isolated from sweat glands and the establishment of a protocol for culturing and grafting them will pave the way for practical cell-based therapy for wound healing, and in particular, tissue grafts for the treatment of burns and tissue reconstitution.
Slow cycling is a common feature shared among several stem cells (SCs) identified in adult tissues including hair follicle and cornea. Recently, existence of unipotent SCs in basal and lumenal layers of sweat gland (SG) has been described and label retaining cells (LRCs) have also been localized in SGs, however, whether these LRCs possess SCs characteristic has not been investigated further.
Here, Applicant used a H2BGFP LRCs system for in vivo detection of infrequently dividing cells. This system allowed Applicant to specifically localize and isolate SCs with label-retention and myoepithelial characteristics restricted to the SG proximal acinar region. Using an alternative genetic approach, Applicant demonstrated that SG LRCs expressed keratin 15 (K15) in the acinar region and lineage tracing determined that K15 labeled cells contributed long term to the SG structure but not to epidermal homeostasis. Surprisingly, wound healing experiments did not activate proximal acinar SG cells to participate in epidermal healing. Instead, predominantly non-LRCs in the SG duct actively divided, whereas the majority of SG LRCs remained quiescent. However, when Applicant further challenged the system under more favorable isolated wound healing conditions, Applicant was able to trigger normally quiescent acinar LRCs to trans-differentiate into the epidermis and adopt its long term fate. In addition, dissociated SG cells were able to regenerate SGs and, surprisingly, hair follicles demonstrating their in vivo plasticity. By determining the gene expression profile of isolated SG LRCs and non-LRCs in vivo, Applicant identified several Bone Morphogenetic Protein (BMP) pathway genes to be up-regulated and confirmed a functional requirement for BMP receptor 1A (BMPR1A)-mediated signaling in SG formation.
This data highlight the existence of SG stem cells (SGSCs) and their primary importance in SG homeostasis. It also emphasizes SGSCs as an alternative source of cells in wound healing and their plasticity for regenerating different skin appendages.
In view of the above, the present disclosure provides an isolated self-renewable sweat gland (“SG”) stem cell and a clonal population of the stem cell that are useful in such therapies. The self-renewable sweat gland stem cell or clone is multipotent can be isolated from the proximal acinar gland region and not in the SG ductal region of mammalian sweat glands. In some embodiments, these multipotent stem cells are capable of differentiating into at least one, or alternatively at least two, or alternatively at least three, of sweat glands, hair follicles and epidermis, making them particularly useful for skin grafts.
Also provided is an isolated population of self-renewable multipotent sweat gland stem cells. In some embodiments, the isolated population of self-renewable multipotent sweat gland stem cells is substantially homogenous, i.e., greater than 60%, or alternatively greater than 70%, or alternatively greater than 80%, or alternatively greater than 85%, or alternatively greater than 90%, or alternatively greater than 95%, of the multipotent sweat gland stem cells.
Methods of isolating, preparing, culturing, expanding, propagating and/or differentiating the stem cells, and methods of using the cells or populations for treatment are also disclosed in the current disclosure.
Table 1 shows common DEG list for both SG LRCs and SG non-LRCs. Functionally categorized list of genes commonly identified in both SG LRCs (GFP+/α6+) and SG non-LRCs (GFP−/α6+) when compared to the basal layer of the sole's epidermis.
Table 2 shows unique DEG list for SG LRCs. Functionally categorized list of genes identified in SG LRCs (GFP+/α6+) when compared to the basal layer of the sole's epidermis.
Table 3 shows unique DEG list for SG non-LRCs. Functionally categorized list of genes identified in the basal layer SG non-LRCs (GFP−/α6+) when compared to the basal layer of the sole's epidermis.
Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods, devices, and materials are now described. All technical and patent publications cited herein are incorporated herein by reference in their entirety. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.
The practice of the present invention will employ, unless otherwise indicated, conventional techniques of tissue culture, immunology, molecular biology, microbiology, cell biology and recombinant DNA, which are within the skill of the art. See, e.g., Sambrook, Fritsch and Maniatis (1989) Molecular Cloning: A Laboratory Manual, 2nd edition; F. M. Ausubel, et al. eds. (1987) Current Protocols In Molecular Biology; the series Methods in Enzymology (Academic Press, Inc.): PCR 2: A Practical Approach (1995) (M. J. MacPherson, B. D. Hames and G. R. Taylor eds.); Harlow and Lane, eds. (1988) Antibodies, A Laboratory Manual; Harlow and Lane, eds. (1999) Using Antibodies, a Laboratory Manual; and R. I. Freshney, ed. (1987) Animal Cell Culture.
All numerical designations, e.g., pH, temperature, time, concentration, and molecular weight, including ranges, are approximations which are varied (+) or (−) by increments of 1.0 or 0.1, as appropriate. It is to be understood, although not always explicitly stated that all numerical designations are preceded by the term “about”. It also is to be understood, although not always explicitly stated, that the reagents described herein are merely exemplary and that equivalents of such are known in the art.
As used in the specification and claims, the singular form “a,” “an” and “the” include plural references unless the context clearly dictates otherwise.
As used herein, the term “comprising” is intended to mean that the compositions and methods include the recited elements, but do not exclude others. “Consisting essentially of” when used to define compositions and methods, shall mean excluding other elements of any essential significance to the combination when used for the intended purpose. Thus, a composition consisting essentially of the elements as defined herein would not exclude trace contaminants or inert carriers. “Consisting of” shall mean excluding more than trace elements of other ingredients and substantial method steps. Embodiments defined by each of these transition terms are within the scope of this invention.
The term “isolated” means separated from constituents, cellular and otherwise, in which the cell, tissue, polynucleotide, peptide, polypeptide, protein, antibody or fragment(s) thereof, which are normally associated in nature. For example, an isolated polynucleotide is separated from the 3′ and 5′ contiguous nucleotides with which it is normally associated in its native or natural environment, e.g., on the chromosome. As is apparent to those of skill in the art, a non-naturally occurring polynucleotide, peptide, polypeptide, protein, antibody or fragment(s) thereof, does not require “isolation” to distinguish it from its naturally occurring counterpart. An isolated cell is a cell that is separated form tissue or cells of dissimilar phenotype or genotype. In one aspect, the isolated naturally occurring stem cell or other composition is combined with an element with which it is not normally found in nature. Non-limiting examples of such include, detectable labels, polynucleotides, proteins or peptides and in combination with other compositions such as carriers, e.g., pharmaceutically acceptable carriers and supports and growth factors.
As used herein, “stem cell” defines a cell with the ability to divide (and self-renewal) for indefinite periods in culture and/or long-term contribution in vivo in tissue during normal homeostasis as well as reconstitution and give rise to specialized cells (fates) in tissue specific differentiation. At this time and for convenience, stem cells are categorized as somatic (adult), embryonic or induced pluripotent stem cells. A somatic stem cell is an undifferentiated cell found in a differentiated tissue that can renew itself (clonal) and (with certain limitations) differentiate to yield all the specialized cell types of the tissue from which it originated. An embryonic stem cell is a primitive (undifferentiated) cell from the embryo that has the potential to become a wide variety of specialized cell types. Non-limiting examples of embryonic stem cells are the HES2 (also known as ES02) cell line available from ESI, Singapore and the H1 or H9 (also known as WA01) cell line available from WiCell, Madison, Wis. Additional lines are pending NIH review. See for examplegrants.nih.gov/stem_cells/registry/current.htm (last accessed Oct. 2, 2009). Pluripotent embryonic stem cells can be distinguished from other types of cells by the use of markers including, but not limited to, Oct-4, alkaline phosphatase, CD30, TDGF-1, GCTM-2, Genesis, Germ cell nuclear factor, SSEA1, SSEA3, and SSEA4. An induced pluripotent stem cell (iPSC) is an artificially derived stem cell from a non-pluripotent cell, typically an adult somatic cell, produced by inducing expression of one or more stem cell specific genes.
The term “propagate” means to grow or alter the phenotype of a cell or population of cells. The term “growing” refers to the proliferation of cells in the presence of supporting media, nutrients, growth factors, support cells, or any chemical or biological compound necessary for obtaining the desired number of cells or cell type. In one embodiment, the growing of cells results in the regeneration of tissue. In yet another embodiment, the tissue is comprised of neuronal progenitor cells or neuronal cells.
The term “culturing” refers to the in vitro propagation of cells or organisms on or in media of various kinds. It is understood that the descendants of a cell grown in culture may not be completely identical (i.e., morphologically, genetically, or phenotypically) to the parent cell. By “expanded” is meant any proliferation or division of cells.
As used herein and as set forth in more detail below, “conditioned medium” is medium which was cultured with a mature cell that provides cellular factors to the medium such as cytokines, growth factors, hormones, and extracellular matrix.
“Differentiation” describes the process whereby an unspecialized cell acquires the features of a specialized cell such as a heart, liver, or muscle cell. “Directed differentiation” refers to the manipulation of stem cell culture conditions to induce differentiation into a particular cell type. “Dedifferentiated” defines a cell that reverts to a less committed position within the lineage of a cell. As used herein, the term “differentiates or differentiated” defines a cell that takes on a more committed (“differentiated”) position within the lineage of a cell. As used herein, “a cell that differentiates into a mesodermal (or ectodermal or endodermal) lineage” defines a cell that becomes committed to a specific mesodermal, ectodermal or endodermal lineage, respectively. Examples of cells that differentiate into a mesodermal lineage or give rise to specific mesodermal cells include, but are not limited to, cells that are adipogenic, leiomyogenic, chondrogenic, cardiogenic, dermatogenic, hematopoetic, hemangiogenic, myogenic, nephrogenic, urogenitogenic, osteogenic, pericardiogenic, or stromal.
Examples of cells that differentiate into ectodermal lineage include, but are not limited to epidermal cells, neurogenic cells, and neurogliagenic cells.
As used herein, the term “differentiates or differentiated” defines a cell that takes on a more committed (“differentiated”) position within the lineage of a cell. “Dedifferentiated” defines a cell that reverts to a less committed position within the lineage of a cell.
As used herein, a “multipotent cell” defines a less differentiated cell that can give rise to at least two distinct (genotypically and/or phenotypically) further differentiated progeny cells. In another aspect, a “pluripotent cell” includes an induced Pluripotent Stem Cell (iPSC) which is an artificially derived stem cell from a non-pluripotent cell, typically an adult somatic cell, produced by inducing expression of one or more stem cell specific genes. Such stem cell specific genes include, but are not limited to, the family of octamer transcription factors, i.e., Oct-3/4; the family of Sox genes, i.e., Sox1, Sox2, Sox3, Sox 15 and Sox 18; the family of Klf genes, i.e. Klf1, Klf2, Klf4 and Klf5; the family of Myc genes, i.e., c-myc and L-myc; the family of Nanog genes, i.e. OCT4, NANOG and REX1; or LIN28. Examples of iPSCs are described in Takahashi et al. (2007) Cell advance online publication 20 Nov. 2007; Takahashi & Yamanaka (2006) Cell 126:663-76; Okita et al. (2007) Nature 448:260-262; Yu et al. (2007) Science advance online publication 20 Nov. 2007; and Nakagawa et al. (2007) Nat. Biotechnol. Advance online publication 30 Nov. 2007.
“Self-renewable” refers to a cell being able to self-renew for over a number of passages without substantial changes of cell properties. In one aspect, the number of passages is at least about 5, or alternatively at least 10, or alternatively at least about 15, 20, 30, 50, or 100.
As used herein, the “lineage” of a cell defines the heredity of the cell, i.e. its predecessors and progeny. The lineage of a cell places the cell within a hereditary scheme of development and differentiation.
As used herein, the term “differentiates or differentiated” defines a cell that takes on a more committed (“differentiated”) position within the lineage of a cell. “Dedifferentiated” defines a cell that reverts to a less committed position within the lineage of a cell.
Clonal and subclonal population of cells are cells that maintain the original phenotypic markers and multipotency as the parent cell from which is was reproduced.
A “clonal culture” is a group of cells originated from one ancestor cell. Subclonal culture is a group of cells originated from one of clonally cultured cell. By comparing parental clonal and descendant subclonal culture, one should be able to determine whether subclonal population maintain the original phenotypic markers and multipotency.
“Bone Morphogenic Proteins” (BMP) are a group of multifunctional growth factors and cytokines with effects in various tissues. For example, BMPs are known to induce the formation of bone and/or cartilage. Examples of BMP may include, but are not limited to BMP1, BMP2, BMP3, BMP4, BMP5, BMP6, BMP7, BMP8a, BMP8b, BMP10 and BMP15.
“BMP signaling” or “BMP signaling pathway” refers to the enzyme linked receptor protein signaling transduction pathway involving proteins that directly or indirectly regulate (activate or inhibit) downstream protein activity or gene expression. Examples of molecules involved in the BMP signaling pathways may be found in the public Gene Ontology (GO) database, under GO ID: GO:0030509, accessible at the web page (amigo.geneontology.org/cgi-bin/amigo/term-details.cgi?term=G0:0030509&session id=5573amigo1226631957), last accessed on Nov. 17, 2008. Without limitation, examples of proteins in the BMP signaling pathway include Activin receptor type-1 (ACVR1, UniProt: Q04771), Activin receptor type-2A (ACVR2A, UniProt: P27037), Activin receptor type-2B (ACVR2B, UniProt: Q13705), BMP1 (UniProt: P13497), BMP2 (UniProt: P12643), BMP3 (UniProt: P12645), BMP4 (UniProt: P12644), BMP5 (UniProt: P22003), BMP6 (UniProt: P22004), BMP7 (UniProt: P18075), BMP8a (UniProt: Q7Z5Y6), BMP8b (UniProt: P34820), BMP10 (UniProt: 095393), BMP15 (UniProt: 095972), Bone morphogenetic protein receptor type-1A (BMPR1A, UniProt: P36894), Bone morphogenetic protein receptor type-1B (BMPR1B, UniProt: 000238), Bone morphogenetic protein receptor type-2 (BMPR2, UniProt: Q13873), Chordin-like protein (CHRDL1, UniProt: Q9BU40), Follistatin-related protein 1 (FSTL1, UniProt: Q12841), Growth/differentiation factor 2 (GDF2, UniProt: Q9UK05), Growth/differentiation factor 6 (GDF6, UniProt: Q6KF10), Growth/differentiation factor 7 (GDF7, UniProt: Q7Z4P5), Gremlin-2 (GREM2, UniProt: Q9H772), RGM domain family member B (RGMB, UniProt: Q6NW40), Ski oncogene (SKI, UniProt: P12755), Mothers against decapentaplegic homolog 4 (SMAD4, UniProt: Q13485), Mothers against decapentaplegic homolog 5 (SMAD5, UniProt: Q99717), Mothers against decapentaplegic homolog 6 (SMAD6, UniProt: 043541), Mothers against decapentaplegic homolog 7 (SMAD7, UniProt: 015105), Mothers against decapentaplegic homolog 9 (SMAD9, UniProt: 015198), E3 ubiquitin-protein ligase SMRF2 (SMURF2, UniProt: Q9HAU4), TGF-beta receptor type III (TGFBR3, UniProt: Q03167), Ubiquitin-conjugating enzyme E2 D1 (UBE2D1, UniProt: P51668), Ubiquitin-conjugating enzyme E2 D3 (UBE2D3, UniProt: P61077) and Zinc finger FYVE domain-containing protein 16 (ZFYVE16, UniProt: Q7Z3T8). Proteins that positively or negatively regulate the BMP signaling, for purpose of this invention, are also considered within the meaning of the BMP signaling. Proteins that positively regulate BMP signaling include, but are not limited to, Serine/threonine-protein kinase receptor R3 (ACVRL1, UniProt: P37023) and Endoglin (ENG, UniProt: P17813). Proteins that negatively regulate BMP signaling include, but are not limited to, Chordin (CHRD, UniProt: Q9H2X0), E3 ubiquitin-protein ligase SMURF1 (SMURF1, UniProt: Q9HCE7), Sclerostin (SOST, UniProt: Q9BQB4) and Brorin (VWC2, UniProt: Q2TAL6). Examples of proteins in the BMP signaling pathway may also include Proprotein convertase subtilisin/kexin type 6 (PCSK6, UniProt: P29122) that regulates BMP signaling.
Small molecules, polynucleotides, polypeptides that enhance or inhibit BMP signaling exist or can be made with procedures known by those skilled in the art. Yanagita (2009) BioFactors 35(2):113-199 is a review article discussing BMP regulators (incorporated by reference). For example, dorsomorphin is a potent small molecule BMP antagonist (Hao et al. (2008) PLoS ONE 3(8):e2904, Yu et al. (2008) Nat Chem Biol. 4(1):33-41). Dorsomorphin is currently commercially available from several vendors. Dorsomorphin was reported to selectively inhibit the BMP receptors, type I: ALK2, ALK3 and ALK6 and thus “blocks BMP-mediated SMAD1/5/8 phosphorylation”. Dorsomorphin has preferential specificity toward inhibiting BMP versus TGF-beta and activin signaling. In published reports, dorsomorphin is characterized by low toxicity. It can be delivered into skin to lower macro-environmental BMP signaling and create favorable conditions for hair growth to occur. A unique property of dorsomorphin is that it is a small molecule and is soluble in DMSO. DMSO is known to significantly facilitate trans-dermal delivery of small molecule drugs. This enhancing effect of DMSO on skin penetration can be used in non-invasive method of pharmacological modulation of dermal macro-environment. Treatment procedure thus consists of simply applying liquid form of dorsomorphin in DMSO onto the surface of intact skin. Dorsomorphin in DMSO can be made in form of cream that can be simply rubbed onto intact skin. Small molecule agonist and antagonists for other signaling pathways also exist and can be used to augment or inhibit BMP signaling. Interaction of these small molecules with pathways including, but not limited to, WNT, SHH and FGF will also have direct or indirect impact on BMP signaling thus serve as effective modulator of hair growth via methods disclosed in this invention.
In some aspects, an agent that can augment or inhibit BMP signaling is a small molecule agonist or antagonist to a BMP agonist or antagonist. In one aspect, the small molecule is a noggin agonist. In another aspect, the small molecule is a noggin antagonist.
Examples of agents that can augment or inhibit BMP signaling also include, but are not limited to, polynucleotides that encode BMP proteins, encode polypeptides augmenting or inhibiting BMP signaling, or augmenting or inhibit expression of BMP proteins, or polypeptides augmenting or inhibiting BMP signaling. In some embodiments, the agent is small interference RNA (siRNA) or double strand RNA (dsRNA) that inhibits expression of proteins that augment or inhibit BMP signaling.
Examples of agents that can augment or inhibit BMP signaling may also include, but are not limited to, an isolated or recombinant BMP protein, or isolated or recombinant polypeptide enhancing or inhibiting BMP signaling. In some aspect, the agent further comprises a pharmaceutically acceptable carrier. In another aspect, the compositions contain carriers that modulate (controlled release) the release of the active agent when administered to a subject in need thereof.
Examples of polypeptide agents that augment or inhibit BMP signaling may also include, but are not limited to, antibodies or modified antibodies including, but not limited to, blocking fragments of antibodies, that activate, stabilize or inhibit proteins in the BMP signaling pathway or proteins modulating the BMP signaling pathway, thereby augmenting or inhibiting BMP signaling.
As used herein, the term “modulate” refers to an act by an agent to regulate, to control or to change certain characteristics of the formation of pilosebaceous units. Examples of the agent may include, but are not limited to, proteins or polypeptides, DNA, RNA, siRNA, dsRNA or other polynucleotides, small molecules. The agent may also mean a temperature change, physical movement or stimulus or any other therapeutic or clinical means that alter the formation of pilosebaceous units. Without limitation, the object may mean a biochemical molecule or pathway, a biochemical activity, a medical condition or any other chemical, biochemical, physical or medical aspect of a subject. In one aspect, the term “modulate” means to enhance the formation of pilosebaceuous units in a plane. In another aspect, the term “modulate” means to inhibit the formation of pilosebaceous units on a plane.
A “composition” is also intended to encompass a combination of active agent and another carrier, e.g., compound or composition, inert (for example, a detectable agent or label) or active, such as an adjuvant, diluent, binder, stabilizer, buffers, salts, lipophilic solvents, preservative, adjuvant or the like. Carriers also include pharmaceutical excipients and additives proteins, peptides, amino acids, lipids, and carbohydrates (e.g., sugars, including monosaccharides, di-, tri-, tetra-, and oligosaccharides; derivatized sugars such as alditols, aldonic acids, esterified sugars and the like; and polysaccharides or sugar polymers), which can be present singly or in combination, comprising alone or in combination 1-99.99% by weight or volume. Exemplary protein excipients include serum albumin such as human serum albumin (HSA), recombinant human albumin (rHA), gelatin, casein, and the like. Representative amino acid/antibody components, which can also function in a buffering capacity, include alanine, glycine, arginine, betaine, histidine, glutamic acid, aspartic acid, cysteine, lysine, leucine, isoleucine, valine, methionine, phenylalanine, aspartame, and the like. Carbohydrate excipients are also intended within the scope of this invention, examples of which include but are not limited to monosaccharides such as fructose, maltose, galactose, glucose, D-mannose, sorbose, and the like; disaccharides, such as lactose, sucrose, trehalose, cellobiose, and the like; polysaccharides, such as raffinose, melezitose, maltodextrins, dextrans, starches, and the like; and alditols, such as mannitol, xylitol, maltitol, lactitol, xylitol sorbitol (glucitol) and myoinositol.
“Substantially homogeneous” describes a population of cells in which more than about 50%, or alternatively more than about 60%, or alternatively more than 70%, or alternatively more than 75%, or alternatively more than 80%, or alternatively more than 85%, or alternatively more than 90%, or alternatively, more than 95%, of the cells are of the same or similar phenotype. Phenotype can be determined by a pre-selected cell surface marker or other marker.
“Detectable labels” or “markers” include, but are not limited to radioisotopes, fluorochromes, chemiluminescent compounds, dyes, and proteins, including enzymes. Non-limiting examples of such include a gene encoding an enhanced green fluorescent protein (EGFP), red flouresence protein (RFP), green fluorescent protein (GFP) and yellow fluorescent protein (YFP) or the like. These are commercially available and described in the technical art.
Sweat gland stem cell (SGSC) are a multipotent cell type that can generate a variety of cell types, including sweat glands, hair follicles and the epidermis. The cells can be identified by a series of markers which include but are not limited to genes important for Bone Morphogenetic Protein (BMP) signaling, including Bmpr1, Bmpr2, Smad5, id2 id3 and decorin that are shown to be upregulated in the SGSC when compared to the epidermis. Marker analysis of the SGSC is provided in the Example and incorporated herein by reference.
The SGSC can also be identified by its multipotency, e.g., the capacity to differentiate into at least one tissue or cell type selected from the group of a sweat gland, hair follicle and epidermis.
“Treating” or “treatment” of a disease includes: (1) preventing the disease, i.e., causing the clinical symptoms of the disease not to develop in a patient that may be predisposed to the disease but does not yet experience or display symptoms of the disease; (2) inhibiting the disease, i.e., arresting or reducing the development of the disease or its clinical symptoms; or (3) relieving the disease, i.e., causing regression of the disease or its clinical symptoms.
The term “effective amount” refers to a concentration or amount of a reagent or composition, such as a composition as described herein, cell population or other agent, that is effective for producing an intended result, including cell growth and/or differentiation in vitro or in vivo, or for tissue regeneration. It will be appreciated that the number of cells to be administered will vary depending on the specifics of the disorder to be treated, including but not limited to size or total volume/surface area to be treated, as well as proximity of the site of administration to the location of the region to be treated, among other factors familiar to the medicinal biologist and/or treating physician.
The terms effective period (or time) and effective conditions refer to a period of time or other controllable conditions (e.g., temperature, humidity for in vitro methods), necessary or preferred for an agent or composition to achieve its intended result, e.g., the differentiation of cells to a pre-determined cell type.
The term patient or subject refers to animals, including mammals, such as murine, canine, feline, equine, bovine, simian or humans, who are treated with the pharmaceutical compositions or in accordance with the methods described herein.
The term pharmaceutically acceptable carrier (or medium), which may be used interchangeably with the term biologically compatible carrier or medium, refers to reagents, cells, compounds, materials, compositions, and/or dosage forms that are not only compatible with the cells and other agents to be administered therapeutically, but also are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other complication commensurate with a reasonable benefit/risk ratio. Pharmaceutically acceptable carriers suitable for use in the present invention include liquids, semi-solid (e.g., gels) and solid materials (e.g., cell scaffolds and matrices, tubes sheets and other such materials as known in the art and described in greater detail herein). These semi-solid and solid materials may be designed to resist degradation within the body (non-biodegradable) or they may be designed to degrade within the body (biodegradable, bioerodable). A biodegradable material may further be bioresorbable or bioabsorbable, i.e., it may be dissolved and absorbed into bodily fluids (water-soluble implants are one example), or degraded and ultimately eliminated from the body, either by conversion into other materials or breakdown and elimination through natural pathways.
The term administration shall include without limitation, administration by oral, topical. parenteral (e.g., intramuscular, intraperitoneal, intravenous, ICV, intracisternal injection or infusion, subcutaneous injection, or implant), by inhalation spray nasal, vaginal, rectal, sublingual, urethral (e.g., urethral suppository) or topical routes of administration (e.g., gel, ointment, cream, aerosol, etc.) and can be formulated, alone or together, in suitable dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers, adjuvants, excipients, and vehicles appropriate for each route of administration. The disclosue is not limited by the route of administration, the formulation or dosing schedule.
The terms autologous transfer, autologous transplantation, autograft and the like refer to treatments wherein the cell donor is also the recipient of the cell replacement therapy. The terms allogeneic transfer, allogeneic transplantation, allograft and the like refer to treatments wherein the cell donor is of the same species as the recipient of the cell replacement therapy, but is not the same individual. A cell transfer in which the donor's cells and have been histocompatibly matched with a recipient is sometimes referred to as a syngeneic transfer. The terms xenogeneic transfer, xenogeneic transplantation, xenograft and the like refer to treatments wherein the cell donor is of a different species than the recipient of the cell replacement therapy.
In one aspect, this invention provides an isolated self-renewable sweat gland stem cell (SGSC). The isolated self-renewable SGSC stem cell can be isolated from any source, examples of which include without limitation, any animal (alive or dead) so long as the tissue containing the SGSC is viable. Thus, the isolated SGSC can be animal, e.g., mammalian such as equine, feline, canine, porcine, bovine, murine, simian, and human.
The SGSC is isolated from the tissue source by any means that allows for isolation of a single cell by use of an identifying marker, e.g., FACS analysis. Details of this procedure are provided herein.
In one aspect, the isolated SGSC are isolated using FACS analysis and the stem cell markers to isolate the cell and composition are provided herein.
In addition to the markers, the isolated cell is identifiable by its multipotency, e.g., it is capable of differentiation into at least one, two or all three cell or tissue type selected from sweat gland, hair follicle and epidermis. Confirmation of the differentiation state of the cells can be performed by identification of cell type specific markers as known to those of skill in the art and as identified herein. In one aspect, the isolated sweat gland stem cell is capable of differentiation into at least two of the cell types. In another aspect, the isolated sweat gland stem cell is capable of differentiation into at least two, or alternatively at three tissue or cell types
In a further aspect, this invention provides isolated clonal population or a population of substantially homogeneous, i.e., at least 50%, or alternatively at least 70%, or alternatively at least 80%, or alternatively at least 85%, or alternatively at least 90%, or alternatively at least 95%, of the isolated sweat gland stem cell as described above. The clonal population contains majorities of the characteristics of the isolated cell as identified above.
This disclosure also provides an isolated SGSC as described above or an isolated population of same further comprising an exogenous agent, e.g., a small molecule, detectable label (e.g., a label for use in FACs analysis), growth factor, differentiating factor, protein, polypeptide, fibroblast, antibody or a non-naturally occurring nucleic acid, e.g., a therapeutic nucleic acid. Thus, these compositions are useful in the therapeutic and diagnostic methods as described herein as well as the screens for new therapeutic agents. In one aspect, the cells and compositions are useful for the treatment of wound in a subject by administering and effective amount of the cells and/or compositions. Another aspect relates to a method for promoting wound healing, promoting or increasing wound healing, decreasing the size of a wound, or decreasing the time to wound healing in a subject patient in need thereof comprising administering the isolated cell or population of the isolated cell as described herein.
This disclosure also provides methods for isolating a SGSC and/or a method for preparing a substantially homogeneous population of isolated sweat gland stemcells or populations as described. To isolate the SGSC, the method requires contacting a source cell, population or tissue likely to contain the SGSC with a detectably labeled antibody or other ligand that is specific for one or more identifying marker as identified above. After sufficient time and under appropriate conditions to allow the ligand to bind the marker to form a ligand-marker complex. The cells having the ligand-marker complex are then separated by any appropriate means, e.g., by FACs, from those that do not have a ligand-marker complex, thereby preparing an isolated SGSC.
In a further aspect, this disclosure provides a method for preparing a clonal population, a mass culture and/or differentiating an isolated sweat gland stem cell as described above or the population as described above by contacting the cell or population with an effective amount of a clonal expansion medium or differentiation medium as described herein and culturing of the cells under the appropriate conditions to obtain any of a clonal population or a mass culture or yet further differentiation into a selected lineage. In one aspect, the method prepares an expanded substantially homogenous population of SGSCs, or sweat glands, epidermal cells, or hair follicle cells. These populations are useful in the therapeutic and diagnostic methods as described herein as well as the screens for new therapeutic agents. The contacting may be performed in vitro or in vivo, depending on the intended use. For example, the isolated cell or population of cell can be implanted (autologous or allogeneic) into a subject and appropriate conditions can be locally administered to induce expansion and/or differentiation. Alternatively, the microenvironment of the cells will induce the appropriate differentiation of the cells into the cells and tissue. Yet further, agents can be administered to the subject to induce local expression of the agents that in turn, induce expansion and differentiation.
The isolated cells and/or populations of cells as described herein can be further combined with carrier, e.g., a pharmaceutically acceptable carrier or biocompatible matrix, for ease of administration.
The cell compositions as described herein are useful therapeutically and diagnostically. The compositions comprise, or alternatively consisting essentially of, or yet consisting of an isolated population of stem cells and a carrier, that optionally comprise an agent that maintains pluripotency of the cells in composition and/or a preservative. In one aspect, this disclosure provides a method for treating a wound, a burn or tissue grafting or associated disease, disorder or condition as is apparent to those of skill in the art, in a subject in need thereof, comprising, alternatively consisting essentially of, or yet further consisting of administering to the subject an effective amount of the isolated sweat gland stem cell as described above or the population as describe herein thereby treating the SGSC treatable disease, disorder or condition. Methods of administering cell populations are well known in the art and will depend on the treatment and individual. One or more administrations may be necessary. The cells may be autologous, allogeneic syngeneic or xenogeneic to the subject being treated. The subjects can be mammalian, e.g., bovine, feline, canine, equine or a human patient.
This disclosure also provides the use of the isolated sweat gland stem cell or the population of as described herein in the manufacture of a medicament as well as compositions containing the same. In one aspect, the medicament is to treat a SGSC treatable disease, disorder or condition.
The invention provides an article of manufacture, comprising packaging material and at least one vial comprising a solution of at least one agent or composition with the prescribed buffers and/or preservatives, optionally in an aqueous diluent, wherein said packaging material comprises a label that indicates that such solution can be held over a period of 1, 2, 3, 4, 5, 6, 9, 12, 18, 20, 24, 30, 36, 40, 48, 54, 60, 66, 72 hours or greater. The invention further comprises an article of manufacture, comprising packaging material, a first vial comprising at least one agent or composition and a second vial comprising an aqueous diluent of prescribed buffer or preservative, wherein said packaging material comprises a label that instructs a patient to reconstitute the therapeutic in the aqueous diluent to form a solution that can be held over a period of twenty-four hours or greater.
A method for identifying an agent that modulates the growth or differentiation of the isolated sweat gland stem cell is further provided by this invention. The method comprises, or alternatively consisting essentially of, or yet further consisting of, using the isolated cell or the population of cells and contacting the cell or the population with the agent wherein a change of growth or differentiation of the cell or population indicates that the agent modulates the growth or differentiation of the cell or the population.
All frozen sections were fixed in 4% Paraformaldehyde. Tissue sections were stained with hematoxylin and eosin for H&E visualization. For LacZ visualization, frozen sections were fixed in 0.2% Glutaraldehyde for 1 min, washed with PBS, and stained with 1 mg/ml X-gal overnight at 37° C. For immunofluorescence staining, sections were permeabilized with 0.1% Triton X-100 for 10 min and blocked in 0.1% Triton-PBS, 0.5% goat serum, and 0.1% BSA for 1 h at room temperature. Primary antibodies were incubated in the blocking buffer overnight at 4° C., wash with PBS. Secondary antibodies were incubated in 0.1% BSA for 1 h at room temperature. The following primary antibodies were used: K14 (1:200; gift from E. Fuchs Lab), CD104 (1:100; BD Pharmingen, 553745), K8 (TROMA-1, 1:100; Developmental Studies Hybridoma Bank), K18 (1:200; gift from E. Fuchs Lab), p63a (H-129, 1:100; Santa Cruz Biotech, sc-8344), SMA (1:200; Sigma, A5228), Laminin (1:100; Thermo Scientific, RB-082-A1), K15 (1:100; Thermo Scientific MS-1068-P1), Na+/K+ ATPase (1:300; abcam ab58475), K5 (1:300; gift from C. Jamora), Ki67 1:200 (Leica, NCL-Ki67p), P-Smad1/5/8 1:50 (Cell Signaling, 9511), BrdU 1:200 (abcam ab6326), K1 1:300 (gift from C. Jamora), Loricrin 1:300 (gift from C. Jamora), AE15 1:100 (Santa Cruz Biotech, sc57012), AE13 1:100 (Santa Cruz Biotech, sc80607). Secondary antibodies: Rabbit anti-Rat TRITC 1:300 (Sigma T4280), Goat anti-Rabbit TRITC 1:300 (Sigma T6778), Goat anti-Mouse TRITC 1:300 (Sigma T6528), Alexa 594 Goat anti-Chicken 1:500 (Invitrogen A11042), Alexa 488 Goat anti-Chicken 1:500 (Invitrogen A11039), Goat anti-Rabbit FITC 1:300 (Sigma F9887), Alexa 350 Goat anti-Rat 1:150 (Invitrogen A21093), Alexa 350 Donkey anti-Rabbit 1:150 (Invitrogen A10039).
KSTetOff/TreH2BGFP animals were fed 1 mg/g doxycycline food for 4 weeks starting around P21-28. GFP+ sweat glands were dissected out with its surrounding sole's epidermis from the fingertips of 20-30 mice and treated with 1000 U/ml Collagenase type I for 1 h at 37° C. with shaking Sweat glands were mechanically separated from its epidermis and treated further with 1000 U/ml Collagenase type I and 500 μg/μl Hyaluronidase (Sigma) for 1 h at 37° C. with shaking Purified sole's epidermis and SGs were independently washed with DPBS and digested in 0.25% Trypsin-EDTA for 20 min at 37° C. with shaking Neutralize and filter cells through a 40 um cell strainer.
For FACS, isolated 4 weeks chased H2BGFP labeled sweat gland cells were stained with a primary antibody: anti-α6 integrin (CD49f) conjugated to PE (1:200; BD Pharmingen) for 30 min and sorted using the FACS Aria II cell sorter (BD, Bioscience) for H2BGFP+/α6+ and H2BGFP−/α6+ populations. Cells were collected in RNAprotect Cell Reagent (Qiagen) for later RNA isolation. Similarly, FACS analysis were performed on isolated K15-GFP labeled sweat gland cells, stained with the primary antibody against anti-α6 integrin as described above.
A silicon chamber was implanted onto the backs of immunocompromised “nude” mice with a full-thickness skin wound as previously described (Weinberg, W. C. et al. (1993) J Invest Dermatol. 100:229-236). 4 weeks chased whole H2BGFP sweat glands were dissected out with its surrounding sole's epidermis from the fingertips and treated with 1000 U/ml Collagenase type I for 1 h at 37° C. with shaking After separation from the sole's epidermis, purified dermis with remaining sweat glands were transplanted into the humidified silicone chamber. The upper chamber was removed 2 weeks after transplantation and the bottom half is removed 3 weeks after transplantation as the skin is healing. The nude mice were either fed regular mouse diet or doxycycline food after transplantation for the duration of the experiments.
Similarly, dissociated unsorted 4 weeks chased SG single cell suspension labeled with H2BGFP after separation from the sole's epidermis was mixed with freshly isolated unmarked newborn dermal fibroblasts (approximately 6 million cells total) at a 1:1 proportion and injected into the chamber. Mice were sacrificed and samples from the graft regions were taken for GFP+ expression and tissue analysis. All mice work was conducted according to the Institutional Animal Care and Use Committee (IACUC) at the University of Southern California. The protocols (No. 11306 and 11325) were approved by the IACUC Committee. All surgery was performed under either isoflurane or ketamine anesthesia and all efforts were made to minimize suffering with analgesics (Buprenex prior and post-surgery was administrated).
Dissociated unsorted SG single cell suspension labeled with H2BGFP after 4 weeks of chase after separation from the sole's epidermis was mixed with freshly isolated unmarked newborn dermal fibroblasts at a 1:1 proportion and injected subcutaneously underneath the back skin of an immunocompromised “nude” mouse (approximately 1.5 million cells per spot).
Confocal Microscopy of sweat gland LRCs and 3D reconstruction of sweat glandsTissue was imaged on a Zeiss (Carl Zeiss, LLC) Axiovert 200 inverted microscope with an LSM 510 meta confocal scan head using a 40×/1.2NA water immersion lens. Tissue was dissected, stained and placed in a 35 mm glass bottom tissue culture dish (MatTek Corporation, Asland, Md.). Tissues were submerged in deionized water to minimize refractivity. Histone 2B GFP and TRITC stained laminin (1:100; Thermo Scientific, RB-082-A1) were visualized using conventional confocal imaging using argon laser lines at 488 nm and 543 nm, respectively. DAPI was imaged with 2-photon excitation using a Coherent Chameleon (Coherent Inc, Santa Clara, Calif.), pulsed laser tuned to 800 nm. Images were collected at 0.22 μm in plane (xy) and optically sectioned at 2 μm (in z). 3D reconstruction and visualizations were performed in ImageJ (http://rsbweb.nih.gov/ij/), Fiji (http://fiji.sc/wiki/index.php/Fiji), Avizo 6.3 (VSG, Burlinton, Mass.) and Vaa3D (http://www.vaa3d.org/).
RNA Isolation and qPCR
Total RNAs were purified from FACS-sorted SG LRCs, SG non-LRCs, and the basal layer of the sole's epidermis using Qiagen's RNeasy Micro kit according to the manufacturer's instructions. Equal amounts of RNA were reverse transcribed using the Superscript III First-Strand Synthesis System (Invitrogen) according to the manufacturer's instructions. cDNAs were amplified by PCR and used in triplicate for each qPCR sample primer set with all primer sets designed to work under the same conditions. Real-time PCR amplification of particular genes of interest was performed using an Applied Biosystems 7900HT Fast Real-Time PCR System and the fold difference between samples and controls were calculated based on the 2−ΔΔCT method, normalized to β-actin levels.
Total RNAs from FACS of SG LRCs (GFP+/α6 integrin+), SG non-LRCs (GFP−/α6 integrin+), and sole's epidermis (α6 integrin+) were purified using a RNeasy Micro Kit (Qiagen, Valencia Calif., United States), and quantified (Nanodrop, United States) for two separate microarray analysis from two independent biological samples. RNA 6000 Pico Assay (Agilent Technologies, Palo Alto, Calif., United States) was used for RNA quality check. Amplification/labeling were performed on 50 nanogram (ng) and 250 ng to obtain biotinylated cRNA (Ovation™ RNA Amplification System; Nugen, San Carlos, Calif., United States and Ambion Kit; Affymetrix, Santa Clara, Calif., United States, respectively), and either 3.75 μg or 5.5 μg ssDNA were used for fragmentation, labeling and hybridization. Hybridization was performed at 45° C. for 18 h to Mouse Gene 1.0 ST array (Affymetrix, Santa Clara, Calif., United States). Processed chips were read by GeneChip Scanner 3000 7G (Genomics Core Facility, Children's Hospital Los Angeles, Los Angeles, Calif., United States). The raw expression intensity data was imported into Partek Genomic Suite v6 (Partek Inc., St. Louis, Mo., United States). The data was pre-processed using the RMA algorithm with the default Partek setting. Following fold change calculations, differentially expressed gene (DEG) lists containing probe sets with 2-fold intensity changes in either direction were generated. Common DEG list was generated by comparing the DEG list of the sweat gland LRCs experiment and GFP-α6+ sweat glands experiment to the sole's epidermis. Functional annotation of the DEG list was carried out using the “Database for Annotation, Visualization and Integrated Discovery” (DAVID). The microarray data are available in a public GEO database with an accession number (#GSE49011).
Slow Cycling LRCs are Localized to the Proximal—Acinar Region of Sweat Glands.
Applicant employed the recently developed H2BGFP system, composed of two transgenic mouse lines: keratin 5-driven tetracycline repressor mice (K5-tTA) (Diamond, I. et al. (2000) J Invest Dermatol. 115:788-794) and tetracycline response element-driven histone H2B-GFP transgenic mice (pTRE-H2B-GFP) (Tumbar, T. et al. (2004) Science 303:359-363), to detect live, slow cycling LRCs in vivo. In these animals, H2BGFP expression was uniformly detected in all cells of the epidermis, hf and SGs (ducts and glands) prior to Doxy treatment (
Sweat Gland LRCs are Attached to the Basement Membrane and Demonstrate Myoepithelial Characteristics.
SGs are composed of three different cell types, dark apical cells of the lumen, clear and myoepithelial cells of the basal layer. Therefore, Applicant used immunofluorescence staining with a number of different markers to determine where SG LRCs are localized. Applicant demonstrated that these SG LRCs are attached to the basement membrane expressing β4 integrin (
SGs exist as 3-dimensional (3D) structures therefore, Applicant performed whole mount staining of 4 weeks chased SGs with a basement membrane marker, laminin, (with DAPI nuclear counterstain) to examine how these LRCs are organized within this appendage (
Sweat Gland LRCs Express Keratin 15 (K15) in the Acinar Region and K15 Marked Cells Contribute Long Term to the Sweat Gland Structure but not to Epidermal Homeostasis.
It has been previously shown that another LRC population located in the hf bulge specifically expresses K15 (Morris, R. J. et al. (2004) Nat Biotechnol. 22:411-417), therefore, Applicant examined whether K15 expression is also present in SGs. First, using K15 Ab staining, Applicant demonstrated that mouse SG LRCs co-localized with K15 (
To demonstrate whether K15 marked cells in SGs co-localized with LRCs, Applicant used a K15CrePR system with a Rosa26-tdTomato reporter mouse crossed onto the KSTetOff/TreH2BGFP background. After 4 weeks of chase with Doxy treatment (at ˜P49) when LRCs (green) were present in SGs, Applicant labeled the K15 expressing cells using a short RU treatment for 2 days to mark K15 positive cells in SGs with tdTomato expression (
Isolating LRCs from Sweat Glands
To isolate pure fractions of SG LRCs, Applicant used a combination of surgical dissection with subsequent enzymatic digestions. To avoid contamination from hf LRCs, Applicant collected the whole paw with the toes and dissected out SGs with the surrounding sole's epidermis (
To identify the transcriptional gene expression profile of SG basal layer cells, total RNA was extracted from the GFP+/α6+ population (SG LRCs), GFP−/α6+ adjacent basal layer cells (SG non-LRCs), and α6+ basal layer cells of the sole's epidermis for microarray analyses from two independent experiments. Purification and microarray hybridization (Affymetrix Mouse Gene 1.0ST) of each fraction were performed in duplicate. Then, each population, SG LRCs and non-LRCs, were compared separately to the basal layer of the sole's epidermis (
As SG LRCs showed myoepithelial characteristics, Applicant further probed how the gene expression profile in this population corresponded to its function when compared to SG non-LRCs basal cells. To this end, Applicant performed functional annotations (grouped according to the DAVID software) which enabled us to categorize a number of identified genes in LRCs and non-LRCs (
Acinar Sweat Gland Cells do not Contribute to the Epidermis During Wound Healing.
Previously, it has been reported that bulge hfSCs with LRCs characteristic do not participate in epidermal homeostasis, however, they can actively deliver cells to the epidermal wound during skin injury (Ito, M. et al. (2005) Nat Med. 11:1351-1354). In addition, keratinocytes in the region directly above bulge LRCs, marked by Lgr6, can postnatally generate the sebaceous gland and interfollicular epidermis contributing to epidermal homeostasis and can execute long term wound repair (Snippert, H. J. et al. (2010) Science 327:1385-1389; Petersson, M. et al. (2011) EMBO J 30:3004-3018). However, little is known about the role of SGs in active epidermal regeneration initiated upon wounding. In human SGs, it has been reported that basal cells of the straight duct undergo division when provoked by skin injury (Lobitz, W. C., Jr. et al. (1954) J Invest Dermatol. 22:189-198).
Since Applicant has demonstrated that SG acinar cells marked by K15CrePR/R26LacZ do not participate in epidermal keratinocyte lineages during homeostasis, Applicant next examined if these acinar SG cells could respond and actively contribute to epidermal wound repair upon injury. Wounds where the epidermis was effectively scraped off were performed on K15CrePR/R26LacZ mice in order to trace K15 positive SG cells and their progeny. Wounds were allowed to heal for 24 h, 48 h, and 72 h when samples were collected for analysis. X-gal staining for LacZ enabled visualization of K15 positive SG cells and their progeny (blue). At all time points, no blue cells were detected in the regenerating epidermis (
Sweat Gland LRCs can Trans-Differentiate into the Epidermis Under Prolonged Isolated Wound Healing
Although the SG acinar cells did not contribute to wound healing under normal circumstances, Applicant further challenged the system using more favorable conditions. For this, Applicant isolated 4 weeks chased H2BGFP labeled whole SGs through collagenase digestion (as described in
However, since these experiments were performed “off Doxy” Applicant was not able to rule out whether the SG H2BGFP LRCs themselves proliferated and contributed to this newly formed epidermis or whether other non-LRC SG cells “turned on” H2BGFP expression in the absence of Doxy. To address this, Applicant repeated this experiment using 4 weeks chased H2BGFP labeled SGs. In this case, the host mouse with transplanted SG dermis was kept on Doxy treatment for the entire experiment; thus, only SG LRCs and their direct descendents would be marked by H2BGFP. At 30 and 40 days after transplantation, the H2BGFP label appeared to have been diluted out of some acinar SG structures (confirmed by K8 lumenal layer staining) but not all (
Finally, since Applicant was unable to passage and expand these KSTetOff/TreH2BGFP cells in culture, Applicant could not probe their in vitro potential and subsequently use them for in vivo reconstitution assays. Instead, Applicant used unsorted dissociated SG cells isolated directly from whole SGs. To further probe the regenerative potential of all SG cells, Applicant dissociated 4 weeks chased, H2BGFP labeled, SGs into a single cell suspension after separation from the sole's epidermis (as in
Here, Applicant demonstrates that cells with slow cycling characteristic exist in SGs as a scattered population localized in the SG basal layer of the proximal acinar region. As hair follicle LRCs have been previously described as SCs (Tumbar, T. et al. (2004) Science 303:359-363), Applicant asked if these newly identified SG LRCs also possess bona fide stem cell characteristics in vivo. Although LRCs have been reported in both mouse and human SGs (Nakamura, M. et al. (2009) J Invest Dermatol. 129:2077-2078), their characterization, precise localization and function has not been addressed so far. The KSTetOff/TreH2BGFP approach allows us to mark and isolate live SG LRCs in vivo for further characterization. Thus, Applicant was able to localize LRCs in the basal layer of the proximal acinar part of SGs and demonstrate their myoepithelial characteristic by SMA co-expression. In addition, Applicant demonstrated that SG LRCs specifically co-localize with p63 expression which has been shown to be specifically expressed in mammary gland myoepithelial cells (Barbareschi, M. et al. (2001) Am J Surg Pathol. 25:1054-1060). Previous studies illustrated that p63 is not only essential for epithelial development, but is also important for epidermal self-renewal and differentiation (Koster, M. I. et al. (2004) Genes Dev 18:126-131; Yang, A. et al. (1999) Nature 398:714-718). In addition, p63 is believed to be a marker of corneal and epidermal SCs (Pellegrini, G. et al. (2001) Proc Natl Acad Sci. USA 98:3156-3161).
Recently, some similar findings regarding SG LRCs were reported by Lu et al. (Lu, C. P. et al. (2012) Cell 150:136-150). However, they did not further characterize this SG LRC population or address their in vivo function. Instead, they employed elegant systems, previously published in mammary glands (Van Keymeulen, A. et al. (2011) Nature 479:189-193), to identify and characterize distinct SC populations in the basal and lumenal layers of SGs (Lu, C. P. et al. (2012) Cell 150:136-150). In Applicant's study, Applicant used a different approach and focused predominantly on basal, myoepithelial LRCs (GFP+/α6+) after 4 weeks of chase. Although Applicant was able to characterize this population of SG LRCs, this genetic approach did not allow Applicant to study the lumenal layer of SGs in more detail.
As an alternative and parallel approach, Applicant used genetic K15CrePR in vivo systems to mark cells specifically in the proximal acinar part of SGs including SG LRCs in the basal layer (
Since the K15CrePR system permanently marks K15 expressing cells and its progeny, Applicant used it to evaluate the contribution of K15 marked acinar cells in overall SG and skin homeostasis. Applicant's results demonstrate that K15 labeled cells localized exclusively in the acinar part of SGs and contributed long term to only the proximal glandular part, but not to homeostasis of the distal SG ducts or the surrounding epidermis (
SG LRCs Possess Multipotency and Stem Cells Characteristic In Vivo and has Potential to Trans-Differentiate into the Epidermis Under Prolonged Isolated Wound Healing
As Applicant demonstrated here, K15CrePR/R26LacZ labeled cells in the acinar part of SGs appear to be generally slow cycling, but these cells were able to selectively maintain and participate in the long term homeostasis of the glandular part of SGs (
To assess the stem cell properties of SG LRCs in vivo, Applicant had to challenge Applicant's system further since regular wound healing conditions failed to provoke SG acinar cells to contribute to wound healing of the epidermis. Under this special wound condition where Applicant gave SG cells an advantage by preventing wound closure from the surrounding epidermis, Applicant observed that 4 weeks chased H2BGFP labeled SG LRCs can proliferate and trans-differentiate into all epidermal layers (
Together, Applicant's results remain in agreement with previously published results on human, mouse and porcine (Miller, S. J. et al. (1998) J Invest Dermatol. 110:13-19; Biedermann, T. et al. (2010) J Invest Dermatol. 130:1996-2009; Lobitz, W. C., Jr. (1956) J Invest Dermatol. 26:247-259, discussion:259-262; Rittie, L. et al. (2013) Am J Pathol. 182:163-171; Lu, C. P. et al. (2012) Cell 150:136-150; Lobitz, W. C., Jr., et al. (1954) J Invest Dermatol. 23:329-344), demonstrating that in general, SG cells can respond and re-epithelialize the skin after wounding. However, for the first time, Applicant shows that under more favorable, isolated, and prolonged wound healing condition, normally quiescent myoepithelial SG LRCs can contribute to and reconstitute a stratified epidermis. Thus, Applicant demonstrates that under favorable conditions, these relatively quiescent SG LRCs can be activated and work as an alternative source of cells confirming that these cells are multipotent with SC characteristics in vivo.
Purification and Characterization of Basal Layer Myoepithelial SG LRCs from the Acinar Sweat Gland Region
To further characterize these SG stem cells (SGSCs), Applicant used the KSTetOff/TreH2BGFP approach to localize and isolate SG myoepithelial LRCs from the proximal acinar part of SGs. Applicant purified SG LRCs and adjacent basal layer cells representing SG non-LRCs, which were predominantly composed of basal layer cells from the acinar and ductal regions. Although all SG LRCs showed myoepithelial characteristics co-expressing SMA and p63, only a fraction of SMA positive cells were LRCs while the remaining majority of SMA positive cells did not display label-retaining characteristics (
In Applicant's reconstitution assay, Applicant showed that dissociated SG cells were able to generate H2BGFP positive SG structures expressing SG markers K8 and Na+/K+ ATPase (
Taken together, Applicant has explored the role of SG LRCs in SGs and were able to localize them to the basal layer myoepithelial cells of the proximal acinar region. Applicant was able to isolate these SG LRCs which allowed Applicant to further characterize them and determine their gene expression profile. Among these genes, a number of BMP signaling genes were identified and Applicant demonstrated the requirement of this signaling pathway in SG formation. Applicant proposes that SG LRCs are the SC population required for the maintenance and homeostasis of the SG skin appendage. This suggests that at least one distinct stem cell population exists in the proximal acinar region of SGs, which contains relatively quiescent cells contributing only to their own glandular structures during homeostasis and typical wound healing. In fact, Applicant's results are in agreement with previously published observations in human SGs, where SG ducts were completely or partially injured in the dermis (Lobitz, W. C., Jr. (1956) J Invest Dermatol. 26:247-259, discussion:259-262). Interestingly, they observed that the deep portion of SGs maintained their quiescence and survived similar to the acinar part containing SGSCs in Applicant's study. In contrast, the ductal part of human SGs were not able to rebuild the lower acinar part of SGs in vivo, but had instead slowly disappeared (Lobitz, W. C., Jr. (1956) J Invest Dermatol. 26:247-259, discussion:259-262). Moreover, Applicant demonstrated that SG LRCs in the acinar compartment in fact possess multipotency and SCs characteristic in vivo having the potential to trans-differentiate into the epidermis under prolonged isolated wound healing conditions. Finally, Applicant's data also suggest plasticity of SG cells to reconstitute both SGs and hfs in vivo.
The present technology is not limited in scope by the examples, which are intended as illustrations of aspects of the present technology. Any methods that are functionally equivalent are within the scope of the present technology. Various modifications of the present technology in addition to those described herein will become apparent to those skilled in the art from the foregoing description and accompanying figures. Such modifications fall within the scope of the appended claims.
It is to be understood that while the invention has been described in conjunction with the above embodiments, that the foregoing description and examples are intended to illustrate and not limit the scope of the invention. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.
In addition, where features or aspects of the invention are described in terms of Markush groups, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group.
All publications, patent applications, patents, and other references mentioned herein are expressly incorporated by reference in their entirety, to the same extent as if each were incorporated by reference individually. In case of conflict, the present specification, including definitions, will control.
This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 62/051,422, filed Sep. 17, 2014, the content of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62051422 | Sep 2014 | US |
