Patent Application
20210139907
The present disclosure provides materials and methods for the delivery of therapeutic nucleic cells (and imaging agents) to tissues.
This application contains, as a separate part of the disclosure, a Sequence Listing in computer readable form (Filename: 53048A_Seqlisting.txt; Size: 116,998 bytes; Created: May 8, 2019), which is incorporated by reference in its entirety.
Diabetes is a group of metabolic disorders in which there are high blood sugar levels over a prolonged period caused by the insufficiency of the hormone insulin produced by the pancreatic beta cells. In particular, type 1 diabetes is caused by the progressive autoimmune destruction of beta cells whereas in type 2 diabetes insulin is not produced in quantities sufficient for the body needs. Although for many years the contribution of beta cell loss to type 2 diabetes was debated, in the last decade it became clear that a loss of beta cells is involved also in the pathophysiology of type 2 diabetes (Rojas et al., Journal of Diabetes Research, vol. 2018, Article ID 9601801, 19 pages, 2018; Donath et al., Diabetes. 2005 December;54 Suppl 2:S108-13). Despite this knowledge to date there are no available methods to directly measure the number of beta cell (beta cell mass) in vivo or to deliver therapeutics specifically to these important cells. Indeed, methods to determine diabetes progression rely mostly on the indirect measurement (i.e the determination of glucose or c-peptide concentration in the blood) and cannot discriminate whether many cells produce little insulin or few cells produce large quantities of this hormone. Thus, these methods cannot measure the progressive beta cell loss in patients with diabetes. The lack of adequate marker specific for beta cell make also impossible to deliver therapeutics specifically to beta cells to halt or reverse beta cell loss.
RNA aptamers have emerged as effective delivery vehicles for siRNAs in the treatment of many human diseases because they actively enhance the intracellular accumulation of therapeutic cargo by receptor-mediated internalization or by clathrin-mediated endocytosis (35-39,43-74). The use of aptamers to deliver the therapeutic RNA of interest to the β cells offers advantage over the use of viral vectors such for example the transient modulation of the gene of interest, the lack of immunogenicity, and a great safety profile. To date, adenoviral vectors have been mostly used for efficient delivery of genes and siRNA to primary pancreatic islets in vitro (79-84). In vivo, however, beside the technical difficulties in using of viral vectors, their inherent immunogenicity and possible recombination with wild type virus raises serious safety concerns. Indeed, viral vectors can induce strong immune responses with secondary complications that may include multi-organs failure and even death (85). The advent of lentiviral vectors alleviated some of the immunogenicity concerns, but lentiviruses are not as efficient as adenoviruses in transducing intact human islets (86,87); although current in vitro protocols are being optimized88. Nevertheless, lentiviral integration in the genome still raises safety concerns, risks of insertional mutagenesis and recombination with wild type viruses.
In one aspect, the disclosure provides a method of delivering one or more agents to a tissue comprising contacting the tissue with a construct comprising an aptamer that is specific for the tissue conjugated to the agent. In some embodiments, the tissue is from an organ selected from the group consisting of pancreas, heart, lung, kidney, stomach, skin and brain. In some embodiments, the tissue is pancreatic islets. In some embodiments, the agent is a therapeutic nucleic acid. In some embodiments, the therapeutic nucleic acid is a therapeutic RNA. In some embodiments, the therapeutic RNA is selected from the group consisting of siRNA and saRNA. In some embodiments, the agent is an imaging reagent. Exemplary imaging reagents include, but are not limited to, fluorochromes, Positron emission tomography tracer such as Fluorine-18, oxygen-15, gallium 68, magnetic resonance imaging contrast agents such as gadolinium, iron oxide, iron platinum and manganese. The contacting step can occur in vitro or in vivo.
In another aspect, the disclosure provides a construct comprising an aptamer conjugated to a small activating RNA (saRNA). In some embodiments, the aptamer is specific for human pancreatic islets. In some embodiments, the aptamer is selected from the group consisting of M12-3773 and 1-717.
In some embodiments, the aptamer is specific for clusterin (CLU, gene id 1191). In some embodiments, the aptamer is specific for “Transmembrane emp24 domain-containing protein 6” (TMED6, gene id 146456).
In some embodiments, the tissue is adrenal tissue or bone marrow and the aptamer is 173-2273, 107-901 or m6-3239. In some embodiments, the tissue is breast tissue, lung tissue or lymph node tissue and the aptamer is 107-901 and m6-3239. In some embodiments, the tissue is brain cerebellum and the aptamer is 173-2273, 107-901, m1-2623 or m6-3239. In some embodiments, the tissue is brain cerebral cortex tissue, pituitary tissue, colon tissue, endothelium tissue, esophagus tissue, heart tissue or kidney tissue and the aptamer is 107-901, m1-2623 or m6-3239. In some embodiments, the tissue is fallopian tube tissue and the aptamer is m6-3239. In some embodiments, the tissue is liver tissue and the aptamer is 166-279, 107-901, m1-2623 or m6-3239. In some embodiments, the tissue is ovarian tissue and the aptamer is 107-901. In some embodiments, the tissue is placenta tissue and the aptamer is 166-270, 173-2273, 107-901, m1-2623 or m6-3239. In some embodiments, the tissue is prostate tissue and the aptamer is 173-2273 or 107-901. In some embodiments, the tissue is spinal cord tissue and the aptamer is 166-279 or 173-2273. In some embodiments, the tissue is testis tissue and the aptamer is 166-279, 173-2273, 107-901, m1-2623, m6-3239 and m12-3773. In some embodiments, the tissue is thymus tissue and the aptamer is 173-2273, 107-901 or mf-2623. In some embodiments, the tissue is thyroid tissue and the aptamer is m1-2623. In some embodiments, the tissue is ureter tissue and the aptamer is 107-901. In some embodiments, tissue is cervical tissue and the aptamer is 166-279. In some embodiments, the tissue is islets of Langerhans or pancreatic tissue and the aptamer is 166-279, 173-2273, 107-901, 1-717, m1-2623, m6-3239 or m12-3773.
In another aspect, the disclosure provides a method of delivering one or more agents to pancreatic islets comprising contacting the islets with a construct comprising an aptamer that is specific for islets conjugated to the agent. In some embodiments, the agent is a therapeutic nucleic acid. In some embodiments, the therapeutic nucleic acid is a therapeutic RNA. In some embodiments, the therapeutic RNA is selected from the group consisting of siRNA and saRNA. In some embodiments, the agent is an imaging reagent. Exemplary imaging reagents include, but are not limited to, fluorochromes, Positron emission tomography tracer such as Fluorine-18, oxygen-15, gallium 68, magnetic resonance imaging contrast agents such as gadolinium, iron oxide, iron platinum and manganese. The contacting step can occur in vitro or in vivo.
In some embodiments, the aptamer is selected from the group consisting of M12-3773 and 1-717. In some embodiments, the aptamer is specific for clusterin (CLU, gene id 1191). In some embodiments, the aptamer is specific for “Transmembrane emp24 domain-containing protein 6” (TMED6, gene id 146456).
In another aspect, the disclosure provides a method of measuring beta cell mass comprising contacting the beta cell with a construct comprising an aptamer conjugated to an imaging reagent in an amount effective to measure the mass of the beta cell. In some embodiments, the aptamer is selected from the group consisting of M12-3773 and 1-717. In some embodiments, the imaging reagent is a fluorochrome. In some embodiments, the imaging reagent is a PET tracer. In some embodiments, the imaging reagent is a MRI contrast reagent. In some embodiments, the imaging reagent can be conjugated to the aptamer via chelators.
In another aspect, the disclosure provides a method of modulating proliferation of beta cell comprising contacting the beta cell with a construct comprising an aptamer conjugated to a therapeutic nucleic acid in an amount effective to modulate proliferation of the beta cell. In some embodiments, the aptamer is selected from the group consisting of M12-3773 and 1-717. In some embodiments, the therapeutic nucleic acid is a therapeutic RNA. In some embodiments, the therapeutic RNA is selected from the group consisting of siRNA and saRNA. The contacting step can occur in vitro or in vivo.
In another aspect, the disclosure provides a method for inhibiting beta cell apoptosis comprising contacting the beta cell with a construct comprising an aptamer conjugated to a therapeutic nucleic acid in an amount effective to inhibit apoptosis of the beta cell. In some embodiments, the aptamer is selected from the group consisting of M12-3773 and 1-717. In some embodiments, the therapeutic nucleic acid is a therapeutic RNA. In some embodiments, the therapeutic RNA is selected from the group consisting of siRNA and saRNA. In some embodiments the therapeutic RNA upregulate the protein XIAP (X-linked inhibitor of apoptosis gene id 331). The contacting step can occur in vitro or in vivo.
In another aspect, the disclosure provides a method for inhibiting tissue graft apoptosis in a subject in need thereof comprising contacting the tissue graft with a construct comprising an aptamer conjugated to a therapeutic nucleic acid in an amount effective to inhibit apoptosis of the tissue graft. In some embodiments, the therapeutic nucleic acid is a therapeutic RNA. In some embodiments, the therapeutic RNA is selected from the group consisting of siRNA and saRNA. In some embodiments, the therapeutic RNA upregulates the protein XIAP (X-linked inhibitor of apoptosis gene id 331). The contacting step can occur in vitro or in vivo. In some embodiments, the tissue graft is from an organ selected from the group consisting of pancreas, heart, lung, kidney, stomach and skin. In some embodiments, the aptamer is a muscle specific aptamer and the tissue is heart tissue.
In some embodiments, the tissue is contacted with the therapeutic RNA that upregulates the protein XIAP in the absence of an aptamer. For example, in another aspect, the disclosure provides a method for inhibiting tissue graft apoptosis in a subject in need thereof comprising contacting the tissue graft with a therapeutic RNA that upregulates the protein XIAP (X-linked inhibitor of apoptosis gene id 331) in an amount effective to inhibit apoptosis of the tissue graft. The contacting step can occur in vitro or in vivo. In some embodiments, the tissue graft is from an organ selected from the group consisting of pancreas, heart, lung, kidney, stomach and skin.
In another aspect, the disclosure provides a method for protecting a beta cell from T-cell mediated cytotoxicity of the beta cell comprising contacting the beta cell with a construct comprising an aptamer conjugated to a therapeutic nucleic acid in an amount effective to inhibit T cell mediated cytotoxicity of the beta cell. In some embodiments, the aptamer is selected from the group consisting of M12-3773 and 1-717. In some embodiments, the therapeutic nucleic acid is able to increase immune checkpoint. In some embodiments, the therapeutic nucleic acid is a therapeutic RNA. In some embodiments, the therapeutic RNA is selected from the group consisting of siRNA and saRNA. In some embodiments the therapeutic RNA upregulate the protein CD274 (Programmed death-ligand 1, PDL1, gene id 29126). The contacting step can occur in vitro or in vivo.
In another aspect, the disclosure provides a method of treating diabetes in a subject in need thereof comprising administering to the subject a construct comprising an aptamer conjugated to a small activating RNA (saRNA) in an amount effective to treat diabetes in the subject. In some embodiments, the aptamer is selected from the group consisting of M12-3773 and 1-717.
In another aspect, one or more aptamers specific for the beta cells can be used in combination to increase delivery of the therapeutic agent or imaging reagents. In some embodiments, the aptamers are selected from the group consisting of M12-3773 and 1-717.
An aptamer comprising a nucleotide sequence set forth in SEQ ID NO: 264 or 259 is also contemplated. In some embodiments, the aptamer is conjugated to an saRNA. In some embodiments, the saRNA upregulates the protein XIAP (X-linked inhibitor of apoptosis gene id 331). In some embodiments, saRNA upregulates the protein CD274 (Programmed death-ligand 1, PDL1, gene id 29126,
As described in the Examples, therapeutic RNA/aptamer chimeras were generated to modulate gene expression in human β cells in vivo to induce their transient proliferation and improve their resistance to auto/alloimmunity. In particular, we have optimized and validate the use of islet-specific aptamers to deliver: A) siRNA against p57kip2 to induce β cell proliferation, B) saRNA promoting Xiap expression to protect islets from apoptosis, and C) saRNA promoting PDL1 expression to protect β from T cell cytotoxicity. Because of the absence of reliable humanized mouse model of autoimmune T1D, our approach is based on the use of NSG or humanized NSG mice transplanted with human islets before aptamer treatment. The use of human islets is dictated by species specific difference in p57kip2 biology (14) and by the specificity of PDL1 and Xiap saRNAs for the human genes. Ex vivo and innovative in vivo techniques are employed to quantify the response to in vivo treatment through imaging of β cell proliferation, apoptosis, and interaction with the immune system. We envision the use of these aptamers as mono or multimodal approach where difference genes can be modulated simultaneously.
The in vivo use of RNA aptamers is particularly appealing because this class of molecules has low immunogenicity, high capacity to penetrate deep into the tissues, and ability to recognize the cognate target with high affinity and specificity. The fluorinated backbone of the aptamers make them resistant to RNAse degradation and incapable to trigger TLR signaling (41,42). RNA aptamers have emerged as effective delivery vehicles for siRNAs and other drugs to specific cell subsets or tissues for the treatment of many human diseases (60,62-75). Indeed, through the interactions between the aptamer and its cellular membrane target, aptamers actively enhance the intracellular accumulation of therapeutic agents (37-39,43-61). Some aptamer drugs are FDA-approved and more than 30 are being tested in clinical trials (16-24). When administered in vivo, aptamers that do not find a specific target are rapidly eliminated via the kidney; those that find their target in tissues or cells remain detectable for up two weeks. Their bioavailability, plasma half-life, and pharmacokinetic properties can be easily engineered by increasing their size by the addition of Polyethylene glycol (PEG) during synthesis, or by conjugation with nanoparticles (60,62-74). Aptamers can be conjugated to siRNA, miRNA or saRNA to deliver the desirable therapeutic effect in specific targets. The ability to directly engineer aptamers with high specificity and defined functions is a distinct advantage over antibodies and other small molecules.
Unsupervised toggled-SELEX was performed starting with a polyclonal aptamer library against mouse islets and using islet depleted human acinar cells and handpicked human islets from 4 different cadaveric donors as negative and positive selectors, respectively. This allowed for the depletion of non-specific (acinar tissue binding) RNA aptamers and enrich the library for those aptamers specific for mouse and human islets.
As shown in
Table 2. Putative human islet specific aptamers isolated via cluster SELEX (from
As shown in
Table 3—aptamer sequences specific for human islets
Table 4. Putative human islet specific aptamers isolated via toggle-cluseter SELEX (from
Next, the specificity for human islets of the identified monoclonal aptamers were tested with the two high throughput cluster SELEX strategies described in
In order to evaluate further the specificity of the chosen monoclonal aptamers, the best performers of
To evaluate if aptamer 1-717 and m12-3772 can recognize not only human islets but also the mouse counterpart, staining with these two Cy-3 labelled monoclonal aptamers were performed on tissues microarrays each containing 11 tissues from healthy mice. These experiments show that both aptamer 1-717 and aptamer m12-3773 can also recognize mouse islets. See
To evaluate better the specificity of the aptamers within the islets, two different techniques were employed: confocal microscopy (
For flow cytometry, single cell suspension of human islets were stained with Cy3 labelled aptamer M12-3773 (
Clusterin is a possible target for aptamer m12-3773. 3′biotin-aptamer m12-3773 was synthetized with a oligo synthesizer and used to label single cell suspension from human islets. Cells were washed and their cytoplasm lysed with tween20/BSA solution. Aptamers bound to their ligand recovered with magnetic beads and magnetic separation. Capture ligands were released by the aptamer-beads complex at 95° C. in SDS and run in SDS page. Bands were cut and subjected to mass spectrometry and mascot-based analysis (
To evaluate whether aptamer 1-717 and m12-3773 can recognize human islets in vivo, we employed immunodeficient NSG mice engrafted with human islets in the epydidimal fatpad. Additionally, we use a new formulation of aptamer 1-717 and aptamer m12-3773 in which each monoclonal aptamer is biotinylated and complexed with streptavidin to form a tetrameric nanoparticle (hereafter called tetraptamer). This formulation has a superior pharmacokinetic and better affinity than the corresponding monomeric aptamer.
Biotin/streptavidin Alexafluor (AF750)-labeled aptamers (amptamer 1-717 or aptamer m12-3773, or an equimolar mixture of the two aptamers) were injected intravenously in immunodeficient NSG mice (engrafted with human islets in the epididymal fat pad (EFP)) to evaluate whether m12-3773 and 1-717 can recognize human islets in vivo. A cumulative-synergistic signal was observed in the EFP region when the mixture of both aptamers was used possibly because different islet epitopes were targeted by each aptamer (
To determine if aptamers m12-3773 and 1-717 can be used to measure β mass in vivo, immune deficient NSG mice were transplanted with different quantities (range 62.5-500 IEQ) of human islets in the epididymal fatpad. 21 days later, mice were injected iv with Alexafluor 750 tetraptamer generated by the complexation of an equimolar mixture of aptamer 1-717 and m12-3773 to streptavidin. 4 hours later signal was quantified by IVIS.
In summary, the selected aptamers m12-3773 and 1-717 bind mouse and human β cells with good specificity in vitro and in vivo and thus may be useful in targeting therapeutics to human β in vivo.
As shown in
To evaluate if aptamers can be a non-viral alternative for transfecting β cells, we conducted proof of principle experiments aimed to knockdown via aptamer delivery insulin (INS) 1 and 2 in non-dissociated mouse islets.
As shown in
P57kip2 silencing in β cells has important therapeutic implications. Indeed, mutations of p57Kip2 are associated with focal hyperinsulinism of infancy (FHI), a clinical syndrome characterized by a dramatic non-neoplastic clonal expansion of β cells (14), overproduction of insulin, and severe uncontrollable hypoglycemia (89,90). FHI's focal lesions are characterized by excessive β cell proliferation that correlates with p57kip2 loss (91,92). Although the pro-proliferative activity of p57kip2 silencing is not desirable in FHI and in cancers, a temporally defined silencing might be useful to promote adult β cell proliferation in T1D. Indeed, adenoviral-shRNA mediated silencing of p57kip2 in human islets obtained from deceased adult organ donors increased β cell replication by more than 3-fold once the islets were transplanted into hyperglycemic, immune-deficient mice (14). The newly replicated cells retained properties of mature β cells, such as expression of insulin, PDX1, and NKX6.114. Interestingly, no β cell proliferation was observed in normoglycemic mice indicating that hyperglycemia may provide additional pro-proliferative signals (93). These findings opened the possibility for a new therapeutic intervention to restore an adequate β cell mass in patients with T1D and/or to reduce the number of islets needed during transplantation. However, to date the translatability of these finding was hindered by safety concerns associated with use of viral vectors and neoplasm formation as a result of stable p57Kip2silencing. Indeed, p57Kip2 is frequently downregulated in human cancers (94) and has been proposed as a tumor suppressor gene since its ectopic expression is sufficient to halt neoplastic cell proliferation (94). However, a temporally controlled modulation of p57kip2 through aptamer delivery may be important in diabetes to increase β cell proliferation in a temporally controlled manner. This might be sufficient to increase β cell mass during timed administrations while avoiding the safety concerns with non-controllable, neoplastic-like proliferation of β that may results with stable silencing.
Apoptotic cell death is a hallmark in the loss of insulin-producing β in all forms of diabetes (99-101). Leukocytes infiltration and activation as well as high glycemia within the islets leads to high local concentrations of apoptotic trigger including inflammatory cytokines, chemokines, and reactive oxygen species 99. Most of these apoptotic pathways converge onto caspase (CASP) 3 and 7 activation leading to genetic reprogramming, phosphatidylserine flip, and apoptotic bodies formation (102).
β cell apoptosis can further feed the autoimmune process by stimulating self-antigen presentation and autoreactive T cell activation (103). Similarly, in islets transplantation setting, primary non-function, i.e. the partial but significant and sometimes total loss of the grafted islet mass, which occurs early after transplantation (104-106). β cell apoptosis initiates during the isolation procedure and upon transplantation is exacerbated by hypoxia and hyperglycemia as well as pro-coagulatory and proinflammatory cascades (107). Primary-non-function accounts for more than 50% of the functional islet mass loss occurring during the first 48 hours after transplantation (106).
Thus, blocking even temporally apoptotic β cell death is highly desirable not only to preserve β cell mass in type 1 diabetes (T1D) and in islet transplantation but also to reduce auto-reactive T cell activation and further immune damage.
This protein is most potent member of the apoptosis-inhibitor family and prevents the activation of CASP 3, 7 and 9 (108); ii) Xiap overexpression using viral vector improved β cell viability, prevented their cytokine- or hypoxia-induced apoptosis (109-111), iii) Xiap transduced human islets prolonged normoglycemia when are transplanted in diabetic NOD-SCID mice (11). However, since Xiap is upregulated in many cancers, its stable overexpression raise important safety concerns. Therefore, a controlled Xiap activation via saRNA delivered with islets specific aptamers can be useful alternative to reduce primary nonfunction, prevent β cell loss and the self-feeding autoimmune process in T1D.
Small activating RNAs (saRNAs) are oligonucleotides that exert their action in specific promoter regions and upregulate mRNA and protein expression for up to 4 weeks (depending on cell replication, mRNA and protein turn-over) (112-122). saRNA-mediated gene upregulation through mechanisms still not fully understood but is thought to involve epigenetic changes or down-modulation of inhibitory RNA (123-125). saRNAs provide safe, specific, and temporary gene activation without the insertion of DNA elements since their specificity is comparable to that of gRNA in CRISP/CAS9 system but no irreversible DNA modification are induced 126. While therapeutic saRNAs are being investigated for cancer treatment, to our knowledge no studies have been performed in T1D (127-130).
Therefore, we have identified saRNAs capable of specifically upregulating the anti-apoptotic gene XIAP. Briefly, we have first examined the human XIAP promoter using the previously described algorithms (112,131). This analysis that includes genome blast analysis to avoid non-specific sequences, returned more than 156 putative saRNA target regions. We synthetized the 96 putative saRNA with highest scores and tested them for their capacity to upregulate Xiap by transfecting the human epithelial cell line A549. This cell line was used because it is easily transfectable, has low basal expression of PDL1 and Xiap. qRT-PCR was performed 96 hours after transfection and results were normalized on the same cell line transfected with scrambled saRNA (
In vitro proof of principle experiments were performed using human islets isolated from cadaveric donors to determine if Xiap-saRNA delivered by aptamer can protect β cell from apoptosis. Xiap-saRNA aptamer chimeras were generated as described in
Interestingly, untreated islets in the absence of cytokines showed higher proportion in α cells (β/α cell ratio=0.8) in the presence of CTRL-chimera (
Human islets from cadaveric donors were transfected with Xiap-saRNA aptamer chimera or control-chimera as detailed in
Provided in
The clinical importance of PDL1 expression in the maintenance of tissue specific tolerance is highlighted by the success of PDL1-PD1 antagonists in cancer (135). Engagement of PD1 by PDL1 down-regulates effector T cell proliferation and activation, induces T cell cycle arrest and apoptosis, and promotes IL10-producing Treg (136-139). Interestingly, one of the emerging side effect anti-PD1 treatment is T1D140. This suggests that PDL1/PD1 may play an important role in controlling T cell tolerance against β cells. Indeed, in NOD mice PDL1 blockade accelerate T1D in female mice and induce it in male (13). Conversely, PDL1 ectopic expression in syngeneic transplanted islets protects NOD mice against T1D recurrence (12,13). NOD transgenic mice expressing PDL1 under control of the insulin promoter shows delayed incidence in diabetes, reduction T1D incidence, and a systemic, islet specific, T cell anergy (141). In humans, PDL1 polymorphisms is associated with T1D (OR=1.44) (142).
Given the importance that PDL1 expression might play in controlling T cell reactivity to β cells, we identified saRNAs specific for PDL1 (
Next whether the islet-specific-aptamers described herein can effectively deliver PDL1-saRNAs to human islets and upregulate PDL1 expression was tested. Aptamer-PDL1-saRNA chimeras were generated by conjugating aptamer 1-717 to PDL1-saRNA-636 (Table 6) as described in
Next, the ability of PDL1-saRNA/aptamer chimera to upregulate PDL1 in vivo was assessed. As shown in
These results indicated that: i) it is possible to detect PDL1 in human islet cells in vivo, ii) our aptamer chimeras transfect human islets in vivo, and iii) it is possible to upregulate PDL1 in human islets in vivo via aptamer chimera.
In the first set of experiments, NSG mice will be engrafted with human islets in the ACE. Three weeks after transplant, mice will be treated with Xiap saRNA-aptamer chimera(s) or control chimera. At different time points, human islet grafts will be challenged by intraocular injection of IL1β, TNF-α, and IFNγ to induce apoptosis in β cells via activation of caspase 3 and 7. Caspase 3 and 7 activity will be evaluated in vivo by our intraocular imaging system using CASP3/7 Green Detection Reagent. This cell-permeant reagent consists of a four-amino acid peptide (DEVD) conjugated to a nucleic acid-binding dye. Upon activation, caspase 3 and 7 cleave the probe, allow the dye to bind to the DNA, and emit a bright, fluorogenic signal that can be detected at the cellular level in the ACE28. Additionally, in vivo staining with anti-Annexin V antibodies will be used to directly measured islet cell apoptosis in vivo (
The second set of experiment aims to evaluate the effect of Xiap modulation on anti-islet allo-immunity. Briefly, STZ-diabetic NSG mice will be transplanted with 500 IEQ human islets in the ACE or EFP. 3 weeks later mice will be treated with Xiap chimera(s) or scrambled controls. Treatment will be repeated as determine in Aim2b. One week after the first treatment, mice will receive CFSE labelled human T cells mismatched for HLA to the islet. Without any treatment, the adoptive transfer of allogeneic T cells results in graft loss and return to hyperglycemia within 3 weeks. Thus, we will assess the protective effect of Xiap chimera treatment on the human islet allograft survival using as readouts: i) glycemia, ii) human c-peptide plasma levels and, in the ACE group, iii) the longitudinal evaluation of T cell infiltration and volumetric analysis of engrafted islets as we showed in (77,78).
To ensure data reproducibility of Xiap chimera effect among individuals, the chimera identified in the EndoC-BH3 cells will be further validated using primary human islets from 6 cadaveric donors; this will provide 88% of power to detect 1.25SD difference from control in one tailed paired t-test. To avoid artifacts, 3 different readout methods (qPCR, western blot, and enzymatic assay) will be used and at least 3 independent repetitions will be performed for each experiment using human islets from 3 different cadaveric donors. In transplantation studies, a total of 9 mice per group (3 in each repetition) will be used to ensure 90% of power (ANOVA, α=0.05) and detect 1.6SD difference to control.
In a first set of experiments, NSG mice transplanted with 500 IEQ human islets in the EFP will be treated i.v. or s.c. with different doses (6, 20, and 60 pmoles/g) of islets-specific aptamers conjugated with p57kip2siRNA or scrambled siRNA (control-chimera) as negative control. We will use adenovirus encoding the same p57kip2 shRNA-transfected islets as positive control (14). At predefined time-points (e.g., day 1, 2, 3, 4, and 5 after administration), grafts will be harvested, and p57kip2 expression quantified by i) qRT-PCR on laser captured islets, and ii) by quantitative computer assisted immunofluorescence analysis 95. Both techniques are optimized at the Diabetes Research Institute (96,97) and in the laboratories of the PIs95. To evaluate possible dose-dependent toxicity, sera and organs of interest (spleen, liver, lymph nodes, lung, kidney, and brain) will be collected and sent to the mouse pathology laboratory of University of Miami for histopathological evaluation.
In the second set of experiments, NSG mice will be transplanted with 500 IEQ human islets in the ACE. Three weeks later, mice will be treated i.v. or by intraocular injection (i.o) with different doses (6, 20, 60 pm/g) of our aptamer-chimera loaded with p57kip2 siRNA or AF647-scrambled siRNA (control-chimera) as negative control. In vivo transfection efficiency of the AF647 siRNA will be evaluated with our intraocular imaging system 2, 3, 4, 8, and 24 hours after injection (28). At selected time-points (e.g., 2, 3, 4, and 7 days after treatment), graft will be removed and p57kip2 expression quantified by qRT-PCR on islets explanted from the ACE and by i) qRT-PCR on laser capture islets and ii) by quantitative computer assisted immunofluorescence microscopy analysis (95).
Once the optimal dose and route of administration are identified and the kinetics of p57kip2 silencing evaluated, we will determine the number of administrations of p57kip2siRNA-aptamer chimera needed to induce substantial changes (i.e., ≥100% increase) in β cell mass. Since p57kip2 silencing was shown to induce β cell proliferation only in hyperglycemic micel4, sub-marginal human islet mass (250 IEQ) will be transplanted in the EFP or ACE of NSG mice. 21 days after transplant, mice will be rendered hyperglycemic by streptozotocin (STZ) treatment. STZ selectively eliminates mouse islets as human β are considerably more resistant (98). Once the mice become hyperglycemic (usually 5-6 days after treatment), mice will receive 1, 2, 3, or 4 administration of islet-specific or control aptamer chimeras. The frequency of the aptamer administration will be determined based on the time course established in Example 5. BrdU will be administered in drinking water for ex vivo determination of proliferation. β cell mass in the EPF group will be evaluated longitudinally (baseline, during treatment, 5 and 10 days after the last treatment) by IVIS (
The purpose of this Example is to test if aptamer mediated p57kip2 silencing can restore normoglycemia in diabetic mice transplanted with suboptimal number of human islets.
In the first set of experiments, STZ-diabetic NSG mice maintained on insulin therapy (s.c pellet implant for sustained insulin release) will be transplanted with different quantities of human islets (50, 150, 350 IEQ) in the ACE. Three weeks later, insulin pellets will be removed, and mice will be treated with p57kip2siRNA-aptamer chimera or scrambled control, locally or systemically. To compare this treatment with today gold standard for islets transfection, two additional groups of mice will be treated locally with adenoviral vector encoding for p57kip2shRNA or RFP as control. Pilot experiments using RFP encoding adenovirus will be performed in the ACE to determine the minimal dose necessary for transducing at least 90% of the islets. Transduction efficiency will be quantified using our in vivo imaging system (28). In the experimental groups (which received 50, 150, and 350 IEQ), blood glucose will be used as readout for treatment efficacy in addition to intravital imaging and volume analysis of the ACE islet grafts. The varied sub-marginal islet mass in the different groups may also reveal the degree of the hyperglycemic drive on human islet proliferation.
In the second set of experiments, STZ-diabetic mice will be transplanted in the EFP with the same sub-marginal human islet masses (50, 150, 350 IEQ) and maintained on insulin during the engraftment period. 3 weeks later insulin pellet will be removed and mice will be treated with p57kip2siRNA-aptamer chimera or the scrambled control. We will monitor glycemia and β cell mass by IVIS longitudinally as readouts.
In both sets of experiments, glucose tolerance tests (GTTs) will be performed in mice with restored normoglycemia to further evaluate the islet function under stress conditions.
To ensure reproducibility in the results, at least 3 independent repetitions will be performed for each experiment using human islets from 3 different cadaveric donors. The use a total of 9 mice per experimental group (3 in each repetition) gives 90% of power (One way ANOVA, α=0.05) to detect an effect size of 1.6 SD to control. 12 mice per group will be used to accounting for the higher expected variation of the read-out. To minimize readout-specific artifacts, the same phenomenon will be measured with at least 2 independent methods.
The present application claims the benefit of priority to U.S. Provisional Application No. 62/668,463 filed May 8, 2018, the disclosure of which is incorporated herein by reference in its entirety.
This invention was made with government support under grant number 1UC4DK116241-01 awarded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US19/31346 | 5/8/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62668463 | May 2018 | US |
