The MicroRNA Landscape of Acute Beta Cell Destruction in Type 1 Diabetic Recipients of Intraportal Islet Grafts

Small RNA-Seq and real time rt-qPCR reveal islet miRNA released under stress conditions

Replacement of beta cells through transplantation is a potential therapeutic approach for individuals with pancreas removal or poorly controllable type 1 diabetes. However, stress and death of beta cells pose significant challenges. Circulating miRNA has emerged as potential biomarkers reflecting early beta cell stress and death, allowing for timely intervention. The aim of this study was to identify miRNAs as potential biomarkers for beta cell health. Literature review combined with small RNA sequencing was employed to select islet-enriched miRNA. The release of those miRNA was assessed by RT-qPCR in vivo, using a streptozotocin induced diabetes mouse model and in vitro, through mouse and human islets exposed to varying degrees of hypoxic and cytokine stressors. Utilizing the streptozotocin induced model, we identified 18 miRNAs out of 39 candidate islet-enriched miRNA to be released upon islet stress in vivo. In vitro analysis of culture supernatants from cytokine and/or hypoxia stressed islets identified the release of 45 miRNAs from mouse and 8 miRNAs from human islets. Investigation into the biological pathways targeted by the cytokine- and/or hypoxia-induced miRNA suggested the involvement of MAPK and PI3K-Akt signaling pathways in both mouse and human islets. We have identified miRNAs associated with beta cell health and stress. The findings allowed us to propose a panel of 47 islet-related human miRNA that is potentially valuable for application in clinical contexts of beta cell transplantation and presymptomatic early-stage type 1 diabetes.

Significant expansion of the donor pool achieved by utilizing islets of variable quality in the production of allogeneic "Neo-Islets", 3-D organoids of Mesenchymal Stromal and islet cells, a novel immune-isolating biotherapy for Type I Diabetes

Novel biotherapies for Type 1 Diabetes that provide a significantly expanded donor pool and that deliver all islet hormones without requiring anti-rejection drugs are urgently needed. Scoring systems have improved islet allotransplantation outcomes, but their use may potentially result in the waste of valuable cells for novel therapies. To address these issues, we created "Neo-Islets" (NIs), islet-sized organoids, by co-culturing in ultralow adhesion flasks culture-expanded islet (ICs) and Mesenchymal Stromal Cells (MSCs) (x 24 hrs, 1:1 ratio). The MSCs exert powerful immune- and cyto-protective, anti-inflammatory, proangiogenic, and other beneficial actions in NIs. The robust in vitro expansion of all islet hormone-producing cells is coupled to their expected progressive de-differentiation mediated by serum-induced cell cycle entry and Epithelial-Mesenchymal Transition (EMT). Re-differentiation in vivo of the ICs and resumption of their physiological functions occurs by reversal of EMT and serum withdrawal-induced exit from the cell cycle. Accordingly, we reported that allogeneic, i.p.-administered NIs engraft in the omentum, increase Treg numbers and reestablish permanent normoglycemia in autoimmune diabetic NOD mice without immunosuppression. Our FDA-guided pilot study (INAD 012-0776) in insulin-dependent pet dogs showed similar responses, and both human- and canine-NIs established normoglycemia in STZ-diabetic NOD/SCID mice even though the utilized islets would be scored as unsuitable for transplantation. The present study further demonstrates that islet gene expression profiles (α, β, γ, δ) in human "non-clinical grade" islets obtained from diverse, non-diabetic human and canine donors (n = 6 each) closely correlate with population doublings, and the in vivo re-differentiation of endocrine islet cells clearly corresponds with the reestablishment of euglycemia in diabetic mice. Conclusion: human-NIs created from diverse, "non-clinical grade" donors have the potential to greatly expand patient access to this curative therapy of T1DM, facilitated by the efficient in vitro expansion of ICs that can produce ~ 270 therapeutic NI doses per donor for 70 kg recipients.

miRNAs as Biomarkers in Diabetes: Moving towards Precision Medicine

Diabetes mellitus (DM) is a complex metabolic disease with many specifically related complications. Early diagnosis of this disease could prevent the progression to overt disease and its related complications. There are several limitations to using existing biomarkers, and between 24% and 62% of people with diabetes remain undiagnosed and untreated, suggesting a large gap in current diagnostic practices. Early detection of the percentage of insulin-producing cells preceding loss of function would allow for effective therapeutic interventions that could delay or slow down the onset of diabetes. MicroRNAs (miRNAs) could be used for early diagnosis, as well as for following the progression and the severity of the disease, due to the fact of their pancreatic specific expression and stability in various body fluids. Thus, many studies have focused on the identification and validation of such groups or "signatures of miRNAs" that may prove useful in diagnosing or treating patients. Here, we summarize the findings on miRNAs as biomarkers in diabetes and those associated with direct cellular reprogramming strategies, as well as the relevance of miRNAs that act as a bidirectional switch for cell therapy of damaged pancreatic tissue and the studies that have measured and tracked miRNAs as biomarkers in insulin resistance are addressed.