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Generation of pure pancreatic progenitor (PP) cells is critical for clinical translation of stem cell-derived islets. Herein, we performed PP differentiation with and without AKT/P70 inhibitor AT7867 and characterized the resulting cells at protein and transcript level in vitro and in vivo upon transplantation into diabetic mice. AT7867 treatment increased the percentage of PDX1 + NKX6.1 + (-AT7867: 50.9% [IQR 48.9%-53.8%]; +AT7867: 90.8% [IQR 88.9%-93.7%]; p = 0.0021) and PDX1 + GP2 + PP cells (-AT7867: 39.22% [IQR 36.7%-44.1%]; +AT7867: 90.0% [IQR 88.2%-93.6%]; p = 0.0021). Transcriptionally, AT7867 treatment significantly upregulated PDX1 (p = 0.0001), NKX6.1 (p = 0.0005), and GP2 (p = 0.002) expression compared with controls, while off-target markers PODXL (p < 0.0001) and TBX2 (p < 0.0001) were significantly downregulated. Transplantation of AT7867-treated PPs resulted in faster hyperglycemia reversal in diabetic mice compared with controls (time and group: p < 0.0001). Overall, our data show that AT7867 enhances PP cell differentiation leading to accelerated diabetes reversal., Competing Interests: Declaration of interests A.M.J.S. serves as a consultant to ViaCyte Inc., Vertex Pharmaceuticals Inc., Betalin Therapeutics Ltd., and Aspect Biosystems Inc., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Type 1 Diabetes (T1D) is an autoimmune destruction of pancreatic beta cells. The development of the Edmonton Protocol for islet transplantation in 2000 revolutionized T1D treatment and offered a glimpse at a cure for the disease. In 2022, the 20-year follow-up findings of islet cell transplantation demonstrated the long-term safety of islet cell transplantation despite chronic immunosuppression. The Edmonton Protocol, however, remains limited by two obstacles: scarce organ donor availability and risks associated with chronic immunosuppression. To overcome these challenges, the search has begun for an alternative cell source. In 2006, pluripotency genomic factors, coined "Yamanaka Factors," were discovered, which reprogram mature somatic cells back to their embryonic, pluripotent form (iPSC). iPSCs can then be differentiated into specialized cell types, including islet cells. This discovery has opened a gateway to a personalized medicine approach to treating diabetes, circumventing the issues of donor supply and immunosuppression. In this review, we present a brief history of allogenic islet cell transplantation from the early days of pancreatic remnant transplantation to present work on encapsulating stem cell-derived cells. We review data on long-term outcomes and the ongoing challenges of allogenic islet cell and stem cell-derived islet cell transplant.

The paucity of human donors limits broadened application of β-cell replacement therapy. Insulin-producing cells derived from human embryonic stem cells (hESCs) have recently been investigated clinically as a feasible surrogate to primary tissue. Herein, we examine the long-term efficacy of hESC-derived pancreatic endoderm cells (PECs) to maintain normoglycemia posttransplant and characterize the phenotype of the PEC grafts. Mice with chemically induced diabetes were transplanted with PECs into the subcutaneous device-less site. Transplant function was assessed through nonfasting blood glucose measurements, intraperitoneal glucose tolerance testing (IPGTT), and human C-peptide secretion for 517 days. Explanted grafts were assessed for ex vivo function and immunohistochemically. All PEC recipients ( n = 8) maintained normoglycemia until graft retrieval. IPGTTs at 365 and 517 days posttransplant did not differ ( P > 0.05), however, both demonstrated superior glucose clearance compared with nondiabetic and transplant controls ( P < 0.001). Serum C-peptide levels demonstrated significant glucose responsiveness (fasted vs. stimulated) ( P < 0.01). Small intragraft cysts were palpable in all mice, which resolved but recurred after aspiration. Cysts showed monomorphic neuroendocrine proliferation and lined by ductal epithelium. Explanted grafts demonstrated similar insulin secretory capacity as human islets and stained positively for endocrine cells. Our results demonstrate the ability of PECs to differentiate in vivo and restore glycemic control while confirming minimal proliferation and absence of neoplastic change within the grafts during the time evaluated., (© 2019 by the American Diabetes Association.)

Background: Islet transplantation is a successful β-cell replacement therapy for selected patients with type 1 diabetes mellitus. However, despite early insulin independence, long-term graft attrition gradually reverts recipients to exogenous insulin dependency. Undoubtedly, as insulin producing stem cell therapies progress, a transplant site that is retrievable is desirable. This prerequisite is currently incompatible with intrahepatic islet transplantation. Herein, we evaluate the functional capacity of a prevascularized subcutaneous site to accommodate marginal islet mass transplantation in mice., Methods: Syngeneic mouse islets (150) were transplanted either under the kidney capsule (KC), into a prevascularized subcutaneous device-less (DL) site, or into the unmodified subcutaneous (SC) tissue. The DL site was created 4 weeks before diabetes induction and islet transplantation through the transient placement of a 5-Fr vascular catheter. Recipient mice were monitored for glycemic control and intraperitoneal glucose tolerance., Results: A marginal islet mass transplanted into the DL site routinely reversed diabetes (n = 13 of 18) whereas all SC islet recipients failed to restore glycemic control (n = 0 of 10, P < 0.01, log-rank). As anticipated, nearly all islet-KC mice (n = 15 of 16) became euglycemic posttransplant. The DL recipients' glucose profiles were comparable to KC islet grafts, postintrapertioneal glucose tolerance testing, whereas SC recipients remained hyperglycemic postglucose challenge. All normoglycemic mice maintained graft function for 100 days until graft retrieval. DL and KC islet grafts stained positively for insulin, microvessels, and a collagen scaffold., Conclusions: The device-less prevascularized approach supports marginal mass islet engraftment in mice.