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Diabetes mellitus, a significant global public health challenge, severely impacts human health worldwide. The organoid, an innovative in vitro three-dimensional (3D) culture model, closely mimics tissues or organs in vivo. Insulin-secreting islet organoid, derived from stem cells induced in vitro with 3D structures, has emerged as a potential alternative for islet transplantation and as a possible disease model that mirrors the human body\'s in vivo environment, eliminating species difference. This technology has gained considerable attention for its potential in diabetes treatment. Despite advances, the process of stem cell differentiation into islet organoid and its cultivation demonstrates deficiencies, prompting ongoing efforts to develop more efficient differentiation protocols and 3D biomimetic materials. At present, the constructed islet organoid exhibit limitations in their composition, structure, and functionality when compared to natural islets. Consequently, further research is imperative to achieve a multi-tissue system composition and improved insulin secretion functionality in islet organoid, while addressing transplantation-related safety concerns, such as tumorigenicity, immune rejection, infection, and thrombosis. This review delves into the methodologies and strategies for constructing the islet organoid, its application in diabetes treatment, and the pivotal scientific challenges within organoid research, offering fresh perspectives for a deeper understanding of diabetes pathogenesis and the development of therapeutic interventions.

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Pancreatic islet transplantation is an emerging treatment for type I diabetes; however, it is limited by donor matching and availability. Porcine islet xenotransplantation offers a promising alternative to allotransplantation, with the potential for large-scale production of on-demand, functional islets. The yield and viability of isolated islets is highly susceptible to the quality of the donor pancreas and the method of procurement, particularly the duration of warm-ischemia time. To improve organ preservation and subsequent islet yield and viability, we have developed a protocol for surgical perfusion and resection of the porcine pancreas. This protocol employs direct infrarenal aortic cannulation and organ perfusion to both minimize warm-ischemia time and simplify the procedure for operators who do not have extensive surgical expertise. Subsequent arterial perfusion of the pancreas via the aorta flushes stagnant blood from the microvasculature, thereby reducing thrombosis and oxidative damage to the tissue. This manuscript provides a detailed protocol for surgical perfusion and resection of the porcine pancreas, followed by islet isolation and purification.

BACKGROUND: Total pancreatectomy with islet autotransplantation (TPIAT) is a potentially curative treatment for patients with chronic pancreatitis (CP) refractory to medical and endoscopic therapies. Patients often receive the initial follow-up medical care at the surgery-performing center, but then may follow up closer to where they live. We sought to describe the characteristics and outcomes of pediatric patients who underwent TPIAT at a national surgical referral center and were subsequently followed at our regional subspecialty center, the Children\'s Hospital Colorado.
METHODS: We performed a retrospective analysis of baseline and outcomes data for the 10 pediatric patients who underwent TPIAT from 2007 to 2020 and received follow-up care at our institution.
RESULTS: All patients had a diagnosis of CP, and nine of 10 patients had an identified underlying genetic risk factor. Insulin usage was common immediately following TPIAT, but at 1 year of follow-up, five of nine patients (55.6%) were insulin-independent and nine of nine had an HbA1c below 6.5%. For the four patients on insulin 1 year after TPIAT, total daily insulin dose ranged from 0.06 to 0.71 units/kg/day. All patients who underwent mixed meal tolerance testing had a robust peak C-peptide response at 1 year. There were significant improvements in nausea, school/work absences, narcotic dependence, and pancreas-related hospital admissions 1 year after TPIAT.
CONCLUSIONS: Patients followed at our center had long-term improvements with low-insulin usage, detectable C-peptide, and improved pancreatitis-related outcomes after TPIAT. Pediatric patients who undergo TPIAT can be successfully co-managed in conjunction with the original surgery-performing center.

The longevity of grafts remains a major challenge in allogeneic transplantation due to immune rejection. Systemic immunosuppression can impair graft function and can also cause severe adverse effects. Here, we report a local immuno-protective strategy to enhance post-transplant persistence of allografts using a mesenchymal stem cell membrane-derived vesicle (MMV)-crosslinked hydrogel (MMV-Gel). MMVs are engineered to upregulate expression of Fas ligand (FasL) and programmed death ligand 1 (PD-L1). The MMVs are retained within the hydrogel by crosslinking. The immuno-protective microenvironment of the hydrogel protects allografts by presenting FasL and PD-L1. The binding of these ligands to T effector cells, the dominant contributors to graft destruction and rejection, results in apoptosis of T effector cells and generation of regulatory T cells. We demonstrate that implantation with MMV-Gel prolongs the survival and function of grafts in mouse models of allogeneic pancreatic islet cells and skin transplantation.

Diabetes is a prevalent chronic disease that traditionally requires severe reliance on medication for treatment. Oral medication and exogenous insulin can only temporarily maintain blood glucose levels and do not cure the disease. Most patients need life-long injections of exogenous insulin. In recent years, advances in islet transplantation have significantly advanced the treatment of diabetes, allowing patients to discontinue exogenous insulin and avoid complications.Long-term follow-up results from recent reports on islet transplantation suggest that they provide significant therapeutic benefit although patients still require immunotherapy, suggesting the importance of future transplantation strategies. Although organ shortage remains the primary obstacle for the development of islet transplantation, new sources of islet cells, such as stem cells and porcine islet cells, have been proposed, and are gradually being incorporated into clinical research. Further research on new transplantation sites, such as the subcutaneous space and mesenteric fat, may eventually replace the traditional portal vein intra-islet cell infusion. Additionally, the immunological rejection reaction in islet transplantation will be resolved through the combined application of immunosuppressant agents, islet encapsulation technology, and the most promising mesenchymal stem cells/regulatory T cell and islet cell combined transplantation cell therapy. This review summarizes the progress achieved in islet transplantation, and discusses the research progress and potential solutions to the challenges faced.

Islet transplantation may be the most efficient therapeutic technique for patients with type 1 diabetes mellitus (T1DM). However, the clinical application of this method is faced with numerous limitations, including isolated islet apoptosis, recipient rejection, and graft vascular reconstruction. Mesenchymal stem cells (MSCs) possess anti-apoptotic, immunomodulatory, and angiogenic properties. Here, we review recent studies on co-culture and co-transplantation of islets with MSCs. We have summarized the methods of preparation of co-transplantation, especially the merits of co-culture, and the effects of co-transplantation. Accumulating experimental evidence shows that co-culture of islets with MSCs promotes islet survival, enhances islet secretory function, and prevascularizes islets through various pretransplant preparations. This review is expected to provide a reference for exploring the use of MSCs for clinical islet co-transplantation.

OBJECTIVE: Despite islet transplantation has proved a great potential to become the standard therapy for type 1 diabetes mellitus (T1DM), this approach remains limited by ischemia, hypoxia, and poor revascularization in early post-transplant period as well as inflammation and life-long host immune rejection. Here, we investigate the potential and mechanism of human amniotic mesenchymal stem cells (hAMSCs)-islet organoid to improve the efficiency of islet engraftment in immunocompetent T1DM mice.
METHODS: We generated the hAMSC-islet organoid structure through culturing the mixture of hAMSCs and islets on 3-dimensional-agarose microwells. Flow cytometry, whole-body fluorescent imaging, immunofluorescence, Calcein-AM/PI staining, ELISA, and qPCR were used to assess the potential and mechanism of shielding hAMSCs to improve the efficiency of islet transplantation.
RESULTS: Transplant of hAMSC-islet organoids results in remarkably better glycemic control, an enhanced glucose tolerance, and a higher β cell mass in vivo compared with control islets. Our results show that hAMSCs shielding provides an immune privileged microenvironment for islets and promotes graft revascularization in vivo. In addition, hAMSC-islet organoids show higher viability and reduced dysfunction after exposure to hypoxia and inflammatory cytokines in vitro. Finally, our results show that shielding with hAMSCs leads to the activation of PKA-CREB-IRS2-PI3K and PKA-PDX1 signaling pathways, up-regulation of SIL1 mRNA levels, and down-regulation of MT1 mRNA levels in β cells, which ultimately promotes the synthesis, folding and secretion of insulin, respectively.
CONCLUSIONS: hAMSC-islet organoids can evidently increase the efficiency of islet engraftment and might develop into a promising alternative for the clinical treatment of T1DM.

Clinical outcomes for total-pancreatectomy followed by intraportal islet autotransplantation (TP-IAT) to treat chronic pancreatitis (CP) are suboptimal due to pancreas inflammation, oxidative stress during islet isolation, and harsh engraftment conditions in the liver\'s vasculature. We describe a thermoresponsive, antioxidant macromolecule poly(polyethylene glycol citrate-co-N-isopropylacrylamide) (PPCN) to protect islet redox status and function and to enable extrahepatic omentum islet engraftment. PPCN solution transitions from a liquid to a hydrogel at body temperature. Islets entrapped in PPCN and exposed to oxidative stress remain functional and support long-term euglycemia, in contrast to islets entrapped in a plasma-thrombin biologic scaffold. In the nonhuman primate (NHP) omentum, PPCN is well-tolerated and mostly resorbed without fibrosis at 3 months after implantation. In NHPs, autologous omentum islet transplantation using PPCN restores normoglycemia with minimal exogenous insulin requirements for >100 days. This preclinical study supports TP-IAT with PPCN in patients with CP and highlights antioxidant properties as a mechanism for islet function preservation.