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Engraftment, function and beta cell regulation in the adrenal transplant model

Subject Area Endocrinology, Diabetology, Metabolism
Term from 2011 to 2018
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 189897882
 
Final Report Year 2019

Final Report Abstract

Pancreatic islet transplantation is a viable treatment option for selected patients with type 1 diabetes mellitus. However, a number of factors hamper widespread utilization of this therapeutic modality. A major limiting factor for long-term survival and function of islet transplants are still insufficient. A major determinant is the microenvironment of is in regard to the inappropriate microenvironment after intraportal transplantation. We aim to evaluate the microenvironment of the adrenal as a beneficial transplantation site that promotes beta cell engraftment, survival and long-term function as the adrenal offers extensive vascularization, anti-apoptotic and pro-proliferative effects of various signalling molecules and a local anti-inflammatory and immunosuppressive microenvironment. For in vitro analysis of islet viability, function and reactive oxygen species (ROS) a co-culture system of adrenal cells and pancreatic islets was established. The co-culture setting did not significantly impact on islet viability, insulin content and secretion and there is evidence that oxidative stress is markedly reduced in the presence of adrenal cells. For islet transplantation, the adrenal of diabetic NuNu-mice was exteriorized and 300 islets were injected through the upper pole of the gland or the kidney. Animals showed a fast decrease in blood glucose levels within the first days after transplantation in both groups, at around 10 days the curves between adrenal and kidney site drifted apart in favor of the adrenal site. Regardless of the transplantation site, islets showed a well preserved morphology and intense insulin staining. The intra-adrenally engrafted islets show higher vascularization compared to the kidney capsule control. The preliminary work underlined the feasibility of islet transplantation into the adrenal with first promising results on the restoration of normoglycemia in streptozotocin-induced diabetic mice. The results achieved could prove the beneficial effect of the adrenal microenvironment on islet engraftment and function in vitro and in vivo and elucidate the underlying mechanisms in regards to promoting islet revascularization, protection from oxidative stress, and enhancement of islet proliferative capacity. This novel concept might allow reducing the islet mass that is currently needed to reverse diabetes.

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