Endothelial Cells in Endogenous and Transplanted Pancreatic Islets: Differences in the Expression of Angiogenic Peptides and Receptors

Background/Aims: An important reason for the large amount of islets required for successful islet transplantation is likely to be inadequate engraftment of the transplanted islets. Thus, the revascularization is of major importance for graft survival. In order to study the expression of angiogenic peptides and receptors on islet endothelial cells (EC), we needed methods giving access to such endothelium. Therefore, we developed methods to isolate EC from islets transplanted intraportally or beneath the kidney capsule. Methods: Pancreatic islets were isolated, cultured and syngeneically transplanted into the liver or beneath the kidney capsule of C57BL/6 mice. One month post-transplantation, the islets were retrieved and EC from these islets were explanted. EC were also collected from freshly isolated and cultured non-transplanted islets. The EC were purified with Dynabeads and identified with immunocytochemistry. Angiogenesis GEArray technology was used to study angiogenic gene expression.Results: Several angiogenic genes were expressed in EC; e.g. endostatin, pigmentepithelial derived factor, vascular endothelial growth factor and angiopoietin-2, and their expression were affected by culture.Conclusion: The expression of angiogenesis-related genes in islet EC from non-transplanted islets is affected by culture. Moreover, we also describe a technique, which makes it possible to obtain EC from transplanted islets.