Aggregation of Engineered Human β-Cells Into Pseudoislets: Insulin Secretion and Gene Expression Profile in Normoxic and Hypoxic Milieu

Innovative treatments to cure type 1 diabetes are being actively researched. Among the different strategies, the replacement of beta-cells has given promising results. Classically, islets from cadaveric donors are transplanted into diabetic patients, but recently phase I clinical trials that use stem cell-derived beta-cells have been started. Such protocols require either an immunosuppressive treatment or the macroencapsulation of the beta-cells. They involve cell aggregation and the exposure of the cells to hypoxia. Using an engineered human beta-cell, we have addressed these two problems: a novel human beta-cell line called EndoC-beta H3 was cultured as single cells or aggregated clusters. EndoC-beta H3 cells were also cultured at normal atmospheric oxygen tension (pO(2) =21%) or hypoxia (pO(2) = 3%) in the presence or absence of modulators of the hypoxia-inducible factor lot (HIF1 alpha) pathway. Cell aggregation improved glucose-stimulated insulin secretion, demonstrating the benefit of cell-cell contacts. Low oxygen tension decreased beta-cell viability and their sensitivity to glucose, but did not alter insulin production nor the insulin secretion capacity of the remaining cells. To investigate the role of HIF1 alpha, we first used a HIF stabilizer at pO(2) = 21%. This led to a mild decrease in cell viability, impaired glucose sensitivity. and altered insulin secretion. Finally, we used a HIF inhibitor on EndoC-beta H3 pseudoislets exposed to hypoxia. Such treatment considerably decreased cell viability. In conclusion, aggregation of the EndoC-beta H3 cells seems to be important to improve their function. A fraction of the EndoC-beta H3 cells are resistant to hypoxia, depending on the level of activity of HIF1 alpha. Thus, these cells represent a good human cell model for future investigations on islet cell transplantation analysis.