2025-LB: Anti-apoptotic BCL2 Delivery to Protect Stem Cell–Derived Beta Cells from Transplantation-Induced Cell Death

Cadaveric islet transplantation in most type 1 diabetic (T1D) patients restores euglycemia. However, cadaveric islets are limited, transplantation often requires multiple organ donors, and significant apoptotic cell death shortly after transplantation prevents widespread implementation of this curative approach. Recent improvements in the differentiation of stem cell-derived beta cells (sBC) provide an abundant source of functional beta cells, with the first clinical trials evaluating the efficacy and safety of sBCs. Similar to cadaveric islets, sBCs experience severe apoptotic cell death following transplantation with the majority of graft mass lost within the first day following transplantation. We hypothesize that temporarily arresting the intrinsic apoptotic pathway by expression of BCL2 in transplanted sBCs can prevent significant cell death and improve graft survival. Using genome engineering strategies, we inserted a doxycycline inducible BCL2 expression cassette into a human induced pluripotent stem cell line. Under nutrient deprivation conditions, cells with induced BCL2 expression displayed a 60% increase in viable cells after treatment, this increase in viability was also observed in complementary in vitro models of apoptosis and radical oxygen species. These results give evidence to the role of BCL2 in saving cells under intrinsic apoptosis stress conditions. Future experiments will evaluate if BCL2 can similarly rescue sBCs cell death after transplant in vivo. Rescuing transplanted sBCs from apoptotic cell death will increase the efficacy of islet transplantation therapy for T1D patients by reducing the total beta cell mass needed to achieve insulin independence.