Lentivirus-mediated Bcl-2 expression in beta TC-tet cells improves resistance to hypoxia and cytokine-induced apoptosis while preserving in vitro andin vivo control of insulin secretion

beta TC-tet cells are conditionally immortalized pancreatic beta cells whic h can confer long-term correction of hyperglycemia mia when transplanted in syngeneic streptozocin diabetic mice. The use of these cells for control o f type I diabetes in humans will require their encapsulation and transplant ation in non-native sites where relative hypoxia and cytokines may threaten their survival. in this study we genetically engineered beta TC-tet cells with the anti-apoptotic gene Bcl-2 using new lentiviral vectors and showed that it protected this cell line against apoptosis induced by hypoxia, stau rosporine and a mixture of cytokines (IL-1 beta, IFN-gamma and TNF-alpha). We further demonstrated that Bcl-2 expression permitted growth at higher ce ll density and with shorter doubling time. Expression of Bcl-2, however, di d not interfere either with the intrinsic mechanism of growth arrest presen t in the beta TC-tet cells or with their normal glucose dose-dependent insu lin secretory activity. Furthermore, Bcl-2 expressing beta TC-tet cells ret ained their capacity to secrete insulin under mild hypoxia. Finally, transp lantation of these cells under the kidney capsule of streptozocin diabetic C3H mice corrected hyperglycemia for several months. These results demonstr ate that the murine beta TC-tet cell line can be genetically modified to im prove its resistance against different stress-induced apoptosis while prese rving its normal physiological function. These modified cells represent an improved source for cell transplantation therapy of type I diabetes.