RGD peptide-modified adenovirus expressing hepatocyte growth factor and X-linked inhibitor of apoptosis improves islet transplantation

Abstract

Background Islet transplantation has the potential for treating type I diabetes; however, its widespread clinical application is limited by the massive apoptotic cell death and poor revascularization of transplanted islet grafts. Methods We constructed a surface-modified adenoviral vector with RGD (Arg-Gly-Asp) sequences encoding human X-linked inhibitor of apoptosis and hepatocyte growth factor (RGD-Adv-hHGF-hXIAP). In vitro transgene expression in human islets was determined by enzyme-liniked immunosorbent assay. RGD-Adv-hHGF-hXIAP-transduced human islets were transplanted under the kidney capsule of streptozotocin-induced diabetic NOD/SCID mice. The blood glucose levels of mice were measured weekly. The kidneys bearing islets were isolated at the end of the experiment and subjected to immunofluorescence staining. Results The transduction efficiency on human islets was significantly improved using RGD-modified adenovirus. HGF and XIAP gene expressions were dose-dependent after viral transduction. When exposed to a cocktail of inflammatory cytokines, RGD-Adv-hHGF-hXIAP-transduced human islets showed decreased caspase 3 activity and reduced apoptotic cell death. Prolonged normoglycemic control could be achieved by transplanting RGD-Adv-hHGF-hXIAP-transduced human islets. Immunofluorescence staining of kidney sections bearing RGD-Adv-hHGF-hXIAP-transduced islets was positive for insulin and von Willebrand factor (vWF) at 200 days after transplantation. Conclusions These results indicated that ex vivo transduction of islets with RGD-Adv-hHGF-hXIAP decreased apoptotic islet cell death and improved islet revascularization, and eventually might improve the outcome of human islet transplantation.