Transplantation of betacellulin-transduced islets improves glucose intolerance in diabetic mice

Type 1 diabetes is an autoimmune disease caused by permanent destruction of insulin-producing pancreatic beta cells and requires lifelong exogenous insulin therapy. Recently, islet transplantation has been developed, and although there have been significant advances, this approach is not widely used clinically due to the poor survival rate of the engrafted islets. We hypothesized that improving survival of engrafted islets through ex vivo genetic engineering could be a novel strategy for successful islet transplantation. We transduced islets with adenoviruses expressing betacellulin, an epidermal growth factor receptor ligand, which promotes beta-cell growth and differentiation, and transplanted these islets under the renal capsule of streptozotocin-induced diabetic mice. Transplantation with betacellulin-transduced islets resulted in prolonged normoglycemia and improved glucose tolerance compared with those of control virus-transduced islets. In addition, increased microvascular density was evident in the implanted islets, concomitant with increased endothelial von Willebrand factor immunoreactivity. Finally, cultured islets transduced with betacellulin displayed increased proliferation, reduced apoptosis and enhanced glucose-stimulated insulin secretion in the presence of cytokines. These experiments suggest that transplantation with betacellulin-transduced islets extends islet survival and preserves functional islet mass, leading to a therapeutic benefit in type 1 diabetes.

Expression of human BTC with biological activity / 上海第二医科大学学报

Objective To obtain abundant human betacellulin(BTC) with biological activity. Methods The whole mature protein coding sequence of BTC gene was amplified by polymerase chain reaction(PCR) method applied to human pancreatic ?-cell tumors cDNA.The fragment was cloned into prokaryotic expression vector pET32a(+) plasmid.The recombinant plasmid was transformed into E.coli BL21 and the fusion protein was expressed under isopropyl-beta-D-thiogalactopyranoside(IPTG).The fusion protein was purified by Ni2+ affinity chromatography.SDS-PAGE and Western blot were employed to determine the expression and purification of the expected protein.BTC was added to culture NIH3T3 cells for 5 days,and cell proliferation was detected by MTT. Results Lots of fusion protein were produced,and the purified protein can stimulate the proliferation of NIH3T3 cells. Conclusion The human BTC can be successfully obtained from the pET32a(+) system with the biological activity of stimulating the proliferation of NIH3T3 cells.

Study of The Effect on Islets Cultured In vitro and STZ-induced Diabetic Rats In vivo of EGF-like Domain of Betacellulin / 生物化学与生物物理进展

Betacellulin (BTC) is one of "islets regeneration factors" which received more and more attention these years. BTCe is the C-terminal 50-residue region of mature BTC protein and can bind with erbB-1?erbB-4 receptor. It has the same mitogenic activity on cells as the whole section. BTC and BTCe can improve the level of glucose-stimulated insulin secretion (GSIS) during islets culture in vitro though they had no effect on the acute insulin secretion. BTCe also effectively ameliorated the hyperglycemia of STZ-induced diabetic rats by a single plasmid injection into muscle of rats. It is supposed that BTCe promote the proliferation of PDX-1 positive cells or repair some signal transduction pathway. Perhaps the latter is more important.