The Effect of Sirtuin 1 Gene Expression on Mouse Islet Graft Survival

Abstract

Purpose: Islet transplantation is a promising therapy for Type 1 diabetes, however clinical application has not been as successful as organ transplantation due to early graft injury as well as immune reaction. Sirtuin 1 (SIRT1), a nicotinamide adenosine dinucleotide-dependent histone deacetylase, has been shown to up-regulate insulin secretion in response to glucose stimulation in pancreatic Β-cells. SIRT1 gene transfection of islet before transplantation could ameliorate their capacity to survive and engraft in the implanted site.

Materials and Methods: In this study, we investigated whether SIRT1 gene could be transfected into islets by adenoviral vector and protect them from cytokine-mediated damage. We also examined the protective effect of SIRT1 transfected islets on graft failure after islet transplantation.

Results: We confirmed that adenoviral vector transfection of islets was efficient by quantitative analysis of GFP positive cell. In addition, SIRT1 expression was shown in transfected islets by Western blotting. Viability and insulin secretion were similar between transfected and control islets in normal condition. However in TNF-Α and IL-1Β treatment, significantly improved Ad SIRT1 transfected islet survival and function were detected compared with marked cell death in control islet. Furthermore, inhibition of SIRT1 activity by EX527 impaired viability and insulin secretion. We transplanted syngeneic islets (400 islet equivalents per recipient) with or without Ad-SIRT1 into the kidney capsule of diabetic C57BL/6 mice. Regarding blood glucose control, diabetic mice transplanted with a marginal mass of Ad-SIRT1 transfected islets became normoglycemic days more rapidly and 100% of the recipients were normoglycemic at 4.5 post-transplant day, whereas only 66% of the mice transplanted with Ad-LacZ transfected islets were normoglycemic at 18.5 post-transplant day (P<0.05).

Conclusion: These results suggested that delivery of the SIRT1 gene to islets enhanced islet cell survival during the early post-transplant period, and preserved islet mass and functions over time in the murine islet transplant model.