Department of surgery
The second affiliated hospital of Zhejiang University
Protective effect of Cyanidin-3-O-Glucoside on xenotransplanted neonatal porcine islets through ERK1/2 and PI3K/Akt-induced Nrf2-mediated HO-1 induction
Chao Li1, Bin Yang1, Zhihao Xu3, Xian Li2, Kunsong Chen2, Ray V Rajotte3, Yulian Wu1, Gina R. Rayat3.
1Department of Surgery, The Second Affiliated Hospital of Zhejiang University, Hangzhou, People's Republic of China; 2Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, People's Republic of China; 3Department of Surgery, Surgical-Medical Research Institute, Alberta Diabetes Institute, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
Dr. Gina R. Rayat's Group. Dr. Yulian Wu's Group. Dr. Kunsong Chen's Group.
Background: It was previously shown that oxidative stress is a major cause of islet injury and dysfunction during islet isolation and transplantation procedures. The aim of this study was to determine whether cyanidin-3-O-glucoside (C3G), an antioxidant extracted from Chinese bayberry, could improve the function of neonatal porcine islets (NPI) transplanted under the kidney capsule and if so, investigate the underlying mechanism whereby C3G protects the islets.
Methods: The toxicity of various concentrations (0.1, 05, 1.0, and 5.0 µM) of C3G on NPI was determined by Trypan blue exclusion dye staining and flow cytometry analysis (n=4). The effects of C3G on extracellular signal-regulated kinase1/2 (ERK1/2), phosphatidylinositol 3-kinase (I3K/Akt) signaling pathways, as well as the protein expressions of nuclear erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were assessed by western blot (n=3). The C3G-treated (1.0 μM) or -untreated islets were transplanted under the kidney of diabetic B6 rag1-/- mice, fed with (n=4) or without C3G (n=5), and their blood glucose levels were monitored for 17 weeks. The gene (HO-1, Bcl-2 and Survivin) and protein (insulin and glucagon) expressions on C3G-treated or -untreated islets and grafts were evaluated by quantitative polymerase chain reaction (qPCR) and immunohistochemistry analysis, respectively.
Results: The islets treated with low concentrations of C3G showed significantly higher viability and HO-1 gene expression compared to the untreated control (p<0.05). In addition, western blot analysis showed the phosphorylation of ERK1/2 and PI3K/Akt, the nuclear translocation of Nrf2, and the significantly elevated expression of HO-1 protein when islets were treated with C3G (p<0.001). Mice that received 2,000 islet equivalent (IEQ) and fed with C3G achieved normoglycemia much faster (8 weeks), followed by the mice transplanted with C3G-cultured islets (10 weeks). Recipients of untreated islets reached normoglycemia later than these two groups (12 weeks). There was no significant difference observed in mice that received 1,000 IEQ. All NPI xenografts stained strongly positive for insulin and glucagon at 15 weeks post-transplantation.
Conclusion: C3G could promote the viability of NPI and enhance their function after transplantation through the activation of ERK1/2 and PI3K/Akt-induced Nrf2-mediated HO-1 pathway.
University of Alberta Office of the Provost and VP Academic. Alberta Diabetes Institute. Alberta Diabetes Foundation. Edmonton Civic Employees Charitable Assistance Fund. Canadian Institutes of Health Research. Faculty of Medicine and Dentistry, University of Alberta. National Natural Science Foundation of China (No. 81172158, 81272332, 81301889 and 81100549). Special Foundation for Innovative Talents Training Project of Zhejiang University “985 program”.
 Bottino R, Balamurugan AN, Tse H, et al. Response of human islets to isolation stress and the effect of antioxidant treatment. Diabetes. 2004;53:2559-2568.
 Hennige AM, Lembert N, Wahl MA, Ammon HP. Oxidative stress increases potassium efflux from pancreatic islets by depletion of intracellular calcium stores. Free Radic Res. 2000;33:507-516.
15:30 - 17:00
|Islet Quality Assessment and Engraftment||Protective effect of Cyanidin-3-O-Glucoside on xenotransplanted neonatal porcine islets through ERK1/2 and PI3K/Akt-induced Nrf2-mediated HO-1 induction||Plenary Room 1|