Introduction: Pancreatic islet transplantation has recently emerged as one of the most promising therapeutic approaches for improving glycemic control in Type 1 diabetes patients. However, there were some barriers like deficiency of islet supply and immune-mediated islet destruction after transplantation. Xenotransplantation with pig is one of the candidate for clinical transplantation into diabetic patients. But, some antigen are the obstacle to successful xenotransplantation. For these reasons, we isolated quadruple knockout (GGTA1/CMAH/iGb3s/B4GalNT2 knockout, QKO) porcine islets and transplanted into STZ induced diabetic C57BL/6 and NOD-SCID mice. We identified efficacy of QKO porcine islet with transplantation in diabetic mice with/without immunosuppressive agent (anti-CD154, MR1).

Methods: Quadruple porcine pancreatic islets were isolated from 12 to 18 month old pig using standard enzymatic digestion and purification. Recipients (C57BL/6 and NOD-SCID mice) were injected with STZ for diabetes induction (160 mg/kg, IP injection). Porcine islet were transplanted into the renal capsule to diabetic C57BL/6 and NOD-SCID mice (n=10 per group). For prevent immune rejection, some recipient groups were treated immunosuppressive agent (anti-CD154, MR1). To compare with QKO islet efficiency, we transplanted wildtype (WT) porcine islet into diabetic C57BL/6 and NOD-SCID recipients with or without immunosuppressive agent (anti-CD154, MR-1). We monitored body weight, non-fasting blood glucose level and porcine insulin in serum. Intraperitoneal glucose tolerance test (IPGTT) was performed in POD31 and 123. 

Results: Transplantation of QKO and WT porcine islets under the kidney capsule into diabetic mice, hyperglycemia was reversed and became normoglycemia (BGL< 200mg/dL) at day 1. However, the WT porcine islet transplanted group became hyperglycemia within 7 days. On the other hands, QKO porcine islet transplanted group maintained normoglycemia up to 100 days without any immunosuppressive agent (p<0.05 ANOVA). Measured porcine insulin and c-peptide level in serum, normoglycemic mice detected porcine insulin, c-peptide and mouse insulin was not detected. 

Conclusion: In this study, we identified that xenotransplantation of QKO islets in diabetic mice improved glucose profile and survival rate in STZ induced diabetic mice. Transplantation of transgenic pig islets could have a significant clinical impact on the treatment of type 1 diabetes. Islet transplant studies in diabetic primates are currently underway.