316.7: Significant efficacy of GTKO-CD55-CD59-HT adult porcine islets in treating diabetic monkeys with xenogeneic islet transplantation

Introduction: Islet xenotransplantation has emerged as a prospective β-cell replacement therapy for insulin-deficient diabetes. Pigs can be genetically modified to protect islet xenografts from immune challenges, including an intense innate response triggered by intraportal delivery, the immediate blood-mediated inflammatory response (IBMIR). The rhesus macaque is one of the most widely used NHP models for islet xenotransplantation. Therefore, we used transgenic porcine islets to treat diabetic rhesus monkeys to verify its effectiveness. Methods: GGTA1P gene knockout and humanized CD55 and CD59 gene insertion were performed on Xeno-1 pigs by CRISPR/Cas9 technology, and the successful insertion of the two gene sequences was confirmed by gene sequencing. Diabetes was induced by i.v. injection of streptozotocin. Rhesus macaques were considered truly diabetic if they had persistent hyperglycemia requiring exogenous insulin administration and were unresponsive to IVGTT and AST. The islets of gene-modified adult pig (over 2 years old) were extracted by enzyme perfusion and continuous density gradient centrifugation. Porcine islets were transplanted into two diabetic monkeys by mesenteric venipuncture. One monkey received 10,000 islet equivalents (IE)/kg and the other 20,000 IE/kg. Graft function was monitored by measuring blood glucose and porcine C-peptide. Results: The first diabetic monkey returned to normal levels of blood glucose 110 days after transplantation. Before the transplantation, the average blood glucose was about 18mmol/L, and the insulin dosage was about 12 IU/day. 110 days after the transplant, the average blood glucose was about 8mmol/L, and the insulin dosage was about 3 IU/day. The amount of insulin is reduced by about 75%. Postoperative D-dimer increased slightly, reached the peak on the 3rd day, and returned to normal on the 5th day. The C-peptide test result was 42.5 pmol/L 3 months after the operation. Blood glucose in the second diabetic monkey returned to normal levels 30 days after transplantation. The average blood glucose was about 17 mmol/L and the insulin dosage was about 12 IU/day before the transplantation. 30 days after transplantation, the average blood glucose was about 7 mmol/L, and the insulin dosage was about 2.5 IU/day. Insulin doses were reduced by approximately 79%. There was no significant fluctuation of D-dimer after operation. Conclusion: GTKO-CD55-CD59-HT adult porcine islets can effectively treat diabetic monkeys. Compared with before transplantation, the blood glucose of the two diabetic monkeys returned to normal after transplantation, the blood glucose fluctuation was small, the average insulin consumption decreased by 77%, and the islet transplantation dosage was positively correlated with the transplantation effect. The blood coagulation indexes after transplantation were basically normal, indicating that there was no postoperative thrombosis. the National Key Research and Development Program (Grant No. 2019YFA0110703).