Xenotransplantation of porcine neonatal islets of Langerhans and Sertoli cells: a 4-year study.

OBJECTIVE: Porcine islets of Langerhans for xenotransplantation into humans have been proposed as a solution to the shortage of human donors. Rejection is one of the main constraints. This study presents the results of a clinical trial using a novel method for transplanting and immunoprotecting porcine islets in type 1 diabetic patients. DESIGN: A 4-year follow up of a clinical trial involving 12 patients, with no immunosuppressive drugs at any point. Eleven age matched untransplanted diabetics served as controls. METHODS: We have developed a procedure for protecting neonatal porcine islets by combining them with Sertoli cells and placing them in a novel subcutaneous autologous collagen-covered device. RESULTS: In the patients in the treatment group, no complications arose and no porcine endogenous retrovirus infection was detected. Half of the patients showed a significant reduction in insulin requirements compared with both their pre transplant levels and controls, and this reduction was maintained for up to 4 years. Two patients became insulin-independent for several months. Porcine insulin was detected in three patients' sera following glucose stimulation up to 4 years post transplant. Three years post transplant, one of four devices was removed from four patients, and the presence of insulin-positive cells in the transplant was demonstrated by immunohistology in all 4 patients. CONCLUSIONS: Long-term cell survival with concurrent positive effects on metabolic control are possible by this technique.

Unexpected immunoresponse to Gal and APA antigens in diabetic type 1 patients receiving neonatal pig islets after 6 years.

Cotransplantation of porcine islets and Sertoli cells into preimplanted subcutaneous devices improve metabolic control in type 1 diabetic patients, and survive grafted for more than 4 years. We report here, further assessment of the endocrine and porcine nature of the surviving cells and the immune responses elicited toward Gal alpha(1,3)-Gal beta(1,4)-GlcNAc (Gal) antigen in patients who received a second and third transplants. No immunosuppressive drugs were administered. We were able to immunostain insulin- and glucagon-positive cells in all biopsies of patients and Sertoli cell markers in 60.9% of biopsies. Additionally, all biopsies tested, amplified the porcine COII gene. Patients demonstrated an increase in antipig antibodies in response to the first transplant with a decreasing response toward the second and third transplants. In all transplants, the IgG levels promptly returned to basal values after 3-4 months. The long-term survival of porcine cells and the reduced humoral immune response to multiple transplants indicate a form of tolerance. We have not been able to find CD25-positive cells, indicating that it is probably an immune accommodation of the graft.