Pig islet cell transplants tested in diabetic dogs

Abstract

INTRODUCTION: Pig islet xenotransplantation represents an attractive way to solve our human organ shortage. In this preclinical protocol, we implanted adult porcine islets microencapsulated in alginate-polylysin into insulin-dependent diabetic dogs. METHODS: Pancreata were obtained from animals weighing 100 to 150 kg in a slaughterhouse. The islets were isolated by collagenase digestion. The encapsulation technique was a modification of Sun's method. Isolated islets (5000 islet equivalents per kilogram of dog weight) were mixed with 1.6% low-viscocity alginate. Microcapsules were cultured for 36 hours before implantation. The five dogs were in healthy prior to induction of diabetes mellitus at least 1 year prior. Under sedation, we implanted microcapsules. We performed determinations of peripheral blood insulin at baseline and every 3 months as well as glycosylated hemoglobin at baseline and every 4 months. During follow-up, glycemia was estimated twice a day at 3 hours after morning and night meals using a blood glucose monitoring system. RESULTS: We observed significant decrease (20%-80%) in insulin needs (P < .01). Of note, before the procedure no hormone was detected in the blood at 6 to 12 months after transplantation, plasma insulin had improved significantly (P < .05) and glycosylated hemoglobin also showed a significant decrease (P < .01). All owners subjectively claimed that their animals were enjoying a better quality of life. DISCUSSION: Our preliminary data suggested that pig islet microencapsulation achieved metabolic control in type I diabetic dogs without the risk of immunosuppression using one or two procedures per year.