Safety and Viability of Microencapsulated Human Islets Transplanted Into Diabetic Humans

OBJECTIVE: Transplantation of insulin-producing cells placed inside microcapsules is being trialled to overcome the need for immunosuppressive therapy. RESEARCH DESIGN AND METHODS: Four type 1 diabetic patients with no detectable C-peptide received an intraperitoneal infusion of islets inside microcapsules of barium alginate (mean 178,200 islet equivalents on each of eight occasions). RESULTS: C-peptide was detected on day 1 post-transplantation, and blood glucose levels and insulin requirements decreased. C-peptide was undetectable by 1–4 weeks. In a multi-islet recipient, C-peptide was detected at 6 weeks after the third infusion and remains detectable at 2.5 years. Neither insulin requirements nor glycemic control was affected. Capsules recovered at 16 months were surrounded by fibrous tissue and contained necrotic islets. No major side effects or infection occurred. CONCLUSIONS: While allografting of encapsulated human islets is safe, efficacy of the cells needs to improve for the therapy to make an impact on the clinical scene.