Biocompatibility of purified sodium alginate-barium chloride microcapsule and functional assessment of transplanted pancreas islet via the microcapsule for type Ⅰ diabetes / 中国组织工程研究

ABSTRACT

BACKGROUND: Sodium alginate-poly-lysine can cause foreign body reaction to induce functional inactivation of the microencapsulated islets following transplantation. Can barium chloride solve this problem?OBJECTIVE: To assess the biocompat ibility of purified sodium alginate-barium chloride microcapsules and the bioactivity of the microencapsulated islets of rats.DESIGN: A randomized controlled experiments based on the experimental animals.SETTING: Department of endocrinology in a university hospital.MATERIALS: This experiment was completed in the Laboratory of Endocrinology and Department of Laboratory Animals, First Affiliated Hospital of Nanjing Medical University during July to December 2002. Specific pathogen-free SD and Wistar rats were provided by Center of Animal Experiment, Nanjing Medical University and Animal Experiment Center of Shanghai respectively.METHODS: Purified and non-purified sodium alginate-barium chloride microcapsules were prepared with one-step method using domestically made equipment. The microcapsule was transplanted intraperitoneally into normal SD rats and its biocompatibility was observed 4 weeks later. The bioactivity of the microencapsulated islets was also observed following transplantation in streptozotocin(STZ)-induced diabetic Wistar rat models.MAIN OUTCOME MEASURES: ① The recovery rate of the transplanted empty microcapsule; ② Results of bioactivity assessment of the insulin from the microencapsulated islets; ③ Histological examination.RESULTS: Four weeks after the transplantation, the recovery rate of the transplanted empty microcapsules in the purified group was higher that that in non-purified group( P > 0.05), and the purified microcapsules retained intact and smooth morphology with out causing fibrosis. The islets encapsulated by purified sodium alginate-barium chloride microcapsules showed good insulin-ecreting function in in vitro culture, without significant difference from non-microencaps ulated islets( P > 0. 05) . The islets transplanted via the microcapsules into diabetic Wistar rat models induced by STZ had a survival time over 6 weeks.CONCLUSION: The purified sodium alginate-barium chloride microcapsules have good bioactivity and tissue compatibility, which might provide a solution for the source of donor diabetic islets in the treatment of type Ⅰ diabetes.