Hypoxia and fibrosis are one of the most important obstacles for encapsulated islet transplantation. Previously, we have developed alginate-based microcapsules improving fibrosis (alginate-chitosan) or hypoxia (alginate-perfluorodecalin) and proved their effects. In this study, we compared long-term graft survival of encapsulated islet with microcapsule against fibrosis or hypoxia in diabetic mice model, using 1,3-galactosyltransferase gene-knockout (GalT-KO) pigs. Islets were isolated form GalT-KO pigs and then encapsulated with alginate-chitosan or alginate-perfluorodecalin microcapsule. To magnify graft survival gap between different microcapsules, marginal dose of islets were transplanted into streoptozotocin-induced diabetic mice intraperitoneally. Blood glucose level were measured for a year. Intraperitoneal glucose tolerance test (IPGTT) was performed at 6 and 12 months after transplantation. In the alginate-chitosan group, the blood glucose level of diabetic mice decreased after encapsulated islet transplantation. However, blood glucose level increased again within two months in 3 out of 4 mice. In the alginate-perfluorodecalin group, the blood glucose level of diabetic mice decreased after transplantation and maintained normoglycemia more than 6 months. Although blood glucose level tended to increase 6 months after transplantation, it remained below 300 mg/dL by one year. The area under curve (AUC) of IPGTT was similar between two groups at baseline. At 6 months after transplantation, AUC of IPGTT in alginate-perflourodecalin group lower than AUC of alginate-chitosan group. At one year after transplantation, microcapsules were retrieved. Dithizone stain was positive in most retrieved islet and fibrosis was minimal in both groups.
In conclusion, microcapsule against hypoxia showed a longer xenograft survival than microcapsule against fibrosis in diabetic mice.
E. Lee: None. Y. Yang: None. Y. Cho: None. S. Lee: None. J. Cho: None. K. Yoon: None.
Cooperative Research Program for Agriculture Science and Technology Development (PJ01345301); Rural Development Administration, Republic of Korea