In situ gelling-polypeptide hydrogel systems for the subcutaneous transplantation of MIN6 cells

Subcutaneous islet transplantation can be easily conducted with minimum invasiveness, and the implant can be monitored easily. However, a major disadvantage of this transplantation technique is its poor efficacy which could be attributed to poor oxygenation and inadequate vascularization at the subcutaneous tissue. In this study, we explored the use of thermosensitive methoxy-poly(ethylene glycol)-poly(Ala), mPEG-poly(Ala) hydrogels as cell-encapsulating materials for the subcutaneous transplantation of MIN6 cells. We confirmed favorable biocompatibility between the materials and cells in vitro, including cell viability and insulin secretion. Histopathological tissue analysis revealed that transplanted MIN6 cells survived and contained insulin in nude mice 14 days after implantation. Moreover, we observed positive CD31 staining, implying new vessel formation, in the graft without MIN6 cells at 7 and 14 days after implantation. These results indicate the feasibility of using mPEG-poly(Ala) hydrogels as delivery carriers for subcutaneous transplantation of MIN6 cells.