Subcutaneous Transplantation of MIN6 Beta Cells Embedded in mPEG-Ala Hydrogel

The liver is the current site of choice for clinical islet transplantation, but many intraportal grafts were lost in the early stage of transplantation. Other disadvantages include the difficulty of monitoring the islets and procedure-associated complications. In contrast, the subcutaneous space offers the advantages of a large space, a less invasive procedure and easy graft monitoring and removal. However, islet transplantation into an unmodified subcutaneous site has poor efficacy; possibly due to poor oxygenation and inadequate vascularization of the transplanted tissue. In this study, we tested the feasibility of subcutaneous transplantation of MIN6 beta cells embedded in temperature-sensitive poly(ethylene glycol) methyl ether (mPEG)-Ala hydrogels as scaffolds. After culturing for 14 days, the viability of MIN6 beta cells in mPEG-Ala hydrogel was comparable with those in medium, either assayed by MTT or LIVE/DEAD. Static incubation showed that both had comparable insulin secretion. For in vivo experiments, we infected MIN6 beta cells with luciferase by AAV and then transplanted 5*10 6 cells embedded in mPEG-Ala hydrogel into the subcutaneous space of each nude mouse’s upper back. Positive In Vivo Imaging System (IVIS) images and positive insulin staining of tissue histology were observed up to 41 days after transplantation. Meanwhile, we incubated MIN6 beta cells with chitosan-coated superparamagnetic iron oxide (CSPIO) overnight and then transplanted 5*10 6 MIN6 beta cells into the subcutaneous tissue of each nude mouse’s left flank. The graft of CSPIO-labeled MIN6 beta cells was visualized on Magnetic Resonance (MR) scans as distinct hypointense spots on T2-weighted images located at the transplantation site at day 6 and 20. These results indicate that subcutaneous transplantation of MIN6 beta cells embedded in temperature-sensitive mPEG-Ala hydrogels is feasible. Moreover, the IVIS and MR imaging are useful tools for detecting and monitoring beta cells at the subcutaneous site. Disclosure J. Juang: None. H. Lin: None. C. Chen: None. C. Kao: None. S. Wu: None. S. Lin: None. C. Shen: None. J. Wang: None. I. Chu: None.