Impact of PEG-packed islets upon anti-rejection therapy in homogeneous murine islet transplantation

Abstract

To investigate the impact of polyethylene glycols (PEG) upon islet survival in homogeneous murine islet transplantation and understand the impact of PEGylation in combination with rapamycin upon anti-rejection therapy in homogeneous mice islet transplantation. The subcutaneously pre-vascularized STZ-induced diabetic mice treated with transplanted islets of BALB/c mice were randomly divided into 6 groups: Group A with normal mice islets; Group B with PEG-packed islets; Group C with normal mice islets and 1.5 mg x kg(-1) x d(-1) rapamycin; Group D with PEG-packed islets and 1.5 mg x kg(-1) x d(-1) rapamycin; Group E with normal mice islets and 3 mg x kg(-1) x d(-1) rapamycin; Group F with PEG-packed islets and 3 mg x kg(-1) x d(-1) rapamycin. The post-transplantation blood glucose was monitored. Transplanted islets were analyzed by H&E and insulin immunostain. The survival time in group B was significantly prolonged as compared with group A (P < 0.01). The survival time in group C were (35.0 +/- 3.1) d and groups D, E, F had survival of up to 6 weeks. Transplantation sites of group A were observed with a more abundant infiltration of immune cells than group B. And the unmodified islets in group A were completely destroyed after transplantation. Insulin-positive islet cells were not detected at the entire transplantation site in group A while the presence was found at the transplantation site in group B. PEG-packed islets can significantly improve the survival time of transplanted islets. When combined with rapamycin, it can reduce the dose of rapamycin.