The effects of 8-arm-PEG-catechol/heparin shielding system and immunosuppressive drug, FK506 on the survival of intraportally allotransplanted islets.

This study proposed a double-layer shielding method of using 8-arm-PEG-catechol (PEG(8)) and N-hydroxysuccinimidyl-linked unfractionated heparin (UFH-NHS) for the prevention of instant blood-mediated inflammatory reaction (IBMIR) and immune reactions against transplanted pancreatic islets. The surface of islet was evenly covered by PEG(8) and UFH-NHS. Both viability and functionality of islets were evaluated in vitro, and the anti-coagulation effect of conjugated heparin on the islet surface was also evaluated. The inhibition effects of PEG(8)/UFH double-layer shielding system on immune reactions and IBMIR induced by transplanted islets were evaluated in an allograft model. When pancreatic islets of Sprague-Dawley (SD) rats were transplanted in the liver of F344 rats, the mean survival time (MST) of PEG(8)/UFH double-layer shielded islets (6.8 ± 1.6 days) was statistically increased, compared to that of unmodified islets (3.6 ± 1.1 days). Furthermore, when 0.5 mg/kg of FK506 was daily administered, the MST of double-layer shielded islet (15.0 ± 2.1 days) was increased by two-fold, compared to that of unmodified islets treated with the same dose of FK506 (8.0 ± 2.4 days). Therefore, a newly developed strategy of combining the PEG(8)/UFH double-layer shielding system with FK506 would certainly be effective for preventing immune activation and IBMIR against allotransplanted islets.