A novel simple method to purify recombinant soluble human complement receptor type 1 (sCR1) from CHO cell culture

Inhibition of instant blood-mediated inflammatory responses by co-immobilization of sCR1 and heparin on islets

Intraportal transplantation of islets of Langerhans is followed by marked islet loss, mainly caused by instant blood-mediated inflammatory responses (IBMIR). We previously developed a method of co-immobilizing sCR1 and heparin on islets. Here we examined whether this process could reduce islet loss following intraportal islet transplantation in a syngeneic mouse model. sCR1-heparin islets or unmodified islet controls were transplanted into the livers of streptozotocin-induced diabetic mice. Transplantation of 100 and 125 sCR1-heparin islets normalized blood glucose levels in 8 of 9 (88.9%) and 9 of 9 diabetic mice (100%), respectively, whereas transplantation of 100 and 125 non-treated islets induced normoglycemia in 0 of 9 and 2 of 9 diabetic mice, respectively. Fibrin staining and plasma insulin measurements indicated that, compared to non-treated islets, sCR1-heparin islet transplantation was associated with fewer blood clots around islets, and significantly less insulin leakage from damaged islets at 1 h post-transplantation. Long-term follow-up of the sCR1-heparin islet group showed islet cells in the livers and insulin expression. In conclusion, co-immobilization of sCR1 and heparin on islets could effectively reduce islet damage by IBMIR, and might be useful to enable transplantation with only one donor and one recipient.

Cytotoxicity for porcine islet cells by complement of six animal species

Complement-mediated cytotoxicity for porcine islet cells (PICs) was evaluated using sera of six animal species. Then soluble complement receptor type-1 (sCR1) as an anti-complement agent was added to those sera, and the changes in 50% hemolytic unit of complement serum (CH50) and cytotoxic effect of those sera on PICs were examined. All the sera except for that of pig showed cytotoxicity. However, the extent of toxicity was considerably different between species. In the rat and human serum, sCR1 significantly reduced CH50 and cytotoxicity, however in the dog serum, sCR1 had no suppressive effects. These results may suggest that complement contribute to humoral cytotoxicity for PICs as a main factor, and the compatibility of complement with PICs differs between animal species.