Abstract： Objective To investigate the effects of the overexpression of HO-1 induced by CoPP in the donor on the survival of transplanted allogeneic islets of rats and the mechanism.Methods (1) Brown Norway rats were randomly divided into control group, and CoPP-induced group receiving intraperitoneal injection of CoPP (2.5 mg/kg) at 3rd and 1st day prior to islet isolation.By using the cytoimmunofluorescenee and Western blot, the expression of HO-1 in isolated islets was detected.The insulin level in the supernatant of the cultured islets stimulated with glucose was determined by ELISA.(2) Lewis male rat diabetic models were established by a single intravenous injection of alloxan, and then randomly divided into CoPP group and control group.Islets were transplanted under the left kidney capsule of each diabetic recipient.The survival time after transplantation, and pathological changes following rejection of the islet grafts were analyzed.Results The HO-1 was highly expressed in the islets isolated from CoPP-treated rats by cytoimmunofluorescence and Western blot.After stimulation with 16.7 mmol/L glucose, the insulin concentration in Copp-treated and Copp-untreated groups was (46.60± 1.13) and (19.01 ± 1.49) mIU/L respectively (P<0.05).The insulin concentration in Copp-treated and Copp-untreated groups in islets stimulated with 5.6 mmol/L glucose was (15.65 ± 0.89) and (12.28 ± 0.89) mU/L respectively (P>0.05).The stimulated index in Copp-treated and Copp-untreated groups was (2.98 ± 0.10) and 1.55 + 0.01 respectively (P< 0.05).The survival time of islets allograft in Copp-treated and Copp-untreated groups was separately (12.20±5.67) and (5.60± 1.14) days respectively (P<0.05).Histological analysis revealed the presence of more islands of insulin-positive cells and considerably fewer lymphocytes or inflammatory infiltration than the controls.Conclusions CoPP could induce the HO-1 expression of islets, and improve their function.Over-expression of HO-1 in islets could prolong survival time of islets allograft.