Abstract： Objective By using ProtEx~(TM) technology to decorate target cells with an exogenous protein and observe its function for immunomodulation.Methods Donor splenocytes were decorated with chimeric SA-FasL protein.The expression of FasL and its impact on other molecules on the surface of splenocytes was detected.Heterotopic rat heart transplantation was performed from inbred WF rat to ACI rat.According to the different donor splenocytes perioperatively injected into recipients,the recipients were divided into 3 groups:SA-FasL group (n=23),SA group (n=20) and control group(n=10).Heart beating was examined by palpation on daily basis,the cessation was regarded as reiection,while surival over 100 days was considered as graft long-term survival.Diabetes models in C57BL/6 mice were induced by intravenous injection of STZ.Islets from BALB/C mice were decorated by SA-FasL protein,islets transplant was performed from BABL/c to C57BL/6 mice.Based on the different treatments of donor islets,recipients were divided into three groups:islet-FasL group (n=21),islet-SA group (n=21) and islet-untreated group(n=14).Rejection was identified while urine glucose was positive and blood glucose value was over 250 mg/ml for consecutive two days.Urine glucose negative over 100 days was regarded as graft long-term survival.Results The mean exDression rate of FasL in splenocytes was 94.49%±4.27% tested by flow cytometry and FasL showed red color 0n the surface of splenocytes by fluorescent stammg.FasL deeoration did not disturb the expression of CD3,CD4,D8,MHC I and CD80.The long-term survival rate o,f heart transplant showed significant difference between tWO groups(SA-FasL:70% vs SA:25%,P<0.05).67% FasL-decorated islets had normal function 30 days post transplant,and 29%FasL-decorated islets achieved long-term survival,which was significantly differed from the other groups(P<0.05).Conclusion ProtEx~(TM) is a simple,fast,safe and efficient approach for exogenous protein modmcation.Decoration of target cells with Chimeric FasL by this technique plays an umportant role in immunomodulatiorn.