INHIBITORY EFFECT OF DOUBLE TRANSFECTION TO XENOENDOTHELIAL CELLS USING BOTH DECAY-ACCELERATING FACTOR AND HOMOLOGOUS RESTRICTION FACTOR-20GENES ON COMPLEMENT-DEPENDENT CYTOLYSIS

Hyperacute rejection in discordant xenotransplantation occurs due to t he complement activation via classical and/or alternative pathway. Reg ulator of complement activation (RCA) molecules inhibit species-specif ic complement dependent cytolysis. To confirm the effect of gene engin eering using double RCA molecules on xenogeneic cells, the inhibitory effect on complement dependent cytolysis was compared between bovine a ortic endothelial cells (BAEC) doubly transfected with both decay acce lerating factor (DAF) and homologous restriction factor (HRF) 20 cDNA and BAEC singly transfected with DAF alone using retroviral vector. Th e positive percent expression of DAF and HRF20 antigen on double trans fectant (BAEC/D + H) was 97.0% and 95.0%, respectively, whereas that o f DAF antigen on single transfectant (BAEC/D) was 97.0%. After incubat ed with 25% human serum and anti-BAEC antibody, the viability of doubl e transfectant (BAEC/D + H) was significantly preserved, compared with that of single transfectant (BAEC/D). These findings demonstrated tha t xenoendothelial cells doubly transfected with both DAF and HRF20 cDN A could be protected from complement dependent cytolysis more effectiv ely than those singly transfected with DAF alone in the presence of an tixenoendothelial antibody. (C) 1996 Academic Press, Inc.