Effects of combined expression of human complement regulatory proteins and H-transferase on the inhibition of complement-mediated cytolysis in porcine embryonic fibroblasts

The expression of human complement regulatory proteins (CRP) and H-transferase (HT) in porcine cells is one of the strategies for suppression of hyperacute rejection (HAR) of xenotransplants in human recipients. In this study, we investigated the inhibitory effect of combined expression of human complement regulators and HT on human serum-mediated cytolysis in porcine embryonic fibroblasts. For the combinated expression of human CRPs in transformed pig cells, cDNAs of human DAF, MCP, and CD59 were cloned into the same insertional plasmid under the control of pCMV IE and LTR. The double combination of CRPs, hDAF-hMCP, and hMCP-hCD59 survived over 50% in the presence of 50% human serum, compared to the control. Moreover, the cell viability was increased more than 65% and 80% in the combination of human DAF-CD59 and DAF-MCP-CD59, respectively. In addition, the combination of HT gene to hDAF-hCD59 vector increased the viability close to 80%, similar to the triple combination of CRPs. These observations suggest that the combined expression of human CRPs and HT in the same insertional vector may be more effective in protecting porcine cells from human complement-mediated cytolysis.