The generation and evaluation of TKO/hCD55/hTM/hEPCR gene-modified pigs for clinical organ xenotransplantation.

Introduction: Genetically edited pigs, modified using CRISPR-Cas9 technology, hold promise as potential sources for xenotransplantation. However, the optimal combination of genetic modifications and their expression levels for initial clinical trials remains unclear. This study investigates the generation of TKO/hCD55/hTM/hEPCR (6GE) pigs and evaluates their compatibility with human immune and coagulation systems. Methods: The 6GE pigs were generated through iterative genome editing and F1 generation breeding. Genotyping, flow cytometry, and immunohistochemistry confirmed the knockout of GGTA1, CMAH, and B4GALNT2. Expression levels of human genes (hCD55, hTM, hEPCR) were quantified. In vitro assays using aortic endothelial cells (pAECs) from 6GE pigs assessed human serum IgM and IgG binding, complement cytotoxicity, and thrombin-antithrombin (TAT) complex levels. Blood from gene-edited pigs was used for pathophysiological analysis. Results: Complete knockout of GGTA1, CMAH, and B4GALNT2 was confirmed in 6GE pigs. The expression of hCD55 and hTM was approximately seven and thirteen times higher than in humans, respectively, while hEPCR levels were comparable to those in humans. Discussion: Highly expressing hCD55, along with the co-expression of hEPCR and hTM genes, is expected to effectively reduce human complement cytotoxicity and enhance anticoagulant efficacy in genetically modified pigs. The 6GE pigs exhibited robust compatibility with human physiological and immune systems, fulfilling the criteria for clinical trials. Furthermore, it is imperative to rear donor pigs in pathogen-free (DPF) facilities to mitigate infection risks and prevent the transmission of porcine pathogens to humans.