Production and Functional Verification of 8-Gene (GGTA1, CMAH, β4GalNT2, hCD46, hCD55, hCD59, hTBM, hCD39)-Edited Donor Pigs for Xenotransplantation.

Abstract

Gene-edited (GE) pig-to-human xenotransplantation continues to make breakthroughs, but which kind of gene combination is suitable for organ-specific transplantation remains unclear. In this study, we utilised CRISPR/Cas9 gene editing technology, PiggyBac transposon system, and serial somatic cell cloning technology to develop GTKO/CMAHKO/β4GalNT2KO/hCD46/hCD55/hCD59/hCD39/hTBM 8 gene-edited cloned (GEC) donor pigs and performed pig-to-non-human primate (NHP) transplantation to evaluate the effectiveness of these GEC pigs. The 8-GEC pigs were obtained by recloning with a 33-day-old 8-GEC fetus with O blood type, which was generated after cell transfection, screening of cell colonies, and somatic cell cloning. Molecular identification at DNA, mRNA, and protein levels confirmed successful 8-gene editing. Three copies of transgenes were identified by droplet digital polymerase chain reaction and whole genome sequencing, which were inserted into the introns of pig RFTN1 and MYO10 genes, as well as the intergenic region between PRLR and LOC110257300 genes of these 8-GEC pigs. The 8-GEC pigs also exhibited the ability of germline transmission when mated with our previously generated 4-GEC male pigs. Moreover, antigen-antibody binding assay and complement-dependent cytotoxicity assay demonstrated that 8-gene editing effectively reduced the immune incompatibility and kidney xenograft from 8-GEC pigs survived for 15 and 17 days in two NHPs, respectively. Postoperatively, the recipient serum antibodies IgA, IgG and IgM, complements C3 and C4, coagulation indicators PT, APTT, TT and FIB, as well as most electrolytes and liver function indicators remained relatively stable. Serum creatinine was normal within 10 days post operation. However, the kidney xenograft developed active antibody-mediated rejection at necropsy, characterised by the deposition of antibodies IgG and IgM, as well as complements C4d, C3c and C5b-C9, infiltration of CD68⁺ macrophages, and micro-thrombotic embolism of glomerular capillaries, etc. In conclusion, we successfully developed fertile 8-GEC pigs, which effectively alleviated immune rejection and exerted life-supporting kidney function in the recipients.