Reduced endothelial activation upon human blood perfusion of pig kidney xenografts lacking MHC class I and three xenoantigens

Genetically tailored pigs to eliminate human immune rejection of xenografts is one promising solution to the global donor organ shortage. The development of xenograft transplantation has however been hampered by incomplete understanding of its immune rejection and the inability to test this in a human transplantation setting. Here we use an ex vivo organ perfusion system with human whole blood to assess the initial immune activation within the xenograft endothelium at single cell transcriptome level. Renal injury, complement deposition, coagulation and lymphocyte influx are all strongly reduced in genetically modified pig kidneys with porcine MHC class I and three xenoantigens (GGTA1, CMAH, B4GALNT2) eliminated (4KO) compared to wildtype (WT) pig kidneys after 6-hours human blood perfusion. Single cell RNA sequencing of endothelial cells (EC) from 4KO and WT pig kidneys respectively reveal that there is a compartment (cortex, glomeruli and medulla) specific endothelial activation, with cortical and glomeruli endothelial cells being more affected. Differential gene expression analysis shows a downregulation of endothelial transcriptome activation response to human blood perfusion in the 4KO ECs. Pathway enrichment analysis further identify the NF-kB pathway as strongly activated in human blood perfused WT ECs but diminished in the 4KO. In conclusion, the 4KO pig model has strongly reduced endothelial immune activation response when perfused with human whole blood, that goes beyond prevention of humoral rejection. Our data support further development of the 4KO for use in clinical transplantation.