Modified glycan models of pig-to-human xenotransplantation do not enhance the human-anti-pig T cell response

•New glycan-deletion porcine models of xenotransplantation are closer to the clinic than ever.•Silencing porcine GGTA1 and CMAH glycan genes have no deleterious effect on the cell-mediated xenogeneic response.•Conventional immunosuppression can limit the human-anti-pig cell-mediated response to GGTA1−/− CMAH−/− pigs.

Genetically modified porcine models of pig-to-human xenotransplantation offer the most immediate answer to a growing shortage of available solid organs. Recently a modified porcine glycan model has been discovered that reduces human antibody binding to levels comparable with allograft standards. As this background provides an answer to the problem of acute humoral xenograft rejection (AHXR), it is important to consider the impact these modifications have on measures of cell-mediated rejection. The objective of this study was to examine the impact of currently relevant glycan knockout models of pig-to-human xenotransplantation in a lymphocyte proliferation assay. To accomplish these goals, genetically modified pigs were created through CRISPR/Cas9-directed silencing of the GGTA1, and CMAH genes. Peripheral blood mononuclear cells (PBMCs) and spleen cells were obtained from these animals and used as a source of stimulation for human responders in one-way mixed lymphocyte reactions. The response was tested in the presence and absence of clinically available immunomodifiers. Conclusions: Clinically relevant glycan knockout models of pig-to-human xenotransplantation do not enhance the human-anti-pig cellular response. Currently available and conventional immunosuppression has the capacity to mediate the human xenogeneic T cell response to these knockout cells.