Background

Various durations of survival have been observed in the xenotransplantation of life-supporting α-1,3-galactosyltransferase knockout (GalT-KO) porcine kidneys into nonhuman primates. Although others have demonstrated loss of GalT-KO-transplanted kidneys within 2 weeks, we have reported an average survival of 51 days with the cotransplantation of the kidney and vascularized thymus and an average of 29 days with the kidney alone. To determine the factors responsible for this difference in survival time, we performed xenogeneic kidney transplantations into cynomolgus monkeys with an anti-CD40L-based regimen using two different strains of GalT-KO swine, one derived from MGH miniature swine and the other obtained from Meji University.

Materials and methods

Eight cynomolgus moneys received GalT-KO kidneys. Three kidney grafts were from Massachusetts General Hospital (MGH)-Nippon Institute for Biological Science (NIBS) GalT-KO pigs and five GalT-KO grafts were from MEIJI GalT-KO swine. All cynomolgus recipients were treated identically.

Results

Recipients of kidneys from the MGH GalT-KO kidneys swine, produced by nuclear transfer in Japan, survived an average of 28.7 days, whereas recipients of MEIJI GalT-KO kidneys swine survived an average of 9.2 days. Among the differences between these two groups, one potentially revealing disparity was that the MEIJI swine were positive for porcine cytomegalovirus, whereas the MGH-derived swine were negative.

Conclusion

This is the first study comparing renal xenotransplantation from two different sources of GalT-KO swine into nonhuman primates at a single center. The results demonstrate that porcine cytomegalovirus may be responsible for early loss of GalT-KO swine kidney xenografts.