Comparative analysis of survival rates between single GTKO and TKO pig to monkey kidney xenotransplantation

Department of Surgery, Konkuk University School of Medicine. Department of Nephrology, Konkuk University School of Medicine. Department of Surgery, Seoul National University School of Medicine. Department of Pathology, Konkuk University School of Medicine. Department of Urology, Konkuk University School of Medicine. Animal Biotechnology Division, National Institute of Animal Science. Department of Transgenic Animal Research, Optipharm. Non-Human Primate Minipig Translational Toxicology Research, Korea Institute of Toxicology. Division of Nephrology, National Medical Center. Introduction: In Korea, although αGal-knockout (GTKO) pigs are developed early in the middle of the year 2000, pig-to-non-human primate (NHP) trials of solid organs have been done only since 2011. Triple KO (TKO) pigs have been used in primate experiments since 2011 to perform xenotransplantation experiments. 15 transgenic pigs were subjected to preclinical NHP xenotransplantation experiments by the xenotransplantation research team of Konkuk University. We performed kidney transplantation in NHP using GTKO and TKO transgenic pigs and observed the effects of number of KO in the survival rates of transplanted grafts. Methods: The GTKO and TKO transgenic pigs weighing 1.7-11.5 kg (age, <12 months old) were used. In our research, comparative donor transgenic pigs were GTKO-based and GGTA1/CMAH/B4galNT2 TKO pigs. The types of knock-in genes were complement decay-accelerating factor (CD55), and ectonucleoside triphosphate diphosphohydrolase-1 (CD39). The recipient animal was the cynomolgus monkey. Cynomolgus monkeys weighing 2.5–6.13 kg (age, 2–4 years) were used. Characteristics of the donor kidney obtained from GTKO (n = 4), GTKO+CD55+CD39 (n = 8) transgenic pigs and TKO+CD55+CD39 (n = 3) transgenic pigs. After the general anesthesia, dissection, and cold perfusion for the left kidney of transgenic pig is done. We extract the right kidney of host monkey before intraabdominal anastomosis of pig kidney to aorta and inferior vena cava (IVC). We used the immunosuppressants of anti-CD154 antibody, rituximab, anti-thymocyte globulin, tacrolimus, mycophenolate mofetil, and steroids. In addition, we confirmed functioning grafts of the surviving transplanted kidneys after the second-look operation of removal of all the host kidney. Results: Except for a 1 case for which survival durations were <3 days due to technical failure, the average graft survival duration of the GTKO single-based kidneys were 14.5 days. On the other hand, the average survival duration of the grafts of the GTKO-based kidneys and knock-in genes were CD55 and CD39 which survived 46.8 days. As well as the average survival duration of TKO-based kidneys and knock-in genes were CD55 and CD39 which still surviving after 74.3 days until now. The present study showed the long-term survival of >POD121 (on-going) after the removal of the remained kidney. Furthermore, in practice, graft survival was higher in TKO-based kidneys than in GTKO-based kidneys. We also confirmed functioning grafts for the transplanted kidneys that survived after the second-look operation of removal of the host kidney and observed no signs of hyperacute rejection of the transplanted graft. Conclusions: The survival rate after transplantation was higher especially in TKO-based kidneys than in GTKO-based kidneys. TKO-based seems to have more survival merits than GTKO-based. Therefore, it seems that multiple KO (eg. quadruple KO, QKO) should become the basis for KO in the future.