Human-Pig Spleen Transplantation Leading to High Level of Chimerism

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Y. Li, K. Wang, J. Cheng, F. Li, Y. Ma, and Y. Yang

NE OF the serious problems in allogenic clinical peritoneal cavity adhesion. The remaining two had diar- O transplantation is the shortage of grafts. The pig is rhea, anorexia, listlessness, and hair-raised 2 to 3 weeks now widely accepted as the most appropriate candidate for posttransplantation for 1-week but survived for a long time. xenotransplantation.1 It is very important to establish a In group 5, one died of operation complication and two large animal model to mimic pig-to-human xenotransplan- were sacrificed at the third week after transplantation. The tation and to evaluate the donor-recipient interaction dur- remained two appeared a xGVDH-like symptom around 2 ing the whole course in vivo. Our previous study showed to 3 weeks after transplantation for about 1 week. that human bone marrow and spleen cells could survive in The extent of peripheral blood chimerism in group 4 was recipient pig for a long time after transplant. In this study, the highest followed by group 5, while no difference was human spleen or spleen tissue was transplanted into pig to observed in both 1 and 2. Chimeric cell migrated into pig establish a higher level of chimerism. Therefore, it is bone marrow 24 hours after operation in all groups, but the possible to observe the interaction of human against pig, ratio in groups 4 and 5 is higher than in 1, 2, and 3. In group and it might be possible to develop xenogenic graft-versus- 5, the donor cell even more than recipient cells at bone host disease (xGVHD). morrow but very few scattered in other organs and peripheral blood. It was noted that the grafted human spleen were METHODS rejected and substituted by fibrosis with severe ischemia 2–8 Castrated male Neijiang pigs (6 months, 40 to 60 kg, n ϭ 26) were narcosis and heavy pig anti-human IgG deposition. immunosuppressed and then divided into five groups. (1) Human The xGVHD symptom (such as diarrhea, anorexia, list- splenocytes injection intraperitoneally (n ϭ 7). (2) Human spleno- lessness, and hair-raised) were observed in a total of four cytes injection intravenously (n ϭ 7). (3) Human splenocytes pigs in groups 4 and 5 following the second peak of secondary injection on chemaric pigs from groups 1 and 2 (n ϭ 3). peripheral chimeric extent about 2 to 3 weeks postoperation (4) Spleen tissue transplantation (n ϭ 4). (5) Spleen transplanta- for about 1 week. At the same time the chimeric donor cell tion (n ϭ 5). ϩ ϩ ϩ were mainly CD2 70.17%, no CD19, and CD34 cells were Pigs were treated with cyclophosphamide (30 mg/kg) intrave- detected (before transplantation the lineage of donor cells ϩ ϩ ϩ nously 4 days before transplantation for immunosuppression. The are CD 24.3%, CD19 58%, CD 0.2%).9–11 spleen from brain-dead human (hot ischemic time Ͻ 10 minutes, 2 19 34 cold ischemic time Ͻ 6 hours) were transplanted into pigs as splenocytes (by injection), spleen tissue (implanted into peritoneal DISCUSSION cavity by laparotomy), or spleen (anastomosed end to end with pig renal arteries and veins), respectively. Although the extent of chimerism is not the same among Chimerism and xGVHD were monitored by flowcytometer and different groups, they all have the frist peak about 2 to 3 immunohistochemistry systematically before and after transplanta- weeks postoperation. The lineage of chimeric donor cells tion. ϩ ϩ ϩ switched from CD2 24.3%, CD19 58% and CD34 0.2% to ϩ mainly CD2 70.17%, indicating the second peak may be RESULTS All pigs in group 1 survived normally for a long time except one died 1 week after transplantation. In group 2 four pigs From the Lab of Transplant Immunology (Y.L., J.C., F.L., Y.M.), died within 24 hours after transplant with severe dyspnea, and The Department of Urology (K.W., Y.Y.), The First University Hospital, West China University of Medical Sciences, Chengdu, pink frothy sputum gushing from mouth and nostril while China. other three survived definitely, although two of them had This work was supported by Grant 39993430 from the Natural diarrhea and anorexia at the 5th month for 1 week. All pigs Science Foundation of China. of group 3 survived normally for a long time without Address reprint requests to Y. Li, Lab of Transplant Immunol- showing any sign of xGVHD. In group 4, one pig died ogy, The First University Hospital, West China University of within 24 hours with bloody ascites; another died 1 week Medical Sciences, Chengdu, 610041, Peoples Republic of posttransplant with severe intestinal obstruction caused by China.

Transplantation Proceedings, 32, 1103–1104 (2000) 1103

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1104 LI, WANG, CHENG ET AL

facilitate xGVHD. It might be very useful as a large animal model to mimic pig to human xenotransplantation and to observe human immune reactions against pig dynamically in vivo. The spleen tissues transplantation maybe the best way to do this comparing with spleen transplantation and splenocytes transplantation.

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