Kozlowski T, Shimizu A, Lambrigts D, Yamada K, Fuchimoto Y, Glaser R, Monroy R, Xu Y, Awwad M, Colvin R B, Cosimi A B, Robson S C, Fishman J, Spitzer T R, Cooper D K, Sachs D H
Transplantation Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Boston 02129, USA.
Transplantation. 1999 Jan 15;67(1):18-30. doi: 10.1097/00007890-199901150-00004.
Xenotransplantation would provide a solution to the current shortage of organs for transplantation. Our group has been successful in inducing tolerance in mice and monkey models of allogeneic transplantation. The present study attempts to extend the same tolerance-inducing regimen to a pig-to-baboon organ transplantation model.
Nine baboons underwent a conditioning regimen (consisting of nonmyeloablative or myeloablative whole body and thymic irradiation, splenectomy, antithymocyte globulin, pharmacologic immunosuppression and porcine bone marrow transplantation [BMTx]), which has previously been demonstrated to induce donor-specific allograft tolerance in monkeys. In addition, immunoadsorption of anti-alphaGal antibody (Ab) was performed. Four of the nine baboons received pig kidney transplants (KTx), and one also underwent repeat transplantation with an SLA-matched kidney. Two received heterotopic pig heart transplants (HTx). Three baboons underwent conditioning without organ transplantation for long-term studies of natural Ab kinetics.
In the three baboons that received the conditioning regimen without an organ transplant, immunoadsorption reduced Ab by approximately 90%, but recovery of Ab to pretreatment level or higher occurred within 7 days. In contrast, the level of Ab remained low after organ transplant. No Ab to pig antigens other than alphaGal was detected in any baboon before or after BMTx, KTx, or HTx. No graft succumbed to hyperacute rejection. KTx function began to deteriorate within 3-6 days, with oliguria and hematuria progressing to anuria, and the kidneys were excised after 3, 6, 9, 11, and 14 days, respectively. One HTx ceased functioning at 8 days; the second baboon died with a contracting HTx at 15 days. Features of coagulopathy and thrombocytopenia developed in all six transplanted baboons (high D-dimer, prolonged prothrombin time and partial thromboplastin time, and falling fibrinogen) resulting in serious bleeding complications in two baboons, one of which died on day 9. Donor organs showed progressive acute humoral rejection with deposits of IgM, IgG, and complement; a focal mononuclear cellular infiltrate was also observed. The ureter was the earliest structure of the KTx affected by rejection, with progression to necrosis.
This conditioning regimen prevented hyperacute rejection but was ineffective in preventing the return of Ab, which was associated with the development of acute humoral rejection with features of coagulopathy. No baboon developed anti-pig Ab other than alphaGal Ab. Further modifications of the protocol directed toward suppression of production of Ab are required to successfully induce tolerance to pig organs in baboons.
异种移植将为当前移植器官短缺问题提供解决方案。我们的研究小组已成功在同种异体移植的小鼠和猴模型中诱导出免疫耐受。本研究试图将相同的免疫耐受诱导方案扩展至猪到狒狒的器官移植模型。
九只狒狒接受了预处理方案（包括非清髓性或清髓性全身及胸腺照射、脾切除术、抗胸腺细胞球蛋白、药物免疫抑制和猪骨髓移植[BMTx]），该方案先前已被证明可在猴中诱导供体特异性同种异体移植耐受。此外，还进行了抗αGal抗体（Ab）的免疫吸附。九只狒狒中有四只接受了猪肾移植（KTx），其中一只还接受了与SLA匹配的肾脏的再次移植。两只接受了异位猪心脏移植（HTx）。三只狒狒接受了预处理但未进行器官移植，用于自然抗体动力学的长期研究。
在三只接受了预处理方案但未进行器官移植的狒狒中，免疫吸附使抗体减少了约90%，但抗体在7天内恢复到预处理水平或更高。相比之下，器官移植后抗体水平保持较低。在BMTx、KTx或HTx之前或之后，任何狒狒中均未检测到除αGal以外的针对猪抗原的抗体。没有移植物死于超急性排斥反应。KTx功能在3 - 6天内开始恶化，少尿和血尿进展为无尿，肾脏分别在3、6、9、11和14天后被切除。一只HTx在8天时停止功能；第二只狒狒在15天时因收缩的HTx死亡。所有六只接受移植的狒狒均出现凝血病和血小板减少症的特征（高D - 二聚体、凝血酶原时间和部分凝血活酶时间延长以及纤维蛋白原下降），导致两只狒狒出现严重出血并发症，其中一只在第9天死亡。供体器官表现出进行性急性体液排斥反应，伴有IgM、IgG和补体沉积；还观察到局灶性单核细胞浸润。输尿管是KTx中最早受排斥影响的结构，进而发展为坏死。
该预处理方案预防了超急性排斥反应，但在预防抗体恢复方面无效，抗体恢复与伴有凝血病特征的急性体液排斥反应的发生有关。没有狒狒产生除αGal抗体以外的抗猪抗体。需要对方案进行进一步修改以抑制抗体产生，从而成功诱导狒狒对猪器官的耐受。
