Bühler L, Basker M, Alwayn I P, Goepfert C, Kitamura H, Kawai T, Gojo S, Kozlowski T, Ierino F L, Awwad M, Sachs D H, Sackstein R, Robson S C, Cooper D K
Transplantation Biology Research Center, Massachusetts General Hospital, Boston 02129, USA.
Transplantation. 2000 Nov 15;70(9):1323-31. doi: 10.1097/00007890-200011150-00010.
Efforts to achieve tolerance to transplanted pig organs in nonhuman primates by the induction of a state of mixed hematopoietic chimerism have been associated with disorders of coagulation and thrombosis. Activation of recipient vascular endothelium and platelets by porcine hematopoietic cells and/or activation of donor organ vascular endothelium and/or molecular differences between the species may play roles. Irradiation or drug therapy could possibly potentiate endothelial cell activation and/or injury.
We have investigated parameters of coagulation and platelet activation in nonhuman primates after (1) a regimen aimed at inducing mixed hematopoietic chimerism and tolerance (TIR that included total body irradiation, T cell depletion, and splenectomy; (2) pig bone marrow or pig peripheral blood mobilized progenitor cell transplantation (PCTx); and/or (3) pig organ transplantation (POTx). Five experimental groups were studied. Baboons were the recipient subjects in all groups except Group 1. Gp 1 Cynomolgus monkeys (n=6) underwent TIR + allotransplantation of hematopoietic cells and a kidney or heart or TIR + concordant xenotransplantation (using baboons as donors) of cells and a kidney; Gp 2 Baboons (n=4) underwent TIR with or without (+/-) autologous hematopoietic cell infusion; Gp 3 (n=12) PCTx+/-TIR; Gp 4 (n=5) POTx+/-TIR; Gp 5 (n=4) TIR + PCTx + POTx. Platelet counts, with plasma prothrombin time, partial thromboplastin time, fibrinogen levels, fibrin split products and/or D-dimer were measured.
In the absence of a discordant (porcine) cellular or organ transplant (Groups 1 and 2), TIR resulted in transient thrombocytopenia only, in keeping with bone marrow depression from irradiation. PCTx alone (Group 3) was associated with the rapid development of a thrombotic thrombocytopenic (TTP)-like microangiopathic state, that persisted longer when PCTx was combined with TIR. POTx (+/-TIR) (Group 4) was associated with a gradual fall (over several days) in platelet counts and fibrinogen with disseminated intravascular coagulation (DIC); after graft excision, the DIC generally resolved. When TIR, PCTx and POTx were combined (Group 5), an initial TTP-like state was superseded by a consumptive picture of DIC within the first week, necessitating graft removal.
Both PCTx and POTx lead to profound alterations in hemostasis and coagulation parameters that must be overcome if discordant xenotransplantation of hematopoietic cells and organs is to be fully successful. Disordered thromboregulation could exacerbate vascular damage and potentiate activation of coagulation pathways after exposure to xenogeneic cells or a vascularized xenograft.
通过诱导混合造血嵌合状态来实现非人类灵长类动物对移植猪器官的耐受，这一过程与凝血和血栓形成紊乱有关。猪造血细胞对受体血管内皮细胞和血小板的激活及/或供体器官血管内皮细胞的激活及/或物种间的分子差异可能起作用。辐射或药物治疗可能会增强内皮细胞的激活及/或损伤。
我们研究了非人类灵长类动物在以下情况后的凝血和血小板激活参数：（1）旨在诱导混合造血嵌合和耐受的方案（包括全身照射、T细胞清除和脾切除术的TIR）；（2）猪骨髓或猪外周血动员祖细胞移植（PCTx）；和/或（3）猪器官移植（POTx）。研究了五个实验组。除第1组外，所有组的受体均为狒狒。第1组食蟹猴（n = 6）接受TIR + 造血细胞和肾脏或心脏的同种异体移植，或TIR + （使用狒狒作为供体）细胞和肾脏的协调性异种移植；第2组狒狒（n = 4）接受有或无（+/-）自体造血细胞输注的TIR；第3组（n = 12）PCTx+/-TIR；第4组（n = 5）POTx+/-TIR；第5组（n = 4）TIR + PCTx + POTx。测量血小板计数以及血浆凝血酶原时间、部分凝血活酶时间、纤维蛋白原水平、纤维蛋白降解产物和/或D - 二聚体。
在没有不一致的（猪的）细胞或器官移植的情况下（第1组和第2组），TIR仅导致短暂的血小板减少，这与辐射引起的骨髓抑制一致。单独的PCTx（第3组）与血栓性血小板减少性紫癜（TTP）样微血管病状态的快速发展相关，当PCTx与TIR联合时，这种状态持续时间更长。POTx（+/-TIR）（第4组）与血小板计数和纤维蛋白原在数天内逐渐下降以及弥散性血管内凝血（DIC）相关；移植切除后，DIC通常会缓解。当TIR、PCTx和POTx联合使用时（第5组），最初的TTP样状态在第一周内被DIC的消耗性表现所取代，需要切除移植物。
PCTx和POTx都会导致止血和凝血参数的深刻改变，如果造血细胞和器官的不一致异种移植要完全成功，就必须克服这些改变。血栓调节紊乱可能会加剧血管损伤，并在接触异种细胞或血管化异种移植物后增强凝血途径激活。
