Sun Zhaoli, Zhang Xiuying, Locke Jayme E, Zheng Qizhi, Tachibana Shingo, Diehl Anna Mae, Williams George Melville
Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Hepatology. 2009 Feb;49(2):587-97. doi: 10.1002/hep.22653.
Despite major histocompatibility complex incompatibility, liver transplants from Lewis rats to dark agouti (DA) rats survive indefinitely without immunosuppression, and the studies we report sought the mechanism(s) responsible for this. At 1 year, most of the liver reacted positively to host anti-DA antibody. When small (50%) grafts were transplanted, recruitment was more rapid because most of the organ assumed the host phenotype at 3 months. After transplantation, the Y chromosome was detected in the hepatocytes of XX to XY grafts by both in situ hybridization and polymerase chain reaction. Further, livers from transgenic Lewis rats carrying strong green fluorescent protein (GFP) markers lost the marker with time after transplantation to DA, GFP-negative hosts. Few liver cells contained the Y chromosome in syngeneic XX to XY liver grafts or when the hosts of Lewis XX to DA XY allografts were treated with cyclosporine A at 10 mg/kg/day. This dosage also impeded enlargement of the liver at 10 days. Using GFP-positive XX Lewis donors transplanted to GFP-negative XY DA hosts, we found little Y DNA in GFP-positive cells at 10 days. Host-derived OV-6-positive and c-kit-positive, albumin-positive cells were present at 3-10 days, but cells with the CD34 marker were less common and some clearly still had the donor phenotype at 10 days. Cells positive for chemokine cysteine-X-cysteine receptor-4 increased with time and were abundant 1 month after transplantation. We conclude: (1) extrahepatic cells can differentiate into liver tissues; (2) regenerative stimuli accelerate stem cell recruitment; (3) both regeneration and recruitment are impeded by cyclosporine A immunosuppression, and (4) donor GFP-positive cells contained little host Y chromosome after transplantation, suggesting that cell fusion was uncommon and, therefore, unlikely to be the mechanism leading to the changes in genotype and phenotype we observed.
尽管存在主要组织相容性复合体不相容性，但从刘易斯大鼠到暗褐鼠（DA）的肝移植在没有免疫抑制的情况下能无限期存活，我们所报告的研究旨在探寻其背后的机制。移植1年后，大部分肝脏对宿主抗DA抗体呈阳性反应。当移植小（50%）移植物时，招募速度更快，因为大部分器官在3个月时呈现宿主表型。移植后，通过原位杂交和聚合酶链反应在XX到XY移植物的肝细胞中检测到Y染色体。此外，携带强绿色荧光蛋白（GFP）标记的转基因刘易斯大鼠的肝脏在移植到DA、GFP阴性宿主后，随着时间推移失去了该标记。在同基因XX到XY肝移植物中，或当刘易斯XX到DA XY同种异体移植物的宿主以10毫克/千克/天的剂量接受环孢素A治疗时，很少有肝细胞含有Y染色体。这个剂量在10天时也阻碍了肝脏的增大。使用移植到GFP阴性XY DA宿主的GFP阳性XX刘易斯供体，我们在10天时在GFP阳性细胞中几乎未发现Y DNA。在3 - 10天时存在宿主来源的OV - 6阳性、c - kit阳性、白蛋白阳性细胞，但具有CD34标记的细胞较少见，并且一些细胞在10天时显然仍具有供体表型。趋化因子半胱氨酸 - X - 半胱氨酸受体 - 4阳性的细胞随时间增加，在移植后1个月时大量存在。我们得出结论：（1）肝外细胞可分化为肝组织；（2）再生刺激加速干细胞招募；（3）再生和招募均受到环孢素A免疫抑制的阻碍；（4）移植后供体GFP阳性细胞几乎不含宿主Y染色体，这表明细胞融合不常见，因此不太可能是导致我们观察到的基因型和表型变化的机制。
