猪-人-鼠嵌合体动物模型的建立及介导人T细胞对猪异种抗原的耐受

目的： 通过共移植人胎胸腺、胎肝组织及猪骨髓细胞于SCID鼠体内，建立猪-人-鼠嵌合体模型，介导人T细胞对猪异种抗原的免疫耐受。方法:实验鼠分成3组：A组为猪骨髓细胞移植组，B组为人胎胸腺、肝脏组织移植组，C组为猪骨髓细胞＋人胎胸腺+肝脏组织移植组；在移植后每3周，用流式细胞仪测定猪和人嵌合体的水平，直至20周；通过混和淋巴细胞反应确定人T细胞的功能及对猪异种抗原的耐受情况。 结果:猪嵌合体在所有实验鼠（包括共移植人组织的实验鼠）中持续时间均超过20周；在移植人胎组织20周时，T细胞的数量为0.7×106/L,在外周血细胞中所占的百分比为0.14%±0.01%；人嵌合体在所有实验鼠（包括共移植猪骨髓细胞的实验鼠）中持续时间亦超过20周。结论: 通过共移植人胎胸腺、胎肝组织及猪造血干细胞于SCID鼠体内，可以建立猪-人-鼠嵌合体模型，并能诱导人T细胞对猪异种抗原的免疫耐受。

Human T-cells developed in a triple chimera animal model and tolerant to porcine xenoantigens

AIM: To determine the characteristics (including stability) of a triple chimera animal model generated by implantation of human fetal thymus/liver (Thy/Liv) fragments, fetal liver hematopoietic cells, and porcine bone marrow cells (BMCs) in NOD/SCID mice. METHODS: NOD/SCID mice were treated with 3 Gy of whole-body irradiation (WBI) and divided into three groups. Group A was given intravenous porcine BMCs. Group B was given an implant of human fetal Thy/Liv fragments (1-2 mm3) under the right kidney capsule and additionally an intravenous injection of human fetal liver mononuclear cells (MNCs) purified from the fetal livers. The treatment of group C was the combination of both group A and B. Three weeks after Thy/Liv transplantation and every three weeks thereafter, peripheral blood was drawn to determine the level of porcine and human chimerism using multicolor flow cytometric (FCM) analysis. The proliferation of the T cells was tested in a standard mixed lymphocyte reaction (MLR). RESULTS: Porcine chimerism persisted (>20 weeks) in all mice that received porcine BMCs, including mice that underwent human Thy/Liv implantation later. Human chimerism persisted >20 weeks in all mice that received Thy/Liv implants, regardless of whether they received porcine BMCs transplants. CONCLUSION: Human immune system is reconstituted by co-transplantation of human fetal Thy/Liv and human fetal liver MNCs in NOD/SCID mice with porcine hematopoietic chimerism. The human T cells are immunocompetent and tolerant to donor porcine BMCs.