Basic studies on animal model for regenerative medicine using severe immunodeficient mice.

我们将IL-2 R γ κ基因导入NOD/Shi-scid小鼠，建立了严重免疫缺陷的NOD/Shi-scid，IL-2 R γ κ KO（NOG）小鼠<null>。这些小鼠显示出人类细胞的优异发育和分化，表明NOG小鼠用于产生“人源化小鼠”的有用性。在这项研究中，我们研究了NOG小鼠作为再生医学模型的用途。对于器官移植，当将一小片人卵巢移植到肾包膜中时，产生人Graff卵泡。将人子宫内膜组织皮下移植于小鼠背部，然后注射人激素，观察子宫内膜的月经周期。作为使用胚胎干（ES）细胞的再生医学模型，我们研究了C57 BL/6 J来源的ES细胞在移植到NOG小鼠的各种器官后的体内分化。当ES细胞被注射到用博莱霉素治疗受损的NOG肺或用四氯化碳治疗受损的NOG肝中时，ES细胞生长并在器官中形成畸胎瘤。然而，不能证实ES细胞分化为肺或肝细胞。我们还使用从SD大鼠建立的胚胎生殖（EG）细胞进行了相同的实验。将大鼠EG细胞注射到因博莱霉素治疗而受损的GFP转基因SD大鼠的肺中后，取出肺并皮下移植到NOG小鼠的背部。移植后2、4、8周取肺组织行病理学检查。结果，植入的肺部分植入，但EG细胞形成了畸胎瘤。这些结果表明，ES细胞必须分化为祖细胞，而不是ES细胞本身用于再生医学。

We recently developed severe immunodeficient NOD/Shi-scid, IL-2Rγ KO (NOG) mice by introducing IL-2Rγ^<null> gene into NOD-scid mice. These mice show excellent development and differentiation of human cells, indicating the usefulness of NOG mice to generate "humanized mice". In this study, we investigated the use of NOG mice as models for regenerative medicine. For organ transplantation, human Graff follicles were developed when a small piece of human ovary was transplanted into a renal capsule. The menstrual cycle in the endometrium was also observed when human endometrial tissue was subcutaneously transplanted in the back of the mice followed by injection of human hormones. As a model for regenerative medicine using embryonic stem (ES) cells, we investigated in vivo differentiation of C57BL/6J-derived ES cells after their transplantation in various organs of NOG mice. When ES cells were injected into NOG lungs impaired by treatment with bleomycin or NOG livers impaired by treatment with carbon tetrachloride, ES cells grew and formed teratomas in the organs. However, differentiation of ES cells into lung or liver cells could not be confirmed. We also performed the same experiment using embryonic germ (EG) cells established from SD rats. After rat EG cells were injected into the lung of GFP transgenic SD rats impaired by treatment with bleomycin, the lung was removed and subcutaneously transplanted into the back of NOG mice. At 2, 4 and 8 weeks after transplantation, the implanted lungs were removed and examined histologically. As a result, the implanted lungs were partially engrafted, but the EG cells formed tereratomas. These results suggest that ES cells must be differentiated into progenitor cells but not ES cells by themselves for use in regenerative medicine.