胚胎胸腺的替代治疗

Replacement therapy of fetal thymus

目的 探索小鼠同种异体胚胎胸腺移植可否作为T淋巴细胞缺陷的治疗方法。方法 选择切除C57小鼠的胸腺作为制作细胞免疫缺陷的模型。30只小鼠被分为三组，每组10只。第一组为正常小鼠作为对照组；第二组行胸腺切除术，作为模型对照组；第三组是胚胎胸腺移植为实验组。检测脾脏总T细胞计数及其平均体重所含T细胞数；流式细胞术检测Th（helper T cell）细胞，Tc（cytotoxic T cell）细胞以及调节性T细胞（regulatory T cells, Tregs）的含量，并用简化的RT-PCR方法检测T细胞DNA删除环（TRECs）。结果 三组小鼠分别剩余9只、8只，8只。T淋巴细胞总数三组分别为（16.24±2.98）×107、（4.58±1.29）×107、（9.92±2.24）×107。平均体重T淋巴细胞含量分别为（7.53±1.35）×106、（2.38±0.66）×106、（5.23±1.10）×106。两组都有统计学意义（P〈0.05）。对照组含量最高，胸腺切除组含量最少，胚胎胸腺移植组位于两者之间。T淋巴细胞亚群分析中，三组Th细胞分别为（7.19±0.38）%、（1.51±0.37）%、（3.33±0.40）%；Tc细胞为（7.21±0.41）%、（1.31±0.32）%、（3.41±0.48）%；Tregs为（2.17±0.21）%、（0.48±0.12）%、（1.12±0.12）%。Th，Tc以及Tregs含量在三组间有统计学意义（P〈 0.05），A组含量最高，B组含量最少，C组位于两者之间。RT-PCR分析中，ΔΔCT值进行统计分析及进行三组ΔΔCT值的总体趋势的比较。ΔΔCT值对照组为17.04±1.69，胸腺切除组为9.53±0.84；胚胎胸腺移植组为12.45±1.51，三组的差异有统计学意义（P〈0.05）。结论 胚胎胸腺移植可以提高细胞免疫功能的恢复，但无法使其恢复到正常水平。

Objective To investigate whether the allogeneic thymus transplantation can be a method to cure the deficiency of the T-cells. Methods In this study, a murine thymus excision model was developed to receive an intra-species embryonic thymus transplantation.The mice were divided into three groups with 10 animals per group.The first group was normal mice that served as the control group.The second group is the thymectomy-only model which served as control group.The third group received the embryonic thymus transplantation.Total T-cell counts and the number of T-cells per unit weight of the mice in these three groups were determined.Additionally, T-cell subsets were detected by flow cytometry, using the number of CD3＋ CD4＋ double-positives to determine helper T-cells（Th）, CD3＋ CD8＋ double-positives to determine the cytotoxic T-cells（Tc）, and CD4＋ CD25＋ foxp3 triple-positive cells to determine the regulatory T cells（Tregs）content.A new simplified method was used to determine the T-cell receptor excision circles（TRECs）from tissues.Results The number of surviving mice in each group were nine for controls; eight for embryonic thymus transplant recipients; and eight for thymectomy alone.The T thymocyte count results showed that the total and mean value of T lymphocytes between the three groups were significantly different（P〈0.05）and the datas are（16.24±2.98）×107、（4.58±1.29）×107、（9.92±2.24）×107 and （7.53±1.35）×106、（2.38±0.66）×106、（5.23±1.10）×106.For all T lymphocyte subsets analyzed, the datas of Th were （7.19±0.38）%、（1.51±0.37）%、（3.33±0.40）%; the datas of Tc were（7.21±0.41）%、（1.31±0.32）%、（3.41±0.48）%; and the datas of Tregs were（2.17±0.21）%、（0.48±0.12）%、（1.12±0.12）%.Statistical analyses demonstrated that there were significantly different in Th, Tc and Treg lymphocytes in each group（P〈 0.05）. Statistical analyses showed that these three groups were significantly different（P〈0.05）in TRECs.Control mice（17.04±1.69）had the highest content of TRECs and mice with embryonic thymus transplant（12.45±1.51）had fewer TRECs than the control mice but more than the mice with thymectomy（9.53±0.84）.Conclusion This study demonstrated that embryonic thymus transplantation can improve cellular immune function, confirming that the embryonic thymus can restore myriad T-cell lineages.