人胎盘间充质干细胞CD200^+亚群细胞对同种异基因移植排斥的调节效应

Immunoregulation of allograft rejection: a role played by human CD200^+ sub-population from human placenta-derived mesenchymal stem cells

背景:免疫排斥反应仍是皮肤异体移植面临的重要难题,实验室前期研究发现高表达CD200的人胎盘间充质干细胞亚群细胞具备较强的免疫调节能力。目的:进一步研究人胎盘间充质干细胞CD200+亚群细胞对同种异基因移植排斥的调节作用。方法:构建同种异基因小鼠皮肤移植模型,经尾静脉分别将PBS(对照组)、人胎盘间充质干细胞(PMSCs组)、人胎盘间充质干细胞CD200^+亚群细胞(CD200^+-PMSCs组)输注C57BL/6小鼠体内。观察移植物的开始坏死时间、存活时间、皮片状态;细胞治疗7 d,采集小鼠外周血进行白细胞计数,采用Q-PCR、ELISA方法检测小鼠脾脏与外周血中白细胞介素10、干扰素γ及肿瘤坏死因子α的表达。结果与结论:①与对照组相比,PMSCs组与CD200^+-PMSCs组移植物状态良好,存活时间明显延长(P<0.001);CD200^+-PMSCs组移植物状态及存活时间均优于PMSCs组(P<0.01);②细胞治疗7d,PMSCs组与CD200^+-PMSCs组白细胞数量明显少于对照组(P <0.01);③与对照组相比,CD200^+-PMSCs组脾脏中白细胞介素10 mRNA表达明显升高(P <0.05),PMSCs组、CD200^+-PMSCs组干扰素γ及肿瘤坏死因子αm RNA表达量则明显下调(P <0.05,P <0.01),同时CD200^+-PMSCs组干扰素γ及肿瘤坏死因子αm RNA表达量明显低于PMSCs组(P <0.01,P <0.05);④与对照组相比,PMSCs组、CD200+-PMSCs组血液中白细胞介素10水平明显升高(P <0.05,P <0.01),而干扰素γ及肿瘤坏死因子α水平则明显下调(P <0.05,P <0.001;P <0.01,P <0.001),同时CD200^+-PMSCs组干扰素γ及肿瘤坏死因子α水平明显低于PMSCs组(P<0.05);⑤结果表明,人胎盘间充质干细胞对同种异基因皮肤移植排斥具有调节作用;CD200+亚群细胞抑制免疫排斥反应能力更强,其机制可能是CD200通过调节白细胞介素10、干扰素γ及肿瘤坏死因子α等免疫相关因子参与免疫反应。

BACKGROUND: Immune rejection of skin allograft is a clinical problem to be solved. Our previous study has shown that human placenta-derived CD200+ mesenchymal stem cells may have a strong capability of immunoregulation. OBJECTIVE: To investigate the effects of human placenta-derived CD200+ mesenchymal stem cells on rejection of skin allograft. METHODS: Skin allograft models of c57/BL6 mice were established and divided into three groups as control group, human placenta-derived mesenchymal stem cells group(PMSCs group), and CD200+ mesenchymal stem cells group(CD200+-PMSCs group). PBS(control group), normal PMSCs and CD200+-PMSCs were injected into the mice through the tail vein, respectively. The necrotic time, survival time and situation of grafted skin were observed. The number of peripheral white blood cells was counted after 7 days of treatment. The expression levels of interleukin-10, interferon-γ and tumor necrosis factor-α were detected by Q-PCR and ELISA. RESULTS AND CONCLUSION:(1) Compared with the control group, in the PMSCs and CD200+-PMSCs groups, the condition of skin allograft was better, and the survival time was significantly prolonged(P < 0.001). The condition and survival time of skin allograft in the CD200+-PMSCs group were significantly superior to those in the PMSCs group(P < 0.01).(2) After 7 days of treatment, the number of peripheral white blood cells in the PMSCs and CD200+-PMSCs groups was significantly less than that in the control group(P < 0.01).(3) Compared with the control group, the mRNA expression level of interleukin-10 in the spleen was significantly increased in the CD200+-PMSCs group(P < 0.05), and the mRNA expression levels of interferon-γ and tumor necrosis factor-α in the spleen were significantly down-regulated in the PMSCs and CD200+-PMSCs groups(P < 0.05, P < 0.01). The mRNA expression levels of interferon-γ and tumor necrosis factor-α in the spleen in the CD200+-PMSCs group were significantly lower than those in the PMSCs group(P < 0.01, P < 0.05).(4) Compared with the control group, the expression level of interleukin-10 in the blood was significantly increased(P < 0.05, P < 0.001), and the expression levels of interferon-γ and tumor necrosis factor-α in the blood were significantly down-regulated in the CD200+-PMSCs and PMSCs groups(P < 0.05, P < 0.001;P < 0.01, P < 0.001). The expression levels of interferon-γ and tumor necrosis factor-α in the blood in the CD200+-PMSCs group were significantly lower than those in the PMSCs group(P < 0.05). These results indicate that human placenta-derived mesenchymal stem cells have immunosuppressive effect on the rejection of skin allograft, and CD200+ cells may have better immunoregulatory effects by regulating the expressions of interleukin-10, interferon-γ and tumor necrosis factor-α.