骨髓间充质干细胞对放射性胸腺损伤的修复作用

Repairment Effects of Bone Marrow Mesenchymal Stem Cells on Thymus Tissue Injury Induced by Ionizing Radiation

目的观察骨髓间充质干细胞（MSCs）对放射性胸腺损伤的修复作用.方法 C57BL/6小鼠行1.75 Gy X线全身照射,每周1次,连续4周.实验设正常对照组、照射组及照射＋MSCs组,于末次照射后30、60、90 d称量各组小鼠体质量.取胸腺组织,计算胸腺质量指数,并通过组织学观察MSCs对胸腺组织损伤的修复作用.结果辐射组和MSCs组在照射期间体质量下降,在观察期间内,小鼠体质量随时间逐渐增加,并且MSCs组小鼠体质量略高于辐射组.对照组小鼠胸腺指数随周龄增大而逐渐减小,辐射组和MSCs组小鼠随照射后时间的延长胸腺指数逐渐增加,MSCs组90 d时胸腺指数与对照组小鼠接近.通过观察病理结果可知,正常对照组小鼠胸腺组织皮、髓质结构清楚.辐射组小鼠30 d时胸腺组织淋巴细胞可见变性、坏死,细胞数量减少;60 d时辐射组可见胸腺淋巴细胞出现修复性再生与增生;90 d时辐射组可见胸腺瘤癌前病变.MSCs移植30 d时胸腺组织皮质高度增生,髓质缩小,皮髓质内可见新生的淋巴组织;60 d时胸腺结构趋于正常.结论 MSCs可促进损伤胸腺再生与修复.

Objective To observe the repairment effects of bone marrow mesenchymal stem cells（MSCs） on thymus tissue injury induced by ionizing radiation in mice.Method The whole bodies of mice were irradiated with 1.75 Gy X-irradiation（once a week,total four weeks） and the mice were divided into normal group,irradiation group and MSCs group.Body weights of the mice were weighed and the thymus weight indices were calculated on the 30th day,60th and 90th after the irradiation.Repairment effects of MSCs on thymus were observed by using a histopathological method.Results The mice body weights of MSCs group and radiation group were lost during the irradiation,and increased gradually within the observation period.The mice body weight of MSCs group was slightly higher than that in the radiation group.The thymic index in the control group gradually decreased with the increase of weeks age and that in radiation group and the MSCs group gradually increased with time after the irradiation.The thymic index in MSCs group was close to that in the control group on the 90th day.The structures of cortex and medulla of mice＇s thymus were clear in the control group.The thymus lymphocyte degeneration and necrosis could be seen and cell number decreased after the 30 d in MSCs group;the proliferation of reparative regeneration could be seen on the 60th day and precancerous lesions of thymoma can be seen on the 90th day after the irradiation.The cortical tissue of thymus proliferated significantly,the medulla was reduced,and a newborn lymphoid tissue in the cortex and marrow could be seen on the 30th day after MSCs transplantation;The thymus structure tended to be normal on the 60th day.Conclusion MSCs can promote regeneration and repairment of damaged thymus induced by irradiation.