人脐血CD34^+细胞在NOD/SCID小鼠体内重建体液免疫的实验研究

Reconstitution of Humoral Immunity by the Transplantation of Human Umbilical Cord Blood CD34^+ Cells into NOD/SCID Mice

目的探讨人脐血CD34+造血干细胞(HSC)在NOD/SCID小鼠模型体内体液免疫功能重建的作用。方法从新鲜脐血中分离出单个核细胞(MNC),利用免疫磁珠分选法筛选CD34+造血干细胞,经尾静脉输注入经亚致死剂量照射的NOD/SCID小鼠体内,移植后4、6、8、10周分批处死存活的小鼠,取其脾脏和外周血,分别进行细胞表型分析、体液免疫分析,监测小鼠体液免疫功能重建情况。结果照射2周后,阴性对照组小鼠全部死亡,6周后移植组小鼠存活率为37.5%,空白对照组小鼠存活率为100%。移植4、6、8、10周移植组外周血人CD45+细胞表达(%)分别为4.87±1.23、9.22±2.07、12.34±2.38、8.14±2.36,CD19+B淋巴细胞表达(%)分别为1.07±0.50、2.17±0.95、3.34±0.90、1.67±0.90。移植后10周,在移植组小鼠脾脏可见CD19+B淋巴细胞分布。结论经照射后的NOD/SCID小鼠通过人脐血CD34+细胞植入可建立起人鼠嵌合免疫模型。缺少相应细胞因子刺激,CD34+细胞分化能力随时间减弱。

Objective To investigate the immune reconstitution by the transplantation of human umbilical cord blood CD34＋ cells in the NOD/SCID mouse.Methods Mononuclear cells（MNC） were isolated from human fresh cord blood and CD34＋ hematopoietic stem cells were selected by magnetic activated cell sorting method.The selected cells were transplanted via tail vein injection into 16 NOD/SCID mice after sublethal whole-body irradiation.Four mice were sacrificed respectively at 4th,6th,8th and 10th week after the transplantation,the harvested spleen and peripheral blood cells were used to cell phenotype analysis and humoral immune analysis,respectively.There were 14 mice in another two groups,7 mice did not receive the transplantation after irradiation,7 were used as blank control（no irradiation,no transplantation）.Results The mice without transplantation all died within 2weeks after irradiation.The survival rate of the mice with transplantation was 37.5% at 6th week after the irradiation,while the survival rate of blank control was 100%.At 4th,6th,8th and 10th week,the percentage of human CD45＋ cells in transplantation group were 4.87±1.23,9.22±2.07,12.34±2.38,8.14±2.36,respectively,and the percentage of CD19＋ B lymphocytes were 1.07±0.50,2.17±0.95,3.34±0.90,1.67±0.90,respectively.10 weeks after the transplantation,human CD19＋ B lymphocytes distribution were found in the transplanted mice spleen.Conclusion The human-mouse chimeric immune model can be built in irradiated NOD/SCID mice by the transplantation of human cord blood CD34＋ cells.CD34＋ cell differentiation declined with time,which might be due to the lack of appropriate cytokines.