脐带间充质干细胞对CD34+细胞在小鼠体内归巢的影响及其机制研究

目的 探讨脐带来源间充质干细胞(MSC)对脐血来源CD34+细胞在NOD/SCID小鼠体内归巢的影响及其可能的机制.方法 将CD34+细胞与MSC细胞共移植入经放射线照射后的NOD/SCID小鼠,采用流式细胞术和RT-PCR检测移植后20 h NOD/SCID小鼠骨髓及脾脏中人CD34+细胞,计算其相应的骨髓和脾脏的归巢效率.将脐血CD34+细胞与脐带MSC体外共培养,检测MSC细胞对CD34+细胞趋化功能的影响;并于培养4、7 d检测培养后CD34+细胞表面CD49e、CD31、CD62L、CD11a等归巢相关黏附分子表达情况.结果 ①移植后20 h采用流式细胞术成功在小鼠骨髓和脾脏中检测到人CD45+细胞.共移植组CD34+细胞骨髓归巢率(7.2±1.1)%]高于单移植组(5.4±0.9)%](P<0.05).②RT-PCR结果 显示共移植组小鼠骨髓细胞和脾脏细胞,单移植组小鼠脾脏细胞扩增得到人GAPDH基因片段,而单移植组小鼠骨髓细胞未见明显扩增条带.③MSC存在时,CD34+细胞的体外迁移能力为(35.7±5.8)%,显著高于CD34+细胞自发迁移率(3.5±0.6)%,P<0.05].④CD34+细胞与MSC体外共培养后细胞表面CD49e、CD31和CD62L黏附分子的表达水平高于CD34+细胞单独培养组.结论 MSC细胞与CD34+细胞共移植有利于CD34+细胞向骨髓、脾脏等造血器官归巢,这可能与MSC促进CD34+细胞迁移以及维持CD34+细胞表面归巢相关黏附分子的表达相关.

Study of influence of umbilical cord mesenchymal stem cells on CD34+ cells in vivo homing in NOD/SCID mice and its mechanism

Objective To investigate the effect and the potential mechanism of umbilical cord (UC) derived mesenchymal stem cells (MSCs) on umbilical cord blood(UCB) derived CD34+ cells in vivo homing in xenotransplanted NOD/SCID mice model. Methods CD34+ cells and MSCs were derived from fresh UCB and UC, respectively. CD34+ cells (5×105 per mice) and MSC cells(5×106 per mice) were co-transplan-ted into irradiated NOD/SCID mice intravenously. CD34+ cells(5×105 per mice) alone were transplanted into the mice as control group. CD34+ cells homed in bone marrow and spleen of recipient mice were detected 20 hours after transplant by FACS and RT-PCR, and the homing efficiencies were calculated. The effect of MSCs on CD34+ cells chemotactic fuction was investigated after co-cultured UCB CD34+ cells with UC MSCs in vitro. After 4 and 7 days coculture, the homing rehted adhesion molecules (the CD49e, CD31, CD62L,CD11a)expressed on CD34+ cells were detected by FACS. Results ①The homing efficiencies in bone marrow in experimental and control group were (7.2±1.1) % and (5.4±0.9) %, respectively (P < 0.05). ②Human GAPDH gene was detected in bone marrow in experimental group and in spleen in both groups. ③The migration efficiency of CD34+ cells was significantly higher in experimental group (35.7±5.8) % than in control group (3.5±0.6)% (P <0.05). ④The expression of CD49e,CD31 ,CD62L on CD34+cells kept higher level in MSCs cocuitured group than in CD34+ cells alone group. Conclusions MSCs can efficiently increase homing of CD34+ cells to bone marrow and spleen in vivo by keeping a high level of hom-ing adhesion molecules expression and improving migration efficiency of UCB CD34+ cells.