SDF-1/CXCR4增强骨髓间质干细胞的造血支持作用

目的探讨基质细胞衍生因子-1(SDF-1)/CXCR4在骨髓间质干细胞(MSCs)支持CD34 造血干/祖细胞(HSPCs)扩增中的作用。方法在长期培养基(LTC)中,以大鼠骨髓MSCs作为饲养层体外扩增骨髓CD34 细胞,每周分别加入SDF-1、SDF-1抗体或CXCR4抗体至5周。计算CD34 细胞数和集落形成细胞(CFC)数,以评价造血支持功能。为评估SDF-1/CXCR4对CD34 细胞增殖周期的影响,进行了杀伤试验以计算增殖指数。流式细胞术检测MSCs和CD34 细胞中SDF-1与CXCR4的表达;ELISA检测MSCs和CD34 细胞培养基中SDF-1的含量。结果CD34 细胞数、CFC数和增殖指数在加入SDF-1后明显增加(P<0.01),加入SDF-1抗体或CXCR4抗体后明显减少(分别为P<0.05,P<0.01)。CD34 细胞表面表达CXCR4,MSCs则不表达;MSCs细胞内表达SDF-1,而CD34 细胞不表达。在MSCs培养基中检测到SDF-1,在CD34 细胞培养基中未发现。结论SDF-1/CXCR4在骨髓MSCs支持HSPCs扩增中起重要作用。

Effect of SDF-1/CXCR4 on the hematopoietic-supporting activity of bone marrow mesenchymal stem cells

Objective To study the effect of stromal cell-derived factor-1(SDF-1)/CXCR4 on the proliferation of CD34 hematopoietic stem/progenitor cells(HSPCs) supported by bone marrow mesenchymal stem cells(MSCs).Methods Rat bone marrow MSCs were plated as feeder layer in long-term cultures(LTC) with bone marrow CD34 cells in vitro.Cultures were weekly supplemented with SDF-1,anti-SDF-1 antibody,or anti-CXCR4 antibody separately for 5 weeks.The hematopoietic-supporting activity was evaluated by the number of CD34 cells and colony forming cell(CFC).To assess the effect of SDF-1/CXCR4 on CD34 cell proliferation cycle,killing assays were carried out and proliferation indexes were calculated.Expression of SDF-1 and CXCR4 in MSCs and CD34 cells were determined by flow cytometry.SDF-1 in MSC-and CD34 cell-conditioned medium was also measured by ELISA.Results The number of CD34 cells,CFC and proliferation indexes were significantly increased in treat-ment with SDF-1(P<0.01),and were significantly decreased after treatment with anti-SDF-1 antibody(P<0.05) and anti-CXCR4 antibody(P<0.01).CXCR4 presents on the surface of CD34 cells,but not on the surface of MSCs.Intracellular production of SDF-1(iSDF-1) was detected in MSCs,but not in CD34 cells.SDF-1 was detected in MSC-conditioned medium,but not in CD34 cell-conditioned medium.Conclusion SDF-1/CXCR4 play important roles in hematopoietic-supporting activity of MSCs.