SDF-1／CXCR4轴在人脐血源基质细胞促进巨核细胞增殖中的作用

本研究探讨基质细胞衍生因子（stromal cell derived factor-1，SDF-1）及其受体CXCR4在人脐血源基质细胞（human umbilical cord blood-derived stromal cells，hUCBSCs）促进巨核细胞增殖中的作用。以巨核细胞系HEL细胞作为研究对象，实验分HEL／hUCBSC共培养组、HEL／骨髓基质细胞（human bone marrow stromal cells，hBMSCs）共培养组和HEL悬浮培养组。应用ELISA法检测huCBSC和hBMSC培养上清SDF-1水平，应用激光共聚焦和流式细胞仪检测HEL细胞CXCR4蛋白表达，RT—PCR检测CxcR4mRNA表达。结果表明：hUCBSC高分泌表达SDF-1，其分泌高峰在培养第8天，稍迟于hBMSCs。与hUCBSCs共培养的HEL细胞，流式细胞仪和激光共聚焦检测均显示其CXCR4蛋白的表达较弱（P〈0．05），且可在部分HEL细胞胞浆中发现红色点状荧光。RT-PCR检测结果显示，不同培养条件下HEL细胞CXCR4mRNA表达无显著性差异（P〉0．05）。结论：hUCBSC在分泌SDF-1和调控巨核细胞表达CXCR4方面起重要作用。

Contribution of SDF-1/CXCR4 Axis on Proliferation of Megakaryocyte Co-cultured with Human Umbilical Cord Blood-derived Stromal Cells

In order to investigate the effect of stromal cell derived factor-1 （ SDF-1 ）/CXCR4 on the proliferation of megakaryocytic line-HEL cells co-cultured with human umbilical cord blood-derived stromal cells （hUCBSCs） and to further elucidate the mechanism of SDF-1/CXCR4-mediated functions, the HEL cells were co-cultured with hUCBSCs or human bone marrow stromal cells （hBMSCs）, the suspended HEL was used as control. The concentrations of SDF-1 in supernatant of hUCBSCs and hBMSCs were detected by ELISA assay. The expression of CXCR4 membrane-bound protein of HEL cells was detected by laser confocal scanning microscopy and flow cytometry, and the expression of CXCR4 mRNA was detected by RT-PCR. The result showed that the concentrations of SDF-1 in different groups were the same at the early stage of culturing. But at 6 days after seeding, the concentrations of SDF-1 increased significantly in the hUCBSCs group, even though the passage was done. By means of laser contocal microscopy, the expression of CXCR4 protein and also red dots of fluorescence could be detected in cytoplasm of HEL cells co-cultured with hUCBSCs. However, there was no significant differences of the CXCR4 mRNA level between different groups （p 〉 0.05）. It is concluded that hUCBSCs may play important roles in secreting high level of SDF-1 and regulating megakaryocyte expression of CXCR4.