造血微环境决定脐血造血干/祖细胞的早期分裂行为

目的 在特定生长因子的培养体系中，观察模拟造血微环境及粘附因素对人类脐血造血干/祖细胞早期分裂行为影响。方法 （1）应用流式细胞仪（FACS）分选CD34^ CD38^-细胞；（2）细胞培养体系中应用干细胞支持性基质AFT024及单一粘附因素纤维结合素（Fn)。并观察其对细胞早期分裂行为的影响。结果 （1）在联合生长因子的条件下，人类脐血CD34^ CD38^-细胞早期分裂呈现固定比例的静止，慢分裂，快分裂以及不对称分裂状态；（2）未观察到单一粘附因子Fn对其早期分裂行为的影响；（3）干细胞支持性基质AFT024所模拟的体外造血微环境可促使脐血造血干/祖细胞广泛增殖并更多地进行不对称分裂。结论 （1）CD34^ CD38^-细胞群体具有异质性。由具有不同增殖行为的亚群组成，在体外培养早期存在不对称分裂；（2）体外模拟的骨髓微环境AFT024基质滋养层较细胞因子及单一粘附因素能够更好地支持造血干/祖细胞的增殖并保持其自我更新的特性。

Initial division behavior of cord blood hematopoietic stem cells depends on micrOenvironment

OBJECTIVE: The influence of the mimic hematopoietic microenvironment and adhesion factor on the initial divisional behavior of human cord blood hematopoietic progenitors was studied in the culture system with certain cytokines. METHODS: (1) CD(34)(+) CD(38)(-) single cell was sorted by FACS. (2) The stem cell supporting stromal feeder layer AFT024 and single adhesive factor fibronectin (Fn) were used in the culture system and their influence on the initial division was observed. RESULTS: (1) In the presence of the combined cytokines, the CD(34)(+) CD(38)(-) human cord blood cells displayed fixed fraction of quiescent, slow and fast division, and asymmetric division. (2) There was no influence of adhesive factor itself on initial division of CD(34)(+) CD(38)(-) cells. (3) The hematopoietic microenvironment mimicked by AFT024 promoted CD(34)(+) CD(38)(-) cells to proliferate extensively and undergo more asymmetric division. CONCLUSIONS: (1) CD(34)(+) CD(38)(-) cells are heterogeneous and composed of various subpopulations with different initial proliferative behavior, including asymmetric division. (2) The hematopoietic microenvironmental mimicked by AFT024 supports the hematopoietic progenitors better than cytokines and single adhesion factor do, for their proliferation extensively and preservation the self-renewal capacity.