小鼠胚胎AGM区Flk-1+细胞的造血特性

摘要

This study aimed to investigate the expression of Flk-1 on distinct hematopoietic precursor cells in E10. 5mouse AGM region. By flow cytometry, we found that < 10% of Flk-1+ cells of E10. 5 AGM region co-expressed CD41 and CD45/Ter119. Then, E10.5 AGM cells were fractionated into two subsets, the CD31+ CD45- Ter119- Flk-1 + CD41 + cells (R1, putative immature hematopoietic cells) and the CD31+ CD45- Ter119- Flk- 1 + CD41- cells (R2, putative endothelial cells), followed by methylcellulose-based CFU-C assay and OP9-based stromal co-culture to examine their myeloid or/and lymphoid potential in vitro. The results showed that only Rl cells could give rise to typical hematopoietic colonies in CFU-C assay. In contrast, after co-cultured with OP9 for 7 - 9 days, both subsets could generate abundant hematopoietic progenitor cells ( CD45 + c-Kit+ ), myeloid cells ( Gr-1 VMac-1+ ), erythroid cells (Terl 19+), and B lymphocytes (CD19+). It is concluded that both maturing CD41+ CD45" hematopoietic precursor cells and hemogenic endothelial cells express Flk-1 in E10. 5 AGM region. It requires further functional assay in vivo to clarify whether the hematopoietic stem cells (HSCs) and their precursors retain Flk-1 expression at this developmental stage.%本研究旨在考察Flk-1分子在胚胎期10.5 d(E10.5)的主动脉-性腺-中肾区(AGM区)不同类型造血前体细胞的表达情况.通过流式细胞术分析发现低于10％的Flk-1+细胞与CD41、CD45/Ter1 19有共表达,继而分选出CD31+ CD45-Ter119-Flk-1+ CD41+(R1,代表不成熟的造血前体细胞)和CD31+CD45-Ter119-Hk-1+CD41-(R2,代表内皮细胞)两群细胞,利用造血集落培养和OP9共培养体系分别考察其体外的髓系与淋系潜能.结果表明:仅R1组细胞能在造血集落培养体系中形成典型的造血集落,但与OP9共培养7-9d后,两组细胞均能产生丰富的造血前体细胞(CD45+ c-Kit+)、髓系细胞(Gr-1+/Mac-1+)、红细胞(Ter119+)和B淋巴细胞(CD19+).结论:E10.5的小鼠胚胎AGM区Flk-1仍然在幼稚的造血前体细胞以及更早期的生血内皮细胞表达,但是此时的造血干细胞前体和造血干细胞是否表达Flk-1仍需通过体内功能实验明确.