[Biological characteristics of hematopoietic progenitor cells at different stages of hematopoietic development].

The aim of the present paper is to better understand the mechanism of hematopoietic development through studying the biological characteristics of hematopoietic progenitor cells at different stages of development. Firstly, the c-kit expression levels of the mononuclear cells from murine embryonic aorta-gonad-mesonephros (AGM) region at embryonic day (E)10.5 and E11.5, fetal liver (FL) at E12.5, E14.5, E16.5, E18 and bone marrow (BM) were assayed with fluorescence activated cell sorting (FACS). Secondly, hematopoietic progenitor cells derived from AGM at E10.5, FL at E14.5 and BM were isolated by using c-kit microbeads. Isolated c-kit(+) population cells from AGM, FL and BM were then co-cultured with E14.5 FL-derived stromal cells in transwell co-culture system in vitro. After 3, 7, 10 days of co-culture, numerous floating cells were generated. The floating cells generated in transwell inserts were collected for FACS cell count, migration activity detection and colony forming unit (CFU) formation assay. The results showed that the c-kit was highly expressed in E10.5 AGM, with the percentage of c-kit(+) cells declining during AGM development. c-kit expression was highly expressed again in E12.5 FL, declining along with the progressive development of the FL region. Co-cultured with FL-derived stromal cells, E10.5 AGM-derived c-kit(+) cells produced the highest number of hematopoietic cells, while BM-derived c-kit(+) cells produced the lowest number of hematopoietic cells. Compared with E10.5 AGM-derived c-kit(+) cells, E14.5 FL- and BM- derived c-kit(+) cells inclined to differentiate after 7 to 10 days of culture in vitro. E10.5 AGM and E14.5 FL-derived c-kit(+) cells exhibited a higher migration activity than BM-derived c-kit(+) cells. Moreover, E10.5 AGM-derived c-kit(+) cells showed a higher ability to form mixed colony-forming unit (CFU-Mix) colony. In conclusion, compared with FL- and BM-derived c-kit(+) cells, E10.5 AGM-derived c-kit(+) hematopoietic progenitor cells exhibit better proliferation, migration potential, and have a higher ability to maintain the undifferentiation state in vitro, providing an insight into their clinical manipulation.