Primary endothelial cells isolated from the yolk sac and para-aortic splanchnopleura support the expansion of adult marrow stem cells in vitro

The embryonic origin and development of hematopoietic and endothelial cells is highly interdependent. We hypothesized that primary endothelial cells from murine yolk sac and para-aortic splanchnopleura (P-Sp) may possess the capacity to expand hematopoletic stem cells (HSCs) and. progenitor cells ex vivo. Using Tie2-GFP transgenic mice in combination with fluorochrome-conjugated monoclonal antibodies to vascular endothelial growth factor receptor-2 (Flk1) and CD41, we have successfully isolated pure populations of primary endothelial cells from 9.5-days after coitus (dpc) yolk sac and P-Sp. Adult murine bone marrow Sca-1(+)c-Kit(+)lin(-) cells were cocultured with yolk sac or P-Sp Tie2-GFP(+)Flk-1(+)CD41(-) endothelial cell monolayers for 7 days and the total number of nonadherent cells increased 47- and 295-fold, respectively, and hernatopoletic progenitor counts increased 9.4- and 11.4-fold, respectively. Both the yolk sac and P-Sp endothelial cell cocultures facilitated long-term (> 6 months) HSC competitive repopulating ability (2.8- to 9.8-fold increases, respectively). These data suggest that 9.5-dpc yolk sac- and P-Sp-derived primary Tie2GFP(+)Flk-1(+)CD41(-) endothelial cells possess the capacity to expand adult bone marrow hematopoietic progenitor cell and HISC repopulating ability ex vivo. (C) 2003 by The American Society of Hematology.