In vitro hematopoietic and endothelial cell development from cells expressing TEK receptor in murine aorta-gonad-mesonephros region

Recent studies have shown that long-term repopulating hematopoietic stem ce lls (HSCs) first appear in the aorta-gonad-mesonephros (AGM) region. Our im munohistochemistry study showed that TEK+ cells existed in the AGM region. Approximately 5% of AGM cells were TEK+, and most of these were CD34(+) and c-Kit(+). We then established a coculture system of AGM cells using a stro mal cell line, OP9, which is deficient in macrophage colony-stimulating fac tor (M-CSF). With this system, we showed that AGM cells at 10.5 days postco itum (dpc) differentiated and proliferated into both hematopoietic and endo thelial cells. Proliferating hematopoietic cells contained a significant nu mber of colony-forming cells in culture (CFU-C) and in spleen (CFU-S). Amon g primary AGM cells at 10.5 dpc, sorted TEK+ AGM cells generated hematopoie tic cells and platelet endothelial cell adhesion molecule (PECAM)-1(+) endo thelial cells on the OP9 stromal layer, while TEK- cells did not. When a li gand for TEK, angiopoietin-1, was added to the single-cell culture of AGM, endothelial cell growth was detected in the wells where hematopoietic colon ies grew. Although the incidence was still low (1/135), we showed that sing le TEK+ cells generated hematopoietic cells and endothelial cells simultane ously, using a single-cell deposition system. This in vitro coculture syste m shows that the TEK+ fraction of primary AGM cells is a candidate for hema ngioblasts, which can differentiate into both hematopoietic cells and endot helial cells. (C) 1999 by The American Society of Hematology.