To investigate the behavior of hematopoietic stem cells (HSCs) in cord blood (CB), we analyzed the expression and function of TIE2, a tyrosine kinase receptor. A subpopulation of Lineage (Lin)-/lowCD34+ cells in CB expressed TIE2 (18.8%). Assays for long-term culture-initiating cells (LTC-IC) and cobble-stone formation revealed that Lin-/lowCD34+TIE2+ cells showed to have a capacity of primitive hematopoietic precursor cells in vitro. When Lin-/lowCD34+TIE2+ cells were cultured on the stromal cells, they transmigrated under the stromal layers and kept an immature character for a few weeks. By contrast, Lin-/lowCD34+TIE2- cells differentiated immediately within a few weeks. Finally, we confirmed that 1 × 104 Lin-/lowCD34+TIE2+ cells were engrafted in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice, while 1 × 104 Lin-/lowCD34+TIE2- cells were not. Taken together, we conclude that TIE2 is a marker of HSCs in CB. A ligand for TIE2, Ang-1 promoted the adhesion of sorted primary Lin-/lowCD34+TIE2+ cells to fibronectin (FN), and this adhesion may play a critical role in keeping HSCs in an immature status under the stromal cells.
|ジャーナル||Biochemical and Biophysical Research Communications|
|出版ステータス||Published - 2002|
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