Tunica Interna endothelial cell kinase expression and hematopoietic and angiogenic potentials in cord blood CD34+ cells

Tunica interna endothelial cell kinase (TEK) is expressed in both hematopoietic and endothelial cells and plays a crucial role in hematopoiesis and angiogenesis in mouse development. In humans, however, little is known about the hematopoietic and angiogenic potentials of TEK-expressing cells in umbilical cord blood (CB) cells, which originate during the human fetal period. We therefore compared the hematopoietic and angiogenic abilities of CB CD34(+)TEK(+) and CD34(+)TEK(-) cells by using a clonogenic assay and xenotransplantation into immunodeficient NOD/SCID mice. The results showed that colony-forming cells and cells capable of repopulating in NOD/SCID mice were present in both CD34(+)TEK(+) and CD34(+)TEK(-) cells and that the hernatopoietic activities of the cell types were similar. In contrast, the potential to differentiate into endothelial cells in vivo was greater in the CD34(+)TEK(+) cells. All NOD/SCID mice engrafted with CD34(+)TEK(+) cells had human CD31-expressing and VE-cadherin-expressing endothelial cells in the vessels of the ischemic muscles and/or human endothelial cells expressing CD31, kinase-insert domain-containing receptor, and endothelial nitric oxide synthase in liver sinusoidal cells, whereas such endothelial cells were detected in only 3 of the 7 recipients engrafted with CD34(+)TEK(-) cells. This result has important implications in cell therapy using CB cells for treating hematopoietic disorders and vascular diseases. (C) 2003 The Japanese Society of Hematology.