Role of Flk-1 in mouse hematopoietic stem cells

It was reported that human hematopoietic stem cells in bone marrow were restricted to the CD34(+)KDR(+) cell fraction. We found that expression levels of Flk-1, a mouse homologue of KDR, were low or undetectable in mouse Lin(-)c-Kit(+)Sca-1(+)CD34(low) cells as well as Hoechst33342(-) cells (side population), which have long-term reconstitution capacity. Furthermore, neither Fik-1(+)CD34(low) cells nor Fik-1(+)CD34(+) cells had long-term reconstitution capacity in mouse. Taken together with other observations using Flk-1-deficient mice, these results indicate that Flk-1 is essential for the development of hematopoietic stem cells in embryo but not for the function of hematopoietic stem cells in adult mouse bone marrow. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.