c-Kit expression and stem cell factor-induced hematopoietic cell proliferation are up-regulated in aged B6D2F1 mice

Abstract

Expression of c-Kit (CD117) and stem cell factor/c-Kit-mediated cell proliferation were tested in vitro in young and old B6D2F1 mice to study the role of c-Kit signaling in hematopoietic stem cell (HSC) senescence. Increasing age is associated with a significant increase in bone marrow (BM) cells without affecting mature blood cells. The number of c-Kit-expressing BM cells increased significantly in old mice when compared to young controls, to 201% in total BM cells, 261% in Lin- cells, 517% in Lin-CD34 +Sca1+ progenitor cells, and 1272% in Lin -CD34-Sca1+ HSCs. Sorted Lin -Sca1+CD117+ BM cells from an old mouse expanded 5-fold when cultured in vitro for 72 hours with stem cell factor at 25 ng/ml, which was significantly higher than a 2.5-fold expansion of the same cells from a young donor. HSCs and progenitor cells from B6D2F1 mice maintain extremely high proliferative potentials and do not reach proliferative arrest at old age during a normal life span. Copyright 2005 by The Gerontological Society of America.