The c-Kit expression level is decreased in regenerating bone marrow, and such bone marrow performs poorly when co-transplanted with normal bone marrow. We asked whether diminished numbers of c-Kit receptors on hematopoietic stem and progenitor cells (HSPCs) after their internalization induced by the binding of the cytokine stem cell factor (SCF) would jeopardize transplantability of HSPCs. We used a battery of functional assays to evaluate the capacity of HSPCs with markedly different c-Kit expression levels to be transplanted. Surprisingly, our experiments testing the homing of transplanted HSPCs to bone marrow of recipient mice and their short-term and long-term engraftment did not reveal any defects in HSPCs with severely reduced numbers of c-Kit receptor molecules. This unexpected result can be ascribed to the fact that HSPCs exposed to SCF replace the consumed c-Kit receptors rapidly. This article demonstrates that exposure of HSPCs to SCF and diminished number of c-Kit receptors in their cell membranes do not compromise the capacity of HSPCs to reconstitute damaged hematopoietic tissue.

Department of Biological Science and Technology National Pingtung University of Science and Technology Pingtung Taiwan

Institute of Pathological Physiology 1st Faculty of Medicine Charles University Prague Czech Republic

Institute of Pathological Physiology 1st Faculty of Medicine Charles University Prague Czech Republic; Department of Biological Science and Technology National Pingtung University of Science and Technology Pingtung Taiwan

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Altered Erythro-Myeloid Progenitor Cells Are Highly Expanded in Intensively Regenerating Hematopoiesis