In vivo and in vitro stem cell function of c-kit- and Sca-1-positive murine hematopoietic cells

Abstract

c-kit is expressed on hematopoietic stem cells and progenitor cells, but not on lymphohematopoietic differentiated cells. Lineage marker- negative, c-kit-positive (Lin-c-kit+) bone marrow cells were fractionated by means of Ly6A/E or Sca-1 expression. Lin-c-kit+Sca-1+ cells, which consisted of 0.08% of bone marrow nucleated cells, did not contain day-8 colony-forming units-spleen (CFU-S), but 80% were day-12 CFU-S. One hundred cells rescued the lethally irradiated mice and reconstituted hematopoiesis. On the other hand, 2 x 10(3) of Lin-c- kit+Sca-1- cells formed 20 day-8 and 11 day-12 spleen colonies, but they could not rescue the lethally irradiated mice. These data indicate that Lin-c-kit+Sca-1+ cells are primitive hematopoietic stem cells and that Sca-1-cells do not contain stem cells that reconstitute hematopoiesis. Lin-c-kit+Sca-1+ cells formed no colonies in the presence of stem cell factor (SCF) or interleukin-6 (IL-6), and only 10% of them formed colonies in the presence of IL-3. However, approximately 50% of them formed large colonies in the presence of IL-3, IL-6, and SCF. Moreover, when single cells were deposited into culture medium by fluorescence-activated cell sorter clone sorting system, 40% of them proliferated on a stromal cell line (PA-6) and proliferated for more than 2 weeks. In contrast, 15% of the Lin-c- kit+Sca-1-cells formed colonies in the presence of IL-3, but no synergistic effects were observed in combination with SCF plus IL-6 and/or IL-3. Approximately 10% proliferated on PA-6, but most of them degenerated within 2 weeks. The population ratio of c-kit+Sca-1+ to c-kit+Sca-1- increased 2 and 4 days after exposure to 5-fluorouracil (5-FU). These results are consistent with the relative enrichment of highly proliferative colony-forming cells by 5-FU. These data show that, although c-kit is found both on the primitive hematopoietic stem cells and progenitors, Sca-1+ cells are more primitive and respond better than Sca-1- cells to a combination of hematopoietic factors, including SCF and stromal cells.

The Lineage−c-Kit+Sca-1+ Cell Response toEscherichia coliBacteremia in Balb/c Mice

“…As shown in Figure 1, the lin−c‐kit+Sca‐1+ cell population in the bone marrow of control mice was very small. Similar observations have been reported in C57BL/6 mice previously [22]. However, the number of lin−c‐kit+Sca‐1+ cells in the bone marrow was markedly increased following E. coli infection.…”

“…challenge with Escherichia coli . Previous studies have shown that C57BL/6 mouse bone marrow lineage (lin)−c‐kit+Sca‐1+ cells are highly purified (or enriched) hematopoietic stem cells, whereas lin−c‐kit+Sca‐1− cells contain more committed progenitors [22, 23]. Similarly, in Balb/c and FVB/N mouse strains, colony‐forming unit (CFU)‐spleen cells express high levels of the Sca‐1 antigen [24].…”

TIS21/BTG2 Negatively Regulates Estradiol-Stimulated Expansion of Hematopoietic Stem Cells by Derepressing Akt Phosphorylation and Inhibiting mTOR Signal Transduction

“…Hematopoietic stem/progenitor cells (HSCs) undergo self‐renewal and differentiation into all types of blood cells throughout life and have been identified in the lineage‐negative (Lin − )/stem cell antigen‐1‐positive (Sca‐1 + )/c‐Kit + (LSK) population that comprises only 0.05%–0.08% of the murine bone marrow (BM) cells [23, –25]. Differentiation and self‐renewal of HSCs are strictly regulated by various feedback mechanisms to maintain homeostasis of the blood system.…”

CD34−Hematopoietic Stem Cells: Current Concepts and Controversies

“…Transplantation studies with injection of HSCs into myeloablated recipients allow for the analysis of the presence of donor cells and their capacity to proliferate and repopulate, thereby indicating HSC activity [1]. In these animal models, murine HSCs have been demonstrated to be negative for lineage markers (Lin − ), including myeloid and B and T cell lineages, and positive for c‐kit, Sca‐1, and CD34 [1–5].…”