In Vitro Self-Renewal Division of Hematopoietic Stem Cells

Abstract

Little is known about how hematopoietic stem cells (HSCs) self-renew. We studied the regeneration of HSCs in culture. Effects of various cytokines on cell division of CD34−/low c-Kit+Sca-1+ lineage marker–negative (CD34−KSL) bone marrow cells of the mouse were first evaluated in serum-free single cell culture. We then performed a competitive repopulation assay on divided cells to ask if such cell division involved self-renewal of HSCs.In the presence of stem cell factor (SCF), thrombopoietin (TPO) induced a first cell division of CD34−KSL cells more efficiently than did interleukin (IL)-3 or IL-6. Multilineage repopulating cells were detected in a significant proportion of cells derived from single cells in culture with TPO and SCF, although this culture condition led to a substantial decrease in HSC number. These regenerated repopulating cells could be further transplanted into secondary recipients. When paired daughter cells were separately studied, one of a pair gave rise to repopulating cells with self-renewal potential, suggesting asymmetric self-renewal division. This study provides evidence that one HSC regenerates at least one HSC in culture.

The Actin Polymerization Regulator WAVE2 Is Required for Early Bone Marrow Repopulation by Hematopoietic Stem Cells

“…Rac1 À/À HSPCs reportedly responded to SCF with reduced in vitro cell growth, [16] but showed a normal proliferative response to combinations of multiple cytokines [15]. The CD34 À KSL cell fraction used in this study represents a highly purified HSC population in which SCF alone does not support sufficient cell growth [25]. We therefore used multiple cytokines to study the proliferative responses of these cells [22,25].…”

“…The CD34 À KSL cell fraction used in this study represents a highly purified HSC population in which SCF alone does not support sufficient cell growth [25]. We therefore used multiple cytokines to study the proliferative responses of these cells [22,25]. As shown in Figure 3A, CD34 À KSL HSCs transduced with either control virus (top) or WAVE2 shRNA virus (bottom) yielded substantial numbers of myeloid colonies (>1 mm diameter), most of which showed GFP fluorescence (>85% transduction efficiency).…”

Primitive human hematopoietic cells give rise to differentially specified daughter cells upon their initial cell division

“…[12][13][14] Recently, some evidence for the occurrence of asymmetric cell division of mouse HSCs was provided in a transplantation model. 15,16 In studies using human HSC-enriched cells of the CD34 ϩ CD38 Ϫ fraction we and others have shown that CD34 ϩ CD38 Ϫ cells are heterogeneous in respect to their function and their proliferation kinetics (ie, the proliferation rate of more primitive cells is lower than that of committed ones). [17][18][19] Furthermore, it was observed that approximately 30% of the CD34 ϩ CD38 Ϫ cells gave rise to daughter cells with heterogeneous proliferation kinetics, perhaps the result of an asymmetric cell division.…”

Basic Fibroblast Growth Factor Supports Undifferentiated Human Embryonic Stem Cell Growth Without Conditioned Medium

“…For instance, factors in the IL-6 family maintain the pluripotentiality of mouse embryonic stem (ES) cells through activation of the STAT3 pathway [22][23][24][25][26][27]. In addition, growth of human primordial germ cells requires LIF, SCF, and bFGF [28], whereas SCF, FLT3L, TPO, and IL-6 synergize with each other to promote expansion of hematopoietic progenitors [29][30][31][32][33][34][35][36][37]. In this report, we demonstrate that hESCs can be maintained in bFGF or bFGF in combination with other growth factors in a serum replacement nonconditioned medium (SR medium).…”