Hematopoietic stem cell regulatory volumes as revealed in studies of the bgj/bgj:W/WV chimera.

Abstract

Foremost among the open questions of hematopoiesis is the nature of the mechanisms that govern the behavior of pluripotent stem cells. Several types of evidence suggest that stem cell activities are directed by local control systems. Local regulation is apparently expressed in the centripetal movement of active marrow during postnatal growth of many species, in the predilection of hematopoietic foci for endosteal surfaces (1), in the selective distribution of erythroid and granuloid colonies arising from stem cells implanted in Xirradiated mice (2), and in the microenvironmental defect seen in genetically anemic mice carrying the mutant steel locus (3, 4). The effects of adherent cells derived from marrow as seen in heterotopic implants (5) and in bone marrow cultures (6) are also strongly suggestive of a regulatory role of bone marrowassociated elements in the activities of pluripotent stem cells. Because the W/W v mouse has very few macrocolony-forming stem cells (CFUs) ~ but an apparently normal marrow microenvironment, this genotype may be useful for studying the interaction between CFUs and their immediate environment. This follows from the comparative ease with which CFUs from +/+ littermates or congenic mouse strains can be transplanted to W/W ~ mice without irradiation or other treatment (7-9). We are concerned here with the evolution of bone marrow chimerism in the W/W v mouse as a function of marrow transplantation dose. The results of this study point to the existence of discrete stem cell regulatory vol of about 10 8 ftm 3, a dimension consistent with concepts of shortrange cell-cell interactions. Materials and MethodsWe chose histocompatible bgJ/bg ~ (beige) mouse marrow as the source of CFUs for the W/W ~ mouse because the giant sudanophilic granules (>1 ~m) characteristic of bgJ/bg j neutrophils provide a convenient marker of W/W ~" marrow replacement (8). W/V~ and bg~/bg J mice were purchased from The Jackson Laboratory, Bar Harbor, Maine. Both male and female bgJ/bg J mice, 2-4 mo of age and weighing 20-25 g, were used as marrow donors, but only male W/W ~ mice of similar age weighing 15--20 g were used as bone marrow recipients because of incompatibility of a male graft in a female host. Donor marrow was obtained from a femur shaft, suspended in Hanks' balanced salt solution for total nucleated cell counts, and then serially diluted with additional Hanks' solution to the desired cell concentrations. Each W/V~" recipient was injected with 0.5 ml of the appropriate bgJ/bg J marrow cell suspension by tail vein.* Supported by the U. S. Department of Energy.1 Abbreviation used in this paper: CFUs, macrocolony-forming stem cells. J. ExP. Mzv.

High c-Kit expression identifies hematopoietic stem cells with impaired self-renewal and megakaryocytic bias

“…Although various strategies to identify long-term HSCs based on surface antigen expression have been described, almost all immunophenotypic definitions of HSCs rely on expression of c-Kit, which is a functional signaling receptor critical for maintaining HSC self-renewal and niche interactions ( McCulloch et al, 1964 ; Maloney et al, 1978 ; Nakano et al, 1989 ; Wang and Bunting, 2008 ). Remarkably, despite the fact that the most highly purified HSCs exhibit a log-fold variation in expression of this receptor that is known to be critical for HSC function, relatively little effort has been devoted to investigating whether HSCs with varying c-Kit levels may represent functionally distinct HSC subtypes.…”

The Coat Colors of Mice

“…Indeed, the fact that beige mice possess giant granules in a variety of cells has been employed as a cell marker. Thus, it has been used as a neutrophil marker to study the kinetics of bone marrow replacement in anemic W/Wv [see Chapter 10, section I(G)] mice (E. Murphy et al, 1973;Maloney et al, 1978;Patt and Maloney, 1978). It also has been used to investigate the origin of mast cells (Kitamura et al, 1977; see Chapter 10, note 27).…”

Precise tissue bioengineering and niches of mesenchymal stem cells: Their size and hierarchy matter

“…However, according to the dimensions, such microterritories cannot be classified as niches for single stem cells. It is possible that large pores are tissue domains for MSCs (Khlusov et al, 2018) by analogy with "regulatory volume" (domains) for HSCs (Maloney et al, 1978) due to the ingrowth of bone, bone marrow, and blood vessels.…”