Plastic adherent stromal cells from the bone marrow of commonly used strains of inbred mice: Variations in yield, growth, and differentiation

Bone marrow stroma contains a unique cell population, referred to as marrow stromal cells (MSCs), capable of differentiating along multiple mesenchyma l cell lineages. A standard liquid culture system has been developed to iso late MSCs from whole marrow by their adherence to plastic wherein the cells grow as clonal populations derived from a single precursor termed the colo ny-forming-unit fibroblast (CFU-F). Using this liquid culture system, we de monstrate that the relative abundance of MSCs in the bone marrow of five co mmonly used inbred strains of mice Varies as much as 10-fold, and that the cells also exhibit markedly disparate levels of alkaline phosphatase expres sion, an early marker of osteoblast differentiation. For each strain examin ed, the method of isolating MSCs by plastic adherence yields a heterogeneou s cell population. These plastic adherent cells also exhibit widely Varying growth kinetics between the different strains. Importantly, of three inbre d strains commonly used to prepare transgenic mice that we examined, only c ells derived from FVB/N marrow readily expand in culture. Further analysis of cultures derived from FVB/N marrow showed that most plastic adherent cel ls express CD11b and CD45, epitopes of lymphohematopoietic cells. The later consists of both pre-B-cell progenitors, granulocytic and monocytic precur sors, and macrophages. However, a subpopulation of the MSCs appear to repre sent bona fide mesenchymal progenitors, as cells can be induced to differen tiate into osteoblasts and adipocytes after exposure to dexamethasone and i nto myobtasts after exposure to amphotericin B. Our results point to signif icant strain differences in the properties of MSCs and indicate that standa rd methods cannot be applied to murine bone marrow to isolate relatively pu re populations of MSCs. J. Cell. Biochem. 72:570-585, 1999. (C) 1999 Wiley- Liss, Inc.