title: Changes of bone marrow stromal cells (MSC) in mice after drug induced eradication of hematopoietic cells: in vitro effects on normal bone marrow.
abstract: This study deals with murine marrow stromal cells (MSC) during hematopoietic regeneration. Regenerative marrow was induced in infant mice by two consecutive i. p. injections of hydroxyurea (HU) (2 X 1,000 mg/kg) which kill most cells in DNA synthesis. Two days later the marrow becomes enriched in pluripotent stem cells (CFU-S) and committed progenitors. It was found that fibroblastoid colony-forming-units (CFU-F) become concentrated approximately four fold above controls and give rise to significantly larger fibroblastoid colonies than CFU-F in control marrow. In split-phase semisolid agar cultures, i. e. adherent cells of HU-treated marrow (in under layers) and normal bone marrow cells (in upper layers), inhibition of G/M colonies in the upper layer in observed. In control split-phase cultures of both under layers and upper layers of normal bone marrow, CFU-C inhibition is by far less pronounced. In liquid cultures, pre-established adherent layers of HU-treated marrow have a stimulatory effect on normal marrow CFU-C. It is concluded that during increased demand for pluripotent stem cells and progenitors, such as after HU administration, marrow stromal cells and possibly other adherent cells produce inhibitory factor(s) of CFU-C differentiation. The inhibitory activity possibly is an effective mechanism for stem cell pool preservation. The differing effect of adherent cells of HU-treated marrow on CFU-C in liquid and in semi-solid medium suggests production of two different factors with opposing influences on CFU-C, depending upon the culture conditions.
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000187:drug effects; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D005260:Female; D005347:Fibroblasts / Q000166:cytology; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D006918:Hydroxyurea / Q000494:pharmacology*; D008297:Male; D051379:Mice
chemical_list: D006918:Hydroxyurea