Extracellular matrix production by the adherent cells of long-term murine bone marrow cultures. Blood

We have studied the deposition of extracellular matrix proteins in the adherent stroma of long-term murine bone marrow cultures. Stable hematopoiesis was maintained for greater than 12 wk. At selected intervals, culture dishes were sacrificed by removing all nonadherent cells and air drying the dishes. The adherent stromal layer was analyzed for the presence of intracellular and extracellular collagen, fibronectin, and laminin using double immunofluorescent staining with specific antisera against these matrix compo-nents. In cultures examined during the first 2 wk. large numbers of stromal cells contained collagen. fibronectin. and laminin. Over the next 2 wk, an extensive extracellular T H E H EMATOPOIETIC inductive microenviron-ment is the organ stroma that is thought to be necessary for the specific lodgement, proliferation, an