Adhesion and migration are differentially regulated in hematopoietic progenitor cells by cytokines and extracellular matrix.

The conditions that control the migratory status of hematopoietic progenitor cells on extracellular matrix (ECM) and that decide whether a cell migrates or adheres are incompletely understood. We analyzed the migratory behavior of murine hematopoietic progenitor cells factor-dependent-cell-paterson (FDCP)-mix and purified lin-Sca1+ bone marrow cells on ECM. We found that migration on fibronectin (Fn) or laminin (Lam) becomes dependent on beta1-integrins if a surface restraint force is introduced by tilting the ECM-coated culture vessels. Under these conditions, migration specifically occured on Fn and Lam, and was not detected on collagen IV-, hyaluronate-, or bovine serum albumin- coated surfaces. Migration depended on the continuous presence of hematopoietic cytokines interleukin-3 (IL-3), granulocyte colony-stimulating factor (G-CSF), macrophage-CSF (M-CSF), granulocyte-macrophage-CSF (GM-CSF), or stem cell factor (SCF), whereas other cytokines, such as IL-8, macrophage inflammatory protein-1alpha, macrophage-chemotactic and activating factor, and erythropoietin resulted in very little or no migratory response. IL-3 induced migration was synergistically enhanced by other CSFs, but was completely inhibited by addition of transforming growth factor-beta1. In contrast to firm local adhesion of previously cytokine depleted progenitors that was rapidly inducible within 1 hour after exposure to cytokines, preincubation on Fn matrix for 4 to 6 hours was required before cytokines could induce migration. A sudden increase of cytokine concentration reversibly inhibited migration and induced a fully adhesive state; this effect could be prolonged by consecutive stimulation with heterologous cytokines. Whereas cytokines activated resting progenitor cells to migrate on ECM, cell migration speed was regulated by Fn concentration. These results indicate that beta1-integrin-mediated progenitor cell adhesion and migration are differentially regulated by external stimuli and suggest that this regulation corresponds to different activation states of beta1-integrins in hematopoietic progenitor cells.