Fig. 1

Multiple steps in mesenchymal stem cells (MSCs) homing. The homing processes of MSCs are dependent on a series of molecules of motile potency, including selectins, integrins, chemokine receptors, and proteases. Selectins, which are expressed on endothelial cells (ECs), capture MSCs by interacting with their ligands and then mediating the rolling of MSCs. MSCs can thus be activated by exposure to chemokines, consequently leading to integrin-dependent firm adhesion to the endothelium. At the appropriate location, MSCs cross the endothelial barrier by secreting different proteases before continuing chemokine-mediated migration