The tissue inhibitor of metalloproteinases-1 improves migration and adhesion of hematopoietic stem and progenitor cells.

Homing and engraftment of hematopoietic stem and progenitor cells (HSPCs) during bone marrow transplantation are critically dependent on integrins such as β1-integrin. In the present study, we show that β1-integrin and the tetraspanin CD63 form a cell surface receptor complex for the soluble serum protein tissue inhibitor of metalloproteinases-1 (TIMP-1) on human CD34⁺ HSPCs. Through binding to this receptor complex, TIMP-1 activates β1-integrin, increases adhesion and migration of human CD34⁺ cells, and protects these cells from induced apoptosis. TIMP-1 stimulation in murine bone marrow mononuclear cells also promotes migration and adhesion; this is associated with augmented homing of murine mononuclear cells and of murine LSK⁺ cells during bone marrow transplantation. These results not only indicate that TIMP-1 is conducive to HSPC homing; they also identify CD63 and β1-integrin as a TIMP-1 receptor complex on HSPCs.