Production of matrix metalloproteinase-9 by cord blood CD34+ cells and its role in migration

The transmigration of hematopoietic progenitor cells is a crucial step in the homing of transplanted stem cells into bone marrow (BM) microenvironment; however, the molecular basis for this is not fully understood. Matrix metalloproteinases (MMPs), which are implicated in the migration of leukocytes, are important in degrading components of extracellular matrix molecules. In this study, using zymographic analysis and enzyme-linked immunosorbent assay (ELISA), we investigated the production of MMP-9 in CD34(+) cells from cord blood (CB) and BM, compared their spontaneous migration across a reconstituted basement membrane-coated filter in transwell, and studied the role of MMP-9 in the transmigration. Zymography and ELISA showed that MMP-9 is produced by freshly isolated CD34(+) stem/progenitor cells obtained from CB. CB CD34(+) cells showed significantly higher migrational capacity than BM CD34(+) cells ( p=0.008). Furthermore, the migrational ability of CB CD34(+) cells over the extracellular matrix (ECM) was significantly inhibited by the inhibitor of MMP, o-phenanthroline and anti-MMP-9 monoclonal antibody (73.3+/-11.8% and 37.5+/-10.4% inhibition, respectively). Our results strengthen the potential role of MMP-9 in the higher migrational capacity of CB CD34(+) cells, which may be beneficial to homing of these cells to the BM environment.