Immunoneutralizing antibody for MMP-9 (500 ng/condition) and rhTIMP-1 (300 ng/condition) blocked SDF-1–induced migration of MKs through Matrigel-coated transwells.

This inhibitory effect was not seen with an anti–MMP-2 mAb (500 ng/condition). The anti–MMP-9 mAb and rhTIMP-1 did not block the migration of MK through bare transwells, indicating that MMP-9 is required to break down components of the basement membrane for successful MK migration. Synthetic MMP inhibitors also prevent MK migration. EDTA (1.5 mmol/L) was used as a negative migration control. Results are shown as the percentage of SDF-1–induced migration (SDF-1 alone was considered 100%) and are representative of 4 independent experiments (n = 4; **P < .005 compared to SDF-1 alone).