Migration of IM CD34⁺ cells through Matrigel and the effects of MMP inhibitors. (A) The migration of normal (n = 5), G-CSF mobilized healthy volunteer (n = 3), and IM PB CD34⁺ (n = 8) cells through a preformed basement membrane (Matrigel) and (B) the effects of incubation of 3 inhibitors of MMP activity on CD34⁺ cell migration. Polycarbonate filters (6.5 mm) of 8-μm pore size were precoated with 20 μg Matrigel. The lower compartments of the modified Boyden chambers were filled with IMDM supplemented with 0.1% BSA in the presence of 100 ng/mL SDF-1, and the Matrigel-coated filters were placed between the upper and lower compartments. Freshly isolated PB CD34⁺ cells were suspended in 0.1 mL IMDM/0.1% BSA at a concentration of 2.0 × 10⁶ cells/mL, placed in the upper compartments, and incubated for 4 hours at 37°C in 5% CO₂. Cells that had migrated through the Matrigel-coated filters were recovered from the lower compartments and counted by using a hemocytometer. The percentage of cell migration was calculated from the ratio of the number of cells recovered from the lower compartment to the total number of cells loaded in the upper compartment. Each experiment was performed in triplicate using PB CD34⁺ cells from between 3 and 5 patients with IM. For these experiments, cells were preincubated overnight with 10 nmol/L o-phenanthroline, 10 nmol/L MMP-9/MMP-13 Inhibitor I, or 100 ng/mL interferon-α (IFN-α) before being loaded into the upper compartments of the Boyden chambers. Values are shown as the mean ± SD.