Figure 2.

HBEC containing MMP-9 migrate more rapidly to repair a wound. Primary cultures of confluent HBEC were locally injured with sodium hydroxide. (A) Labeling of cell nuclei with a DNA fluorescent dye (Hoechst 33258) at the edge of the wound on day 1 of the wound-repair process. Positions of cell nuclei are identified by white circles. (B) Trajectories of cell nuclei recorded every 10 min and over a 30-min period. Four cells strongly positive for MMP-9 are indicated (arrowheads) and the four successive positions of the nucleus of one of them is shown. (C) Immunofluorescent labeling of MMP-9 after fixation of the culture at the end of the 30-min recording period. Arrowheads indicate the same intensely labeled cells as in B. MMP-9 also accumulated at the forefront of the cellular protrusions (arrows). (D) Mean cell migration speeds ± SD for six different experiments conducted on primary cultures of HBEC derived from six different bronchial samples. Experiment 6 reports the mean migration speeds for the cells located above the line in A–C. For all six experiments, the black bars in D report the mean migration speeds ± SD of cells strongly positive for MMP-9, whereas white bars correspond to the values of the other cells. The significance of the differences between the two groups was determined using t test. Bar, 100 μm.