THE DISTRIBUTION OF CENTROSOMES IN MIGRATING ENDOTHELIAL-CELLS DURING WOUND-HEALING INSITU

We have examined the distribution of centrioles in rabbit thoracic aortic endothelial cells induced to migrate by wounding the endothelium in situ. Following denudation of the endothelium from a segment of the aorta with a balloon catheter, a wound edge was created from which endothelial cells began to migrate onto the denuded surface. In this in situ model of cell migration, the position of centrioles was determined in cells along the wound edge by immunofluorescence and antibodies which specifically label these cell organelles, and then they were classified in relation to the nucleus and the direction of cell migration as being oriented toward the wound, in the center, or away from wound. At time 0, as in normal unwounded adult rabbit aorta, no preferential orientation of centrioles was evident. Within 12 h after wounding, the centrioles in about 53% of endothelial cells near the wound edge were oriented toward the wound, while in less than 20% of the cells they were oriented away from wound. At 24 h, in cells up to 800 mum from the wound edge, centrioles in only about 10% of the endothelial cells were oriented away from wound, while in about 52% of cells they were found in the center and in 38% of the cells they remained oriented toward the wound. At 48 h, up to 2000 mum from the wound edge, the majority of endothelial cells had their centrioles in the center, possibly as a result of an increase in mitotic index as cells replicate to reestablish an intact endothelium. The results of this study demonstrate that, in endothelial cells starting to migrate on a natural substratum in situ in response to wounding, most centrioles reorient toward the wound edge. This observation is consistent with the hypothesis that the centrosome is involved in defining the direction of cell migration in endothelial cells.