Cellular migration and replication in endothelial regeneration: a study using irradiated endothelial cultures.

Cellular migration and replication were studied during repair of mechanical injuries produced in cultured monolayers of vascular endothelium. Human endothelial cells were obtained by collagenase perfusion of term umbilical cord veins and were grown on glass cover slips in replicate primary cultures. Following standardized mechanical denudation ("wounding") of narrow linear areas in postconfluent cultures, cellular migration and DNA synthesis were assessed at intervals after terminal 3H-thymidine incubation. Migration of cells from the edges of the wound into the denuded area was consistently underway by 12 hours, and by 24 hours there was considerable repopulation of the wound. A significant increase in 3H-thymidine labeling was not observed in the wound area until 36 hours. When cultures were exposed to 1500 rads of x-rays 1 hour prior to wounding, labeling was nearly abolished at 48 and 72 hours despite continuous incubation with 3H-thymidine. However, migration occurred as usual and resulted in repopulation similar to that in nonirradiated replicate cultures. These studies indicate that small endothelial defects can be significantly repaired by migration of adjacent viable cells. Thus, factors influencing both migration and replication should be considered in studies dealing with endothelial regeneration in vivo.