Repair of corneal endothelial
wounds involves two forms of cell translocation: (1) "migration," in which individual cells at the
wound edge break contacts with neighboring cells and move as individuals into the
wound defect, and (2) "spreading," in which cells within the confluent monolayer adjacent to the
wound move as a group into the
wound area. The authors combined morphometric analysis of Giemsa-stained cultures, phase-contrast video microscopy, and
Rh-phalloidin staining of actin filaments to study the effects of
epidermal growth factor (
EGF) and
indomethacin on the migratory and spreading responses to wounding using an in vitro
wound-closure model which mimics the amitotic state and general behavior of human corneal endothelium. They found that
EGF stimulated the migration of individual cells from the
wound edge, induced cellular elongation, and promoted a diffuse distribution of actin filaments.
Indomethacin promoted spreading of the confluent monolayer into the
wound defect, induced enlargement and flattening of cells, and promoted the formation of long, thick actin stress fibers. These results provide evidence that the migration and spreading responses of corneal endothelial cells to wounding can be pharmacologically separated. The findings suggest that migration of individual cells during
wound repair may result from an endogenous form of
EGF-like stimulation and that the elongated shape associated with this form of translocation results, at least in part, from an
EGF-like alteration in actin-filament organization. Spreading of the confluent monolayer to cover the
wound defect may result from a decrease in cyclic
adenosine monophosphate induced by a transient reduction in
prostaglandin E2 synthesis. This form of translocation may result, in part, from enlargement and flattening of corneal endothelial cells secondary to an enhancement of actin stress-fiber formation.