Capillary endothelial cell migration: loss of stress fibres in response to retina-derived growth factor

While the migration of capillary endothelial cells is believed central to the process of new blood vessel development in vivo, the biochemical basis for endothelial motility is unknown. Herein, we demonstrate that retina-derived growth factor (RDGF), a mitogen for endothelial cells (EC), stimulates the migration of microvascular endothelium in vitro. The addition of RDGF directly to the culture medium causes an increase in the random movement (chemokinesis) of the EC as measured by the phagokinetic assay. Release of the factor as a gradient results in a stimulation of the directed migration (chemotaxis) of the microvascular EC. This increased EC migration is associated with a shift in morphology of the stimulated cells from a rounded to a more polarized shape. Concomitant with the RDGF-stimulated migration is a dramatic decrease in stress fibre staining visualized by immunofluorescence microscopy using affinity-purified antibodies to actin and myosin.