Endothelial cells release a chemoattractant for retinal pigment epithelial cells in vitro
P. A. Campochiaro and B. M. Glaser
Though the pathogenesis of choroidal neovascular membranes is uncertain,
there is evidence to support a primary dysfunction in the retinal pigment
epithelium (RPE). This suggests the possibility that a healthy RPE may
provide a physical and/or chemical barrier to subretinal endothelial cell
invasion. It has recently been shown that RPE cells in culture produce an
inhibitor of neovascularization. Histopathologic evidence suggests that RPE
cells tend to surround new blood vessels and contain them. We therefore
investigated the possibility that RPE cells are guided toward endothelial
cells by chemoattractants. Using a modified Boyden chamber technique, we
showed that endothelial cells in culture produce a chemoattractant for RPE
cells. The active component is trypsin sensitive, stable at extremes of pH
(3 through 10), and nondialyzable (12,000- to 14,000-dalton cutoff). It is
partially heat stable but becomes completely heat stable in the presence of
1% sodium dodecyl sulfate. These are all characteristics of the previously
described endothelial cell-derived growth factor, suggesting that this
mitogen might be the chemoattractant. The ability of RPE cells to be
attracted to sites of new blood vessel formation may enhance their
potential function as inhibitors of neovascularization.