Retinovitreal neovascularization in the Royal College of Surgeons rat

Retinovitreal blood vessels, which we have previously reported in the dystrophic retinas of approximately 20% of older (greater than 15 months of age) spontaneously hypertensive (SHR) rats, also occur in about 20% of retinal dystrophic Royal College of Surgeons (RCS) rats greater than 1 year of age. We have demonstrated previously that these vessels, in the SHR rat, have the anatomic characteristics of retinovitreal neovascularization as it has been described in vasoproliferative retinopathies in humans (1). We now provide strong evidence that the endothelial cells and pericytes of the retinovitreal vessels that occur in RCS rats are proliferating, since they demonstrate by autoradiography significantly increased nuclear labeling with [3H]-thymidine over intra-retinal or choroidal vessels, or the abnormal vessels that grow within the retinal pigment epithelium in these dystrophic retinas. One important difference between the neovascularization that occurs in these rats and that which is observed in various human retinal vascular diseases is the frequent association of the new vessels in dystrophic rat retinas with surrounding cords of proliferating retinal pigment epithelium. The retinovitreal vessels in these strains of dystrophic rats represent a new animal model that may be useful for studying the fundamental processes underlying new blood vessel growth in the retina.