Phagocytes that invade the vitreous after injury stimulate DNA synthesis in neural retina in vitro

Phagocytes that invade the rabbit vitreous after intravitreal injection were co-cultured with cells from the rabbit neural retina. Counts of labeled nuclei after exposure to ³H-thymidine indicate an increase in DNA synthesis by retinal cells exposed to the phagocytes. In contrast, using the same procedures, vitreal phagocytes do not promote DNA synthesis by rabbit dermal fibroblasts in vitro. The apparent proliferation stimulus due to vitreal phagocytes may be functionally related to other macrophage-dependent proliferation-stimulating activities. Since blood components promote vitreal phagocyte invasion, ocular hemorrhage may aggravate some extraretinopathies in part by a phagocyte-mediated stimulation of retinal cell proliferation.