Apoptotic cell death in proliferative vitreoretinopathy.

Apoptosis is a selective event of physiological cell deletion that plays a crucial role in the development of numerous tissues, including the retina. In this paper we report the occurrence of apoptosis in epiretinal membranes derived from patients with proliferative vitreoretinopathy (PVR). Detection of apoptosis was performed by an in situ DNA-end labeling technique using terminal transferase-mediated deoxyuridine triphosphate (dUTP) incorporation. Apoptotic nuclei exhibiting chromatin condensation and fragmentation were also identified by acridine orange fluorescence. Apoptosis was detected in varying numbers of cells. The typical appearance of apoptotic nuclei, including nuclear chromatin condensation, was detected scattered inhomogeneously throughout the epiretinal membranes, in clusters, or even in single cells. Induction of apoptosis in human retinal pigment epithelial (RPE) cells by daunomycin could be demonstrated by in situ DNA end labeling and by quantitative determination of cytoplasmatic histone-associated DNA fragments using a photometric enzyme immunoassay. Since apoptosis has been shown to be an important factor in the growth control of various untransformed and neoplastic cell populations, the pharmacological induction of apoptosis in epiretinal membranes could result in a new approach toward inhibiting cellular proliferation in PVR.