The effect of photodynamic therapy with bacteriochlorin a on lens epithelial cells in a capsular bag model

Photodynamic therapy (PDT) with bacteriochlorin a (BCA) has proved to be a successful treatment for many cancers and to be cytocidal for different cel l lines in culture. The present study aimed to investigate in vitro the pot ential of this treatment for killing lens epithelial cells (LECs) left in t he human capsular bag after extracapsular cataract extraction (ECCE). Capsu lar bags were prepared from donor eyes using an ECCE procedure and incubate d in various concentrations of bacteriochlorin a (16-50 mug ml(-1)) during various incubation periods (2-10 min). Subsequently, the capsules were illu minated during various exposure times (2-15 min) with a diode laser (wavele ngth 760 nm). After treatment, the capsular bags were cultured for 7 days i n Eagle's minimal essential medium supplemented with 2% fetal calf serum. T he specimens were fixed in glutaraldehyde/paraformaldehyde and examined wit h routine light microscopy, Hoechst staining for DNA and transmission elect ron microscopy. Proliferation of LECs on the posterior capsule was assessed in flat mounts. Capsular bags receiving BCA without illumination and capsu lar bags receiving illumination only served as controls. BCA alone or light alone have no effect on structure and proliferative acti vity of LECs. At a threshold protocol of incubation in BCA at 10 mug ml(-1) for 10 min and subsequent illumination for 15 min, proliferative activity of cells is largely arrested and nearly all LECs on the capsule exhibit sev ere signs of apoptosis. Photodynamic therapy with bacteriochlorin a induces cell death and suppress ion of proliferation inlens epithelial cells and could be a promising means of prevention of posterior capsule opacification. (C) 2000 Academic Press.