[Photodynamic activity of phthalocyanines in cultivated lens epithelial cells of the pig].

One of the most frequent complications of extracapsular cataract surgery is posterior capsule opacification (PCO), which is caused by proliferation and migration of retained lens epithelial cells on the posterior capsule surface. This complication leads to a reduction in visual acuity. Depending on the age of the patients, the incidence varies between 15 and 50%. Selective elimination of these cells would therefore prevent PCO. Phthalocyanines (Pc) are efficient photosensitizers of various carcinoma cell lines. Their attractive property is the strong absorption of visible light above 600 nm. Upon absorption of a photon, the sensitizer in its excited state can be either directly cytotoxic or produce reactive oxygen species type I (free radicals) or type II (singlet oxygen), which become the mediator of cellular injury by affecting membranes and subcellular organelles. Preconfluent cultures of porcine lens epithelial cells were incubated with aluminum phthalocyanine (AlPc) or aluminum phthalocyanine transulfonate (AlPcS4) in concentrations ranging from 0-20 microM for 1 h at 37 degrees C. Thereafter, cultures were exposed to red light for 5 min. A 300 W quartz halogen light bulb equipped with a cut-off filter that allowed transmission of the whole spectrum above 600 nm was used for activation of the sensitizers. To evaluate the effect of fluoride, 5 mM NaF was added to the dye-loaded cells immediately before light exposure. This treatment had no toxic effect. Subsequently, the treated cells were incubated in culture medium for 24 h. After trypsinization, the cell number was determined by a cell counter. Prior to light exposure neither AlPc nor AlPcS4 was toxic in corresponding controls.(ABSTRACT TRUNCATED AT 250 WORDS)