In vitro photosensitisation of a murine mammary adenocarcinoma cell line with Verteporfin.

Benzoporphyrin derivative monoacid ring A (BPD-MA) is a second generation hydrophobic photosensitiser for PDT that has been approved for ocular disease treatment. In the present paper we report the results of in vitro studies on the photosensitising activity of Verteporfin (liposomally formulated BPD-MA) using an adenocarcinoma derived cell line. Our findings show a quick and efficient uptake of Verteporfin by LM3 cells, reaching maxima concentrations after 5 hr exposure to 18 microg Verteporfin/ml. Independently on the concentration, plateau levels are attained 5 hr after exposure to Verteporfin. Exposure of the cells to the photosensitiser appears to be safe in the darkness within a broad range of concentrations. The hydroxyl radical scavenger mannitol afforded the highest protection against PDT, while L-tryptophan, a well known and efficient singlet oxygen quencher was not an effective protector at all, showing scavenging activity only when it was supplemented at concentration as high as 10 mM and when 50% of the cells were affected, showing that in addition to singlet oxygen, which is considered the primary cytotoxic agent in PDT, other interconvertible reactive oxygen specie (ROS), in particular HO are also generated. Verteporfin-PDT also induced morphological features typical of apoptotic cells. Results of the present work show that the LM3 adenocarcinoma cell can be effectively sensitised with Verteporfin-PDT.