In vitro and in vivo photosensitizing applications of Photofrin in malignant melanoma cells.

BACKGROUND The object of the present study was to evaluate the feasibility of photodynamic therapy (PDT) for malignant melanomas through in vivo and in vitro processes. METHODS Photofrin (porfimer sodium) was evaluated through in vitro processes with human malignant melanoma cells (MMCs). The in vitro absorption and photosensitizing activity of Photofrin was examined in an MMC culture system. The in vivo biological activity of Photofrin applied to subcutaneous implanted melanoma (SIM) in nude mice and exposed to different total light dosages at 630 nm was studied by determining the destruction of the tumors. Subcelluar localization and binding were observed under a fluorescent confocal microscope. RESULTS MMCs incubated with Photofrin at a concentration of about 3.5 microg/ml and exposed to laser light at 630 nm with a power density of 100 mW/cm2, showed 50% cell killing. An electron microscopic study demonstrated significant destruction of the target after PDT. CONCLUSION Detection of the photosensitizer Photofrin was localized and its distribution fully observed. PDT-Photofrin has the capability to destroy MMCs through in vitro and in vivo SIM treatment.