EVALUATION OF 4 NEW CARBOCYANINE DYES FOR PHOTODYNAMIC THERAPY WITH LASERS

The search for improved photosensitizers for laser phototherapy of mal ignancies has led to the examination of a new group of carbocyanine dy es as effective fluorochromes. In this study, four carbocyanine dyes w ith different absorption maxima of 483 nm [DiOC6(3)], 545.5 nm [DiIC5( 3)], 556.6 nm [DiSC5(3)], and 651.0 nm [DiSC3(5)] were tested in vitro . The kinetics of uptake and toxicity of these four dyes were assessed for P3 human squamous cell carcinoma, HT29 colon carcinoma, M26 melan oma, and TE671 fibrosarcoma cell lines at 15, 30, 45, 60, and 180 minu tes after exposure with each dye. After sensitization with DiOC6(3), t he P3 and M26 cell lines were also tested for phototherapy by treatmen t with 488-nm light from an argon laser. The results showed that these four carbocyanine dyes had rapid and significant uptake by the carcin oma cell lines with no toxicity at concentrations < 0.1 mu g/mL. Nonto xic DiOC6(3) levels in sensitized tumor cells after laser phototherapy resulted in similar to 85% inhibition of P3 and similar to 95% inhibi tion of M26 cell lines by MTT assays. The results suggest that these c arbocyanine dyes can be used for tumor photosensitization and waveleng th-matched laser photodynamic therapy. Further in vivo studies will be necessary to define the clinical potential of carbocyanine dyes as tu mor-targeting agents for phototherapy of cancer.