IN-VIVO DAMAGE TO CHORIOALLANTOIC MEMBRANE BLOOD-VESSELS BY PORPHYCENE-INDUCED PHOTODYNAMIC THERAPY

Photodynamic therapy (PDT) was performed in the chick embryo chorioall antoic membrane (CAM) for the purpose of quantitative evaluation of se veral porphycenes as potential photosensitizers. Porphycenes are struc tural isomers of porphine possessing lower symmetry of the macrocycle and are characterized by 10-fold higher absorption at the therapeutic wavelengths for PDT (lambda > 630 nm). PDT-induced damage to CAM blood vessels included vasoconstriction and blanching, as was monitored dur ing irradiation and videotaped. Image analysis techniques enabled us t o follow PDT-induced constriction of vessel diameter (to 50%), reducti on of blood perfusion (to 40% lower optical density) and shrinkage of implanted tumours (to 10% of their original area). The observed PDT ef ficacy of functionalized porphycenes is positively correlated with the number of polar substituents.