Analysis of the photodynamic therapy effects by using chloroaluminum phthalocyanine incorporated into liposomes and fractionation energy in colon tumors of rats

Abstract

Photodynamic therapy (PDT) has been widely studied in the last decades and it is becoming a promising tool in the treatment of tumors of many kinds. PDT is based on photoactivation of a sensitized drug that is restrained in the tumor cells, producing highly reactive species that can destroy tumoral cells with minimum collateral effect. This study aimed to evaluate the effect of the PDT in induced neoplasias of the colon by 1,2-dimetilhidrazine in rats, using as photosensitizing drug the chloroaluminum phthalocyanine incorporated to the liposomes and to compare the methods of irradiation using continuous or fractionated energy in PDT. Ten Wistar rats were distributed randomly in 3 groups (G1, G2 and C), anaesthetized and submitted to PDT with of fractionated (G1) or continuum (G2) irradiation energy using as a source of excitement an InGaAl laser. After 3 hours of the laser irradiation, 2 animals of the G1 group, 2 animals of the G2 group and 1 animal of C group were sacrificed and samples of tumoral tissue were, collected for histological analysis; the same procedure was carried through 24 hours after irradiation. There were no significant differences between the extensions of the induced areas of necrosis for PDT in the groups under fractionated or continuous irradiation for the parameters used in this study. New studies must be carried through, using different parameters and intervals of laser irradiation, aiming to maximize the effect of the PDT for the treatment of colon tumors.