Localization of fluorescent Photofrin II and aluminum phthalocyanine tetrasulfonate in transplanted human malignant tumor LOX and normal tissues of nude mice using highly light-sensitive video intensification microscopy.

A comparative kinetic observation of the in vivo biolocalization of Photofrin II (P-II) and aluminum phthalocyanine tetrasulfonate (AIPCS4) in a transplanted human malignant tumor LOX and in normal tissues of nude mice has been made by means of highly light-sensitive video intensification microscopy at various intervals after i.p. administration. In the human tumor LOX, transplanted to athymic nude mice, fluorescence of P-II was observed on the membrane and in the cytoplasm of tumor cells, and in the stroma 4-48 hr post-injection. From 72 hr post-injection almost all fluorescing P-II had disappeared from the membrane of the tumor cells while strong fluorescence was still found in the stroma. AIPCS4 fluorescence was seen mainly in tumorous stroma with none detected in the tumor cells. Almost no fluorescence was found in the tumorous stroma 24 hr after injection. In most normal tissues observed, P-II was eliminated at a much slower rate than AIPCS4, but the in vivo biolocalization of the 2 drugs was similar. They were observed primarily where collagenous proteins are normally found, i.e. basal lamina, collagenous connective tissue, and in keratinized epithelium, renal epithelium, mononuclear phagocyte system and on the membrane of muscular cells. In addition, AIPCS4 had a strong affinity for the bronchiogenic epithelium. In the skin, P-II was distributed in keratinized epithelium, hair, hair follicles and their accessory, collagenous connective tissue of dermis, whereas AIPCS4 was present only in hair and collagenous connective tissue of dermis. No fluorescence of P-II or of AIPCS4 was found in the skin epidermis, nor in the transitional epithelium of the bladder mucosa.