Anais Brasileiros de Dermatologia
On-line version ISSN 1806-4841
TOMAZINI, Marília Vannuchi; SOUZA, Cacilda da Silva; GARCIA, Sérgio Britto and TEDESCO, Antônio Cláudio. Topical photodynamic therapy with zinc phthalocyanine: evaluation of fluorescence intensity, skin absorption, skin histological and immunohistochemical changes in animal model. An. Bras. Dermatol. [online]. 2007, vol.82, n.6, pp. 535-541. ISSN 1806-4841. http://dx.doi.org/10.1590/S0365-05962007000600006.
BACKGROUND - Phthalocyanines are promising photosensitizers used in photodynamic therapy (PDT). OBJECTIVES - To evaluate the following parameters: intervals, vehicles and enhancer using topical zinc-phthalocyanine (Zn-PC) formulation. To examine macro and micromorphological changes and Fas expression induced by topical Zn-PC-PDT on murine skin. MATERIAL AND METHODS - Using fluorescence spectrometry, different intervals of topical occlusion employing Zn-PC gel or emulsion, with or without monolein 5% were studied. After an 8-hour occlusion of different formulations, the mice were exposed to 670 nm laser, at a 50 J.cm-2 dose. RESULTS - Fluorescence was slightly higher after 8 hours, and also with emulsion formulation at one-, two- and four-hour occlusion periods. The intensity of edema and erosion were correlated to epidermal necrosis and to Fas immunoexpression in skin histological specimens. CONCLUSIONS - The results show the effects of photodynamic action promoted by the interaction between Zn-PC formulation and a 670-nm light source. Macro and micromorphological alterations were correlated and more substantial with monolein and Zn-PC emulsion, suggesting more marked effects with this formulation. The Fas immunoexpression and histological changes suggested that apoptosis plays a role in the mechanism of cell death caused by PDT based in Zn-PC.
Keywords : Apoptosis; Immunohistochemistry; Lasers; Models, animal; Photochemotherapy; Skin absorption; Spectrometry, fluorescence.