Yu.E. Efremova, G.N. Soboleva, E.R. Andreeva, N.V. Radukhina, S.G. Kuzmin, Yu.A. Karpov, E.M. Tararak

Photodynamic therapy is a method that is widely applied in clinical practice since the middle of last century, mainly for the treatment of oncology diseases. This approach is based on the fact that certain cells have the capacity to accumulate photosensitizes (PS). When illuminated with appropriate wave length light these PS are produced reactive oxygen resulting in cell death. Several studies have shown that photosensitizers accumulated within atherosclerotic lesions. The results of these studies suggest that photodynamic may be promising tool in the diagnosis and treatment of atherosclerosis. The aim of this study was to reveal Photosens (sulfonated aluminium phthalocyanine) and Alasens (5-aminolevulinic acid) uptake in atherosclerotic rabbit aortas and immunohistochemical identification of cell types that had accumulated photosensitizers. In our work 25 rabbits were studied. 11 rabbits with experimental atherosclerosis were injected Photosens, 8 - Alasens, 6 animals were taken as a controls. After the killing of animals histological, immunohistochemical and fluorescence analysis of the aorta was performed. Fluorescence analysis showed photosensitizers accumulation in all arteriosclerotic lesions. In contrast, the fluorescence of the photosensitizers was not detected in normal vascular wall. The preferential uptake of photosensitizers was detected in the atherosclerotic intima. The level of PS accumulation was depended on the degree of lesions. Highly cellular plaque segments (most often plaque-s shoulders and superficial layer of plaque) showed markedly increased fluorescence intensity. Fluorescence intensity of photosensitizers was positively correlated with macrophage content in advanced atherosclerotic lesions. In none of the control animals the fluorescence of photosensitizers was identified. In most cases are the causes of serious cardiovascular events the unstable atherosclerotic plaques. These lesions contain large amount of inflammatory cells, particularly macrophages. A pivotal goal of photodynamic therapy in promoting plaque stabilization is sustained macrophage removal. Our data on photosensitizers accumulation in atherosclerotic plaque areas with a large number of macrophages suggest that the photodynamic reaction is promising tool for the diagnosis and treatment of unstable plaque.