Photodynamic therapy with a new photosensitizing agent

The aim of this study was to investigate the cytotoxicity of octal-bromide zinc phthalocyanine (ZnPcBr(8)) before and after irradiation with a low-power laser (AsGaAl) and analyze the effects of photodynamic therapy (PDT) on the nucleus of L929 cells. One of the most recent and promising application...

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Bibliographic Details
Published in:	Photomedicine and laser surgery Vol. 25; no. 3; p. 220
Main Authors:	Machado, Aline Helena Araujo, Braga, Fernanda Maria Prado, Soares, Cristina Pacheco, Pelisson, Marcelo Miguel Martins, Beltrame, Milton, Da Silva, Newton Soares
Format:	Journal Article
Language:	English
Published:	United States 01-06-2007
Subjects:	Cell Nucleus - drug effects Cell Nucleus - radiation effects Coloring Agents Humans Indoles - therapeutic use Low-Level Light Therapy - methods Organometallic Compounds - chemical synthesis Organometallic Compounds - therapeutic use Photochemotherapy - methods Photosensitizing Agents - therapeutic use Tetrazolium Salts Thiazoles
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Summary:	The aim of this study was to investigate the cytotoxicity of octal-bromide zinc phthalocyanine (ZnPcBr(8)) before and after irradiation with a low-power laser (AsGaAl) and analyze the effects of photodynamic therapy (PDT) on the nucleus of L929 cells. One of the most recent and promising applications of phthalocyanine in medicine is in the detection and cure of tumors. We studied the ZnPcBr(8) in agreement with the development of new photosensitizing agents for curing tumors. L929 cells were cultivated at standard conditions, incubated with ZnPcBr(8) for 1 h at different concentrations, irradiated with a semiconductor laser, and incubated in MEM medium for 1, 12, or 24 h. Cells were analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) technique and fluorescence microscopy. The results demonstrated that ZnPcBr(8) at 1 microM was the most effective concentration for PDT, with a decrease of 63% after 1 h, 99% after 12 h, and 100% after 24 h in relation to the control group. The fluorescence microscopy results showed that ZnPcBr(8) was localized in the perinuclear region when analyzed 1 h after incubation. Nucleus staining with DAPI made it possible to observe that nuclear fragmentation occurred 24 h after PDT, cytoplasm retraction at 1, 12, and 24 h after PDT, and vacuoles along the cytoplasm at 12 and 24 h after PDT. According to the results obtained in this study, L929 cell death caused by PDT with ZnPcBr(8) possesses characteristics of apoptosis mediated by the mitochondria, due to the decrease in cells viability, the subcellular localization, and the photodamage found.
ISSN:	1549-5418
DOI:	10.1089/pho.2006.2035