Photodynamic therapy with a new photosensitizing agent.
OBJECTIVE
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.


BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Machado
Aline Helena Araujo
AH
Cell and Tissue Biology Laboratory, Institute for Research and Development (IP&D), Universidade do Vale do Paraíba (UNIVAP), São José dos Campos, São Paulo, Brazil.
Braga
Fernanda Maria Prado
FM
Soares
Cristina Pacheco
CP
Pelisson
Marcelo Miguel Martins
MM
Beltrame
Milton
M
Da Silva
Newton Soares
NS
D002467:Cell Nucleus / Q000187:drug effects / Q000528:radiation effects; D004396:Coloring Agents; D006801:Humans; D007211:Indoles / Q000627:therapeutic use*; D054833:Isoindoles; D028022:Low-Level Light Therapy / Q000379:methods*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000627:therapeutic use*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D013778:Tetrazolium Salts; D013844:Thiazoles; D017967:Zinc Compounds
D004396:Coloring Agents; D007211:Indoles; D054833:Isoindoles; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D013778:Tetrazolium Salts; D013844:Thiazoles; D017967:Zinc Compounds; C524462:octal-bromide zinc phthalocyanine; C052159:Zn(II)-phthalocyanine; C022616:thiazolyl blue