パルス波レーザー励起 PDT における殺細胞機構の検討

Abstract

The purpose of this study is to evaluate morphological changes and biochemical effect of photosensitized HeLa cells after the pulsed and continuous wave (CW) laser irradiation. The fluence of the CW and the pulsed laser held constant at 40 J/cm2. The wavelength of the lasers was 514 nm. After the irradiation, the degree of cytopathy were detected by assessing viability of the cells using the 3-(4, 5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and LDH-release in the medium. Although the cells irradiated the both laser lights showed 90% in survival within 15h, small number of cytotoxicity reaction were observed in the cells exposed to the pulsed laser light after 27h incubation and the rapid release of LDH from the cell, however, was promoted by additional 5 h incubation. The cells irradiated by the CW laser showed the whole membrane degradation and swollen nuclei. In contrast, for the cells irradiated by the pulsed laser showed condensation of chromatin material around the periphery of the nucleus. These results corresponded with observation of pressure-wave exposed cells. On the basis of these results, using a pulsed laser as a light source for PDT was found to allow the pressure wave in the cell, which serves the acoustic effect on disrupting the cell in addition to the well-known photochemical effect.