Comparison of phototoxicity mechanism between pulsed and continuous wave irradiation in photodynamic therapy.

A study has been conducted in which HeLa cells are incubated with hematoporphyrin derivative (HpD) for 1 h (1 microgram/ml of HpD in PBS) to compare the use of continuous wave (CW) and pulsed laser (10 Hz repetition rate and 7-9 ns pulse width) light for photodynamic therapy. Cytotoxic effects on the cells are evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2-5-diphenyl-2H-tetrazolium bromide (MTT) assay and the fluorescein diacetate (FDA)/propidium iodide (PI) stain method using a flow cytometer. The type of cell death is estimated by analysis of the DNA content and observation of the nuclear morphology. The cytotoxicity ratio of cells irradiated by pulsed laser light is estimated to be lower than that for CW laser light. The viability of cells that received pulsed laser light gradually decreases, whereas no significant changes are found in the cells irradiated with CW laser light with the elapse of post-irradiation time. The type of cell death differs between the pulsed and CW laser light irradiations. These findings suggest that the cytotoxic efficacy of the excitation light source is displayed by the difference in the type of cell death, namely apoptosis or necrosis.

[1]  James B. Mitchell,et al.  Evaluation of a tetrazolium-based semiautomated colorimetric assay: assessment of chemosensitivity testing. , 1987, Cancer research.

[2]  R. D. Barabash,et al.  Gold vapor laser versus tunable argon‐dye laser for endobronchial photodynamic therapy , 1996, Lasers in surgery and medicine.

[3]  L. Buja,et al.  Apoptosis and necrosis. Basic types and mechanisms of cell death. , 1993, Archives of pathology & laboratory medicine.

[4]  T. Dougherty,et al.  HOW DOES PHOTODYNAMIC THERAPY WORK? , 1992, Photochemistry and photobiology.

[5]  A. B. Lyons,et al.  Simultaneous analysis of immunophenotype and apoptosis of murine thymocytes by single laser flow cytometry. , 1992, Cytometry.

[6]  D. Kessel,et al.  Mitochondrial photodamage and PDT-induced apoptosis. , 1998, Journal of photochemistry and photobiology. B, Biology.

[7]  D. Kessel,et al.  Delayed Oxidative Photodamage induced by Photodynamic Therapy , 1996, Photochemistry and photobiology.

[8]  G. Wahl,et al.  Sensitivity and selectivity of the DNA damage sensor responsible for activating p53-dependent G1 arrest. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[9]  R. Redmond,et al.  Environmental Effects on Cellular Photosensitization: Correlation of Phototoxicity Mechanism with Transient Absorption Spectroscopy Measurements , 1998, Photochemistry and photobiology.

[10]  J. Ordonez,et al.  Estimation of cell survival by flow cytometric quantification of fluorescein diacetate/propidium iodide viable cell number. , 1989, Cancer research.

[11]  M. Waner,et al.  Comparison of the optical transmission properties of pulses and continuous wave light in biological tissue , 1987, Lasers in surgery and medicine.

[12]  Rick E. Sneed,et al.  Comparative study between pulsed and continuous wave lasers for Photofrin® photodynamic therapy , 1993, Lasers in surgery and medicine.

[13]  D. Kessel.  SITES OF PHOTOSENSITIZATION BY DERIVATIVES OF HEMATOPORPHYRIN , 1986, Photochemistry and photobiology.

[14]  T J Dougherty,et al.  PHOTOSENSITIZERS: THERAPY AND DETECTION OF MALIGNANT TUMORS , 1987, Photochemistry and photobiology.

[15]  Hirofumi Kawabe,et al.  A Comparison between Argon‐dye and Excimer‐dye Laser for Photodynamic Effect in Transplanted Mouse Tumor , 1992, Japanese journal of cancer research : Gann.

[16]  J. Moan,et al.  On the diffusion length of singlet oxygen in cells and tissues , 1990 .

[17]  Z. Darżynkiewicz,et al.  Features of apoptotic cells measured by flow cytometry. , 1992, Cytometry.

[18]  P A Cowled,et al.  COMPARISON OF THE EFFICACY OF PULSED AND CONTINUOUS‐WAVE RED LASER LIGHT IN INDUCTION OF PHOTOCYTOTOXICITY BY HAEMATOPORPHYRIN DERIVATIVE , 1984, Photochemistry and photobiology.

[19]  H J Sterenborg,et al.  Photodynamic therapy with pulsed light sources: a theoretical analysis , 1996, Physics in medicine and biology.

[20]  H. Kato,et al.  Photodynamic therapy with the excimer dye laser in the treatment of respiratory tract malignancies , 1991 .

[21]  R. Kanamaru,et al.  Features of DNA Oligonucleosomal Fragmentation in Human Tumor Cell Lines and Its Detection by Flow Cytometry: Utility and Limitations , 1997, Japanese journal of cancer research : Gann.

[22]  M. Yaniv,et al.  Expression of the papillomavirus E2 protein in HeLa cells leads to apoptosis , 1997, The EMBO journal.

[23]  C J Gomer,et al.  Direct comparison of in‐vitro and in‐vivo photofrin‐II mediated photosensitization using a pulsed KTP pumped dye laser and a continuous wave argon ion pumped dye laser , 1991, Lasers in surgery and medicine.

[24]  E. Ben-Hur,et al.  Pulsed Versus Continuous-Wave 680 Nm Laser Light In Photosensitization By Chloroaluminum Phthalocyanine Tetrasulfonate , 1988, Other Conferences.

[25]  M. Dellinger.  Apoptosis or Necrosis Following Photofrin® Photosensitization: Influence of the Incubation Protocol , 1996, Photochemistry and photobiology.

[26]  D. Kessel,et al.  Rapid Initiation of Apoptosis by Photodynamic Therapy , 1996, Photochemistry and photobiology.

[27]  T. Mosmann.  Rapid colorimetric assay for cellular growth and survival: application to proliferation and cytotoxicity assays. , 1983, Journal of immunological methods.

[28]  D. Kessel,et al.  The Role of Subcellular Localization in Initiation of Apoptosis by Photodynamic Therapy , 1997, Photochemistry and photobiology.