An In Vitro Study on the Electrical Activation of Photosentisizers in the Improvement of Photodynamic Treatments

Low extinction coefficient of photosensitizers is considered to be one of the limitations in the efficacy of photodynamic therapy.It is also a well known fact that each photosensitizer is activated at a specific wavelength of the light spectrum, which is the main limitation encountered in deep therapies.In this research, electrical activation of two photosensitizers have been studied in in-vitro conditions to find out the probable synergistic effect of electric pulses and light in order to improve the efficacy of treatments for the deeply seated tissues. The study was carried out on Wehi-164 fibrosarcoma cell line of Balb/c mouse using two different doses of electric pulses, light as well as two concentrations of the dye. Two hours after the incubation of the cells with 5-Aminolevalenic Acid (5-ALA) and Zinc phthalocyanine sulfate, square electric pulses generated by an electroporator BTX, and illuminating by a non coherent light source at peak wavelengths of 630 and 670 nm was performed. Twenty four hours post treatment the cell survival percentages were determined using MTT method and then it was compared against the control Significant difference was obtained when 0.2 mM of 5-ALA, low and high doses of light and pulses of 900 and 1000 V/cm as well as when the concentration of 5-ALA was increased to 1 mM and three light doses (0, 16, 54 J/cm2) were applied. Significant difference was observed between the samples receiving and not receiving pulses upon using a concentration of one mM of Zinc phthalocyanine and lower light dose. Similar results were obtained under the following conditions: 10 mM concentration of the dye and higher light dose1 mM concentration of the dye, 0 and 1000 V/cm pulses in the dark and lower light dose10 mM concentration of the dye, 0 and 800 V/cm pulses in the dark and higher light doseDiscussion and It seems that electric pulses activate high concentration of protoporphyrin IX. Also, 1000 V/cm pulses are more effective in the activation of 5-ALA than 900 V/cm pulses. It is predicted that the 1000 V/cm pulses applied on post incubated cells with 1 mM concentration of Zinc phthalocyanine have been able to activate the dye in the absence of light exposure. Overall it seems that increasing the height of electric pulses is more effective in the process of the activation of dyes.