The effect of indocyanine green-based photodynamic therapy on healthy fibroblast and keratinocyte cells.

Abstract

Photodynamic therapy is a promising invention to treat infections and cancer where conventional treatments are insufficient and have many side effects. Photodynamic therapy is mainly emphasized as having minimal side effects on healthy cells during local applications, even so photosensitizer can accumulate in any cell and unwanted deaths may occur upon irradiation. This study focused on the degree of photodynamic action with indocyanine green against healthy cells, when it has phototoxic effects on pathogens. Healthy mouse skin fibroblast and human skin keratinocyte cells were exposed to energy densities of 84 and 252 J/cm2 with 4, 10, 25, 50,100, 125 and 150 μg/mL indocyanine green which have efficiently killed gram-positive and gram-negative pathogens. Cell Viability, Lipid Peroxidation and Live/Dead Cell Staining analysis were performed to assess the phototoxicity with defined parameters on the healthy cells. 84 J/cm2 energy density was quite safe for keratinocytes with indocyanine green concentrations ranging from 4 to 125 μg/mL. When 252 J/cm2 energy density was used, most of the keratinocytes were damaged with any photosensitizer concentration. Fibroblasts only tolerate these energy densities together with 4 and 10 μg/mL indocyanine green. Increasing photosensitizer concentrations resulted in high phototoxic effect on them. Photodynamic therapy applications, which destroy pathogens, may also kill healthy eukaryotic cells. While some energy densities are safe, but others cause serious mortality rate on fibroblasts and keratinocytes. Therefore, harm to healthy cells related to photodynamic therapy parameters should be minimized by the optimization of energy densities and photosensitizer concentration properly.