δ-Aminolevulinic acid-based photodynamic reaction in HaCaT cells is enhanced by a low concentration of dimethyl sulfoxide

Abstract

Objective To investigate the effect of 0.1% dimethyl sulfoxide (DMSO) on photody-namic reaction in a human keratinocyte cell line, HaCaT, induced by 5-aminolevulinic acid. Methods HaCaT cells were cultured in vitro with or without the presence of 0.1% DMSO at 37 ℃ and stimulated by δ-aminolevulinic acid (ALA) for 3 hours with light flee. Then, cellular protoporphyrin Ⅸ (PpⅨ) concen-tration in, fluorescence intensity in, proliferation and survival rates of HaCaT cells were determined by high performance liquid chromatography with fluorescence detection (HPLC-FLD), laser scanning confocal microscopy (LSCM), MTT coiorimetric method and trypan blue staining, respectively. Also, a portion of HaCaT cells were treated with ALA-based photodynamic therapy (ALA-PDT) and irradiated by 632.8-nm laser, and 12 hours later, cellular apoptosis and necrosis were detected by flow cytometry with annexin V/PI staining. Results Increased concentrations of PpⅨ were found in DMSO-pretreated HaCaT cells compared with untreated cells (0.57 ± 0.05 μg/L vs 0.44 ± 0.04 μg/L, P 0.05 ) or cell survival rate ( (96.18 ± 2.25 )% vs (94.64 ± 2.40)%, x2 = 1.84, P > 0.05 ) between DMSO-pretreated and untreated cells. After ALA-PDT, the apoptosis and necrosis rate were significantly increased in DMSO-treated HaCaT cells compared with untreated HaCaT cells (2.2% vs 1.5%, x2 = 4.05, P < 0.05; 8.9% vs 0.1%, x2 = 8.23, P< 0.05). Conclusion Low concentration (0.1%) of DMSO could enhance the effect of ALA-PDT on HaCaT cells. Key words: Dimethyl sulfoxide; Aminolevulinic acid; Heme; Keratinocytes; Photochemotherapy