Cytotoxic effect and apoptosis pathways activated by methylene blue-mediated photodynamic therapy in fibroblasts.

Photodiagnosis and photodynamic therapy 2020 Mar

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Antimicrobial photodynamic therapy (aPDT) has been used as an adjuvant treatment of oral infections as a minimal intervention clinical approach. Its antimicrobial efficacy was demonstrated in several studies; however, there is a lack of evidence on its cytotoxic effect on mouse fibroblasts (NIH/3T3). The aim of this study was to evaluate the cytotoxicity and apoptotic pathways of methylene blue-mediated aPDT on mouse fibroblasts. Cells were treated with 0.1 or 1.0 mg.L-1 methylene blue (MB), and 0.075 or 7.5 J.cm-² LED at 630 nm. Cell viability was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and crystal violet (CV) assays, while cDNA expression for Bax, Bad, Bcl-2, VDAC-1, cytochrome C and Fas-L was assessed by qRT-PCR (1, 3, 6 and 24 h). The differences between groups were detected by Kruskal-Wallis and post-hoc Dunn's tests for MTT and CV assays, and by ANOVA and post-hoc Tukey test for qPCR (P < 0.05). The combination of 1.0 mg.L-1 MB and 7.5 J.cm-² LED significantly reduced the cellular viability, whereas MB and LED alone were innocuous to fibroblasts. MB-mediated aPDT increased the expression of cytochrome C and Fas-L after 3 h, and Bax/Bcl-2, Bad/Bcl-2, and VDAC-1 after 6 h from treatment. Based on these results, MB-mediated aPDT induced cytotoxicity on mouse fibroblasts, with consequent activation of Bcl-2 apoptosis signaling pathways. Further studies are needed to determine the adequate parameters of aPDT to inactivate microorganisms without damaging fibroblasts. Copyright © 2020 Elsevier B.V. All rights reserved.

Citation

Giuliana Campos Chaves Lamarque, Daniela Alejandra Cusicanqui Méndez, Adriana Arruda Matos, Thiago José Dionísio, Maria Aparecida Andrade Moreira Machado, Ana Carolina Magalhães, Rodrigo Cardoso Oliveira, Thiago Cruvinel. Cytotoxic effect and apoptosis pathways activated by methylene blue-mediated photodynamic therapy in fibroblasts. Photodiagnosis and photodynamic therapy. 2020 Mar;29:101654