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Item In vitro evaluation of red and near infrared LED photobiomodulation on L929 fibroblasts metabolic activity and morphology(Springer) Segismondi, Larissa Cavallieri; Soares, Luís Eduardo Silva; Pacheco-Soares, CristinaPurpose Fibroblasts, the main cells of connective tissue, are highly susceptible to oxidative stress caused by reactive oxygen species (ROS). Photobiomodulation (PBM) has emerged as a promising therapy capable of modulating biological tissues, enhancing cellular metabolic activity, and promoting the proliferation and survival of fibroblasts. In this study, we aimed to investigate the potential in vitro photoprotective effect of cellular photomodulation using 660 and 850 nm LEDs in L929 fibroblast cells treated with hydrogen peroxide as a model of oxidative stress. Methods Changes in cell viability were observed using the Alamar Blue colorimetric assay, and cell morphology was assessed by inverted microscopy. Mitochondria and nuclei were also labeled in living cells using fluorescence with TMRM and Hoechst, in addition to ROS detection with CellRox Green. Results Our results indicate that pretreatment with LED exerts a cytoprotective effect against oxidative stress, promoting an increase in mitochondrial activity, mitochondrial membrane potential, and a reduction in intracellular reactive oxygen species (ROS) generation while inducing improvements in the morphological characteristics of cells. Conclusion The findings from the present study indicate that Photobiomodulation (PBM) with LED contributes to maintaining cellular homeostasis and can help prevent and mitigate damage resulting from oxidative stress in fibroblasts.Item Modulation of heat shock protein expression and cytokine levels in MCF‐7 cells through photodynamic therapy(Springer-Verlag London Ltd.) Santos, Mariela Inês Batista dos; Godoi, Bruno Henrique; Silva, Newton Soares da; Oliveira, Luciane Dias de; Ramos, Lucas de Paula; Cintra, Ricardo Cesar; Pacheco-Soares, CristinaIn this study, we assess the impact of photodynamic therapy (PDT) using aluminum phthalocyanine tetrasulfonate (AlPcS4) on the viability and cellular stress responses of MCF-7 breast cancer cells. Specifically, we investigate changes in cell viability, cytokine production, and the expression of stress-related genes. Experimental groups included control cells, those treated with AlPcS4 only, light-emitting diode (LED) only, and combined PDT. To evaluate these effects on cell viability, cytokine production, and the expression of stress-related genes, techniques such as 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay, enzyme-linked immunosorbent assays (ELISA), and real-time quantitative PCR (RT‒qPCR) were employed. Our findings reveal how PDT with AlPcS4 modulates mitochondrial activity and cytokine responses, shedding light on the cellular pathways essential for cell survival and stress adaptation. This work enhances our understanding of PDT's therapeutic potential and mechanisms in treating breast cancer.