Segismondi, Larissa CavallieriSoares, Luís Eduardo SilvaPacheco-Soares, Cristina2026-02-052026-02-05https://repositorio.univap.br/handle/123456789/1128Purpose 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.pdfjpegen-USArtigos de PeriódicosLarissa Cavallieri SegismondiLuís Eduardo Silva SoaresCristina Pacheco-Soares10.1007/s42600-025-00445-zFibroblastCell viabilityMitochondrial membrane potentialHydrogen peroxideOxidative stressSEGISMONDI, L. C.; SOARES, L. E. S.; PACHECO-SOARES, C. In vitro evaluation of red and near infrared LED photobiomodulation on L929 fibroblasts metabolic activity and morphology. Research on Biomedical Engineering, [S. l.], v. 41, n. 4, p. 61, dez. 2025. DOI: 10.1007/s42600-025-00445-z. Disponível em: https://link.springer.com/10.1007/s42600-025-00445-z. Acesso em: 18 dez. 2025.Universidade do Vale do ParaíbaUniversidade do Vale do ParaíbaUniversidade do Vale do Paraíba