Efeito do protocolo de fotobiomodulação com irradiação única ou múltipla na viabilidade e proliferação de osteoblastos cultivados em condição de estresse nutricional

Abstract

Photobiomodulation (PBM) via low-level laser irradiation has proven to be an effective tool for enhancing in vitro proliferation rates of various cell types, including osteoblasts, suggesting its potential application in bone tissue engineering. However, the standardization of PBM parameters remains inconsistent, as factors such as wavelength and dose can directly influence biological responses. Moreover, in vitro photobiomodulatory effects tend to be more evident when cells are cultured under nutritional stress conditions, which simulate in vivo pathophysiological environments. This study aimed to evaluate the effects of PBM with single or multiple irradiations, using different wavelengths and doses, on pre-osteoblasts cultured under nutritional stress. MC3T3-E1 cells (pre-osteoblasts derived from mouse calvaria) were cultured in αMEM medium with reduced fetal bovine serum and irradiated with an InGaAlP diode laser either once (T0) or multiple times (T0, T24h, and T48h), using wavelengths of 660 nm (red spectrum – group R) or 790 nm (infrared spectrum – group IR) at doses of 1, 4, or 6 J/cm². Cell viability and proliferation were assessed using the Alamar Blue reduction assay at 24, 48, and 72 hours after the first (or only) irradiation, with non-irradiated cells as the control group. Data were analyzed using ANOVA followed by Dunn’s post-test (p < 0.05). Results showed that IR-irradiated cells at 1 and 6 J/cm² exhibited significantly increased proliferation at 24 hours compared to the control. In the single-irradiation group, this effect was also observed for IR6 at 48 hours and for IR1 and IR6 at 72 hours. In the multiple-irradiation groups, no significant differences in viability or proliferation were observed over time. It is concluded that a single-irradiation protocol using infrared laser (790 nm) at a dose of 6 J/cm² is most effective in promoting MC3T3-E1 pre-osteoblast proliferation under nutritional stress. In contrast, the use of red laser (660 nm) or multiple irradiations did not provide additional benefits in the experimental model.