Photobiomodulation as a modulator of collagen remodeling following fractional CO₂ laser therapy

Skin aging is a multifactorial process and involves loss of volume and elasticity, bone resorption, reduced fibroblast activity, and chronic low-grade inflammation. Among the treatments for skin rejuvenation, fractional CO₂ laser is widely used for its ability to promote skin resurfacing and collagen formation. However, its use is limited by side effects. To mitigate these effects, photobiomodulation (PBM) has been applied, showing potential in accelerating recovery and improving tissue regeneration. Thus, this study aims to evaluate the effects of PBM on collagen remodeling after fractional CO₂ laser treatment in rat skin. 30 Wistar rats were allocated into the following experimental groups: basal (no treatment), CO₂ 7D (fractional CO₂ laser), CO₂+PBM 7D (fractional CO₂ laser combined with PBM), CO₂ 28D (fractional CO₂ laser), and CO₂+PBM 28D (fractional CO₂ laser combined with PBM). The skin was removed at 7 days for the 7D groups and at 28 days for the 28D groups, and submitted to histological evaluation to evaluate the thickness of the extracellular matrix (ECM), collagen type I fibers and elastic fibers. The combined treatment of fractional CO₂ laser and PBM provided faster recovery and better collagen regeneration compared to the CO₂ laser alone or to the basal group. In addition, the increase in the percentage of elastic fibers in the ECM was more pronounced in the CO₂+PBM 28D when compared to CO₂+PBM 7D. PBM may be an effective strategy to optimize the outcomes of fractional CO₂ laser skin rejuvenation, reducing side effects and accelerating dermal regeneration.