Effects of low-level laser therapy on the aging process of human dermal fibroblast cells

Skin aging results from intrinsic factors and extrinsic stressors, particularly ultraviolet (UV) radiation, leading to structural and functional deterioration. Low-Level Laser Therapy (LLLT) has emerged as a potential non-invasive intervention. To evaluate the effectiveness of LLLT in mitigating UV-induced aging in human dermal fibroblasts (HDFs). HDFs were exposed to UV-A (365 nm) and red light (650 nm), individually or sequentially. Cell viability and proliferation were assessed via (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay and flow cytometry. Gene expression of collagen synthesis (Col1A1), apoptosis (Bax, Bcl2, Casp8), and DNA methylation (Dnmt3b) were analyzed by qPCR. UV irradiation reduced cell viability temporarily at 24 h, and subsequent treatment with red light after UV-A (UL group) resulted in partial recovery. The percentage of S-phase cells was higher in the UL group at 72 h (P < 0.05), suggesting an increased proliferative activity in this group. Expression of Col1A1 and Dnmt3b increased (P < 0.05, P < 0.01), while apoptotic markers were altered (P < 0.05, P < 0.01), suggesting enhanced collagen production, epigenetic regulation and reduced apoptosis. LLLT is a promising non-invasive approach to counteract UV-induced skin aging and support dermal regeneration. Further studies are required to optimize treatment protocols and validate clinical applications in dermatology and regenerative medicine.