Red LED Photobiomodulation Enhances Metabolic Activity in Cultured Human Pericytes

Abstract

Photobiomodulation (PBM) using red or near-infrared light modulates cellular functions, particularly mitochondrial activity, thereby contributing to tissue repair and angiogenesis. However, the impact of light-emitting diode (LED)-based PBM on human pericytes remains unclear. Human placenta-derived pericytes were cultured and irradiated with red LED light (655 nm, 5.6 J/cm²) four times at 1.5-hour intervals. Cell proliferation was assessed using the WST-8 assay at 3, 6, and 24 hours post-irradiation. Immunocytochemical analysis for angiogenesis-related markers (angiopoietin-1 [Ang-1], cluster of differentiation 146 [CD146], platelet-derived growth factor receptor beta [PDGFR-β], and vascular endothelial growth factor A [VEGF-A]) was performed at corresponding time points. Pericyte proliferation was significantly higher in the irradiated group than in controls at all time points (p < 0.05). Immunocytochemistry demonstrated greater expression of all four angiogenesis-related markers in the irradiated group, with peak levels at 24 hours post-irradiation. No temperature elevation was detected during LED exposure. Red LED PBM significantly stimulated metabolic activity and proliferation in human pericytes and upregulated key angiogenic markers, suggesting that PBM may promote wound healing and vascular regeneration by activating pericytes, thus offering a promising non-invasive strategy for tissue repair.