The purpose of this study was to examine how low-energy LED red light influences the early to middle stage of osteogenic differentiation of periodontal ligament stem cells (PDLSCs) via the ERK5 signaling pathway. METHODS: PDLSCs were extracted from periodontal membrane tissue using enzymatic digestion. At three time points of 7, 10, and 14 days after irradiation with 5J/cm2 LED red light, the expression levels of early to middle-stage osteogenic-related genes ALP, Col-1, BSP, and OPN were detected by real-time fluorescence quantitative PCR(qRT-PCR) in both control and osteogenesis experimental groups. The addition of BIX02189 could block the ERK5 signaling pathway. Under irradiation with 5J/cm2 LED red light, the expression levels of the ERK5 gene, related proteins ERK5, p-ERK5, as well as early to middle-stage osteogenic-related genes ALP, Col-1, BSP, and OPN were detected by qRT-PCR and Western blot in the osteogenic medium group and the osteogenic medium + BIX02189 group. RESULTS: Both low-energy LED red light and osteogenic medium could induce osteogenesis and differentiation of PDLSCs, upregulating the expression of ALP, Col-1, BSP, and OPN genes in PDLSCs. Their combination also produced a synergistic effect. Moreover, the ERK5 signaling pathway participated in the promoting effect of LED red light on the early to middle-stage osteogenic differentiation of PDLSCs, indicating a positive role of LED red light in this process. CONCLUSIONS: The ERK5 signaling pathway can mediate the promotion of early to middle-stage osteogenic differentiation of PDLSCs by low-energy LED red light.
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