Low-power laser irradiation promotes the proliferation and osteogenic differentiation of human periodontal ligament cells via cyclic adenosine monophosphate

Retaining or improving periodontal ligament (PDL) function is crucial for restoring periodontal defects. The aim of this study was to evaluate the physiological effects of low-power laser irradiation (LPLI) on the proliferation and osteogenic differentiation of human PDL (hPDL) cells. Cultured hPDL cells were irradiated (660 nm) daily with doses of 0, 1, 2 or 4 J⋅cm−2. Cell proliferation was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and the effect of LPLI on osteogenic differentiation was assessed by Alizarin Red S staining and alkaline phosphatase (ALP) activity. Additionally, osteogenic marker gene expression was confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR). Our data showed that LPLI at a dose of 2 J⋅cm−2 significantly promoted hPDL cell proliferation at days 3 and 5. In addition, LPLI at energy doses of 2 and 4 J⋅cm−2 showed potential osteogenic capacity, as it stimulated ALP activity, calcium deposition, and osteogenic gene expression. We also showed that cyclic adenosine monophosphate (cAMP) is a critical regulator of the LPLI-mediated effects on hPDL cells. This study shows that LPLI can promote the proliferation and osteogenic differentiation of hPDL cells. These results suggest the potential use of LPLI in clinical applications for periodontal tissue regeneration. Exposure to low-power laser light could stimulate the repair of jaw tissues that have been damaged in the course of periodontal disease. Dentists have several strategies for addressing severe plaque build-up in the teeth and gums, but these are generally inadequate for repairing the resulting destruction of root, jaw and connective tissue. Inspired by research demonstrating that low-power laser irradiation (LPLI) may promote wound-healing, Yan-Hsiung Wang of Kaohsiung Medical University in Taiwan and colleagues investigated the potential benefits of LPLI in treating periodontal damage. They demonstrated that this treatment stimulated active proliferation and bone-producing activity in human periodontal ligament (hPDL) cells, which are primarily responsible for the formation and maintenance of periodontal tissue. These results indicate that LPLI could be a valuable tool for promoting tissue regeneration in patients.