title: Effects of red light-emitting diode irradiation on dental pulp cells.
abstract: Light irradiation activates a range of cellular processes in a variety of cell types, including stem cells, and can promote tissue repair. This study investigated the effects of light-emitting diode (LED) exposure on dental pulp cells (DPCs). Dose response analysis at 20-second intervals up to 120 seconds demonstrated that a LED array emitting 653-nm red light stimulated significantly increased cell growth at 3 and 7 days post-irradiation with 40 (149 mJ/cm(2)) and 60 (224 mJ/cm(2)) seconds of radiant exposure. Double-dosing cells at days 1 and 4 of a 7-day culture period with 60-second (224 mJ/cm(2)) LED exposure significantly increased cell growth compared with a single dosing regime. BrdU analysis demonstrated significantly increased proliferation rates associated with significantly increased ATP, nitric oxide (NO), and mitochondrial metabolic activity. LED-stimulated NO levels were not reduced by inhibition of NO-synthase activity. Light exposure also rescued the inhibition of mitochondrial dysfunction and increased levels of in vitro mineralization compared with control. Media exchange experiments indicated that autocrine signaling was not likely responsible for red-light-induced DPC activity. In conclusion, data analysis indicated that 653-nm LED irradiation promoted DPC responses relevant to tissue repair, and this is likely mediated by increased mitochondrial activity.
authors.affiliation: Oral Biology, School of Dentistry, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Holder
authors.forename: M R
authors.initials: MR
authors.lastname: Milward
authors.forename: W M
authors.initials: WM
authors.lastname: Palin
authors.forename: M A
authors.initials: MA
authors.lastname: Hadis
authors.forename: P R
authors.initials: PR
authors.lastname: Cooper
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D049109:Cell Proliferation / Q000528:radiation effects*; D003782:Dental Pulp / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004847:Epithelial Cells / Q000528:radiation effects*; D005109:Extracellular Matrix / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D008928:Mitochondria / Q000528:radiation effects; D063269:Mitochondrial Turnover / Q000528:radiation effects*; D009569:Nitric Oxide / Q000096:biosynthesis; D061251:Primary Cell Culture; D051381:Rats; D012666:Semiconductors; D015398:Signal Transduction / Q000528:radiation effects; D014074:Tooth Calcification / Q000528:radiation effects
chemical_list: D009569:Nitric Oxide; D000255:Adenosine Triphosphate