title: Photobiomodulation of human adipose-derived stem cells using 810nm and 980nm lasers operates via different mechanisms of action.
abstract: Photobiomodulation (PBM) using red or near-infrared (NIR) light has been used to stimulate the proliferation and differentiation of adipose-derived stem cells. The use of NIR wavelengths such as 810nm is reasonably well accepted to stimulate mitochondrial activity and ATP production via absorption of photons by cytochrome c oxidase. However, the mechanism of action of 980nm is less well understood. Here we study the effects of both wavelengths (810nm and 980nm) on adipose-derived stem cells in vitro. Both wavelengths showed a biphasic dose response, but 810nm had a peak dose response at 3J/cm2for stimulation of proliferation at 24h, while the peak dose for 980nm was 10-100 times lower at 0.03 or 0.3J/cm2. Moreover, 980nm (but not 810nm) increased cytosolic calcium while decreasing mitochondrial calcium. The effects of 980nm could be blocked by calcium channel blockers (capsazepine for TRPV1 and SKF96365 for TRPC channels), which had no effect on 810nm. To test the hypothesis that the chromophore for 980nm was intracellular water, which could possibly form a microscopic temperature gradient upon laser irradiation, we added cold medium (4°C) during the light exposure, or pre-incubated the cells at 42°C, both of which abrogated the effect of 980nm but not 810nm. We conclude that 980nm affects temperature-gated calcium ion channels, while 810nm largely affects mitochondrial cytochrome c oxidase.
authors.affiliation: Center of Digital Dentistry, Peking University School and Hospital of Stomatology, Beijing, China; National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, China; Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Department of Dermatology, Harvard Medical School, Boston, MA, 02115, USA.
authors.forename: Yuguang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Department of Dermatology, Harvard Medical School, Boston, MA, 02115, USA.
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Huang
authors.affiliation: Center of Digital Dentistry, Peking University School and Hospital of Stomatology, Beijing, China; National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Center of Digital Dentistry, Peking University School and Hospital of Stomatology, Beijing, China; National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, China. Electronic address: kqlpj@bjmu.edu.cn.
authors.forename: Peijun
authors.initials: P
authors.lastname: Lyu
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA; Department of Dermatology, Harvard Medical School, Boston, MA, 02115, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, 02139, USA. Electronic address: hamblin@helix.mgh.harvard.edu.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hamblin
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D003576:Electron Transport Complex IV / Q000378:metabolism; D006801:Humans; D007259:Infrared Rays / Q000627:therapeutic use*; D007834:Lasers; D028022:Low-Level Light Therapy / Q000379:methods; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D017785:Photons; D013234:Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D003576:Electron Transport Complex IV; D002118:Calcium
keywords: 810nm; 980nm; Adipose-derived stem cells; Cytochrome c oxidase; Heat-gated ion channels; Photobiomodulation