title: Green laser light irradiation enhances differentiation and matrix mineralization of osteogenic cells.
abstract: OBJECTIVE
  Low level laser therapy (LLLT) in both infrared and visible light is a therapeutic tool ever more proposed in clinical practice in different fields. The effect of near infrared LLLT has been described in a growing number of scientific publications related to bone tissue healing, both in vitro and in vivo. More recently, green visible light using potassium-titanyl-phosphate KTiOPO4 (KTP, 532 nm) laser has been proposed in dermatology, urology, oral and maxillofacial surgery but has never been tested on bone tissue. The aim of the present work was to perform a preliminary in vitro study to analyze the effects of KTP laser, on the osteogenic differentiation of bone marrow stromal cells (BMSCs).
  
  
  METHODS
  Using a power meter the first step of this study aimed to evaluate the real power emitted by the KTP laser device and the amount of energy absorbed by culture medium and plastic in order to calculate the appropriate irradiation parameters for cultured cells. Primary bone marrow stromal cells prepared from C57BL/6 mice were cultured and induced to differentiate in the osteogenic lineage in the presence or in the absence of KTP LLLT at a fluence of 4 J/cm(2) three times a week. Specific staining of the cells and the extracellular matrix, microscopic analysis as well as quantitative RT-PCR were used to assess cell proliferation and differentiation.
  
  
  RESULTS
  We show here that KTP LLLT enhances the osteogenic differentiation of bone marrow stromal cells and the mineralization of their extracellular matrix.
  
  
  CONCLUSIONS
  Our results highlight that this LLLT experimental protocol with green light (KTP, 532 nm) at 4 J/cm(2) has a positive effect on the osteogenic differentiation of murine bone marrow stromal cells. These preliminary results could be used as a basis to further investigate the effect of this KTP laser protocol on bone tissue engineering models in vivo and in vitro.
authors.affiliation: Université Nice Sophia Antipolis, iBV, U1091, 06100 Nice, France; CNRS, iBV, UMR 7277, 06100 Nice, France; Université Nice Sophia Antipolis, UFR Odontologie, Laboratoire MICORALIS (MICrobiologie ORALe, Immunothérapie et Santé), 06000 Nice, France; Graftys, 13854, Aix en Provence, France. Electronic address: elisabetta.merigo@gmail.com.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Merigo
authors.affiliation: Université Nice Sophia Antipolis, iBV, U1091, 06100 Nice, France; CNRS, iBV, UMR 7277, 06100 Nice, France; Université Nice Sophia Antipolis, UFR Odontologie, Laboratoire MICORALIS (MICrobiologie ORALe, Immunothérapie et Santé), 06000 Nice, France; Graftys, 13854, Aix en Provence, France.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Bouvet-Gerbettaz
authors.affiliation: Université Nice Sophia Antipolis, iBV, U1091, 06100 Nice, France; Inserm, iBV, U1091, 06100 Nice, France; Université Nice Sophia Antipolis, UFR Odontologie, Laboratoire MICORALIS (MICrobiologie ORALe, Immunothérapie et Santé), 06000 Nice, France; Graftys, 13854, Aix en Provence, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Boukhechba
authors.affiliation: Université Nice Sophia Antipolis, UFR Odontologie, Laboratoire MICORALIS (MICrobiologie ORALe, Immunothérapie et Santé), 06000 Nice, France.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Rocca
authors.affiliation: Université Nice Sophia Antipolis, UFR Odontologie, Laboratoire MICORALIS (MICrobiologie ORALe, Immunothérapie et Santé), 06000 Nice, France.
authors.forename: Carlo
authors.initials: C
authors.lastname: Fornaini
authors.affiliation: Université Nice Sophia Antipolis, iBV, U1091, 06100 Nice, France; CNRS, iBV, UMR 7277, 06100 Nice, France; Inserm, iBV, U1091, 06100 Nice, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rochet
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002454:Cell Differentiation / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D008027:Light; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D010012:Osteogenesis / Q000528:radiation effects; D010710:Phosphates / Q000737:chemistry; D014025:Titanium / Q000737:chemistry
chemical_list: D010710:Phosphates; D015675:Osteocalcin; C064806:potassium titanylphosphate; D014025:Titanium
keywords: Bone marrow stromal cells; Green light; KTP; Laser irradiation; Low level laser therapy; Matrix mineralization; Osteogenic differentiation; Power meter