Effects of low-level laser therapy on proliferation and differentiation of murine bone marrow cells into osteoblasts and osteoclasts.
OBJECTIVE
Low-Level Laser Therapy (LLLT) has been suggested to improve bone tissue healing. The cellular and molecular mechanisms involved in this effect are still unclear but bone cell proliferation and differentiation alteration have been proposed. The aim of the present study was to investigate, in vitro, the effect of LLLT on bone cell proliferation, osteoblastic and osteoclastic differentiation, both involved in bone remodeling and regeneration.


METHODS
Murine bone marrow cells, which contain both osteoblast and osteoclast progenitors, were cultured and induced to differentiate in the absence or in the presence of LLLT. Laser exposition parameters were determined using a powermeter and consisted in an 808 nm infrared wavelength laser light in continuous mode, with an energy density of 4 J/cm(2) administered three times a week. Cell proliferation and differentiation were assessed after specific staining and microscopic analysis of the cultures after various times, as well as by quantitative RT-PCR analysis of a panel of osteoblast and osteoclast markers after nucleic acid extraction.


RESULTS
The use of a powermeter revealed that the power emitted by the optical fiber of the laser device was markedly reduced compared to the displayed power. This allowed to adjust the LLLT parameters to a final energy density exposure of 4 J/cm(2). In these conditions, proliferation of bone marrow mesenchymal stem cells as well as osteoclast or osteoblast differentiation of the corresponding progenitors were found similar in control and LLLT conditions.


CONCLUSIONS
Using the present experimental protocol, we concluded that an 808 nm wavelength infrared LLLT does not alter murine bone progenitor cell proliferation and differentiation. Moreover our results confirm the necessary use of a powermeter to fix LLLT protocol parameters.
Laboratory of Genetics, Physiopathology and Bone Tissue Engineering (GéPITOs), University of Nice-Sophia Antipolis, Centre National de la Recherche Scientifique (CNRS), UFR of Medicine, 28 Valombrose Avenue, 06107 Nice, France.
Sébastien
S
Bouvet-Gerbettaz
Elisabetta
E
Merigo
Jean-Paul
JP
Rocca
Georges F
GF
Carle
Nathalie
N
Rochet
D000135:Acid Phosphatase / Q000235:genetics; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000528:radiation effects*; D019485:Bone Morphogenetic Proteins / Q000235:genetics; D002454:Cell Differentiation / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics; D015870:Gene Expression; D028022:Low-Level Light Therapy; D051379:Mice; D008807:Mice, Inbred BALB C; D010006:Osteoblasts / Q000166:cytology*; D015675:Osteocalcin / Q000235:genetics; D010010:Osteoclasts / Q000166:cytology* / Q000201:enzymology
D019485:Bone Morphogenetic Proteins; D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D015675:Osteocalcin; D000135:Acid Phosphatase