Low-intensity laser irradiation stimulates mineralization via increased BMPs in MC3T3-E1 cells.
BACKGROUND
Previously, we reported that low-intensity laser irradiation accelerated bone formation, and that this mechanism deeply involved insulin-like growth factor I expression. However, as bone formation is supported by many local factors, the mechanism involved in laser irradiation remains incompletely understood. Therefore, the purpose of this study was to determine the effects of laser irradiation on the osteogenic response in vitro.


METHODS
Mouse osteoblast-like cells, MC3T3-E1, were cultured and were irradiated for 5-20 minutes (0.96-3.82 J/cm(2)) at the subconfluent stage using a low-intensity Ga-Al-As diode laser apparatus. After laser irradiation, expression of bone morphogenetic proteins (BMPs), transcription factors (Runx2, Osterix, Dlx5, Msx2), and phosphorylation of Smad1 were determined, and calcium content of cell cultures was also determined.


RESULTS
Irradiation at 1.91 J/cm(2) significantly increased the expression of BMPs and Runx2, Osterix, Dlx5, Msx2, and the phosphorylation of Smad1. Noggin, a BMP receptor blocker, inhibited the laser-induced Runx2 expression and phosphorylation of Smad1. Moreover, laser irradiation significantly increased the calcium content of cell cultures, and noggin inhibited this increase.


CONCLUSIONS
These results suggest that low-intensity laser irradiation stimulates in vitro mineralization via increased expression of BMPs and transcription factors associated with osteoblast differentiation.
Fujimoto
Keiko
K
Department of Orthodontics, Nihon University School of Dentistry, 1-8-13, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan.
Kiyosaki
Takeshi
T
Mitsui
Narihiro
N
Mayahara
Kotoe
K
Omasa
Saori
S
Suzuki
Naoto
N
Shimizu
Noriyoshi
N
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000502:physiology; D002478:Cells, Cultured; D050659:Core Binding Factor Alpha 1 Subunit / Q000528:radiation effects; D018398:Homeodomain Proteins; D054023:Lasers, Semiconductor; D028022:Low-Level Light Therapy; D051379:Mice; D010006:Osteoblasts / Q000528:radiation effects*; D010012:Osteogenesis / Q000528:radiation effects*; D010766:Phosphorylation; D051898:Smad1 Protein; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors; D000099176:Noggin Protein
D002118:Calcium; D002352:Carrier Proteins; D050659:Core Binding Factor Alpha 1 Subunit; D018398:Homeodomain Proteins; D051898:Smad1 Protein; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors; D000099176:Noggin Protein; C501120:Dlx5 protein, mouse; C084119:MSX2 protein; C493716:Runx2 protein, mouse; C497401:Smad1 protein, mouse; C479466:Sp7 protein, mouse