Abstract:

Objective
To investigate the effect of low level laser （LLL）irradiation with different doses on proliferation and differentiation of human osteoblast-like cells,and provide the experimental basis for clinical application of LLL.Methods Human osteoblast-like cells MG63 were irradiated by Ga-Al-As diode laser (808 nm,66 mW) with doses of 1 J?cm-2 and 3 J?cm-2 after being seeded into multi-well plates.Untreated cells were used as controls.The proliferation of MG63 was quantified by colorimetric MTT (dimethylthiazol tetrazolium bromide) assay.The expressions of the marker of differentiation osteopontin （OPN） and collagen Ⅰ （Coll Ⅰ） were observed by immunohistochemistry assay.Results There was no difference of proliferation and expressions of OPN and Coll Ⅰ 　between the laser group with dose of 1 J?cm-2 and control group(P>0.05). The laser group with the dose of 3 J?cm-2 showed more increase in cell survival at 24 and 48 h after being seeded as compared with control group(P<0.05).Moreover,the expressions of OPN and Coll Ⅰ in the laser group with dose of 3 J?cm-2 was also higher than those in control group (P<0.05).
Conclusion LLL irradiation with the dose of 3 J?cm-2 may promote the proliferation and differentiation of human osteoblast-like cells,which might improve bone healing.

Key words:  low level laser;osteoblast-like cells;osteopontin;collagen , type Ⅰ