Photobiomodulation effects on osteogenic differentiation of adipose-derived stem cells.

Abstract

Increasing interest has been observed in the use of photobiomodulation (PBM) to enhance the proliferation of stem cells and induce their differentiation. The effects of PBM at two different wavelengths (635 and 809nm) with three different energy densities (0.5, 1 and 2J/cm2) on the osteogenic differentiation of adipose-derived stem cells (ADSC) were investigated. Cell viability and proliferation were evaluated by MTT and Alamar Blue assays. Osteoblast differentiation were assessed by alkaline phosphatase (ALP) activity, Alizarin red staining and reverse-transcription polymerase chain reaction (RT-PCR) for the expression of collagen type I (COL1A), ALP and osteocalcin. 635nm and 809nm laser irradiation had no effect on the cell viability on days7 and 14, except for 0.5J/cm2 group at 14thday after 635nm irradiation (p < 0.05). Cell proliferation was not changed significantly. Mineralization was increased significantly in 809nm laser groups but no enhancement was detected in the osteogenic differentiation by ALP activity and gene expression results. In 0.5 and 1J/cm2 groups, ALP and COL1A expressions were down regulated at day7 after 809nm laser exposure. These results suggest that PBM may alter osteogenic differentiation of ADSC and increase mineralization but further investigation is needed to define adequate parameters.