Low power laser irradiation alters gene expression of olfactory ensheathing cells in vitro

Background and Objectives: Both photobiomodulation (PBM) and olfactory ensheathing cells (OECs) transplantation improve recovery following spinal cord injury. However, neither the combination of these two therapies nor the effect of light on OECs has been reported. The purpose of this study was to determine the effect of light on OEC activity in vitro. Materials and Methods: OECs were purified from adult rat olfactory bulbs and exposed to 810 nm light (150 mW; 0, 0.2, or 68 J/cm²). After 7-21 days in vitro, cells underwent immunocytochemistry or RNA extraction and RT-PCR. Results: Analysis of immunolabeling revealed a significant decrease in fibronectin expression in the cultures receiving 68 J/cm². Analysis of gene expression revealed a significant (P < 0.05) increase in brain derived neurotrophic factor (BDNF), glial derived neurotrophic factor (GDNF), and collagen expression in the 0.2 J/cm² group in comparison to the non-irradiated and 68 J/cm ² groups. OEC proliferation was also found to significantly increase in both light treated groups in comparison to the control group (P < 0.001). Conclusions: These results demonstrate that low and high dosages of PBM alter OEC activity, including upregulation of a number of neurotrophic growth factors and extracellular matrix proteins known to support neurite outgrowth. Therefore, the application of PBM in conjunction with OEC transplantation warrants consideration as a potential combination therapy for spinal cord injury.