Photobiomodulation Therapy to Autologous Bone Marrow in Humans Significantly Increases the Concentration of Circulating Stem Cells and Macrophages: A Pilot Study

Objective: The aim of this study was to examine the effect of photobiomodulation therapy (PBMT) of the bone marrow (BM) on the concentration of stem cells and other cells in the circulating blood (CB) in humans. Background: Circulating stem cells have received increasing attention in recent years due to their potential role in regenerative medicine. Various biological processes have been shown to be affected by PBMT. Methods: The study was conducted on 15 volunteers. Ga-Al-As diode laser 808 nm wavelength was applied to both tibias of each volunteer for PBMT to the BM. The kinetics of concentration of various cells in the CB was followed by comparing blood samples relative to their baseline levels prior to application of PBMT to the BM. CD-34+ cells and macrophages were identified in CB samples using flow cytometry technology. Results: PBMT to the BM caused a significant (p < 0.01) increase in the concentration of CD-34+ cells in the CB from 7.8 ± 3.0% (mean ± SD) of total mononucleated cell to 29.5 ± 10.1% of total commencing at about 2 h post-PBMT. The levels of CD-34+ cells peaked at 2-4 days post-PBMT and then gradually returned to baseline levels. Macrophages in the CB were also significantly (p < 0.01) elevated following PBMT to the BM from 7.8 ± 6.0% (mean ± SD) of the total mononucleated cells to 52.1 ± 7.9% of total. Conclusions: Application of PBMT to the BM in humans can significantly increase the concentration of CD-34+ cells and macrophages in the CB. These cells may consequently home in on the impaired target organs and improve their function, as has been previously shown in experimental animal models. Furthermore, the results may also have clinical relevance in respect to enrichment of CB in cells that may be consequently isolated for cell therapy. Clinical Trial Registration No. is 7/14.