Doses of red and near-IR light have been shown to increase the viability of implanted stem cells used to treat brain damage. Bone marrow mesenchymal stem cell transplantation has been effective in treating neonatal hypoxic-ischemic brain damage, which can be caused by cardiac or respiratory arrest, incomplete suffocation and asphyxia, as well as exposure to carbon monoxide or other poisonous gases, according to the International Brain Injury Association. But in vivo transplantation is not always successful: The stem cells' survival, colonization and differentiation efficiencies are relatively low. Knowing that red or NIR light at 600 to 1000 nm promotes cellular migration and prevents cell death, Dr. Xiaoying Wu and colleagues at Chongqing University combined red light with bone marrow mesenchymal stem cell transplantation as a possible treatment for hypoxic-ischemic brain damage. They cultured the cells on primary neurons following oxygen-glucose deprivation and then measured their migration and colonization. After 40 hours of irradiation under red LEDs at 660 nm and 60 mW/cm2, an increasing number of green fluorescence-labeled stem cells migrated toward damaged primary neurons in vitro, the team found. Meanwhile, neonatal rats with brain damage were given an intraperitoneal injection of bone marrow mesenchymal stem cells, followed by irradiation under the red LEDs for seven successive days. Shuttle box test results showed that, after phototherapy and stem cell transplantation, the active avoidance response rate was significantly increased, and was higher than the rate achieved after transplantation alone. Previous studies suggested that the neuronal differentiation rate of the stem cells during the in vitro culture could reach 78 to 92 percent, but their in vivo transplantation efficiency, and survival and differentiation rates, were very low, according to the researchers. The findings are published in Neural Regeneration Research (doi: 10.4103/1673-5374.128214) For more information, visit: www.international.cqu.edu.cn