The Influence of Low Level Near-infrared Irradiation on Rat Bone Marrow Mesenchymal Stem Cells

摘要

Low-level light irradiation (LLLI) has been known to lead to cell proliferation, increase of ATP synthesis, change in mitochondrial membrane potential and the induction of the synthesis of cell cycle regulatory proteins. The purpose of the study was to find the influence of near-infrared (850 nm) light emitting diodes (LEDs) irradiation on mesenchymal stem cells (MSCs) derived from rat bone marrow. Maximal increase in MSCs proliferation was observed with multiple dose of LLLI at 10 mW/cm2 and 4 J/cm2. No apparent variation in temperature (26.1 to 26.3 °C) during irradiation was found, which suggested photochemical effect could be the key factor for biomodulation. The parameters were used in the subsequent research. The number of CFU-F increased slightly (p<0.05) when rat MSCs were illuminated at 10 mW/cm2 and 4 J/cm2. No apparent increase in lactate dehydrogenase release indicated that membrane integrity remained intact after LLLI. Reactive oxygen species production decreased indicated LLLI might have anti-oxidative effect. Intracellular level of ATP increased 1.53 fold after LLLI. Both alkaline phosphatase activity and osteocalcin secretion increased in osteogenic MSCs treated with multiple dose of LLLI. However, triacylglyceride accumulation in adipogenic cells decreased after LLLI. In conclusion, multiple dose of LLLI at 850 nm not only enhances proliferation but also modulates differentiation of MSCs.