Enhancement of Differentiation of Mesenchymal Stem Cells by Laser Irradiation

Abstract

Circadian rhythms are oscillations in the behavior and biochemical reactions of organisms, and occur with a periodicity of approximately twenty-four hours. The mammalian cryptochromes (CRY) have been proposed as circadian photoreceptor pigments. Mesenchymal stromal cells (MSCs) are multipotent cells that can differentiate to lineages of mesenchymaltissues. Here we show that laser (wave length: 405nm) irradiation can control the differentiation of mouse MSCs into osteoblasts by altering the intracellular localization of the circadian rhythm protein CRY1. Laser irradiation promoted osteogenesisof MSCs, induced the translocation of CRY1 protein from the cytoplasm to the nucleus and downregulated CRY1 mRNA levels.
Our results indicate that CRY1 is a master regulator of circadian rhythm that regulates the differentiation of MSCs. Laserirradiation could provide a simple and effective means of controlling the fate of MSCs as a therapeutic strategy. Furthermore, this model system may be useful for exploring the crosstalk between circadian rhythm and cell differentiation.