Photobiomodulation Effect of Diode Laser on Differentiation of Osteoprogenitor Cells in Rat Bone Marrow.

BACKGROUND/AIM: Bone marrow cells contain nonhematopoietic cells with the ability to differentiate into osteogenic, chondrogenic, and adipogenic lineages. Mechanical stress influences osteoblast differentiation of bone marrow cells into osteogenic, chondrogenic, and adipogenic lineages, measurable as the abundance of alkaline phosphatase-positive (ALP+) colony-forming unit-fibroblasts (CFU-F); however, the effect of diode laser irradiation on osteoblast differentiation is unknown. The aim of this study was to analyze the effects of photobiomodulation on the osteogenic differentiation of mesenchymal stem cells in the bone marrow, using the CFU-F assay. MATERIALS AND METHODS: Bone marrow cells isolated from rat tibiae were cultured and irradiated with a diode laser (wavelength 808 nm) at a total energy of 0 J (control), 50 J, and 150 J. RESULTS: On day 7 after irradiation, ALP+ CFU-F were most abundant in the 50 J group and the least abundant in the 150 J group. Mineralized nodule formation was observed after long-term culture (21 days). Compared with the control group, there were significantly more nodules in the 50 J group and significantly fewer nodules in the 150 J group. Osteocalcin mRNA expression was highest in the 50 J group, and there was no difference between the control and 150 J groups. CONCLUSION: Irradiation with 50 J was effective in stimulating osteogenesis in bone marrow stem cells. These findings suggest that diode laser irradiation can induce osteogenesis in rat bone marrow cells in an energy-dependent manner, and appears suitable for application in bone regeneration therapy.

Establishment of a Primary Culture System of Human Periodontal Ligament Cells that Differentiate into Cementum Protein 1-expressing Cementoblast-like Cells.

BACKGROUND/AIM: A better understanding of cementogenesis and cementoblast differentiation would be useful for periodontal therapy. The aim of this study was to establish a cell culture system that reflects cementum formation in periodontal tissue and determine whether or not isolated and cultured primary human periodontal ligament (PDL) cells could be used for the study of the differentiation of cementoblast. MATERIALS AND METHODS: PDL cells were isolated from the outgrowths of tissue fragments of human PDL. PDL cells were incubated for up to 21 days in differentiation medium containing ß-glycerophosphate and ascorbic acid. The changes in the cells were detected by alkaline phosphatase (ALP) and von Kossa staining. Real-time polymerase chain reaction was also performed for cementum protein 1 (CEMP1), which is a specific marker of cementoblasts and their progenitors. RESULTS: On day 5, a small number of PDL cells, which were fibrous, were positive for ALP. On day 7, almost all cells were positive for ALP. On day 14, mineralization nodules appeared, as seen by positive von Kossa staining; the nodules increased in number and size by day 21. The expression of CEMP1 was detected on day 5, and its expression level increased gradually by day 7, reached a peak on day 14, and decreased by day 21. CONCLUSION: Human PDL cells were used to establish a culture system that reflects cementum formation. Our results suggested that this culture method is convenient and useful for the study of cementogenesis and cementoblast differentiation.