Effects Of Photobiomodulation On Osteogenic Differentiation Of Human Umbilical Mesenchymal Stem Cells

It is difficult to repair bone defects by regeneration and remodeling.Autogenous and allogeneic bone grafts often lead to bone resorption or secondary injury.The development of tissue engineering provides a new choice for bone repair.Photobiomodulatory（PBM）is more and more widely used in medical field because of its non-invasive,high efficiency and no side effects.Objective:the aim of this study was to investigate the direct effect of PBM and the effect of silk fibroin/polycaprolactone（SF/PCL）membrane on osteogenic differentiation of human umbilical cord mesenchymal stem cells（（hUCMSCs））.Methods:The hUCMSCs markers and differentiation ability were identified,and the growth curve was drawn.The effect of cells on cell proliferation at 635 nm wavelength and different power density was detected,and the concentration of dexamethasone was screened by measuring alkaline phosphatase（ALP）activity and cell growth status.ALP staining and activity,mineralized nodule staining and osteogenic gene expression were studied by induction solution combined with laser irradiation to detect the effect of induced differentiation.HUCMSCs was inoculated on SF/PCL membrane to detect the adhesion state and activity,and after laser induction,the ALP activity,secretory factors in the supernatant and the expression level of osteogenic gene in the supernatant were detected.Results:After 635 nm laser irradiation,the proliferation rate of hUCMSCs was significantly higher than that of the control group,and there was no difference in cell stimulation at the same wavelength and different power density.The induced concentration of dexamethasone was 10^-8 mol/L.The results of induction solution combined with laser irradiation showed that after 808 nm laser irradiation,ALP staining and activity determination were better than those of the control group,with the deepest staining of mineralized nodules at the energy density of 4 J/cm².At the same time,the changes of osteogenic genes（BMP-2,Col-1,OCN）were also the most significant.After laser irradiation,ALP qualitative and quantitative analysis,Elisa detection of the secretion of BMP-2,Col-1 and OCN and the expression of osteogenic genes Runx2,ALP and OCN showed that the osteogenic induction of 808 nm was better than that of 635 nm,and 808 nm 2 J/cm² was the best.Conclusion:laser irradiation can promote the proliferation of hUCMSCs,enhance the expression of osteogenic genes and accelerate the osteogenic differentiation of hUCMSCs.SF/PCL membrane has good compatibility with hUCMSCs.Combined with PBM can accelerate the osteogenic rate of hUCMSCs and provide a new idea for bone tissue engineering.