The Effect Of Low Energy Red LED Light On MC3T3-E1 Cells’ Proliferation And Differentiation

Research background: LED(Light-emitting Diode)red light is a visible light of 600nm~700nm wavelength. Recently, with the technology developing, laser light has been replaced by LED light,low energy LED red light was used in vivo and in vitro experiment and clinical therapy. Previous research has shown that low energy LED red light can play a stimulation effect on cells. For example, Promoting wound healing, cytokines secretion, collagen synthesis and also promoting the proliferation and differentiation of osteoblast-like-cells, restoring the bone defect. Because of the light scattering effect between tissue and cells, there is no difference between laser light and LED light in the aspect of biological effect. And LED light has more advantages than laser light in clinical use, it can produce the irradiation in The three dimensional direction on research object. Farther more LED light also has some advantages, for example Energy saving, cheaper and safer. Some studies show that low energy LED red light can play stimulus effects on cells, tissues, etc. For example, anti-inflammatory, accelerating wound healing and promoting bone marrow stem cells proliferation and differentiation. However, there is few report on the research of low energy red LED light on MC3T3-E1 cells’ proliferation and differentiation. MC3T3-E1 cell line is mouse preosteoblast, it comes from cranium cell of neonatal mouse, it can be differentiated into osteoblast in vitro. So MC3T3-E1 cell line is regarded as a good model in osteoblast differentiation research.Object: This study aimed on investigating the effect of low energy red LED light on MC3T3-E1 cells’ proliferation and differentiation.Methods:Low energy LED red light, wavelength is 635 nm, light power density is 10mW/cm2. Different irradiation time could produce different light energy density. According to the irradiation time, light energy density was set as 0J/cm2、 1J/cm2、2J/cm2、4J/cm2 four groups, irradiation time was 0s, 100 s, 200 s and 400 s. 0J/cm2 group was control group, the other three groups were experimental groups, light irradiation was performed every 24 hrs. CCK-8 assay(Cell Counting Kit-8)was performed at 1st, 2nd and3 rd day on each group. According to the irradiation time, light energy density was set as0J/cm2、2J/cm2、4J/cm2、8J/cm2 four groups, irradiation time was 0s, 200 s, 400 s and 800 s. 0J/cm 2 group was control group, the other three groups were experimental groups, light irradiation was performed every 24 hrs. ALP(Alkaline phosphatase)measurement was used at 6th day on each group cells.Results: There was no significant difference between experimental groups and control group in MC3T3-E1 cell proliferation assay(P﹥0.05);After 635 nm LED red light irradiation 3 days, MC3T3-E1 cells’ was stronger than control group(P﹤0.05). And it was found that when the irradiation time was 200 s and the light energy density was 2J/cm2, the proliferation activity of MC3T3-E1 cells was significantly increased. It was observed in microscope that, after 635 nm LED red light irradiation 6 days, the expression of ALP was shown as positive. when the irradiation time was 400 s and the light energy density was 4J/cm2, the ALP expression level was higher than the other groups.Conclusion: 1. The 635 nm low energy LED red light can play a proliferation effect on MC3T3-E1 cells under certain conditions after light irradiation 3 days.2. The 635 nm low energy LED red light can play a promotion differentiation effect on MC3T3-E1 cells after light irradiation 6 days(the early stage of bone formation differentiation).