The Role Of Notch Signaling Pathway In The Effect Of Infrasound On The Growth Of Bone Marrow Mescenchymal Stem Cells

BackgroundBone marrow mesenchymal stem cells(BMSCs)are a class of stem cells derived from the mesoderm with self-renewal and multi-directional differentiation potential.Since they are able to get autografts,easy to culture in vitro,quick to proliferate without ethical limitation,BMSCs has become the ideal seed cells in tissue engineering.There are a lot of studies shows transplantation of BMSCs is applied to treating clinical diseases including spinal cord injury,cerebrovascular disease,brain injury,Parkinson's disease and so on,which is one of the most promising treatments.However,due to the low survival rate of BMSCs transplanted in damaged central nervous system,it is critical to improve the survival rate of BMSCs transplantation.Low sound pressure infrasound is defined as infrasound wave under 90 dB,which exists widely in the natural environment,transportation,industrial production and daily life.The biological effect of low sound pressure level infrasound has been gradually applied in medical research.More and more scholars paid attention to the therapeutic effect of low sound pressure infrasound.In our previous study,we proved that low sound pressure infrasound could stimulate the proliferation and inhibit the apoptosis of BMSCs in 60 min,but the precise mechanisms controlling this process remain unclear yet.Notch signaling is an important signaling pathway that determines the destiny of cell,which involved in the proliferation,apoptosis and differentiation of nearly all cells.The Notchl-Jaggedl pathway exists in BMSCs indicates Notch signaling system can regulate BMSCs in vitro,and DAPT is a y-secretase inhibitor that blocks Notch signaling pathways.In this study,we investigate the effect of infrasound and DAPT on the biological activity of BMSCs.And in order to explore the molecular mechanisms about how infrasound promote BMSCs proliferation,we make further study to explore the relationship between Notch signaling pathway and low sound pressure infrasound on BMSCs,to provide theoretical basis for application of BMSCs combined with low sound pressure infrasound to treat related diseases.ObjectiveThe aim was to investigate the role of Notch signaling pathway in the effect of infrasound on the biological activity of BMSCs.Experimental methodThe primary BMSCs were derived from Sprague-Dawley rats through whole bone marrow adherent cultivation.The cells of passage 3 were randomly divided into 4 groups with different treatments as follow:group 1(DAPT without infrasound),group 2(DAPT with infrasound),group 3(without any treatment)and group 4(infrasound without DAPT).The proliferation of BMSCs above 4 groups was measured by MTT assay,RT-PCR and Western blot were used to detect the expression of Notchl,Jaggedl,Hes1 mRNA and protein respectively.Statistical analysisThe data were analyzed using SPSS version 20.0 software,and all the results are presented as the means ± standard deviation for each group.The results of MTT,RT-PCR and western bolt were analyzed with one-way analysis of variance and LSD method was used to analyze the difference between groups.A difference of P<0.05 was considered to indicate a statistically significant difference.Experimental results1.After being treated with infrasound for 24h,48h,72h and 96h,the optical density(OD)value of group 3 is significantly higher than group 1,group 4 significantly higher than group 2(P<0.05).The OD value of group 4 treated with infrasound for 24h,48h,72h is significantly higher than that in group 3(P<0.05).The OD value of four groups gradually increase and group 4 was the highest(4>3>2>1).2.The expression of Notch signaling pathway related genes and protein was detected by RT-PCR and Western blot.Compared with group3,we found that the expression of Jaggedl,Notchl and Hesl mRNA and protein of BMSCs were significantly increasing under only intervention of low sound pressure infrasound,and the difference was statistically significant(P<0.05).After using ?-secretase inhibitor,we observed that the Jaggedl,Notchl and Hesl mRNA and Protein were significantly decreased,particularly the remarkable reduction of Hesl.When Notch signaling was inhibited,low sound pressure infrasound couldn't decrease or increase Jagged 1,Notchl and Hesl protein and mRNA of BMSCs significantly,there were not significantly different between group 1 and group 2(P>0.05).Conclusion1.Low pressure infrasound could promote the proliferation of BMSCs,when DAPT inhibits Notch signaling pathway,the proliferation of BMSCs can be inhibited.2.The expression of Jaggedl,Notchl and Hesl protein and mRNA of BMSCs were increased while the low pressure infrasound promote the proliferation of BMSCs,and it was presumed that the mechanism of low sound pressure infrasound to promote the proliferation of BMSCs might be through activation of Notch signaling pathway,to provide theoretical basis for application of BMSCs combined with low sound pressure infrasound to treat diseases.