Study On The Response Of Bone Marrow Stromal Cells To Different Linear Increase Of Fluid Shear Stress

Cellullar experiments were carried out using the bone marrow stromal cells(BMSCs) derived from SD rats to figure out the mechanical sensitivity of differentlinear increase of fluid shear stress. The mechano-sensitivity responses of BMSCs tofluid shear stress were studied with flow chamber. Firstly, we found that BMSCsdistinguished the three different linear increase of fluid shear stress in terms ofintracellular calcium concentration [Ca2+]itransient, nitric oxide (NO) production andF-actin formation. And the the osteogenic (using alkaline phosphatase, ALP) orchondrogenic (using glycosaminoglycans, GAG) differentiation of BMSCs induced bythe three different linear increase of fluid shear stress was tested. Ultimately, the effectsof mechanosensitive, cation-selective channel on the mechanical responses of BMSCswas studied by employing GdCl3as a inhibitor.The main contents of this research were shown below:BMSCs were exposed to fluid shear stress reaching the peak magnitude of10dyn/cm2from0dyn/cm2in0,2or20min and continuing at10dyn/cm2totally for20min (termed as the groups of0-0’,0-2’ and0-20’ respectively). The loading of0-2’induced the highest response of intracellular calcium concentration [Ca2+]itransient,nitric oxide (NO) production and F-actin formation, followed by0-0’ and0-20’. Tofurther explain the different fluid shear stress increasing slope induced different [Ca2+]iresponse, BMSCs were subjected to stepwise increased fluid shear stress of0.1and1dyn/cm2, corresponding to the shear stress magnitudes in groups of0-2’ and0-20’inducing their [Ca2+]iresponse. However, the stepwise increased shear stress of0.1and1dyn/cm2induced much less [Ca2+]iresponse compared with the groups of0-2’ and0-20’ respectively. And0-2’ and0-0’ respectively facilitated the osteogenic andchondrogenic phenotype in BMSCs after staying in static for another48h. The resultsindicated that the response of BMSCs under fluid shear stress was linear increasesensitive.To study the contribution of mechanosensitive, cation-selective channel on thedifferent linear increase of fluid shear stress induced the different response of BMSCs,BMSCs were treated with GdCl3for30min prior to fluid shear stress stimulation. Theloading of0-0’ induced the highest response of intracellular calcium concentration[Ca2+]itransient, F-actin formation, followed by0-2’ and0-20’. And the GdCl3 inhibition of mechanosensitive, cation-selective channel abrogated the different linearincrease of fluid shear stress induced discrepancy of differentiation.Our results demonstrated that different linear increase of fluid shear stresscontrolled the commitment and differentiation of BMSCs via mechanosensitive,cation-selective channel directed [Ca2+]itransient and F-actin organization, whichoffered another certification of the high mechano-sensitivity of BMSCs and new insightinto the molecular mechanism that mechanical environment controls the fate of stemcell commitment and differentiation, besides the guidance for exercise training ofosteoporosis and osteoarthritis patients.