ABSTRACT
Objective To investigate the effect of fluid shear stress (FSS) on VWF-A1A2A3-mediated expression of platelet surface P-selectin.Methods Using a parallel plate flow chamber system and mouse anti-human CD62P:FITC as the indicator of P-selectin expression,the alteration of platelet P-selectin expression level with increasing exposure time under different FSS conditions (0,1,2 Pa) specifically mediated by VWF-A1A2A3 was observed and analyzed by fluorescence microscope to obtain the activation characteristics.Results FSS triggered platelet activation and P-selectin expression.The activation ratio of platelet was positively regulated by FSS and their exposure time,reaching the maximum value,9.42％ and 14.59％ under FSS of 1 Pa and 2 Pa,respectively.The level of P-selectin expression exhibited two-phase tendency with the shear stress-exposure time increasing,uplifted at first,then decreased,with the best action time at 7.5 min.The fluorescence peak intensity increased when FSS was enhanced.Conclusions The level of platelet P-selectin expression is co-regulated by VWF-A1A2A3 and FSS,and is closely related to force-signaling exposure time.
ABSTRACT
Objective To investigate the effect of fluid shear stress (FSS) on VWF-A1A2A3-mediated expression of platelet surface P-selectin.Methods Using a parallel plate flow chamber system and mouse anti-human CD62P:FITC as the indicator of P-selectin expression,the alteration of platelet P-selectin expression level with increasing exposure time under different FSS conditions (0,1,2 Pa) specifically mediated by VWF-A1A2A3 was observed and analyzed by fluorescence microscope to obtain the activation characteristics.Results FSS triggered platelet activation and P-selectin expression.The activation ratio of platelet was positively regulated by FSS and their exposure time,reaching the maximum value,9.42％ and 14.59％ under FSS of 1 Pa and 2 Pa,respectively.The level of P-selectin expression exhibited two-phase tendency with the shear stress-exposure time increasing,uplifted at first,then decreased,with the best action time at 7.5 min.The fluorescence peak intensity increased when FSS was enhanced.Conclusions The level of platelet P-selectin expression is co-regulated by VWF-A1A2A3 and FSS,and is closely related to force-signaling exposure time.
ABSTRACT
Objective To investigate the effect of fluid shear stress (FSS) on VWF-A1A2A3-mediated expression of platelet surface P-selectin.Methods Using a parallel plate flow chamber system and mouse anti-human CD62P:FITC as the indicator of P-selectin expression,the alteration of platelet P-selectin expression level with increasing exposure time under different FSS conditions (0,1,2 Pa) specifically mediated by VWF-A1A2A3 was observed and analyzed by fluorescence microscope to obtain the activation characteristics.Results FSS triggered platelet activation and P-selectin expression.The activation ratio of platelet was positively regulated by FSS and their exposure time,reaching the maximum value,9.42％ and 14.59％ under FSS of 1 Pa and 2 Pa,respectively.The level of P-selectin expression exhibited two-phase tendency with the shear stress-exposure time increasing,uplifted at first,then decreased,with the best action time at 7.5 min.The fluorescence peak intensity increased when FSS was enhanced.Conclusions The level of platelet P-selectin expression is co-regulated by VWF-A1A2A3 and FSS,and is closely related to force-signaling exposure time.
ABSTRACT
Objective To investigate the effect of fluid shear stress (FSS) on VWF-A1A2A3-mediated expression of platelet surface P-selectin. Methods Using a parallel plate flow chamber system and mouse anti-human CD62P: FITC as the indicator of P-selectin expression, the alteration of platelet P-selectin expression level with increasing exposure time under different FSS conditions (0, 1, 2 Pa) specifically mediated by VWF-A1A2A3 was observed and analyzed by fluorescence microscope to obtain the activation characteristics. Results FSS triggered platelet activation and P-selectin expression. The activation ratio of platelet was positively regulated by FSS and their exposure time, reaching the maximum value, 9.42% and 14.59% under FSS of 1 Pa and 2 Pa, respectively. The level of P-selectin expression exhibited two-phase tendency with the shear stress-exposure time increasing, uplifted at first, then decreased, with the best action time at 7.5 min. The fluorescence peak intensity increased when FSS was enhanced. Conclusions The level of platelet P-selectin expression is co-regulated by VWF-A1A2A3 and FSS, and is closely related to force-signaling exposure time.
ABSTRACT
Objective To investigate the effect of different perfusion flow rates on proliferation and osteoblastic differentiation of human mesenchymal stem cells (hMSCs) in large scale β-TCP (tricalcium phosphate) scaffold at perfusion bioreactor. Methods hMSCs isolated from iliac bone marrow aspiration were loaded into large scale β-TCP scaffold and cultured in perfusion bioreactor at the perfusion flow rate of 3, 6 or 9 mL/min for 15 days. The culture media were collected for D-glucose consumption assay every 3 days. After perfusion culture for 15 days, the cell-scaffold composites were harvested for assessment of cell viability by MTT colorimetric method, SEM observation and osteogenic gene expression by real-time PCR. Results The proliferation of hMSCs assayed by daily glucose consumption showed that at early stage of culture, cells proliferated faster at flow rate of 9 mL/min than at 3 or 6 mL/min (P<0.001); while at late stage of culture, cells proliferated faster at flow rate of 6 mL/min (P<0.05). The cell viability indicated that the cell-scaffold composites at flow rate of 6 mL/min exhibited the most viable cells (P<0.001). SEM indicated that all the macropores of the scaffold at different flow rates were filled with cellular layers. All cellular layers at flow rate of 3 mL/min were incompact, but that at 9 mL/min were compact; at flow rate of 6 mL/min, the cellular layers were either compact or incompact. Real-time PCR revealed that after perfusion culture for 15 days, the mRNA expression of osteobalstic genes including ALP and OP, were enhanced significantly at flow rate of 6 and 9 mL/min as compared to that at 3 mL/min (P<0.01); however, the 9 mL/min group presented the higher OC expression than 3 and 6 mL/min group (P<0.001). Conclusions At early stage of perfusion culture, the proliferation of hMSCs was promoted at flow rate of 9 mL/min, while at late stage, there was more viable cells in scaffolds at flow rate of 6 mL/min. The osteoblastic differentiation of hMSCs was facilitated with the increase of perfusion flow rate, which was attributed to the increased flow shear stress.
ABSTRACT
Objective To study the mechanisms of vascular remodeling induced by hypertension and/or low shear stress, which will be helpful in the prevention, diagnosis and treatment of cardiovascular diseases. Method The models of low shear stress in carotid artery or of hypertension were established by the ligation of partial distal branches of the left common carotid artery (LCA) or by the coarctation of aorta in SD rats, respectively. For some rats, the low shear stress in LCA was accompanied by the hypertension. The wall thickness and the ratio of wall thickness to inner diameter were determined by morphometrical approach. The MMP-2 activity was detected by gel zymography, and the expression of proteins, including p-Akt, Rho GDIα, was verified by Western blotting in LCA. Results When LCA was subjected to hypertension or low shear stress, MMP-2 activity, the wall thickness, and the ratio of wall thickness to inner diameter were all increased significantly. They were further enhanced when the hypertension and low shear stress were both existed, which would speed the vascular remodeling. Low shear stress induced the expression of p Akt, and the lower shear stress, the higher p-Akt expression would be. However, the highest expression of p-Akt was observed in LCA of hypertension accompanied by low shear stress. The expression of Rho GDIα was upregulated in LCA by either low shear stress or hypertension. The highest expression of Rho GDIα was observed in LCA of hypertension accompanied by low shear stress. Conclusions Vascular remodeling could be mostly influenced in LCA subjected to low shear stress accompanied by hypertension, which was also regulated through the changing expression of p-Akt and Rho GDIα.
ABSTRACT
Objective To investigate the specific roles of gap junction and ATP in mechanical stimulation induced calcium transfer in osteoblasts. Methods The isolated osteoblastic pattern without gap junctions was established by using the micropatterning method. Then fluid shear stress was applied on cells using the flow chamber to observe and analyze the characteristic parameters of calcium response. Results Multiple calcium response still occurred in osteoblastic pattern without gap junction, but the response time to the first responsive peak was much longer than that with gap junction. When the intracellular and extracellular calcium ions were removed, only 40% cells responded to the mechanical stimulation, with single peak and multiple peaks accounting for 50%, respectively. If ATP pathway was blocked, only 20% cells responded, most of which showed single peak. Conclusions ATP was the major pathway mediating intercellular calcium transfer, while the gap junction was not the necessary one.