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.