As an important branch of biomedical engineering, respiratory mechanics helps to understand the physiology of the respiratory system and provides fundamental data for developing such clinical technologies as ventilato...As an important branch of biomedical engineering, respiratory mechanics helps to understand the physiology of the respiratory system and provides fundamental data for developing such clinical technologies as ventilators. To solve different clinical problems, researchers have developed numerous models at various scales that describe biological and mechanical properties of the respiratory system. During the past decade, benefiting from the continuous accumulation of clinical data and the dramatic progress of biomedical technologies （e.g. biomedical imaging）, the theoretical modeling of respiratory mechanics has made remarkable progress regarding the macroscopic properties of the respiratory process, complexities of the respiratory system, gas exchange within the lungs, and the coupling interaction between lung and heart. The present paper reviews the advances in the above fields and proposes potential future projects.展开更多
Cell adhesion and migration are basic physiolog- ical processes in living organisms. Cells can actively probe their mechanical micro-environment and respond to the ex- ternal stimuli through cell adhesion. Cells need ...Cell adhesion and migration are basic physiolog- ical processes in living organisms. Cells can actively probe their mechanical micro-environment and respond to the ex- ternal stimuli through cell adhesion. Cells need to move to the targeting place to perform function via cell migration. For adherent cells, cell migration is mediated by cell-matrix adhesion and cell-cell adhesion. Experimental approaches, especially at early stage of investigation, are indispensable to studies of cell mechanics when even qualitative behaviors of cell as well as fundamental factors in cell behaviors are unclear. Currently, there is increasingly accumulation of ex- perimental data of measurement, thus a quantitative formula- tion of cell behaviors and the relationship among these fun- damental factors are highly needed. This quantitative under- standing should be crucial to tissue engineering and biomed- ical engineering when people want to accurately regulate or control cell behaviors from single cell level to tissue level. In this review, we will elaborate recent advances in the ex- perimental and theoretical studies on cell adhesion and mi- gration, with particular focuses laid on recent advances in experimental techniques and theoretical modeling, through which challenging problems in the cell mechanics are sug- gested.展开更多
Coronary restenosis is an important cause of poor long-term prognosis in patients with coronary heart disease.Here,we show that lysine methyltransferase SMYD2 expression in the nucleus is significantly elevated in ser...Coronary restenosis is an important cause of poor long-term prognosis in patients with coronary heart disease.Here,we show that lysine methyltransferase SMYD2 expression in the nucleus is significantly elevated in serum-and PDGF-BB-induced vascular smooth muscle cells(VSMCs),and in tissues of carotid artery injury-induced neointimal hyperplasia.Smyd2 overexpression in VSMCs(Smyd2-vTg)facilitates,but treatment with its specific inhibitor LLY-507 or SMYD2 knockdown significantly inhibits VSMC phenotypic switching and carotid artery injury-induced neointima formation in mice.Transcriptome sequencing revealed that SMYD2 knockdown represses the expression of serum response factor(SRF)target genes and that SRF overexpression largely reverses the inhibitory effect of SMYD2 knockdown on VSMC proliferation.HDAC3 directly interacts with and deacetylates SRF,which enhances SRF transcriptional activity in VSMCs.Moreover,SMYD2 promotes HDAC3 expression via tri-methylation of H3K36 at its promoter.RGFP966,a specific inhibitor of HDAC3,not only counteracts the pro-proliferation effect of SMYD2 overexpression on VSMCs,but also inhibits carotid artery injury-induced neointima formation in mice.HDAC3 partially abolishes the inhibitory effect of SMYD2 knockdown on VSMC proliferation in a deacetylase activity-dependent manner.Our results reveal that the SMYD2-HDAC3-SRF axis constitutes a novel and critical epigenetic mechanism that regulates VSMC phenotypic switching and neointimal hyperplasia.展开更多
Dynamic remodeling of bone tissue is mediated by the synergistic effects of osteoblast-driven bone formation and Osteoclast-dominated bone resorption.However,how bone cells perceive the mechanical stimuli and regulate...Dynamic remodeling of bone tissue is mediated by the synergistic effects of osteoblast-driven bone formation and Osteoclast-dominated bone resorption.However,how bone cells perceive the mechanical stimuli and regulate bone remodeling have not been fully understood.This study aims to evaluate the effect of cyclic compression loading on trabecular microstructure for 42 days and identify the relationship between the evolution of trabecular microstructure and cell distribution.The eighth caudal vertebrae of rats were subjected to long-term cyclic compression loading with different frequencies.The compression displacement is 1 mm.In vivo micro-computed tomography was performed at 0,14,28 and 42 days to determine the structural parameters.The bone volume fraction(BV/TV)in the 1 Hz cyclic compression loading group was significantly higher than that in the control and 10 Hz groups,whereas the trabecular separation(Tb.Sp)was significantly lower.The 10 Hz cyclic compression group had the lowest BV/TV and highest Tb.Sp.After 14 days of loading,the BV/TV values of 1 Hz group were 29.62%and 41.6%higher than those of the control and 10 Hz groups,respectively.Conversely,the Tb.Sp of 1 Hz group was approximately 12.33%and 16.52%lower than that of the control and 10 Hz group,respectively.More bone formation and less bone resorption were observed in the 1 Hz group than the control group.In addition,more osteoblasts were attached to the area of bone formation,while more osteoclasts were located in the area of bone resorption.These findings may provide a basis for further understanding mechanical stimulation-regulated bone remodeling.展开更多
Focal adhesions are large macromolecular assemblies through which cells are connected with the extracellular matrix so that extracellular signals can be transmitted inside cells.Some studies have focused on the effect...Focal adhesions are large macromolecular assemblies through which cells are connected with the extracellular matrix so that extracellular signals can be transmitted inside cells.Some studies have focused on the effect of cell shape on the differentiation of stem cells,but little attention has been paid to focal adhesion.In the present study,mesenchymal stem cells(MSCs)and osteoblast-like MC3T3-E1 cells were seeded onto micropatterned substrates on which circular adhesive islands with different spacing and area were created for focal adhesion.Results showed that the patterns of focal adhesion changed cell morphology but did not affect cell survival.For MSCs cultured for 3 days,patterns with small circles and large spacing promoted osteogenesis.For MSCs cultured for 7 days,patterns with large circles and spacing enhanced osteogenesis.For MC3T3-E1 cells,the patterns of focal adhesion had no effect on cell differentiation after 3 days of culture,but patterns with small circles and spacing improved osteogenic differentiation after 7 days.Moreover,the assembly of F-actin,phosphorylation of myosin,and nuclear translocation of yes-associated proteins(YAP)were consistent with the expression of differentiation markers,indicating that the pattern of focal adhesion may affect the osteogenesis of MSCs and osteoblasts through changes in cytoskeletal tension and nuclear localisation of YAP.展开更多
Mesenchymal stem pells(MSCs)have been extensively used in the field of tissue engineering and regenerative medicine.The effect of surface properties on the differentiation of MSCs is a very important issue for the des...Mesenchymal stem pells(MSCs)have been extensively used in the field of tissue engineering and regenerative medicine.The effect of surface properties on the differentiation of MSCs is a very important issue for the design and fabrication of scaffolds or biomaterials.This review is mainly focused on the morphological or topographic characteristics of cell adhesion substrate,i.e.cell area and shape for individual cell,cell density and cell-cell contact for multiple cells,substrate roughnessridge width,micropillar height,nanoparticle diameter and aspect ratio of nanowire.The results from different studies were quantitativcly analyzed using comparable or unified parameters and definitions under the specific experimental conditions such as cell source,culture time,induction medium,matrix material and differentiation marker.Some interesting phenomena and properties were discovered by this integrated and systematic analysis,which might give insights into the regulatory mechanism of surface morphology or topography on MSCs differentiation.展开更多
基金supported by the National High Technology Research and Development Program of China (2009AA02Z407)the National Natural Science Foundation of China (30970707)
文摘As an important branch of biomedical engineering, respiratory mechanics helps to understand the physiology of the respiratory system and provides fundamental data for developing such clinical technologies as ventilators. To solve different clinical problems, researchers have developed numerous models at various scales that describe biological and mechanical properties of the respiratory system. During the past decade, benefiting from the continuous accumulation of clinical data and the dramatic progress of biomedical technologies （e.g. biomedical imaging）, the theoretical modeling of respiratory mechanics has made remarkable progress regarding the macroscopic properties of the respiratory process, complexities of the respiratory system, gas exchange within the lungs, and the coupling interaction between lung and heart. The present paper reviews the advances in the above fields and proposes potential future projects.
基金supported by the National Natural Science Foundation of China(11221202and11025208)the State Key Laboratory of Explosive Science and Technology of Beijing Institute of Technology(YBKT12-05)
文摘Cell adhesion and migration are basic physiolog- ical processes in living organisms. Cells can actively probe their mechanical micro-environment and respond to the ex- ternal stimuli through cell adhesion. Cells need to move to the targeting place to perform function via cell migration. For adherent cells, cell migration is mediated by cell-matrix adhesion and cell-cell adhesion. Experimental approaches, especially at early stage of investigation, are indispensable to studies of cell mechanics when even qualitative behaviors of cell as well as fundamental factors in cell behaviors are unclear. Currently, there is increasingly accumulation of ex- perimental data of measurement, thus a quantitative formula- tion of cell behaviors and the relationship among these fun- damental factors are highly needed. This quantitative under- standing should be crucial to tissue engineering and biomed- ical engineering when people want to accurately regulate or control cell behaviors from single cell level to tissue level. In this review, we will elaborate recent advances in the ex- perimental and theoretical studies on cell adhesion and mi- gration, with particular focuses laid on recent advances in experimental techniques and theoretical modeling, through which challenging problems in the cell mechanics are sug- gested.
基金supported by grants from the National Natural Science Foundation of China(Nos.81974013 and 82270512).
文摘Coronary restenosis is an important cause of poor long-term prognosis in patients with coronary heart disease.Here,we show that lysine methyltransferase SMYD2 expression in the nucleus is significantly elevated in serum-and PDGF-BB-induced vascular smooth muscle cells(VSMCs),and in tissues of carotid artery injury-induced neointimal hyperplasia.Smyd2 overexpression in VSMCs(Smyd2-vTg)facilitates,but treatment with its specific inhibitor LLY-507 or SMYD2 knockdown significantly inhibits VSMC phenotypic switching and carotid artery injury-induced neointima formation in mice.Transcriptome sequencing revealed that SMYD2 knockdown represses the expression of serum response factor(SRF)target genes and that SRF overexpression largely reverses the inhibitory effect of SMYD2 knockdown on VSMC proliferation.HDAC3 directly interacts with and deacetylates SRF,which enhances SRF transcriptional activity in VSMCs.Moreover,SMYD2 promotes HDAC3 expression via tri-methylation of H3K36 at its promoter.RGFP966,a specific inhibitor of HDAC3,not only counteracts the pro-proliferation effect of SMYD2 overexpression on VSMCs,but also inhibits carotid artery injury-induced neointima formation in mice.HDAC3 partially abolishes the inhibitory effect of SMYD2 knockdown on VSMC proliferation in a deacetylase activity-dependent manner.Our results reveal that the SMYD2-HDAC3-SRF axis constitutes a novel and critical epigenetic mechanism that regulates VSMC phenotypic switching and neointimal hyperplasia.
基金This work was supported by the National Natural Science Foundation of China[grant numbers:11572043 and 11372043,BH,12102047,YG].
文摘Dynamic remodeling of bone tissue is mediated by the synergistic effects of osteoblast-driven bone formation and Osteoclast-dominated bone resorption.However,how bone cells perceive the mechanical stimuli and regulate bone remodeling have not been fully understood.This study aims to evaluate the effect of cyclic compression loading on trabecular microstructure for 42 days and identify the relationship between the evolution of trabecular microstructure and cell distribution.The eighth caudal vertebrae of rats were subjected to long-term cyclic compression loading with different frequencies.The compression displacement is 1 mm.In vivo micro-computed tomography was performed at 0,14,28 and 42 days to determine the structural parameters.The bone volume fraction(BV/TV)in the 1 Hz cyclic compression loading group was significantly higher than that in the control and 10 Hz groups,whereas the trabecular separation(Tb.Sp)was significantly lower.The 10 Hz cyclic compression group had the lowest BV/TV and highest Tb.Sp.After 14 days of loading,the BV/TV values of 1 Hz group were 29.62%and 41.6%higher than those of the control and 10 Hz groups,respectively.Conversely,the Tb.Sp of 1 Hz group was approximately 12.33%and 16.52%lower than that of the control and 10 Hz group,respectively.More bone formation and less bone resorption were observed in the 1 Hz group than the control group.In addition,more osteoblasts were attached to the area of bone formation,while more osteoclasts were located in the area of bone resorption.These findings may provide a basis for further understanding mechanical stimulation-regulated bone remodeling.
基金supported by the National Key R&D Program of China,No.2018YFF0300800the National Natural Science Foundation of China,Nos.11572043 and 11372043(all to BH).
文摘Focal adhesions are large macromolecular assemblies through which cells are connected with the extracellular matrix so that extracellular signals can be transmitted inside cells.Some studies have focused on the effect of cell shape on the differentiation of stem cells,but little attention has been paid to focal adhesion.In the present study,mesenchymal stem cells(MSCs)and osteoblast-like MC3T3-E1 cells were seeded onto micropatterned substrates on which circular adhesive islands with different spacing and area were created for focal adhesion.Results showed that the patterns of focal adhesion changed cell morphology but did not affect cell survival.For MSCs cultured for 3 days,patterns with small circles and large spacing promoted osteogenesis.For MSCs cultured for 7 days,patterns with large circles and spacing enhanced osteogenesis.For MC3T3-E1 cells,the patterns of focal adhesion had no effect on cell differentiation after 3 days of culture,but patterns with small circles and spacing improved osteogenic differentiation after 7 days.Moreover,the assembly of F-actin,phosphorylation of myosin,and nuclear translocation of yes-associated proteins(YAP)were consistent with the expression of differentiation markers,indicating that the pattern of focal adhesion may affect the osteogenesis of MSCs and osteoblasts through changes in cytoskeletal tension and nuclear localisation of YAP.
基金the National Natural Science Foundation of China[Grants 11572043 and 11372043(BH)].
文摘Mesenchymal stem pells(MSCs)have been extensively used in the field of tissue engineering and regenerative medicine.The effect of surface properties on the differentiation of MSCs is a very important issue for the design and fabrication of scaffolds or biomaterials.This review is mainly focused on the morphological or topographic characteristics of cell adhesion substrate,i.e.cell area and shape for individual cell,cell density and cell-cell contact for multiple cells,substrate roughnessridge width,micropillar height,nanoparticle diameter and aspect ratio of nanowire.The results from different studies were quantitativcly analyzed using comparable or unified parameters and definitions under the specific experimental conditions such as cell source,culture time,induction medium,matrix material and differentiation marker.Some interesting phenomena and properties were discovered by this integrated and systematic analysis,which might give insights into the regulatory mechanism of surface morphology or topography on MSCs differentiation.
