Objective To establish a body composition analysis system based on chest CT,and to observe its value for evaluating content of chest muscle and adipose.Methods T7—T8 layer CT images of 108 pneumonia patients were col...Objective To establish a body composition analysis system based on chest CT,and to observe its value for evaluating content of chest muscle and adipose.Methods T7—T8 layer CT images of 108 pneumonia patients were collected(segmented dataset),and chest CT data of 984 patients were screened from the COVID 19-CT dataset(10 cases were randomly selected as whole test dataset,the remaining 974 cases were selected as layer selection dataset).T7—T8 layer was classified based on convolutional neural network(CNN)derived networks,including ResNet,ResNeXt,MobileNet,ShuffleNet,DenseNet,EfficientNet and ConvNeXt,then the accuracy,precision,recall and specificity were used to evaluate the performance of layer selection dataset.The skeletal muscle(SM),subcutaneous adipose tissue(SAT),intermuscular adipose tissue(IMAT)and visceral adipose tissue(VAT)were segmented using classical fully CNN(FCN)derived network,including FCN,SegNet,UNet,Attention UNet,UNET++,nnUNet,UNeXt and CMUNeXt,then Dice similarity coefficient(DSC),intersection over union(IoU)and 95 Hausdorff distance(HD)were used to evaluate the performance of segmented dataset.The automatic body composition analysis system was constructed based on optimal layer selection network and segmentation network,the mean absolute error(MAE),root mean squared error(RMSE)and standard deviation(SD)of MAE were used to evaluate the performance of automatic system for testing the whole test dataset.Results The accuracy,precision,recall and specificity of DenseNet network for automatically classifying T7—T8 layer from chest CT images was 95.06%,84.83%,92.27%and 95.78%,respectively,which were all higher than those of the other layer selection networks.In segmentation of SM,SAT,IMAT and overall,DSC and IoU of UNet++network were all higher,while 95HD of UNet++network were all lower than those of the other segmentation networks.Using DenseNet as the layer selection network and UNet++as the segmentation network,MAE of the automatic body composition analysis system for predicting SM,SAT,IMAT,VAT and MAE was 27.09,6.95,6.65 and 3.35 cm 2,respectively.Conclusion The body composition analysis system based on chest CT could be used to assess content of chest muscle and adipose.Among them,the UNet++network had better segmentation performance in adipose tissue than SM.展开更多
The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction...The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.展开更多
PZT-based valveless micropump is a microactuator that can be used for controlling and delivering tiny amounts of fluids,and diffuser/nozzle plays an important role when this type of micropump drives the fluid flowing ...PZT-based valveless micropump is a microactuator that can be used for controlling and delivering tiny amounts of fluids,and diffuser/nozzle plays an important role when this type of micropump drives the fluid flowing along a specific direction.In this paper,a numerical model of micropump has been proposed,and the fluidic properties of diffuser/nozzle have been simulated with ANSYS.With the method of finite-element analysis,the increased pressure drop between inlet and outlet of diffuser/nozzle induces the increment of flow rate in both diffuser and nozzle simultaneously,but the increasing rate of diffuser is faster than that of nozzle.The L/R,ratio of L(length of cone pipe) and R(radius of minimal cross section of cone pipe) plays an important role in fluidic performance of diffuser and nozzle as well,and the mean flow rate will decrease with increment of L/R.The mean flow rate reaches its peak value when L/R with the value of 10 regardless the divergence angle of diffuser or nozzle.The simulation results indicate that the fluidic properties of diffuser/nozzle can be defined by its geometric structure,and accordingly determine the efficiency of micropump.展开更多
Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissu...Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissue.However,maintaining the viability of a thick tissue structure during tissue growth and maturation is challenging due to lack of adequate vascular perfusion.In a simple tissue model with展开更多
The brain tumor perivascular niche(PVN),the region in the vicinity of microvessels is a prime location for brain tumor stem-like cells(BTSCs)[1].Tumor microvasculature creates a complex microenvironment consisting of ...The brain tumor perivascular niche(PVN),the region in the vicinity of microvessels is a prime location for brain tumor stem-like cells(BTSCs)[1].Tumor microvasculature creates a complex microenvironment consisting of various cell types,the extracellular matrix,and soluble factors that mediate cell-cell interaction.The brain tumor PVN controls maintenance,expansion,and differentiation of BTSCs via direct cell contact or paracrine signaling cues.BTSCs often receive bidirectional crosstalk from endothelial cells and other cell types in the niche[2].In addition,the perivascular zone may serve as a path for tumor cells to migrate over long distances(3,4)Unlike other solid tumors,glioblastoma multiforme(GBM)cells rarely metastasize to other organs,but they can invade the entire brain by migrating along specific brain tissue structures,such as blood vessels or white matter tracts,leading to high rates of relapse.Despite the success in modeling diffuse brain tumors in both genetically-modified and patient-derived xenograft(PDX)animals,there is an unmet need for an in vitro system that can bridge conventional cell culture and animal models by mimicking not only the anatomy but also the function of the PVN to study the dynamics of BTSCs.In this presentation,I will describe the use of a microvasculature-on-a-chip system as a PVN model to evaluate the dynamics of BTSCs ex vivo from 10 glioblastoma patients [5].We observed that BTSCs preferentially localize in the perivascular zone.Live cell tracking showed that the cells residing in the vicinity of microvessels had the lowest motility,while a fraction of cells on the microvessels unexpectedly possessed the highest motility and migrated over the longest distance.These results indicate that the perivascular zone is a niche for BTSCs,while the microvascular tracks are also a path for long-distance tumor cell migration and invasion.Additionally,the degree of co-localization between tumor cells and microvessels varied significantly across patients.To validate the results from our microvasculature-on-a-chip system,we used single-cell transcriptome sequencing(10 patients and 21,750 single cells in total)to identify the subtype of each tumor cell.The co-localization coefficient was found to correlate positively with proneural(stem-like)or mesenchymal(invasive)but not classical(proliferative)tumor cells.Furthermore,we found that a gene signature profile including PDGFRA correlated strongly with the'homing'of brain tumor cells to the PVN.Our findings demonstrated that ex vivo dynamics of human brain tumor cells in a microvasculature-on-a-chip model can recapitulate in vivo tumor cell dynamics,heterogeneity,and subtypes,representing a new route to the study of human tumor cell biology and uncover patient-specific tumor cell functions.Acknowledgments:We thank Drs.Laura Niklason,Eric Holland,Franziska Michor,and Frank Szulzewsky for scientific discussion.We thank Misha Guy,Vladimir Polejaev,Zhenting Jiang,and Alice Yun for suggestions and help on the simulation computing and SEM/confocal imaging process.This research was supported by the Packard Fellowship for Science and Engineering(R.F.),National Science Foundation CAREER Award CBET-1351443(R.F.),U54 CA193461(R.F.),U54CA209992(Sub-Project ID:7297 to R.F.),R01 NS095817(J.Z.),Yale Cancer Center Co-Pilot Grant(to R.F.).The molds for microfluidic devices were fabricated in the Yale School of Engineering and Applied Science cleanroom.Sequencing was performed at the Yale Center for Genome Analysis(YCGA)facility.Data was analyzed at Yale High Performance Computing(HPC)center.Super resolution confocal imaging was performed at Yale Center for Cellular and Molecular Imaging(CCMI).展开更多
In this work, we analyzed only the patients of the NSTEMI (non ST-segment elevation myocardial infarction) who arrived at the hospital within 12 h after symptoms started. Using NSTEMI follow-up data within, the charac...In this work, we analyzed only the patients of the NSTEMI (non ST-segment elevation myocardial infarction) who arrived at the hospital within 12 h after symptoms started. Using NSTEMI follow-up data within, the characteristics of the clinical data, the risk factor, and the blood tested in the hospital visit were analyzed for MACE (major adverse cardiac events) patients. MACE includes cardiac death, MI (myocardial infarction), Re-PCI, and CABG (coronary artery bypass graft). As a result, from the NSTEMI patients which can be followed up for over 12 m, NT-ProBNP (p=0.014) and age (p=0.045) are found to be the independent risk factors related to MACE. Accordingly, they can be useful for the diagnosis and prognosis for NSTEMI patients as a biomarker.展开更多
Synergic movement of finger's joints provides human hand tremendous dexterities,and the detection of kinematics parameters is critical to describe and evaluate the kinesiology functions of the fingers.The present ...Synergic movement of finger's joints provides human hand tremendous dexterities,and the detection of kinematics parameters is critical to describe and evaluate the kinesiology functions of the fingers.The present work is the attempt to investigate how the angular velocity and angular acceleration of the joints of index finger vary with respect to time during conducting a motor task.A high-speed video camera has been employed to visually record the movement of index finger,and miniaturized(5-mm diameter) reflective markers have affixed to the subject's index finger on the side close to thumb and dorsum of thumb at different joint landmarks.Captured images have been reviewed frame by frame to get the coordinate values of each joint,and the angular displacements,angular velocities and angular acceleration can be obtained with triangle function.The experiment results show that the methods here can detect the kinematics parameters of index finger joints during moving,and can be a valid route to study the motor function of index finger.展开更多
In this study,we hypothesized that Piezo 1 channels mediate the compression-enhanced invasive phenotype of cancer cells via a caveolae-dependent mechanism.To test this hypothesis,we examined in vitro cultured human br...In this study,we hypothesized that Piezo 1 channels mediate the compression-enhanced invasive phenotype of cancer cells via a caveolae-dependent mechanism.To test this hypothesis,we examined in vitro cultured human breast cancer cells for their ability to invade and degrade extracellular matrix in the presence or absence of compressive stress,together with corresponding changes in Piezo1 as well as cytoskeletal remodeling and calcium signaling.Here we show that compressive stress enhanced invasion,matrix degradation,and invadopodia formation of breast cancer cells.We further identified Piezo1 as the putative mechanosensitive cellular component that transmits compression to induce calcium influx,which in turn triggers several downstream pathways.Interestingly,for the first time we observed inv-adopodia with matrix degradation ability on the apical side of the cells, similar to those commonly observed at the cell s ventral side.Furthermore,we demonstrate that Piezo1 and caveolae were both involved in mediating the compressive stress-induced cancer cell invasive phenotype as Piezo 1 and caveolae were often colocalized,and reduction of Cav-1 expression or disruption of caveolae with methyl-β-cyclodextrin led to not only reduced Piezo1 expression but also attenuation of the invasive phenotypes promoted by compressive stress.Taken together,we first observed that in breast cancer cells,simulating uncontrolled growth-induced compressive stress enhanced cancer cell invasion,matrix degradation,and invadopodia and stress fiber formation.Our study also confirmed that Piezo1 channels are highly expressed in breast cancer cells compared to normal breast cells,and is consistent with the data that compressive stress regulates cell migration of breast cancer cells but not normal breast cells.Additionally,we identified that Piezol mediated these processes and the invasive phenotypes also depended on the integrity of caveolae.These findings provide the first demonstration that compressive stress enhances matrix degradation by breast cancer cells and Piezo1 is an essential mechanosensor and transducer for such stress in breast cancer.Additionally,our data supports the model where caveolae might be the'mechanical force foci'which concentrates Piezol to facilitate force sensing and transduction in mammalian cells.Our work may have relevance to human tumors in vivo.As solid tumor experiences high compressive stress due to uncontrolled proliferation and confinement by the stiff extracellular matrix environment,this microenvironment facilitates compression-enhanced cell invasion.The identification of Piezo1’s crucial role in this process provides the first demonstration of the dependence of Piezo1 channels on the response of breast cancer cells to physiological compressive stress.The functional dependence of Piezo1 on caveolae further highlights the importance of membrane organization and composition on forcegated ion channels.Both of these findings underscore the cardinal role that Piezo1 channels play in regulating cell invasion and may inspire further development targeting Piezol as a potential cancer therapeutic target.展开更多
Introduction Cells can sense and respond to the mechanical microenvironment by converting forces into biochemical signals inside the cells,i.e.mechanotransduction<sup>[1-3]</sup>.Focal adhesions are the ma...Introduction Cells can sense and respond to the mechanical microenvironment by converting forces into biochemical signals inside the cells,i.e.mechanotransduction<sup>[1-3]</sup>.Focal adhesions are the major sites of interaction between a cell and its extracellular matrix（ECM）microenvironment,thus outside mechanical signals can be sensed at focal adhesions through transmembrane receptor integrins.In particular,it has been shown that matrix elasticity can control the cell fate<sup>[4]</sup>by modulating the interactions between ECM proteins and their receptor integrins<sup>[5,6]</sup>.For example,different rigidity of polyacrylamide（PA）gels can lead to different density of ECM ancho-展开更多
Pulsed electric field has been used widely as a nonviral approach to improving gene delivery in basic and translational research[1-2].The technique has been called electrotransfection(ET),electroporation,electrogene t...Pulsed electric field has been used widely as a nonviral approach to improving gene delivery in basic and translational research[1-2].The technique has been called electrotransfection(ET),electroporation,electrogene transfer,and gene electroinjection in the literature [1,3].It has a great potential to improve clinical treatment of diseases through delivery of vaccines and therapeutic genes,genome and epigenome editing,and generation of human induced pluripotent stem cells for tissue engineering[1-3].During ET,extracellular transport of plasmid DNA(pDNA)relies on electrophoresis,which is critical for applications in vivo.However,mechanisms of intracellular transport remain to be understood.The lack of understanding has hindered the translation of ET technology to the clinic.It is well known that pulsed electric field can generate transient hydrophilic pores in the plasma membrane(i.e.,electroporation)that permit membrane-impermeant molecules to enter cells.Although the pores have yet to be visualized directly under a microscope,the electric field-induced membrane permeabilization has been demonstrated through experimental measurements of electrical conductance of synthetic lipid membranes and plasma membranes,direct observation of fluorescent markers crossing the membranes facing both cathode and anode,and numerical simulations of the membrane permeabilization[1,3].Results from the simulations have predicted that the cutoff size of the pores is on the order of a few hundred nanometers,and the lifetime of the pores that are larger than 100 nm is on the order of 10 msec.Although these data provide a solid evidence of the membrane permeabilization,recent studies have demonstrated that the generation of the pores is insufficient for ET[1,4].The reasons are as follows.First,the lifetime of the pores is several orders of magnitude shorter than the time scale for pDNA uptake,which is on the order of 10 min.Second,complex formation between pDNA and plasma membrane is a necessary condition for successful gene transfer.Third,inhibition of clathrin mediated endocytosis or Rac-1 dependent micropinocytosis can reduce the amount of pDNA internalized by cells [1].Finally,we demonstrate that few pDNA molecules can be observed in the cytosol that are not associated with the intracellular vesicles[5],suggesting that pDNA uptake is mediated by endocytosis.In addition to the internalization,ET requires the pDNA in the cytoplasm to reach the nucleus.To understand mechanisms of intracellular trafficking of pDNA,we have examined time-dependent pDNA distributions in cells,quantitatively determined percentages of pDNA molecules associated with different endocytic compartments using transmission electron microscopy(TEM),and investigated different approaches to facilitate cytoplasmic transport and nuclear entry of pDNA.Our data have shown that electrotransfected pDNA is located in different vesicular ultrastructures at or near the plasma membrane at10 min post application of electric pulses[5].In the hard-to-transfect cells(e.g.,4T1),pDNA penetration from the cell surface is less active,and the total number of vesicular structures associated with pDNA is low,compared to those in the easyto-transfect cells(e.g.,COS7).Our data have also shown that macropinocytosis is the most common pathway shared by all types of cells.To investigate how improve pDNA transport in cells,we have photochemically treated cells to non-specifically induce pDNA escape from intracellular vesicles,or blocked endosome and autophagic vacuole maturation through treatment of cells with Bafilomycin Al,an inhibitor of vacuolar H+ATPase.Our data demonstrate that both treatments can lead to reduction of ET efficiency although the treatment for inducing endosomal escape can enhance poly-L-lysine mediated gene delivery.These data suggest that the vesicles play an important role in protecting the naked pDNA during intracellular trafficking.The nuclear envelope is another major barrier to ET.To facilitate the nuclear entry,we have examined three different approaches.One is to synchronize the nuclear envelope breakdown(NEBD)prior to ET;the second approach is to pre-treat cells with a nuclear pore dilating agent(i.e.,trans-1,2-cyclohexanediol);and the third one is to incorporate a nuclear targeting sequence(NTS)(i.e.,SV40)into the pDNA.Our data have shown that the synchronization of the NEBD can significantly improve the ET efficiency without compromising the cell viability.The nuclear pore dilation can improve the ET as well but the dilating agent is cytotoxic.The incorporation of NTS into pDNA can improve the gene delivery efficiency but the improvement is cell-type dependent,suggesting that the NTS has to be screened and optimized for the cells of interest.In summary,the transient pores in the plasma membrane induced by the electric pulses will enable cellular uptake of membrane-impermeant molecules up to the size of small proteins.Larger molecules(e.g.,pDNA)have to be internalized via endocytic processes triggered by the pulsed electric field.Within the cells,pDNA transport is mediated by vesicles and can be blocked by non-specific escape from vesicles or inhibition of vesicle maturation.The nuclear entry of pDNA can be enhanced,without compromising cell viability,through the use of the NTS or the synchronization of the NEBD.展开更多
Purpose Ocular hypertension is the primary risk factor for development of glaucoma and the only modifiable endpoint<sup>[1,2]</sup>.Clinical trials involving thousands of patients have shown consistently t...Purpose Ocular hypertension is the primary risk factor for development of glaucoma and the only modifiable endpoint<sup>[1,2]</sup>.Clinical trials involving thousands of patients have shown consistently that lowering intraocular pressure（IOP）in those with glaucoma,whether or not their IOP is above normal,slows vision loss.IOP elevation is the result of diminished outflow facility in the conventional outflow pathway;and the highest resistance to aqueous humor outflow resides in the juxtacanalicular tissue（JCT）layer of trabecular meshwork（TM）and the inner wall of Schlemm’s canal（SC）.However,mechanisms of outflow facility decrease in glaucomatous eyes remain to be determined.展开更多
Objective The binding of cell adhesive peptides(such as RGD)to integrins initiates the recruitment of cytoplasmic adaptor proteins(e.g.,vinculin)and the formation of focal adhesion(FA)complexes required for cell adhes...Objective The binding of cell adhesive peptides(such as RGD)to integrins initiates the recruitment of cytoplasmic adaptor proteins(e.g.,vinculin)and the formation of focal adhesion(FA)complexes required for cell adhesion.The ability to manipulate this ligand-mediated cell adhesion process is crucial for regulating cell migration,cell differentiation,injury healing,and immune response.Some recent studies reported the importance of the tether length/mobility of the cell adhesive ligands in regulating the traction force development of cells.In the native cellular microenvironment,such a dynamic change in the nanoscale tether length of bioactive ligands is often mediated by conformational changes of the structural proteins due to protein folding or degradation.However,no prior studies have demonstrated the modulation of the ligand tether mobility by controlling the intramolecular folding of polymeric linkers.Unfoldable synthetic macromolecules with easy synthetic routes and controllable structures,such as supramolecular host-guest single chain nanogels(SCNGs),are ideal candidates for mimicking the changes in the tether mobility of bioactive ligands via biorthogonal triggers.Methods S,S’-bis(a’a’-dimethyl-a’’-propargyl acetate)trithiocarbonate was first used to mediate the RAFT polymerization of N,N-dimethyl acrylamide,vinyl-adamantane and vinyl-β-cyclodextrin to yield the ADA@CD-SCNGs.The preparation of the unfoldable host-guest SCNGs was evidenced by the by gel permeation chromatography,proton nuclear magnetic resonance spectroscopy,atomic force microscopy and dynamic light scattering.Then the RGD peptide was conjugated to the alkynyl group on one end of the SCNGs before immobilizing the material on the substrate,which was confirmed by scanning electron microscopy(SEM).The regulation of cell behaviours by unfolding of the SCNG-RGD was confirmed by immunofluorescence staining of vinculin and Yes-associated protein(YAP).Results The preparation of ADA@CD-SCNGs was confirmed by GPC which showed a unimodal molecular weight distribution.DLS and AFM data also proved that the SCNGs had an average diameter of 12±3nm.SEM images showed that SCNGs were conjugated as a linker of RGD peptide to thiolated glass substrate at an average density of 162±11 particles/μm2.These particles disappeared after adding free competitive ADA guest molecules,indicating the triggered unfolding of the tether SCNGs.In addition,the unfolding of supramolecular ADA@CD-SCNGs was also evidenced by a decrease in the GPC elution time and a slight increase in the apparent molecular weight.These results show that the immobilized ADA@CD-SCNGs can be unfolded to tune the tether length and mobility of the conjugated RGD ligands.Then we investigated the regulation of the cell behaviors on the substrate by triggering the unfolding of SCNG linkers.A critical level of traction force is required to effectively initiate and maintain integrin-mediated formation of FA complexes and subsequent mechano-transduction signaling.An increased tether length in cell-adhesive ligands can lead to a diminished cell traction force as if cells are adhering to soft substrates.Here,the unfolding of the ADA@CD-SCNG-RGD triggered by the addition of free ADA led to disassembly of the mature focal adhesions in the cells as evidenced by the reduced vinculin and F-actin in staining.Subsequently,nuclear YAP also decreased significantly because of the impaired mechano-sensing and diminished cell cytoskeleton tension.In addition,the extensively spread cells gradually became round after the medium was supplemented with free competitive ADA to unfold the SCNG linker.These finding demonstrates that the substrates with the unfolded ADA@CD-SCNG-RGD only supported weak cell adhesions.In contrast,on the substrate conjugated with the nonunfoldable MBA-SCNG-RGD linker,the addition of free ADA resulted in no change in the spread cell morphology and protein expressions.These results indicate that the unfoldable host-guest ADA@CD-SCNG can be used to manipulate the nanoscale presentation of ligands to regulate cell behaviors.Conclusions We demonstrate the application of SCNGs as the supramolecular linker to tune the nanoscale ligand tether length.These findings demonstrate that the strategy of manipulating the tether mobility of bioactive ligands by using supramolecular SCNGs as linkers provides a highly tunable,biomimetic,and bio-orthogonal approach to study the dynamic events of cell adhesion.展开更多
The development of molecular biomechanics parallels the development of molecular biology.As biological research moves towards understanding the molecular mechanisms of cellular functions,biomechanics research also mov...The development of molecular biomechanics parallels the development of molecular biology.As biological research moves towards understanding the molecular mechanisms of cellular functions,biomechanics research also moves to smaller and smaller scales from tissues to cells to molecules.In many ways,molecular biology and molecular biomechanics represent similar reductionist approaches that attempt to explain the complex cell by examining its constituent molecules in hope that their assemblies would help elucidate the cellular behavior.The development of molecular biomechanics is also driven,at least in part,by the development of molecu-展开更多
Cell and Tissue Engineering provides exciting opportunities for studying development and Disease.In this talk,we will focus on cell chirality,also known as handedness and left-right(LR)asymmetry,which is an intrinsic ...Cell and Tissue Engineering provides exciting opportunities for studying development and Disease.In this talk,we will focus on cell chirality,also known as handedness and left-right(LR)asymmetry,which is an intrinsic capability of the cell telling left from right(1)The development of the vertebrate body plan with left-right asymmetry requires the emerging chiral morphogenesis at multicellular levels at specific embryonic stages.Changes in orientation of the LR axis due to genetic or environmental factors can lead to malformations and disease.However,the concept of cell chirality has never studied in detail until the recent development of novel engineering tools[2-3].We demonstrate that the cultivation of cells on micropatterned 2D surfaces and in 3D graded hydrogels reveals an intrinsic cellular LR asymmetry,which is dependent of cell phenotype and actin cytoskeleton.With these new tools,we examine the role of cell chirality on the embryonic development of cardiac LR asymmetry [4] as well as the barrier function of endothelium layers [5].We find that Protein Kinase C(PKC)activation reverses the inherent chirality from clockwise to counter clockwise in engineering systems [4-5].Interestingly,activation of PKC signaling reverses the directional bias of chick cardiac C-looping [4].Mediating endothelial cell chirality can regulate the permeability of endothelial layers[5].Overall,our results strongly suggest critical roles of cell chirality in cardiovascular development and disease.展开更多
A new ion-selective pH electrode of PVC membrane used formeasuring pH of the upper digestive tract is reported in this paper, which wasprepared with tri-n-octylamine or tris-(2-ehtylhexy)amine sensitive materials,and ...A new ion-selective pH electrode of PVC membrane used formeasuring pH of the upper digestive tract is reported in this paper, which wasprepared with tri-n-octylamine or tris-(2-ehtylhexy)amine sensitive materials,and polyvinylchloride (PVC) as a base. It was shown that the electrode has widelinearity (0.5-8, 3-12), good reproducibility, proper responsible time (【30s),longer life span (15 days). And the measurement was carried out in 50 cases bythe electrode.展开更多
Introduction The endothelial cells(ECs)lining every blood vessel wall constantly expose to the mechanical forces generated by the blood flow.The EC responses to these hemodynamic forces play a critical role in the hom...Introduction The endothelial cells(ECs)lining every blood vessel wall constantly expose to the mechanical forces generated by the blood flow.The EC responses to these hemodynamic forces play a critical role in the homeostasis of the circulatory system.In addition to forming a transport barrier between the blood and vessel wall,vascular ECs play important roles in regulating circulation functions.Besides biochemical stimuli,blood flow induced(hemodynamic)mechanical stimuli,such as shear stress,pressure and circumferential stretch,modulate EC morphology and functions by activating mechanosensors,signaling pathways,and gene and protein expressions.The EC responses to the hemodynamic forces(mechano-sensing and transduction)are critical to maintaining normal vascular functions.Failure in the mechano-sensing and transduction leads to serious vascular diseases including hypertension,atherosclerosis,aneurysms and thrombosis,to name a few[1].On the luminal surface of our blood vessels,there is a thin layer called endothelial surface glycocalyx(ESG)which consists of proteoglycans,glycosaminoglycans(GAGs)and glycoproteins.The GAGs in the ESG are heparan sulfate(HS),hyaluronic acid(HA),chondroitin sulfate(CS),and sialic acid(SA)[2].In order to play important roles in vascular functions,such as being a mechanosensor and transducer for the endothelial cells(ECs)to sense the blood flow,a molecular sieve to maintain normal microvessel permeability and a barrier between the circulating cells and endothelial cells forming the vessel wall,the ESG should have an organized structure at the molecular level.Due to the limitations of optical and electron microscopy,the ultra-structure and organization of ESG has not been revealed until recent development of a super high resolution fluorescence optical microscope,STORM(Stochastic Optical Reconstruction Microscopy).The diffraction of a single fluorescence molecule can be described as the point spread function(PSF).When the light of wavelengthλexcites the fluorophore(emitter),the intensity profile of the spot is defined as the PSF with the width^0.6λ/NA,NA is the numerical aperture of the objective.The diffraction-limited image resolution,for a high numerical aperture objective lens,is^200 nm in the lateral direction and^500 nm in the axial direction,for a conventional fluorescence microscope.The key idea of the single-molecule localization microscopy is to light the molecule,in turn,to achieve the nanometer-level accuracy of their position and reconstruction into a super-resolution image,such as STORM.STORM employs photo-switching mechanisms to stochastically activate individual molecules(photo-switchable or photoactivatable fluorophores)within the diffraction-limited region at different times.Then images with sub-diffraction limit resolution are reconstructed from the measured positions of individual fluorophores[3].To trade the super spatial resolution(accuracy),STORM sacrifices its temporal resolution(efficiency)by switching the state and sequentially exciting the emitters at a high density.Rust et al[3]employed organic dyes and fluorescent proteins as photo-switchable emitters to trade temporal resolution for a super spatial resolution(~20 nm lateral and^50 nm axial at present,can go down to a couple of nanometers if using smaller peptides or antibody fragments instead of currently used whole anti-bodies),which is an order of magnitude higher than conventional confocal microscopy.In the current study,we employed STORM to reveal the major ultra-structural components of the ESG,HS and HA,and their organization at the surface of the cultured EC monolayer[4].Materials and methods We used newly acquired Nikon-STORM system to observe the ESG on in vitro EC(bEnd3,mouse brain microvascular endothelial cells)monolayers.After confluency,the bEnd3 cells were immunolabeled with anti-HS,fol-lowed by an ATT0488 conjugated goat anti-mouse IgG,and with biotinylated HA binding protein,followed by an AF647 conjugated anti-biotin.The ESG was then imaged by the STORM with a 100x/1.49 oil immersed lens.Multiple Reporters of ATT0488 and AF647 with alternating illumination were used to acquire the 3D images of HS and HA.The field of 256×256(40×40μm2)of HS and HA at the surface of ECs was obtained based on totally 40,000 of EM-CCD captured images for each reporter at a capturing speed of 19 ms/frame.Results HA is a long molecule weaving into a network which covers the endothelial luminal surface.The diameter of the HA segments is 185.3±44.7 nm,155.5±57.2 nm,and 156.9±56.1 nm,respectively,at the top,middle and bottom regions of the cell luminal surface.In contrast,HS is a shorter molecule,perpendicular to the cell surface.HA and HS are partially overlapped with each other at the endothelial luminal surface.We quantified the length,diameter,orientation,and density of HS at the top,middle and bottom regions of the endothelial surface.The diameter of the observed HS is 191.0±46.0 nm,284.3±71.1 nm,and 184.2±59.6 nm,and the length of the HS is 621.0±75.7 nm,651.0±118.0 nm,and 575.2±105.6 nm,respectively,at the top,middle and bottom regions of the cell luminal surface.For the HS orientation,its angle with the cell surface is 92.9±1.9,88.7±8.2,and 96.2±10.9 degree,respectively,at the top,middle and bottom regions.The angle of 90 degree is perfectly perpendicular to the cell surface.For the HS distribution,the average density is0.398 elements/μm2,0.345 elements/μm2 and 0.665 elements/μm2,respectively,and the distance between the adjacent HS is 1 694.4±628.1 nm,1 844.8±758.5 nm,and 1 221.9±450.7 nm,respectively,at the top,middle and bottom regions.Conclusions Our results suggest that HS plays a major role in mechanosensing and HA plays a major role in the molecular sieve,due to their organization,ultra-structure and distribution.展开更多
The immune checkpoint blockade has revolutionized cancer treatment.However,not all cancer types are susceptible to this therapy.Even in melanoma,one of the best scenario,about half of the patients do not respond to im...The immune checkpoint blockade has revolutionized cancer treatment.However,not all cancer types are susceptible to this therapy.Even in melanoma,one of the best scenario,about half of the patients do not respond to immune checkpoint blockade.Since CD8+T cell is the main driving force behind cancer elimination,then having a complete and competent T cell repertoire to cover all possible cancer antigens expressed by cancer cells should be a determining factor to the success of this therapy.Conversely,if there are'holes'in patients’T cell repertoire and/or'weak spots'manifested as functional dysregulation or exhaustion on T cells specific to a set of cancer antigens that dominantly expressed by cancer cells,cancer immune escape is inevitable.However,these two types of cancer immune escape might need different treatment strategies:the first group with'holes'in the T cell repertoire,whether the'holes'are taking on a form of missing T cells to cover these cancer antigens or missing high-affinity TCRs that are known to be more sensitive to antigen stimulation,would be benefited from TCR re-directed adoptive cell transfer(ACT)therapy;the other group with T cell repertoire'weak spots'would be benefited from immune checkpoint blockade alone or in combination with additional stimulatory factors such as cytokines and peptide vaccine.In the past decade,we have developed several tools to profile the T cell repertoire from T cell receptor diversity to T cell receptor affinity to high-throughput linking antigen specificity to single T cell receptor sequences in large scale.In this talk,I will first introduce these tools and then give examples on how we use them to answer some of the fundamental questions in systems immunology with a focus on cancer immunology,which in turn help us design new therapeutics immune engineering.展开更多
The technology of induced pluripotent stem cell(iPSCs)has enabled the conversion of somatic cells into primitive undifferentiated cells via reprogramming.This approach provides possibilities for cell replacement thera...The technology of induced pluripotent stem cell(iPSCs)has enabled the conversion of somatic cells into primitive undifferentiated cells via reprogramming.This approach provides possibilities for cell replacement therapies and drug screening,but the potential risk of tumorigenesis hampers further development and application.How to generate required differentia-ted cells without initiating tumor progression remains a huge challenge.Here we show that mouse embryonic fibroblasts could be differentiated into valvular endothelial cell(VEC)like cells.VECs are critical in valve replacements in aortic valve failure.VEC-associated gene and protein expression and functional assays were quantified for these VEC-like cells.We show that mouse embryonic fibroblasts could be converted into VEC-like cells.Our results suggest that it is possible to convert mouse embryonic fibroblasts into VEC-like cells without first reprogramming them into pluripotent stem cells,minimizing the possibility of tumorigenesis.展开更多
Recently we have synthesized a novel small retinoid molecule WYC-209 that can effectively inhibit proliferation of malignant murine melanoma tumor-repopulating cells(TRCs).The molecule can induce 100%TRCs apoptosis at...Recently we have synthesized a novel small retinoid molecule WYC-209 that can effectively inhibit proliferation of malignant murine melanoma tumor-repopulating cells(TRCs).The molecule can induce 100%TRCs apoptosis at 10μM concentration.However,how WYC-209 induces TRCs apoptosis is still elusive.Here we demonstrate that WYC-209 at>6μM concentration started to induce TRCs apoptosis primarily via the caspase 3 pathway by releasing cytochrome c from mitochondria.Interestingly,we found that at concentrations<6μM WYC-209 induced TRCs to elevate dormancy marker COUP TF1 but induced no changes in apoptosis marker P53.Furthermore,proliferation markers Ki67 and PCNA decreased with the increase of WYC-209 concentrations,suggesting that low concentrations of WYC-209 inhibit TRCs growth by inducing cell dormancy instead of causing apoptosis.In addition,TRC traction forces were almost abolished when WYC-209 concentration was at 5μM,preceding the initiation of apoptosis.Our findings demonstrate that inhibition of TRCs by anti-cancer molecule WYC-209 is concentration-dependent and WYC-209 inhibits cellular force generation of the tumor-repopulating cells before inducing apoptosis.展开更多
Objective Patients with repaired tetralogy of Fallot(rTOF)account for the majority of cases with late onset right ventricle(RV)failure.The current surgical approach,including pulmonary valve replacement/insertion(PVR)...Objective Patients with repaired tetralogy of Fallot(rTOF)account for the majority of cases with late onset right ventricle(RV)failure.The current surgical approach,including pulmonary valve replacement/insertion(PVR),has yielded mixed results with some patients recover RV function and some do not.An innovative surgical approach was proposed to help ventricle to contract and improve RV function qualified by ejection fraction with one or more active contracting bands.Computational biomechanical modelling is a widely used method in cardiovascular study for investigation of mechanisms governing disease development,quantitative diagnostic and treatment strategies and improving surgical designs for better outcome.Muscle active contraction caused by zero-load sarcomere shortening leads to change of zero-load configurations.In lieu of experimenting using real surgery on animal or human,computational simulations(virtual surgery)were performed to test different band combination and insertion options to identify optimal surgery design and band insertion plan.Methods Cardiac magnetic resonance(CMR)data were obtained from one rTOF patient(sex:male,age:22.5 y)before pulmonary valve replacement surgery.The patient was suffering from RV dilation and dysfunction with RV end-systole volume 254.49ml and end-diastole volume 406.91 mL.A total of 15 computational RV/LV/Patch/Band combination models based on(CMR)imaging were constructed to investigate the influence of different band insertion surgery plans.These models included 5 different band insertion models combined and 3 different band contraction ratio(10%,15%and 20%band zero-stress length reduction).These models included 5 different band insertion models:Model 1 with one band at anterior to the middle of papillary muscle;Model 2 with one band at posterior to the middle of papillary muscle;Model 3 with 2 bands which are the ones from Models 1&2 combined;Model 4 with a band at the base of the papillary muscle;Model 5 with 3 bands which is a combination of Models 3&4.A pre-shrink process was performed on in-vivo begin-filling and end-systole MRI data to obtain diastole and systole zero4oad ventricle geometries.An extra 5%-8%shrinkage was applied to obtain corresponding systole zero-load geometry reflecting myocardium sarcomere shortening.The zero-load band length in systole was 10%,15%and 20%shorter than that in diastole according to their corresponding contraction ratio.The nonlinear Mooney-Rivlin model was used to describe the ventricle material properties with their material parameter values adjusted to match measured data with CMR.The band material properties were in the same scale with healthy right ventricle.The RV/LV/Band model construction and solution procedures were the same as described.Results Model 5 with band contraction ratio of 20%has the ability to improve RV ejection fraction to 41.07%,which represented a 3.61%absolute improvement,or 9.6%relative improvement using pre-PVR ejection fraction as the baseline number.The ejection fractions for Models 1-4 with band contraction ratio of 20%were 39.28%,39.47%,38.87%and 40.34%respectively.Compared to models with band contraction ratio15%and 20%,models with band contraction ratio 10%has the least ability on RV ejection fraction improvement with ejection fraction 38.28%,38.00%,38.81%,38.50%and 39.36%corresponding to Models 1-5.Conclusions This pilot work demonstrated that the band insertion surgery may have great potential to improve post-PVR RV cardiac function for patients with repaired TOF.More band contraction ratio and inserted band number may lead to better post-surgery outcome.Further investigations using in-vitro animal experiments and final patient studies are warranted.展开更多
文摘Objective To establish a body composition analysis system based on chest CT,and to observe its value for evaluating content of chest muscle and adipose.Methods T7—T8 layer CT images of 108 pneumonia patients were collected(segmented dataset),and chest CT data of 984 patients were screened from the COVID 19-CT dataset(10 cases were randomly selected as whole test dataset,the remaining 974 cases were selected as layer selection dataset).T7—T8 layer was classified based on convolutional neural network(CNN)derived networks,including ResNet,ResNeXt,MobileNet,ShuffleNet,DenseNet,EfficientNet and ConvNeXt,then the accuracy,precision,recall and specificity were used to evaluate the performance of layer selection dataset.The skeletal muscle(SM),subcutaneous adipose tissue(SAT),intermuscular adipose tissue(IMAT)and visceral adipose tissue(VAT)were segmented using classical fully CNN(FCN)derived network,including FCN,SegNet,UNet,Attention UNet,UNET++,nnUNet,UNeXt and CMUNeXt,then Dice similarity coefficient(DSC),intersection over union(IoU)and 95 Hausdorff distance(HD)were used to evaluate the performance of segmented dataset.The automatic body composition analysis system was constructed based on optimal layer selection network and segmentation network,the mean absolute error(MAE),root mean squared error(RMSE)and standard deviation(SD)of MAE were used to evaluate the performance of automatic system for testing the whole test dataset.Results The accuracy,precision,recall and specificity of DenseNet network for automatically classifying T7—T8 layer from chest CT images was 95.06%,84.83%,92.27%and 95.78%,respectively,which were all higher than those of the other layer selection networks.In segmentation of SM,SAT,IMAT and overall,DSC and IoU of UNet++network were all higher,while 95HD of UNet++network were all lower than those of the other segmentation networks.Using DenseNet as the layer selection network and UNet++as the segmentation network,MAE of the automatic body composition analysis system for predicting SM,SAT,IMAT,VAT and MAE was 27.09,6.95,6.65 and 3.35 cm 2,respectively.Conclusion The body composition analysis system based on chest CT could be used to assess content of chest muscle and adipose.Among them,the UNet++network had better segmentation performance in adipose tissue than SM.
基金supported by the Istanbul Technical University Office of Scientific Research Projects(ITUBAPSIS),under grant MYL-2022-43776。
文摘The design of unmanned aerial vehicles(UAVs)revolves around the careful selection of materials that are both lightweight and robust.Carbon fiber-reinforced polymer(CFRP)emerged as an ideal option for wing construction,with its mechanical qualities thoroughly investigated.In this study,we developed and optimized a conceptual UAV wing to withstand structural loads by establishing progressive composite stacking sequences,and we conducted a series of experimental characterizations on the resulting material.In the optimization phase,the objective was defined as weight reduction,while the Hashin damage criterion was established as the constraint for the optimization process.The optimization algorithm adaptively monitors regional damage criterion values,implementing necessary adjustments to facilitate the mitigation process in a cost-effective manner.Optimization of the analytical model using Simulia Abaqus~(TM)and a Python-based user-defined sub-routine resulted in a 34.7%reduction in the wing's structural weight after 45 iterative rounds.Then,the custom-developed optimization algorithm was compared with a genetic algorithm optimization.This comparison has demonstrated that,although the genetic algorithm explores numerous possibilities through hybridization,the custom-developed algorithm is more result-oriented and achieves optimization in a reduced number of steps.To validate the structural analysis,test specimens were fabricated from the wing's most critically loaded segment,utilizing the identical stacking sequence employed in the optimization studies.Rigorous mechanical testing revealed unexpectedly high compressive strength,while tensile and bending strengths fell within expected ranges.All observed failure loads remained within the established safety margins,thereby confirming the reliability of the analytical predictions.
基金Supported by′111′Project and Chongqing Natural Science Foundation(2006BB2043,2006BB2142)
文摘PZT-based valveless micropump is a microactuator that can be used for controlling and delivering tiny amounts of fluids,and diffuser/nozzle plays an important role when this type of micropump drives the fluid flowing along a specific direction.In this paper,a numerical model of micropump has been proposed,and the fluidic properties of diffuser/nozzle have been simulated with ANSYS.With the method of finite-element analysis,the increased pressure drop between inlet and outlet of diffuser/nozzle induces the increment of flow rate in both diffuser and nozzle simultaneously,but the increasing rate of diffuser is faster than that of nozzle.The L/R,ratio of L(length of cone pipe) and R(radius of minimal cross section of cone pipe) plays an important role in fluidic performance of diffuser and nozzle as well,and the mean flow rate will decrease with increment of L/R.The mean flow rate reaches its peak value when L/R with the value of 10 regardless the divergence angle of diffuser or nozzle.The simulation results indicate that the fluidic properties of diffuser/nozzle can be defined by its geometric structure,and accordingly determine the efficiency of micropump.
基金funded by the American Heart Association Scientist Development Grant SDG12050083National Institutes of Health grant R21 HL102773
文摘Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissue.However,maintaining the viability of a thick tissue structure during tissue growth and maturation is challenging due to lack of adequate vascular perfusion.In a simple tissue model with
文摘The brain tumor perivascular niche(PVN),the region in the vicinity of microvessels is a prime location for brain tumor stem-like cells(BTSCs)[1].Tumor microvasculature creates a complex microenvironment consisting of various cell types,the extracellular matrix,and soluble factors that mediate cell-cell interaction.The brain tumor PVN controls maintenance,expansion,and differentiation of BTSCs via direct cell contact or paracrine signaling cues.BTSCs often receive bidirectional crosstalk from endothelial cells and other cell types in the niche[2].In addition,the perivascular zone may serve as a path for tumor cells to migrate over long distances(3,4)Unlike other solid tumors,glioblastoma multiforme(GBM)cells rarely metastasize to other organs,but they can invade the entire brain by migrating along specific brain tissue structures,such as blood vessels or white matter tracts,leading to high rates of relapse.Despite the success in modeling diffuse brain tumors in both genetically-modified and patient-derived xenograft(PDX)animals,there is an unmet need for an in vitro system that can bridge conventional cell culture and animal models by mimicking not only the anatomy but also the function of the PVN to study the dynamics of BTSCs.In this presentation,I will describe the use of a microvasculature-on-a-chip system as a PVN model to evaluate the dynamics of BTSCs ex vivo from 10 glioblastoma patients [5].We observed that BTSCs preferentially localize in the perivascular zone.Live cell tracking showed that the cells residing in the vicinity of microvessels had the lowest motility,while a fraction of cells on the microvessels unexpectedly possessed the highest motility and migrated over the longest distance.These results indicate that the perivascular zone is a niche for BTSCs,while the microvascular tracks are also a path for long-distance tumor cell migration and invasion.Additionally,the degree of co-localization between tumor cells and microvessels varied significantly across patients.To validate the results from our microvasculature-on-a-chip system,we used single-cell transcriptome sequencing(10 patients and 21,750 single cells in total)to identify the subtype of each tumor cell.The co-localization coefficient was found to correlate positively with proneural(stem-like)or mesenchymal(invasive)but not classical(proliferative)tumor cells.Furthermore,we found that a gene signature profile including PDGFRA correlated strongly with the'homing'of brain tumor cells to the PVN.Our findings demonstrated that ex vivo dynamics of human brain tumor cells in a microvasculature-on-a-chip model can recapitulate in vivo tumor cell dynamics,heterogeneity,and subtypes,representing a new route to the study of human tumor cell biology and uncover patient-specific tumor cell functions.Acknowledgments:We thank Drs.Laura Niklason,Eric Holland,Franziska Michor,and Frank Szulzewsky for scientific discussion.We thank Misha Guy,Vladimir Polejaev,Zhenting Jiang,and Alice Yun for suggestions and help on the simulation computing and SEM/confocal imaging process.This research was supported by the Packard Fellowship for Science and Engineering(R.F.),National Science Foundation CAREER Award CBET-1351443(R.F.),U54 CA193461(R.F.),U54CA209992(Sub-Project ID:7297 to R.F.),R01 NS095817(J.Z.),Yale Cancer Center Co-Pilot Grant(to R.F.).The molds for microfluidic devices were fabricated in the Yale School of Engineering and Applied Science cleanroom.Sequencing was performed at the Yale Center for Genome Analysis(YCGA)facility.Data was analyzed at Yale High Performance Computing(HPC)center.Super resolution confocal imaging was performed at Yale Center for Cellular and Molecular Imaging(CCMI).
基金Project(2012-0000478) supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MEST)
文摘In this work, we analyzed only the patients of the NSTEMI (non ST-segment elevation myocardial infarction) who arrived at the hospital within 12 h after symptoms started. Using NSTEMI follow-up data within, the characteristics of the clinical data, the risk factor, and the blood tested in the hospital visit were analyzed for MACE (major adverse cardiac events) patients. MACE includes cardiac death, MI (myocardial infarction), Re-PCI, and CABG (coronary artery bypass graft). As a result, from the NSTEMI patients which can be followed up for over 12 m, NT-ProBNP (p=0.014) and age (p=0.045) are found to be the independent risk factors related to MACE. Accordingly, they can be useful for the diagnosis and prognosis for NSTEMI patients as a biomarker.
基金Supported by the National Natural Science Foundation of China (30770546 )Natural Science Foundation of Chongqing(2006BB2043,2007BB5148)
文摘Synergic movement of finger's joints provides human hand tremendous dexterities,and the detection of kinematics parameters is critical to describe and evaluate the kinesiology functions of the fingers.The present work is the attempt to investigate how the angular velocity and angular acceleration of the joints of index finger vary with respect to time during conducting a motor task.A high-speed video camera has been employed to visually record the movement of index finger,and miniaturized(5-mm diameter) reflective markers have affixed to the subject's index finger on the side close to thumb and dorsum of thumb at different joint landmarks.Captured images have been reviewed frame by frame to get the coordinate values of each joint,and the angular displacements,angular velocities and angular acceleration can be obtained with triangle function.The experiment results show that the methods here can detect the kinematics parameters of index finger joints during moving,and can be a valid route to study the motor function of index finger.
基金supported by Key Program of NSF of China ( 11532003) to L.D.NSF-MCB 1561794 to A.P.L.
文摘In this study,we hypothesized that Piezo 1 channels mediate the compression-enhanced invasive phenotype of cancer cells via a caveolae-dependent mechanism.To test this hypothesis,we examined in vitro cultured human breast cancer cells for their ability to invade and degrade extracellular matrix in the presence or absence of compressive stress,together with corresponding changes in Piezo1 as well as cytoskeletal remodeling and calcium signaling.Here we show that compressive stress enhanced invasion,matrix degradation,and invadopodia formation of breast cancer cells.We further identified Piezo1 as the putative mechanosensitive cellular component that transmits compression to induce calcium influx,which in turn triggers several downstream pathways.Interestingly,for the first time we observed inv-adopodia with matrix degradation ability on the apical side of the cells, similar to those commonly observed at the cell s ventral side.Furthermore,we demonstrate that Piezo1 and caveolae were both involved in mediating the compressive stress-induced cancer cell invasive phenotype as Piezo 1 and caveolae were often colocalized,and reduction of Cav-1 expression or disruption of caveolae with methyl-β-cyclodextrin led to not only reduced Piezo1 expression but also attenuation of the invasive phenotypes promoted by compressive stress.Taken together,we first observed that in breast cancer cells,simulating uncontrolled growth-induced compressive stress enhanced cancer cell invasion,matrix degradation,and invadopodia and stress fiber formation.Our study also confirmed that Piezo1 channels are highly expressed in breast cancer cells compared to normal breast cells,and is consistent with the data that compressive stress regulates cell migration of breast cancer cells but not normal breast cells.Additionally,we identified that Piezol mediated these processes and the invasive phenotypes also depended on the integrity of caveolae.These findings provide the first demonstration that compressive stress enhances matrix degradation by breast cancer cells and Piezo1 is an essential mechanosensor and transducer for such stress in breast cancer.Additionally,our data supports the model where caveolae might be the'mechanical force foci'which concentrates Piezol to facilitate force sensing and transduction in mammalian cells.Our work may have relevance to human tumors in vivo.As solid tumor experiences high compressive stress due to uncontrolled proliferation and confinement by the stiff extracellular matrix environment,this microenvironment facilitates compression-enhanced cell invasion.The identification of Piezo1’s crucial role in this process provides the first demonstration of the dependence of Piezo1 channels on the response of breast cancer cells to physiological compressive stress.The functional dependence of Piezo1 on caveolae further highlights the importance of membrane organization and composition on forcegated ion channels.Both of these findings underscore the cardinal role that Piezo1 channels play in regulating cell invasion and may inspire further development targeting Piezol as a potential cancer therapeutic target.
基金supported in part by NIH HL098472NSF CBET0846429
文摘Introduction Cells can sense and respond to the mechanical microenvironment by converting forces into biochemical signals inside the cells,i.e.mechanotransduction<sup>[1-3]</sup>.Focal adhesions are the major sites of interaction between a cell and its extracellular matrix（ECM）microenvironment,thus outside mechanical signals can be sensed at focal adhesions through transmembrane receptor integrins.In particular,it has been shown that matrix elasticity can control the cell fate<sup>[4]</sup>by modulating the interactions between ECM proteins and their receptor integrins<sup>[5,6]</sup>.For example,different rigidity of polyacrylamide（PA）gels can lead to different density of ECM ancho-
基金supported by grants from National Institutes of Health ( GM098520 and GM130830)National Science Foundation ( CBET-1264186)
文摘Pulsed electric field has been used widely as a nonviral approach to improving gene delivery in basic and translational research[1-2].The technique has been called electrotransfection(ET),electroporation,electrogene transfer,and gene electroinjection in the literature [1,3].It has a great potential to improve clinical treatment of diseases through delivery of vaccines and therapeutic genes,genome and epigenome editing,and generation of human induced pluripotent stem cells for tissue engineering[1-3].During ET,extracellular transport of plasmid DNA(pDNA)relies on electrophoresis,which is critical for applications in vivo.However,mechanisms of intracellular transport remain to be understood.The lack of understanding has hindered the translation of ET technology to the clinic.It is well known that pulsed electric field can generate transient hydrophilic pores in the plasma membrane(i.e.,electroporation)that permit membrane-impermeant molecules to enter cells.Although the pores have yet to be visualized directly under a microscope,the electric field-induced membrane permeabilization has been demonstrated through experimental measurements of electrical conductance of synthetic lipid membranes and plasma membranes,direct observation of fluorescent markers crossing the membranes facing both cathode and anode,and numerical simulations of the membrane permeabilization[1,3].Results from the simulations have predicted that the cutoff size of the pores is on the order of a few hundred nanometers,and the lifetime of the pores that are larger than 100 nm is on the order of 10 msec.Although these data provide a solid evidence of the membrane permeabilization,recent studies have demonstrated that the generation of the pores is insufficient for ET[1,4].The reasons are as follows.First,the lifetime of the pores is several orders of magnitude shorter than the time scale for pDNA uptake,which is on the order of 10 min.Second,complex formation between pDNA and plasma membrane is a necessary condition for successful gene transfer.Third,inhibition of clathrin mediated endocytosis or Rac-1 dependent micropinocytosis can reduce the amount of pDNA internalized by cells [1].Finally,we demonstrate that few pDNA molecules can be observed in the cytosol that are not associated with the intracellular vesicles[5],suggesting that pDNA uptake is mediated by endocytosis.In addition to the internalization,ET requires the pDNA in the cytoplasm to reach the nucleus.To understand mechanisms of intracellular trafficking of pDNA,we have examined time-dependent pDNA distributions in cells,quantitatively determined percentages of pDNA molecules associated with different endocytic compartments using transmission electron microscopy(TEM),and investigated different approaches to facilitate cytoplasmic transport and nuclear entry of pDNA.Our data have shown that electrotransfected pDNA is located in different vesicular ultrastructures at or near the plasma membrane at10 min post application of electric pulses[5].In the hard-to-transfect cells(e.g.,4T1),pDNA penetration from the cell surface is less active,and the total number of vesicular structures associated with pDNA is low,compared to those in the easyto-transfect cells(e.g.,COS7).Our data have also shown that macropinocytosis is the most common pathway shared by all types of cells.To investigate how improve pDNA transport in cells,we have photochemically treated cells to non-specifically induce pDNA escape from intracellular vesicles,or blocked endosome and autophagic vacuole maturation through treatment of cells with Bafilomycin Al,an inhibitor of vacuolar H+ATPase.Our data demonstrate that both treatments can lead to reduction of ET efficiency although the treatment for inducing endosomal escape can enhance poly-L-lysine mediated gene delivery.These data suggest that the vesicles play an important role in protecting the naked pDNA during intracellular trafficking.The nuclear envelope is another major barrier to ET.To facilitate the nuclear entry,we have examined three different approaches.One is to synchronize the nuclear envelope breakdown(NEBD)prior to ET;the second approach is to pre-treat cells with a nuclear pore dilating agent(i.e.,trans-1,2-cyclohexanediol);and the third one is to incorporate a nuclear targeting sequence(NTS)(i.e.,SV40)into the pDNA.Our data have shown that the synchronization of the NEBD can significantly improve the ET efficiency without compromising the cell viability.The nuclear pore dilation can improve the ET as well but the dilating agent is cytotoxic.The incorporation of NTS into pDNA can improve the gene delivery efficiency but the improvement is cell-type dependent,suggesting that the NTS has to be screened and optimized for the cells of interest.In summary,the transient pores in the plasma membrane induced by the electric pulses will enable cellular uptake of membrane-impermeant molecules up to the size of small proteins.Larger molecules(e.g.,pDNA)have to be internalized via endocytic processes triggered by the pulsed electric field.Within the cells,pDNA transport is mediated by vesicles and can be blocked by non-specific escape from vesicles or inhibition of vesicle maturation.The nuclear entry of pDNA can be enhanced,without compromising cell viability,through the use of the NTS or the synchronization of the NEBD.
文摘Purpose Ocular hypertension is the primary risk factor for development of glaucoma and the only modifiable endpoint<sup>[1,2]</sup>.Clinical trials involving thousands of patients have shown consistently that lowering intraocular pressure（IOP）in those with glaucoma,whether or not their IOP is above normal,slows vision loss.IOP elevation is the result of diminished outflow facility in the conventional outflow pathway;and the highest resistance to aqueous humor outflow resides in the juxtacanalicular tissue（JCT）layer of trabecular meshwork（TM）and the inner wall of Schlemm’s canal（SC）.However,mechanisms of outflow facility decrease in glaucomatous eyes remain to be determined.
文摘Objective The binding of cell adhesive peptides(such as RGD)to integrins initiates the recruitment of cytoplasmic adaptor proteins(e.g.,vinculin)and the formation of focal adhesion(FA)complexes required for cell adhesion.The ability to manipulate this ligand-mediated cell adhesion process is crucial for regulating cell migration,cell differentiation,injury healing,and immune response.Some recent studies reported the importance of the tether length/mobility of the cell adhesive ligands in regulating the traction force development of cells.In the native cellular microenvironment,such a dynamic change in the nanoscale tether length of bioactive ligands is often mediated by conformational changes of the structural proteins due to protein folding or degradation.However,no prior studies have demonstrated the modulation of the ligand tether mobility by controlling the intramolecular folding of polymeric linkers.Unfoldable synthetic macromolecules with easy synthetic routes and controllable structures,such as supramolecular host-guest single chain nanogels(SCNGs),are ideal candidates for mimicking the changes in the tether mobility of bioactive ligands via biorthogonal triggers.Methods S,S’-bis(a’a’-dimethyl-a’’-propargyl acetate)trithiocarbonate was first used to mediate the RAFT polymerization of N,N-dimethyl acrylamide,vinyl-adamantane and vinyl-β-cyclodextrin to yield the ADA@CD-SCNGs.The preparation of the unfoldable host-guest SCNGs was evidenced by the by gel permeation chromatography,proton nuclear magnetic resonance spectroscopy,atomic force microscopy and dynamic light scattering.Then the RGD peptide was conjugated to the alkynyl group on one end of the SCNGs before immobilizing the material on the substrate,which was confirmed by scanning electron microscopy(SEM).The regulation of cell behaviours by unfolding of the SCNG-RGD was confirmed by immunofluorescence staining of vinculin and Yes-associated protein(YAP).Results The preparation of ADA@CD-SCNGs was confirmed by GPC which showed a unimodal molecular weight distribution.DLS and AFM data also proved that the SCNGs had an average diameter of 12±3nm.SEM images showed that SCNGs were conjugated as a linker of RGD peptide to thiolated glass substrate at an average density of 162±11 particles/μm2.These particles disappeared after adding free competitive ADA guest molecules,indicating the triggered unfolding of the tether SCNGs.In addition,the unfolding of supramolecular ADA@CD-SCNGs was also evidenced by a decrease in the GPC elution time and a slight increase in the apparent molecular weight.These results show that the immobilized ADA@CD-SCNGs can be unfolded to tune the tether length and mobility of the conjugated RGD ligands.Then we investigated the regulation of the cell behaviors on the substrate by triggering the unfolding of SCNG linkers.A critical level of traction force is required to effectively initiate and maintain integrin-mediated formation of FA complexes and subsequent mechano-transduction signaling.An increased tether length in cell-adhesive ligands can lead to a diminished cell traction force as if cells are adhering to soft substrates.Here,the unfolding of the ADA@CD-SCNG-RGD triggered by the addition of free ADA led to disassembly of the mature focal adhesions in the cells as evidenced by the reduced vinculin and F-actin in staining.Subsequently,nuclear YAP also decreased significantly because of the impaired mechano-sensing and diminished cell cytoskeleton tension.In addition,the extensively spread cells gradually became round after the medium was supplemented with free competitive ADA to unfold the SCNG linker.These finding demonstrates that the substrates with the unfolded ADA@CD-SCNG-RGD only supported weak cell adhesions.In contrast,on the substrate conjugated with the nonunfoldable MBA-SCNG-RGD linker,the addition of free ADA resulted in no change in the spread cell morphology and protein expressions.These results indicate that the unfoldable host-guest ADA@CD-SCNG can be used to manipulate the nanoscale presentation of ligands to regulate cell behaviors.Conclusions We demonstrate the application of SCNGs as the supramolecular linker to tune the nanoscale ligand tether length.These findings demonstrate that the strategy of manipulating the tether mobility of bioactive ligands by using supramolecular SCNGs as linkers provides a highly tunable,biomimetic,and bio-orthogonal approach to study the dynamic events of cell adhesion.
基金supported by National Institutes of Health grants A1077343,A144902,A1038282,HL093723,HL091020,GM096187,and TW008753
文摘The development of molecular biomechanics parallels the development of molecular biology.As biological research moves towards understanding the molecular mechanisms of cellular functions,biomechanics research also moves to smaller and smaller scales from tissues to cells to molecules.In many ways,molecular biology and molecular biomechanics represent similar reductionist approaches that attempt to explain the complex cell by examining its constituent molecules in hope that their assemblies would help elucidate the cellular behavior.The development of molecular biomechanics is also driven,at least in part,by the development of molecu-
基金supported by the National Institutes of Health ( OD / NICHD DP2HD083961)National Science Foundation ( CAREER CMMI-1254656)+2 种基金American Heart Association ( 13SDG17230047)March of Dimes ( MOD 5-FY14-111)Leo Q. Wan is a Pew Scholar in Biomedical Sciences ( PEW 00026185) ,supported by the Pew Charitable Trusts
文摘Cell and Tissue Engineering provides exciting opportunities for studying development and Disease.In this talk,we will focus on cell chirality,also known as handedness and left-right(LR)asymmetry,which is an intrinsic capability of the cell telling left from right(1)The development of the vertebrate body plan with left-right asymmetry requires the emerging chiral morphogenesis at multicellular levels at specific embryonic stages.Changes in orientation of the LR axis due to genetic or environmental factors can lead to malformations and disease.However,the concept of cell chirality has never studied in detail until the recent development of novel engineering tools[2-3].We demonstrate that the cultivation of cells on micropatterned 2D surfaces and in 3D graded hydrogels reveals an intrinsic cellular LR asymmetry,which is dependent of cell phenotype and actin cytoskeleton.With these new tools,we examine the role of cell chirality on the embryonic development of cardiac LR asymmetry [4] as well as the barrier function of endothelium layers [5].We find that Protein Kinase C(PKC)activation reverses the inherent chirality from clockwise to counter clockwise in engineering systems [4-5].Interestingly,activation of PKC signaling reverses the directional bias of chick cardiac C-looping [4].Mediating endothelial cell chirality can regulate the permeability of endothelial layers[5].Overall,our results strongly suggest critical roles of cell chirality in cardiovascular development and disease.
文摘A new ion-selective pH electrode of PVC membrane used formeasuring pH of the upper digestive tract is reported in this paper, which wasprepared with tri-n-octylamine or tris-(2-ehtylhexy)amine sensitive materials,and polyvinylchloride (PVC) as a base. It was shown that the electrode has widelinearity (0.5-8, 3-12), good reproducibility, proper responsible time (【30s),longer life span (15 days). And the measurement was carried out in 50 cases bythe electrode.
基金supported by NIH-1SC1CA153325-01,NSF-MRI CBET 1337746 and 1UG3TR002151-01
文摘Introduction The endothelial cells(ECs)lining every blood vessel wall constantly expose to the mechanical forces generated by the blood flow.The EC responses to these hemodynamic forces play a critical role in the homeostasis of the circulatory system.In addition to forming a transport barrier between the blood and vessel wall,vascular ECs play important roles in regulating circulation functions.Besides biochemical stimuli,blood flow induced(hemodynamic)mechanical stimuli,such as shear stress,pressure and circumferential stretch,modulate EC morphology and functions by activating mechanosensors,signaling pathways,and gene and protein expressions.The EC responses to the hemodynamic forces(mechano-sensing and transduction)are critical to maintaining normal vascular functions.Failure in the mechano-sensing and transduction leads to serious vascular diseases including hypertension,atherosclerosis,aneurysms and thrombosis,to name a few[1].On the luminal surface of our blood vessels,there is a thin layer called endothelial surface glycocalyx(ESG)which consists of proteoglycans,glycosaminoglycans(GAGs)and glycoproteins.The GAGs in the ESG are heparan sulfate(HS),hyaluronic acid(HA),chondroitin sulfate(CS),and sialic acid(SA)[2].In order to play important roles in vascular functions,such as being a mechanosensor and transducer for the endothelial cells(ECs)to sense the blood flow,a molecular sieve to maintain normal microvessel permeability and a barrier between the circulating cells and endothelial cells forming the vessel wall,the ESG should have an organized structure at the molecular level.Due to the limitations of optical and electron microscopy,the ultra-structure and organization of ESG has not been revealed until recent development of a super high resolution fluorescence optical microscope,STORM(Stochastic Optical Reconstruction Microscopy).The diffraction of a single fluorescence molecule can be described as the point spread function(PSF).When the light of wavelengthλexcites the fluorophore(emitter),the intensity profile of the spot is defined as the PSF with the width^0.6λ/NA,NA is the numerical aperture of the objective.The diffraction-limited image resolution,for a high numerical aperture objective lens,is^200 nm in the lateral direction and^500 nm in the axial direction,for a conventional fluorescence microscope.The key idea of the single-molecule localization microscopy is to light the molecule,in turn,to achieve the nanometer-level accuracy of their position and reconstruction into a super-resolution image,such as STORM.STORM employs photo-switching mechanisms to stochastically activate individual molecules(photo-switchable or photoactivatable fluorophores)within the diffraction-limited region at different times.Then images with sub-diffraction limit resolution are reconstructed from the measured positions of individual fluorophores[3].To trade the super spatial resolution(accuracy),STORM sacrifices its temporal resolution(efficiency)by switching the state and sequentially exciting the emitters at a high density.Rust et al[3]employed organic dyes and fluorescent proteins as photo-switchable emitters to trade temporal resolution for a super spatial resolution(~20 nm lateral and^50 nm axial at present,can go down to a couple of nanometers if using smaller peptides or antibody fragments instead of currently used whole anti-bodies),which is an order of magnitude higher than conventional confocal microscopy.In the current study,we employed STORM to reveal the major ultra-structural components of the ESG,HS and HA,and their organization at the surface of the cultured EC monolayer[4].Materials and methods We used newly acquired Nikon-STORM system to observe the ESG on in vitro EC(bEnd3,mouse brain microvascular endothelial cells)monolayers.After confluency,the bEnd3 cells were immunolabeled with anti-HS,fol-lowed by an ATT0488 conjugated goat anti-mouse IgG,and with biotinylated HA binding protein,followed by an AF647 conjugated anti-biotin.The ESG was then imaged by the STORM with a 100x/1.49 oil immersed lens.Multiple Reporters of ATT0488 and AF647 with alternating illumination were used to acquire the 3D images of HS and HA.The field of 256×256(40×40μm2)of HS and HA at the surface of ECs was obtained based on totally 40,000 of EM-CCD captured images for each reporter at a capturing speed of 19 ms/frame.Results HA is a long molecule weaving into a network which covers the endothelial luminal surface.The diameter of the HA segments is 185.3±44.7 nm,155.5±57.2 nm,and 156.9±56.1 nm,respectively,at the top,middle and bottom regions of the cell luminal surface.In contrast,HS is a shorter molecule,perpendicular to the cell surface.HA and HS are partially overlapped with each other at the endothelial luminal surface.We quantified the length,diameter,orientation,and density of HS at the top,middle and bottom regions of the endothelial surface.The diameter of the observed HS is 191.0±46.0 nm,284.3±71.1 nm,and 184.2±59.6 nm,and the length of the HS is 621.0±75.7 nm,651.0±118.0 nm,and 575.2±105.6 nm,respectively,at the top,middle and bottom regions of the cell luminal surface.For the HS orientation,its angle with the cell surface is 92.9±1.9,88.7±8.2,and 96.2±10.9 degree,respectively,at the top,middle and bottom regions.The angle of 90 degree is perfectly perpendicular to the cell surface.For the HS distribution,the average density is0.398 elements/μm2,0.345 elements/μm2 and 0.665 elements/μm2,respectively,and the distance between the adjacent HS is 1 694.4±628.1 nm,1 844.8±758.5 nm,and 1 221.9±450.7 nm,respectively,at the top,middle and bottom regions.Conclusions Our results suggest that HS plays a major role in mechanosensing and HA plays a major role in the molecular sieve,due to their organization,ultra-structure and distribution.
文摘The immune checkpoint blockade has revolutionized cancer treatment.However,not all cancer types are susceptible to this therapy.Even in melanoma,one of the best scenario,about half of the patients do not respond to immune checkpoint blockade.Since CD8+T cell is the main driving force behind cancer elimination,then having a complete and competent T cell repertoire to cover all possible cancer antigens expressed by cancer cells should be a determining factor to the success of this therapy.Conversely,if there are'holes'in patients’T cell repertoire and/or'weak spots'manifested as functional dysregulation or exhaustion on T cells specific to a set of cancer antigens that dominantly expressed by cancer cells,cancer immune escape is inevitable.However,these two types of cancer immune escape might need different treatment strategies:the first group with'holes'in the T cell repertoire,whether the'holes'are taking on a form of missing T cells to cover these cancer antigens or missing high-affinity TCRs that are known to be more sensitive to antigen stimulation,would be benefited from TCR re-directed adoptive cell transfer(ACT)therapy;the other group with T cell repertoire'weak spots'would be benefited from immune checkpoint blockade alone or in combination with additional stimulatory factors such as cytokines and peptide vaccine.In the past decade,we have developed several tools to profile the T cell repertoire from T cell receptor diversity to T cell receptor affinity to high-throughput linking antigen specificity to single T cell receptor sequences in large scale.In this talk,I will first introduce these tools and then give examples on how we use them to answer some of the fundamental questions in systems immunology with a focus on cancer immunology,which in turn help us design new therapeutics immune engineering.
基金supported by funds from Huazhong University of Science and Technology
文摘The technology of induced pluripotent stem cell(iPSCs)has enabled the conversion of somatic cells into primitive undifferentiated cells via reprogramming.This approach provides possibilities for cell replacement therapies and drug screening,but the potential risk of tumorigenesis hampers further development and application.How to generate required differentia-ted cells without initiating tumor progression remains a huge challenge.Here we show that mouse embryonic fibroblasts could be differentiated into valvular endothelial cell(VEC)like cells.VECs are critical in valve replacements in aortic valve failure.VEC-associated gene and protein expression and functional assays were quantified for these VEC-like cells.We show that mouse embryonic fibroblasts could be converted into VEC-like cells.Our results suggest that it is possible to convert mouse embryonic fibroblasts into VEC-like cells without first reprogramming them into pluripotent stem cells,minimizing the possibility of tumorigenesis.
基金supported by funds from Huazhong University of Science and Technology
文摘Recently we have synthesized a novel small retinoid molecule WYC-209 that can effectively inhibit proliferation of malignant murine melanoma tumor-repopulating cells(TRCs).The molecule can induce 100%TRCs apoptosis at 10μM concentration.However,how WYC-209 induces TRCs apoptosis is still elusive.Here we demonstrate that WYC-209 at>6μM concentration started to induce TRCs apoptosis primarily via the caspase 3 pathway by releasing cytochrome c from mitochondria.Interestingly,we found that at concentrations<6μM WYC-209 induced TRCs to elevate dormancy marker COUP TF1 but induced no changes in apoptosis marker P53.Furthermore,proliferation markers Ki67 and PCNA decreased with the increase of WYC-209 concentrations,suggesting that low concentrations of WYC-209 inhibit TRCs growth by inducing cell dormancy instead of causing apoptosis.In addition,TRC traction forces were almost abolished when WYC-209 concentration was at 5μM,preceding the initiation of apoptosis.Our findings demonstrate that inhibition of TRCs by anti-cancer molecule WYC-209 is concentration-dependent and WYC-209 inhibits cellular force generation of the tumor-repopulating cells before inducing apoptosis.
基金supported in part by National Sciences Foundation of China grants ( 11672001, 81571691,81771844)
文摘Objective Patients with repaired tetralogy of Fallot(rTOF)account for the majority of cases with late onset right ventricle(RV)failure.The current surgical approach,including pulmonary valve replacement/insertion(PVR),has yielded mixed results with some patients recover RV function and some do not.An innovative surgical approach was proposed to help ventricle to contract and improve RV function qualified by ejection fraction with one or more active contracting bands.Computational biomechanical modelling is a widely used method in cardiovascular study for investigation of mechanisms governing disease development,quantitative diagnostic and treatment strategies and improving surgical designs for better outcome.Muscle active contraction caused by zero-load sarcomere shortening leads to change of zero-load configurations.In lieu of experimenting using real surgery on animal or human,computational simulations(virtual surgery)were performed to test different band combination and insertion options to identify optimal surgery design and band insertion plan.Methods Cardiac magnetic resonance(CMR)data were obtained from one rTOF patient(sex:male,age:22.5 y)before pulmonary valve replacement surgery.The patient was suffering from RV dilation and dysfunction with RV end-systole volume 254.49ml and end-diastole volume 406.91 mL.A total of 15 computational RV/LV/Patch/Band combination models based on(CMR)imaging were constructed to investigate the influence of different band insertion surgery plans.These models included 5 different band insertion models combined and 3 different band contraction ratio(10%,15%and 20%band zero-stress length reduction).These models included 5 different band insertion models:Model 1 with one band at anterior to the middle of papillary muscle;Model 2 with one band at posterior to the middle of papillary muscle;Model 3 with 2 bands which are the ones from Models 1&2 combined;Model 4 with a band at the base of the papillary muscle;Model 5 with 3 bands which is a combination of Models 3&4.A pre-shrink process was performed on in-vivo begin-filling and end-systole MRI data to obtain diastole and systole zero4oad ventricle geometries.An extra 5%-8%shrinkage was applied to obtain corresponding systole zero-load geometry reflecting myocardium sarcomere shortening.The zero-load band length in systole was 10%,15%and 20%shorter than that in diastole according to their corresponding contraction ratio.The nonlinear Mooney-Rivlin model was used to describe the ventricle material properties with their material parameter values adjusted to match measured data with CMR.The band material properties were in the same scale with healthy right ventricle.The RV/LV/Band model construction and solution procedures were the same as described.Results Model 5 with band contraction ratio of 20%has the ability to improve RV ejection fraction to 41.07%,which represented a 3.61%absolute improvement,or 9.6%relative improvement using pre-PVR ejection fraction as the baseline number.The ejection fractions for Models 1-4 with band contraction ratio of 20%were 39.28%,39.47%,38.87%and 40.34%respectively.Compared to models with band contraction ratio15%and 20%,models with band contraction ratio 10%has the least ability on RV ejection fraction improvement with ejection fraction 38.28%,38.00%,38.81%,38.50%and 39.36%corresponding to Models 1-5.Conclusions This pilot work demonstrated that the band insertion surgery may have great potential to improve post-PVR RV cardiac function for patients with repaired TOF.More band contraction ratio and inserted band number may lead to better post-surgery outcome.Further investigations using in-vitro animal experiments and final patient studies are warranted.
