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Objective To investigate the effects of groove topography on morphology and migration speed of cervical cancer HeLa cells. Methods HeLa cells were cultured on PDMS substrates with four different surface features, namely, flat substrate, 10 μm width parallel groove, 20 μm width parallel groove, bifurcate groove. Immunofluorescence technique was used to transfect F-actin in HeLa cells, and specific probes Mito-Tracker Green were used to label mitochondria. The location, morphology of cells and distribution of mitochondrial at different moments were obtained through the living cell system. Results Compared with 20 μm width parallel groove and flat substrate, HeLa cells in 10 μm width parallel groove were more orderly arranged and more elongated, but their migration speed was much slower. HeLa cells at the bifurcation protruded into branches and mitochondria were mainly distributed at the protrusion and around the nucleus. The bifurcation reduced the average migration speed of HeLa cells in 10 μm width parallel groove. Conclusions Groove topography has a significant effect on morphology and migration speed of HeLa cells. The research findings help to understand the role of topography in in vivo microenvironment during migration of HeLa cells, and provide references for the subsequent research on invasion and metastasis of cervical cancers.
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Objective To establish a finite element model of cell perfusion culture, and study the effect of different perfusion speeds on the movement of suspended cells. Methods The two-dimensional (2D) model of cell and microchannels was established using COMSOL Multiphysics and meshed. Three groups were established according to the perfusion speed, namely, u0=0.196 mm/s, u1=0.117 mm/s, u2=0.04 mm/s. The fluid-structure interaction module was used for calculation. Results The flow field distribution in the microchannel was relatively uniform. During the equal period of time, the ratio of cell suspension perfusion speed was u0∶u1∶u2=5∶3∶1, and the ratio of cell displacement in the microchannel was D0∶D1∶D2=4.1∶ 2.9∶1. When the speed was proportional, the displacement of cells also roughly followed the corresponding proportional change. With the increase of perfusion speed, stress concentration in cells during movement would occur. The stress and fluid shear force (FSS) of cells during movement were within the safe value range, and cell destruction would not occur. Conclusions The suspended cells can enter into the microchannel without injury at a certain perfusion speed. Perfusion techniques can be used in cell implantation of in vitro tissue engineering products.
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At present, acellular matrix is an effective replacement material for the treatment of skin damage, but there are few systematic evaluation studies on its performance. The experimental group of this study used two decellularization methods to prepare the matrix: one was the acellular matrix which sterilized with peracetic acid first (0.2% PAA/4% ethanol solution) and then treated with hypertonic saline (group A), the other was 0.05% trypsin/EDTA decellularization after γ irradiation (group B); and the control group was soaked in PBS (Group C). Then physical properties and chemical composition of the three groups were detected. Hematoxylin eosin (HE) staining showed that the acellular effect of group B was good. The porosity of group A and B were both above 84.9%. In group A, the compressive modulus of elasticity was (9.94 ± 3.81) MPa, and the compressive modulus of elasticity was (12.59 ± 5.50) MPa in group B. There was no significant difference between group A or B and group C. The total content of collagen in acellular matrix of group A and B was significantly lower than that of group C (1. 662 ± 0.229) mg/g, but there was no significant difference in the ratio of collagen Ⅰ/Ⅲ between group B and group C. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that there was no significant difference in microstructure. Qualitative detection of fibronectin and elastin in each group was basically consistent with that in group C. Therefore, acellular matrix of group B had better performance as scaffold material. The experimental results show that the acellular matrix prepared by γ-ray sterilization and decellularization of 0.05% Trypsin enzyme/EDTA could be used for the construction of tissue-engineered skin. It could also provide reference for the preparation and mounting of heterogeneous dermal acellular matrix. It was also could be used for electrostatic spinning or three-dimensional printed tissue engineered skin scaffold which could provide physical and chemical parameters for it.
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Acellular Dermis , Cells, Cultured , Extracellular Matrix , Porosity , Tissue Engineering , Tissue ScaffoldsABSTRACT
Objective To establish the precise finite element model of the head and neck based on human anatomical structure, so as to study neck injuries caused by rear impact at different speeds. Methods The model was based on CT scan images of the head and neck of human body. The Mimics software was used to reconstruct the three-dimensional (3D) bone, and the 3D solid ligaments, small joints and other tissues of the neck were improved and meshed by HyperMesh. The generated models included the head, 8 vertebrae (C1-T1), 6 intervertebral discs (annulus, nucleus pulposus and upper and lower cartilage endplates), facet joints (cartilage and joint capsule ligaments), ligaments, muscles, etc. Finally, the model verification and post-collision calculation were completed in the finite element post-processing software. Results The simulation results of the models under axial impact, front and back flexion and lateral flexion were compared with the experimental data to verify the effectiveness of the model. Then post-collision simulation at the speed of 20, 40, 60 and 80 km/h was conducted. At the speed of 20 km/h, there was no damage to the neck. At the speed of 40, 60 and 80 km/h, the ligament was the first to be damaged. As the speed increased, the stress on tissues of the neck increased continuously. At the speed of 80 km/h, the maximum stresses of the dense bone, cancellous bone and annulus of the cervical vertebrae were 226.4, 11.5, and 162.8 MPa, respectively. When the ligament strain reached the limit, tearing began to occur. Conclusions The finite element model of the head and neck established in this study has high bionics and effectiveness, and can be used for studying neck injury analysis in traffic accidents, which is helpful for the diagnosis, treatment and prevention of cervical spine injury to a certain extent.
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Objective To study the changes of transcriptome levels in a Bama minipig model of hypertrophic scar during wound healing and pressure therapy by using RNA sequencing (RNA-seq) technique. Methods The Bama minipig model was established by skin wounds from the back and pressure (3.4 kPa) was initiated at 60 days after skin injury. Total RNA was extracted from scar tissues at 0, 14, 30, 60, and 90 days after skin injury and then sequenced. The resulting sequences were mapped to porcine reference genomes and transcriptomes were reconstructed to search for differentially expressed genes (DEGs). The DEGs were further subjected to GO and KEGG analysis using bioinformatics method, while part of the genes were selected for verification using qRT-PCR. Results After preprocessing, more than 78% reads in each group were accurately aligned to the reference sequence. The DEGs identification result showed that 568 genes were differentially expressed after pressure treatment, with 289 up-regulated and 279 down-regulated. GO enrichment analysis revealed that DEGs in each group were mainly associated with extracellular matrix, tissue development and skin development. KEGG analysis showed that the DEGs in each group during wound healing were mainly enriched in extracellular matrix-receptor interactions, focal adhesion and apoptosis pathways; while the DEGs after pressure treatment were mainly enriched in PI3K-Akt and MAPK signaling pathway except the pathways mentioned. qRT-PCR showed that the expression patterns of 6 DEGs were consistent with RNA-seq analysis, confirming the reliability of RNA-seq result. Conclusions RNA-Seq analysis identified differentially expressed genes in animal model of scars during wound healing and pressure therapy, which provided experimental evidence for clinical scar treatment.
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Objective To study the changes of transcriptome levels in a Bama minipig model of hypertrophic scar during wound healing and pressure therapy by using RNA sequencing (RNA-seq) technique. Methods The Bama minipig model was established by skin wounds from the back and pressure (3.4 kPa) was initiated at 60 days after skin injury. Total RNA was extracted from scar tissues at 0, 14, 30, 60, and 90 days after skin injury and then sequenced. The resulting sequences were mapped to porcine reference genomes and transcriptomes were reconstructed to search for differentially expressed genes (DEGs). The DEGs were further subjected to GO and KEGG analysis using bioinformatics method, while part of the genes were selected for verification using qRT-PCR. Results After preprocessing, more than 78% reads in each group were accurately aligned to the reference sequence. The DEGs identification result showed that 568 genes were differentially expressed after pressure treatment, with 289 up-regulated and 279 down-regulated. GO enrichment analysis revealed that DEGs in each group were mainly associated with extracellular matrix, tissue development and skin development. KEGG analysis showed that the DEGs in each group during wound healing were mainly enriched in extracellular matrix-receptor interactions, focal adhesion and apoptosis pathways; while the DEGs after pressure treatment were mainly enriched in PI3K-Akt and MAPK signaling pathway except the pathways mentioned. qRT-PCR showed that the expression patterns of 6 DEGs were consistent with RNA-seq analysis, confirming the reliability of RNA-seq result. Conclusions RNA-Seq analysis identified differentially expressed genes in animal model of scars during wound healing and pressure therapy, which provided experimental evidence for clinical scar treatment.
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Objective To study the mechanical properties of porcine descending aorta. Methods The porcine descending aortas were divided into 5 groups by the distance from the heart, and tissues in each group were subdivided into ventral-quadrant part and lateral-quadrant part. Stress-stretch curves were obtained by using uniaxial tension test. The moduli of elastic and collagen fiber and collagen fiber recruitment parameter of tissues in 5 groups (Position 1-5) were first analyzed by a classical mathematical model. Then the mechanical differences between tissues of ventral quadrant and lateral quadrant were compared. Results The modulus of circumferential collagen fibers increased gradually away from the heart. The modulus of circumferential elastic fibers had the same trend except for tissues at Position 5 (the most distal one). The elastic fibers modulus of tissues decreased at Position 5. At the most distal position, the circumferential and axial elastic fiber modulus of the lateral quadrant was lower than that of ventral quadrant by 19% and 33%, respectively. The axial and the elastic fiber modulus of the ventral quadrant was similar with that of tissues at Position 4 and 5. For the whole descending aorta, the circumferential collagen fiber modulus of the lateral quadrant was higher than that of ventral quadrant by 26% and the circumferential elastic fiber modulus of the lateral quadrant was higher than that of ventral quadrant by 16% at the proximal 4 positions. Conclusions The circumferential mechanical properties of porcine descending aorta were related with regions. The ventral quadrant of the most distal aorta showed abnormally soft trend. The research findings can be used to better understand the mechanism of aorta and improve the spatial accuracy of computer models.
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BACKGROUND:Mechanical factors play an important role in wound healing and scar formation. Finite element model is established to stimulate, analyze and optimize different sutures, which has become a hotspot to guide surgies accurately. OBJECTIVE:To analyze the stress distribution of different simple interrupted suturing directions on the skin wound by establishing the skin finite element model, and to provide basic data for the study of scar formation. METHODS:Porcine back skin uniaxial tensile test was performed to provide reference for the mechanical properties of human skin. Orthotropic skin wound model was established using ABAQUS to calculate the stress distribution on the wound in different suturing directions. RESULTS AND CONCLUSION:The anisotropic mechanical properties of skin wound influenced the suture stress significantly. The elastic modulus along the Langer’s line was larger than that in the vertical direction. The stress increased orderly in the Langer’s line direction, the Langer’s line deflected 30°, bias Langer’s line 45° and vertical Langer’s line. These results suggest that the clinical incision should be made along the Langer’s line direction. Additional y, the cut at an angle with Langer’s line can also reduce the stress of suture.
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BACKGROUND:The mechanical environment of skin tissue and spreading state of epithelial cels are closely related with the wound healing and scar formation process. OBJECTIVE:To analyze the effect of extracelular mechanical stimulation on cel spreading, to test the cel proliferation in order to analyze the effect of spreading form on cel proliferation and other physiological activities. METHODS: Cyclic sine wave mechanical stretching was exerted on immortalized human keratinocyte by using FX-4000 flexible substrate loading system, on the condition of 0.2 Hz and at frequency of 10% amplitudes. The spreading form was compared at 0, 24 and 48 hours, the cel proliferation was analyzed with flow cytometry, and the distribution of vinculin was analyzed with immunofluorescence staining. RESULTS AND CONCLUSION: human keratinocyte would keep the spreading state and could induce more cel proliferation by 24 hours mechanical stretching stimulation. Conversely, after stimulated for 48 hours, the morphology of the human keratinocyte was significantly changed, and the number of human keratinocyte in the division stage was larger than that in the static control group; under tensile stress, the distribution of vinculin was transformed from the surrounding nucleus membrane area to the cel edge. The results indicate that proper mechanical stimulate can increase cel proliferation with keeping cel spreading and adhesion state; the stimulating time of continuous cyclic stretching is the major factor to determine cel spreading morphology and adhesion regions of immortalized human keratinocyte.
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The advance of experimental cell division and proliferation in the field of cell biomechanics is presented in this paper. The emphasis is placed on the research in the mechanics mechanism of cleavage furrow and in the measurement of constricting force about cleavage furrow.
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Humans , Biomechanical Phenomena , Cell Division , Physiology , Cytokinesis , PhysiologyABSTRACT
A generally realized phenomenon in the suction experiment of cells is that if the aspiration pressure is larger than a certain threshold, cell flows continuously into the pipette. The point of the threshold aspiration pressure at which the cell can still be held in a stable equilibrium is called the critical point of aspiration. Here we represent a theoretical analysis of the equilibrium behavior and stability of cell by liquid drop model. In the method of analysis, the areal change due to a small movement deltaL of the portion of the membrane in pipette is given to the first approximation. The threshold pressure and the critical point are shown as simple formulas of the model parameters and inner relative radius of pipette. The results derived from formulas are consistent with rigorous ones by numerical computation in the approximate range.
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Cells , Models, Theoretical , Pressure , SuctionABSTRACT
As the basis of cell proliferation, cytokinesis involves the division of the cytoplasm and the plasma membrane into two. In this paper a few models on the active deformation mechanism during cytokinesis process are presented. Discussions are made onvarious models, conclusions, differences between the numerical results and the corresponding experimental results.