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Hughes R, Yeomans JM. Collective chemotaxis of active nematic droplets. Phys Rev E 2020; 102:020601. [PMID: 32942458 DOI: 10.1103/physreve.102.020601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 08/12/2020] [Indexed: 11/07/2022]
Abstract
Collective chemotaxis plays a key role in the navigation of cell clusters in, e.g., embryogenesis and cancer metastasis. Using the active nematic continuum equations, coupled to a chemical field that regulates activity, we demonstrate and explain a physical mechanism that results in collective chemotaxis. The activity naturally leads to cell polarization at the cluster interface which induces outward flows. The chemical gradient then breaks the symmetry of the flow field, leading to a net motion. The velocity is independent of the cluster size, in agreement with experiment.
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Affiliation(s)
- Rian Hughes
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - Julia M Yeomans
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
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2
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Salehi SS, Shamloo A, Hannani SK. Microfluidic technologies to engineer mesenchymal stem cell aggregates-applications and benefits. Biophys Rev 2020; 12:123-133. [PMID: 31953794 PMCID: PMC7040154 DOI: 10.1007/s12551-020-00613-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 01/07/2020] [Indexed: 02/07/2023] Open
Abstract
Three-dimensional cell culture and the forming multicellular aggregates are superior over traditional monolayer approaches due to better mimicking of in vivo conditions and hence functions of a tissue. A considerable amount of attention has been devoted to devising efficient methods for the rapid formation of uniform-sized multicellular aggregates. Microfluidic technology describes a platform of techniques comprising microchannels to manipulate the small number of reagents with unique properties and capabilities suitable for biological studies. The focus of this review is to highlight recent studies of using microfluidics, especially droplet-based types for the formation, culture, and harvesting of mesenchymal stem cell aggregates and their subsequent application in stem cell biology, tissue engineering, and drug screening. Droplet-based microfluidics can be used to form microgels as carriers for delivering cells and to provide biological cues to the target tissue so as to be minimally invasive. Stem cell-laden microgels with a shape-forming property can be used as smart building blocks by injecting them into the injured tissue thereby constituting the cornerstone of tissue regeneration.
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Affiliation(s)
| | - Amir Shamloo
- School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
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3
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Personalised deposition maps for micro- and nanoparticles targeting an atherosclerotic plaque: attributions to the receptor-mediated adsorption on the inflamed endothelial cells. Biomech Model Mechanobiol 2019; 18:813-828. [DOI: 10.1007/s10237-018-01116-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 12/29/2018] [Indexed: 01/25/2023]
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4
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Zhou Y, Li H, Zhang W, Xu J, Li X, Ji B. Automatic directional analysis of cell fluorescence images and morphological modeling of microfilaments. Med Biol Eng Comput 2018; 57:325-337. [PMID: 30117068 DOI: 10.1007/s11517-018-1871-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 06/15/2018] [Indexed: 11/25/2022]
Abstract
Cytoskeleton and nucleus are two important anatomic components in eukaryotic cells. Cell fluorescence images are employed to study their realignment and deformation during cell extrusion. Quantitative analysis and modeling of cell orientation are investigated in this paper. For orientation measurement, alignment orientation of microfilaments is calculated using structure tensor method. Nuclei is segmented and fitted to ellipses in nuclei images. Based on the fitted ellipse, orientation and aspect ratio of each nucleus are computed. A morphological model is proposed to describe the movement of microfilaments quantitatively. The parameters of the model are determined by in-plane stresses obtained by numerical simulation. The proposed automatic orientation measurement algorithms can help to analyze the relationship between cell orientation and stress qualitatively. The proposed morphological model is the first model to quantitatively describe the relationship of microfilament movement with stress. Experimental results show that cell and nucleus tend to align along in-plane maximum shear stress and the proposed morphological model is a reasonable model for cell movement. The modeling of cell behavior under different stress can facilitate biomedical research such as tissue engineering and cancer analysis. Graphical abstract ᅟ.
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Affiliation(s)
- Yue Zhou
- School of Information and Electronics, Beijing Institute of Technology, Beijing, 100081, China
| | - Huiqi Li
- School of Information and Electronics, Beijing Institute of Technology, Beijing, 100081, China.
| | - Wanjun Zhang
- School of Information and Electronics, Beijing Institute of Technology, Beijing, 100081, China
| | - Jiayi Xu
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Xiaojun Li
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Baohua Ji
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China
- Department of Engineering Mechanics, Zhejiang University, Zhejiang, 310027, China
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5
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Mehrafrooz B, Shamloo A. Mechanical differences between ATP and ADP actin states: A molecular dynamics study. J Theor Biol 2018; 448:94-103. [PMID: 29634959 DOI: 10.1016/j.jtbi.2018.04.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 03/31/2018] [Accepted: 04/06/2018] [Indexed: 11/15/2022]
Abstract
This paper aims to give a comprehensive atomistic modeling of the nanomechanical behavior of actin monomer. Actin is a ubiquitous and essential component of cytoskeleton which forms many different cellular structures. Despite for several years great effort has been devoted to the investigation of mechanical properties of the actin filament, studies on the nanomechanical behavior of actin monomer are still lacking. These scales are, however, important for a complete understanding of the role of actin as an important component in the cytoskeleton structure. Based on the accuracy of atomistic modeling methods such as molecular dynamics simulations, steered molecular dynamics method is performed to assess tension of monomeric G-actin molecule under different types of mechanical loading including axial and lateral. As a result, stress-strain curves are obtained in aqueous solution, with either ATP or ADP bound in the nucleotide binding pocket. The obtained results yield evaluation of the tensile stiffness of a single actin monomer in lateral and normal direction. In order to compare the behavior of ATP and ADP G-actins, the number of hydrogen bonds and nonbonded interactions between the nucleotide and the protein are analyzed. Moreover, The effect of virtual spring of steered molecular dynamics on the mechanical behavior of actin monomer is investigated. The results reveal increasing the virtual spring constant leads to convergence of the stiffness. Moreover, in this paper, a generalized model is proposed to extend the obtained results for the monomeric G-actin scale to the actin filament. Our modeling estimated a persistence length of actin filament 15.41 µm, close to experimental measurements. Moreover, In this paper, the breaking force actin-actin bond is evaluated using steered molecular dynamics simulation. By applying a tensile force, actin-actin bond ruptured at 4197.5 pN.
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Affiliation(s)
- Behzad Mehrafrooz
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Amir Shamloo
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
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6
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Shamloo A, Mehrafrooz B. Nanomechanics of actin filament: A molecular dynamics simulation. Cytoskeleton (Hoboken) 2018; 75:118-130. [PMID: 29272080 DOI: 10.1002/cm.21429] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 12/14/2017] [Accepted: 12/18/2017] [Indexed: 11/08/2022]
Abstract
Actin is known as the most abundant essentially protein in eukaryotic cells. Actin plays a crucial role in many cellular processes involving mechanical forces such as cell motility, adhesion, muscle contraction, and intracellular transport. However, little is known about the mechanical properties of this protein when subjected to mechanical forces in cellular processes. In this article, a series of large-scale molecular dynamics simulations are carried out to elucidate nanomechanical behavior such as elastic and viscoelastic properties of a single actin filament. Here, we used two individual methods namely, all-atoms and coarse-grained molecular dynamics, to evaluate elastic properties of a single actin filament. In the other word, based on Brownian motions of the filament and using the principle of the equipartition theorem, in aqueous solution, tensile stiffness, torsional rigidity, and bending rigidity of the single actin filament are studied. The results revealed that increasing the sampling window time leads to convergence of obtained mechanical properties to the experimental values. Moreover, in order to investigate viscoelastic properties of a single actin filament, constant force steered molecular dynamics method is used to apply different external tensile loads and perform five individual creep tests on the molecule. The strain-time response of the filament for each creep test is obtained. Based on the Kelvin-Voigt model, the results reveal that a single actin filament shows a nonlinear viscoelastic behavior, with a Young's modulus of 2.85 GPa, a viscosity of 4.06 GPa.ns, and a relaxation time in the range of 1.42 ns which were measured here for the first time at the single filament level. The findings of this article suggest that molecular dynamics simulations could also be a useful tool for investigating the mechanical behavior of bio-nanomaterials.
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Affiliation(s)
- Amir Shamloo
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Behzad Mehrafrooz
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
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7
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Margination and adhesion of micro- and nanoparticles in the coronary circulation: a step towards optimised drug carrier design. Biomech Model Mechanobiol 2017; 17:205-221. [DOI: 10.1007/s10237-017-0955-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 08/11/2017] [Indexed: 12/22/2022]
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8
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Sarmadi M, Shamloo A, Mohseni M. Utilization of Molecular Dynamics Simulation Coupled with Experimental Assays to Optimize Biocompatibility of an Electrospun PCL/PVA Scaffold. PLoS One 2017; 12:e0169451. [PMID: 28118371 PMCID: PMC5261812 DOI: 10.1371/journal.pone.0169451] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 12/16/2016] [Indexed: 11/19/2022] Open
Abstract
The main focus of this study is to address the possibility of using molecular dynamics (MD) simulation, as a computational framework, coupled with experimental assays, to optimize composite structures of a particular electrospun scaffold. To this aim, first, MD simulations were performed to obtain an initial theoretical insight into the capability of heterogeneous surfaces for protein adsorption. The surfaces were composed of six different blends of PVA (polyvinyl alcohol) and PCL (polycaprolactone) with completely unlike hydrophobicity. Next, MTT assay was performed on the electrospun scaffolds made from the same percentages of polymers as in MD models to gain an understanding of the correlation between protein adsorption on the composite surfaces and their capability for cell proliferation. To perform simulations, two ECM (extracellular matrix) protein fragments, namely, collagen type I and fibronectin, two essential proteins for initial cell attachment and eventual cell proliferation, were considered. To evaluate the strength of protein adsorption, adhesion energy and final conformations of proteins were studied. For MTT analysis, different blends of PCL/PVA electrospun scaffolds were prepared, on which endothelial cells were cultured for one week. Theoretical results indicated that the samples with more than 50% of PCL significantly represented stronger protein adsorption. In agreement with simulation results, experimental analysis also demonstrated that the more hydrophobic the surface became, the better initial cell attachment and cell proliferation could be achieved, which was particularly better observed in samples with more than 70% of PCL.
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Affiliation(s)
- Morteza Sarmadi
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Amir Shamloo
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
- * E-mail:
| | - Mina Mohseni
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
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9
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Yu S, Gao Y, Mei X, Ren T, Liang S, Mao Z, Gao C. Preparation of an Arg-Glu-Asp-Val Peptide Density Gradient on Hyaluronic Acid-Coated Poly(ε-caprolactone) Film and Its Influence on the Selective Adhesion and Directional Migration of Endothelial Cells. ACS APPLIED MATERIALS & INTERFACES 2016; 8:29280-29288. [PMID: 27723284 DOI: 10.1021/acsami.6b09375] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Selective adhesion and migration of endothelial cells (ECs) over smooth muscle cells (SMCs) is very important in the rapid endothelialization of blood-contacting implants to prevent vascular restenosis. In this study, a uniform cell-resistant layer of methacrylate-functionalized hyaluronic acid (HA) was first immobilized on a poly(ε-caprolactone) (PCL) film via polydopamine coupling. Then, a density gradient of thiol-functionalized Arg-Glu-Asp-Val (REDV) peptide was prepared on the HA layer via thiol-ene click chemistry and the continuous injection method. The REDV gradient selectively enhanced EC adhesion and preferential directional migration toward the region of higher REDV density, reaching 86% directionality in the middle of the gradient. The migration rate of ECs was also significantly enhanced twofold compared with that on tissue culture polystyrene (TCPS). In contrast, the gradient significantly weakened the adhesion of SMCs to 25% of that on TCPS but had no obvious impact on the migration rate and directionality. Successful modulation of the selective adhesion and directional migration of ECs over SMCs on biodegradable polymers serves as an important step toward practical applications for guided tissue regeneration.
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Affiliation(s)
- Shan Yu
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Ying Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Xu Mei
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Tanchen Ren
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Su Liang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Zhengwei Mao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, China
| | - Changyou Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University , Hangzhou 310027, China
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Maçon ALB, Li S, Chung JJ, Nommeots-Nomm A, Solanki AK, Stevens MM, Jones JR. Ductile silica/methacrylate hybrids for bone regeneration. J Mater Chem B 2016; 4:6032-6042. [DOI: 10.1039/c6tb00968a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hybrids consisting of co-networks of high cross-linking density polymethacrylate and silica (class II hybrid) were synthesised as a potential new generation of scaffold materials.
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Affiliation(s)
| | - Siwei Li
- Department of Materials Imperial College London
- London
- UK
| | | | | | | | - Molly M. Stevens
- Department of Materials Imperial College London
- London
- UK
- Institute of Biomedical Engineering Imperial College London
- London
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11
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Abeddoust M, Shamloo A. A model for cell density effect on stress fiber alignment and collective directional migration. Phys Biol 2015; 12:066023. [DOI: 10.1088/1478-3975/12/6/066023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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12
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Integrative Utilization of Microenvironments, Biomaterials and Computational Techniques for Advanced Tissue Engineering. J Biotechnol 2015; 212:71-89. [DOI: 10.1016/j.jbiotec.2015.08.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Revised: 08/02/2015] [Accepted: 08/11/2015] [Indexed: 01/13/2023]
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13
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Collective cell migration: guidance principles and hierarchies. Trends Cell Biol 2015; 25:556-66. [DOI: 10.1016/j.tcb.2015.06.003] [Citation(s) in RCA: 227] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 05/21/2015] [Accepted: 06/08/2015] [Indexed: 12/18/2022]
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Acetyl-L-Carnitine Prevents Methamphetamine-Induced Structural Damage on Endothelial Cells via ILK-Related MMP-9 Activity. Mol Neurobiol 2014; 53:408-422. [PMID: 25465237 DOI: 10.1007/s12035-014-8973-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 10/29/2014] [Indexed: 12/18/2022]
Abstract
Methamphetamine (METH) is a potent psychostimulant highly used worldwide. Recent studies evidenced the involvement of METH in the breakdown of the blood-brain-barrier (BBB) integrity leading to compromised function. The involvement of the matrix metalloproteinases (MMPs) in the degradation of the neurovascular matrix components and tight junctions (TJs) is one of the most recent findings in METH-induced toxicity. As BBB dysfunction is a pathological feature of many neurological conditions, unveiling new protective agents in this field is of major relevance. Acetyl-L-carnitine (ALC) has been described to protect the BBB function in different paradigms, but the mechanisms underling its action remain mostly unknown. Here, the immortalized bEnd.3 cell line was used to evaluate the neuroprotective features of ALC in METH-induced damage. Cells were exposed to ranging concentrations of METH, and the protective effect of ALC 1 mM was assessed 24 h after treatment. F-actin rearrangement, TJ expression and distribution, and MMPs activity were evaluated. Integrin-linked kinase (ILK) knockdown cells were used to assess role of ALC in ILK mediated METH-triggered MMPs' activity. Our results show that METH led to disruption of the actin filaments concomitant with claudin-5 translocation to the cytoplasm. These events were mediated by MMP-9 activation in association with ILK overexpression. Pretreatment with ALC prevented METH-induced activation of MMP-9, preserving claudin-5 location and the structural arrangement of the actin filaments. The present results support the potential of ALC in preserving BBB integrity, highlighting ILK as a new target for the ALC therapeutic use.
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