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Wang J, Sarkar D, Mohan A, Lee M, Ma Z, Chortos A. Deep Learning for Strain Field Customization in Bioreactor with Dielectric Elastomer Actuator Array. CYBORG AND BIONIC SYSTEMS 2024; 5:0155. [PMID: 39144697 PMCID: PMC11322265 DOI: 10.34133/cbsystems.0155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 07/09/2024] [Indexed: 08/16/2024] Open
Abstract
In the field of biomechanics, customizing complex strain fields according to specific requirements poses an important challenge for bioreactor technology, primarily due to the intricate coupling and nonlinear actuation of actuator arrays, which complicates the precise control of strain fields. This paper introduces a bioreactor designed with a 9 × 9 array of independently controllable dielectric elastomer actuators (DEAs), addressing this challenge. We employ image regression-based machine learning for both replicating target strain fields through inverse control and rapidly predicting feasible strain fields generated by the bioreactor in response to control inputs via forward control. To generate training data, a finite element analysis (FEA) simulation model was developed. In the FEA, the device was prestretched, followed by the random assignment of voltages to each pixel, yielding 10,000 distinct output strain field images for the training set. For inverse control, a multilayer perceptron (MLP) is utilized to predict control inputs from images, whereas, for forward control, MLP maps control inputs to low-resolution images, which are then upscaled to high-resolution outputs through a super-resolution generative adversarial network (SRGAN). Demonstrations include inputting biomechanically significant strain fields, where the method successfully replicated the intended fields. Additionally, by using various tumor-stroma interfaces as inputs, the bioreactor demonstrated its ability to customize strain fields accordingly, showcasing its potential as an advanced testbed for tumor biomechanics research.
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Affiliation(s)
- Jue Wang
- School of Mechanical Engineering, College of Engineering,
Purdue University, West Lafayette, IN, USA
| | - Dhirodaatto Sarkar
- School of Mechanical Engineering, College of Engineering,
Purdue University, West Lafayette, IN, USA
| | - Atulya Mohan
- School of Mechanical Engineering, College of Engineering,
Purdue University, West Lafayette, IN, USA
| | - Mina Lee
- School of Mechanical Engineering, College of Engineering,
Purdue University, West Lafayette, IN, USA
| | - Zeyu Ma
- School of Mechanical Engineering, College of Engineering,
Purdue University, West Lafayette, IN, USA
- School of Mechanical Engineering, Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Institute of Design Science and Basic Components, Xi’an Jiaotong University, Xi’an, P. R. China
| | - Alex Chortos
- School of Mechanical Engineering, College of Engineering,
Purdue University, West Lafayette, IN, USA
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Chen Z, Xiao L, Hu C, Shen Z, Zhou E, Zhang S, Wang Y. Aligned Lovastatin-loaded Electrospun Nanofibers Regulate Collagen Organization and Reduce Scar Formation. Acta Biomater 2023; 164:240-252. [PMID: 37075962 DOI: 10.1016/j.actbio.2023.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 04/04/2023] [Accepted: 04/12/2023] [Indexed: 04/21/2023]
Abstract
Excessive scar formation caused by cutaneous injury leads to pruritus, pain, contracture, dyskinesia, and unpleasant appearance. Functional wound dressings are designed to accelerate wound healing and reduce scar formation. In this study, we fabricated aligned or random polycaprolactone/silk fibroin electrospun nanofiber membranes with or without lovastatin loading, and then evaluated their scar-inhibitory effects on wounds under a specific tension direction. The nanofiber membranes exhibited good controlled-release performance, mechanical properties, hydrophilicity, and biocompatibility. Furthermore, nanofibers' perpendicular placement to the tension direction of the wound most effectively reduced scar formation (the scar area decreased by 66.9%) and promoted skin regeneration in vivo. The mechanism was associated with its aligned nanofibers regulated collagen organization in the early stage of wound healing. Moreover, lovastatin-loaded nanofibers inhibited myofibroblast differentiation and migration. Both tension direction-perpendicular topographical cues and lovastatin synergistically inhibited mechanical transduction and fibrosis progression, further reducing scar formation. In summary, our study may provide an effective scar prevention strategy in which individualized dressings can be designed according to the local mechanical force direction of patients' wounds, and the addition of lovastatin can further inhibit scar formation. STATEMENT OF SIGNIFICANCE: In vivo, cells and collagen are always arranged parallel to the tension direction. However, the aligned topographic cues themselves promote myofibroblast differentiation and exacerbate scar formation. Electrospun nanofibers' perpendicular placement to the tension direction of the wound most effectively reduces scar formation and promotes skin regeneration in vivo. The mechanism is associated with its tension direction-perpendicular nanofibers reregulate collagen organization in the early stage of wound healing. In addition, tension direction-perpendicular topographical cue and lovastatin could inhibit mechanical transduction and fibrosis progression synergistically, further reducing scar formation. This study proves that combining topographical cues of wound dressing and drugs would be a promising therapy for clinical scar management.
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Affiliation(s)
- Zuhan Chen
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, 430072, China; Department of Kidney Transplantation, Nephropathy Hospital, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, China
| | - Lingfei Xiao
- Department of Spine Surgery and Musculoskeletal Tumor, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, 430071, China
| | - Chaoyu Hu
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, 430072, China
| | - Zixia Shen
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, 430072, China
| | - Encheng Zhou
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, 430072, China
| | - Shichen Zhang
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, 430072, China
| | - Yanfeng Wang
- Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, 430072, China.
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Wang EY, Zhao Y, Okhovatian S, Smith JB, Radisic M. Intersection of stem cell biology and engineering towards next generation in vitro models of human fibrosis. Front Bioeng Biotechnol 2022; 10:1005051. [PMID: 36338120 PMCID: PMC9630603 DOI: 10.3389/fbioe.2022.1005051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 09/26/2022] [Indexed: 08/31/2023] Open
Abstract
Human fibrotic diseases constitute a major health problem worldwide. Fibrosis involves significant etiological heterogeneity and encompasses a wide spectrum of diseases affecting various organs. To date, many fibrosis targeted therapeutic agents failed due to inadequate efficacy and poor prognosis. In order to dissect disease mechanisms and develop therapeutic solutions for fibrosis patients, in vitro disease models have gone a long way in terms of platform development. The introduction of engineered organ-on-a-chip platforms has brought a revolutionary dimension to the current fibrosis studies and discovery of anti-fibrotic therapeutics. Advances in human induced pluripotent stem cells and tissue engineering technologies are enabling significant progress in this field. Some of the most recent breakthroughs and emerging challenges are discussed, with an emphasis on engineering strategies for platform design, development, and application of machine learning on these models for anti-fibrotic drug discovery. In this review, we discuss engineered designs to model fibrosis and how biosensor and machine learning technologies combine to facilitate mechanistic studies of fibrosis and pre-clinical drug testing.
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Affiliation(s)
- Erika Yan Wang
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, United States
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Yimu Zhao
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
| | - Sargol Okhovatian
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
| | - Jacob B. Smith
- Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Milica Radisic
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
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4
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Marcos-Garcés V, Rios-Navarro C, Gómez-Torres F, Gavara J, de Dios E, Diaz A, Miñana G, Chorro FJ, Bodi V, Ruiz-Sauri A. Fourier analysis of collagen bundle orientation in myocardial infarction scars. Histochem Cell Biol 2022; 158:471-483. [PMID: 35948735 PMCID: PMC9630212 DOI: 10.1007/s00418-022-02132-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2022] [Indexed: 11/24/2022]
Abstract
Collagen bundle orientation (CBO) in myocardial infarct scars plays a major role in scar mechanics and complications after infarction. We aim to compare four histopathological methods for CBO measurement in myocardial scarring. Myocardial infarction was induced in 21 pigs by balloon coronary occlusion. Scar samples were obtained at 4 weeks, stained with Masson’s trichrome, Picrosirius red, and Hematoxylin–Eosin (H&E), and photographed using light, polarized light microscopy, and confocal microscopy, respectively. Masson’s trichrome images were also optimized to remove non-collagenous structures. Two observers measured CBO by means of a semi-automated, Fourier analysis protocol. Interrater reliability and comparability between techniques were studied by the intraclass correlation coefficient (ICC) and Bland–Altman (B&A) plots and limits of agreement. Fourier analysis showed an almost perfect interrater reliability for each technique (ICC ≥ 0.95, p < 0.001 in all cases). CBO showed more randomly oriented values in Masson’s trichrome and worse comparability with other techniques (ICC vs. Picrosirius red: 0.79 [0.47–0.91], p = 0.001; vs. H&E-confocal: 0.70 [0.26–0.88], p = 0.005). However, optimized Masson’s trichrome showed almost perfect agreement with Picrosirius red (ICC 0.84 [0.6–0.94], p < 0.001) and H&E-confocal (ICC 0.81 [0.54–0.92], p < 0.001), as well as these latter techniques between each other (ICC 0.84 [0.60–0.93], p < 0.001). In summary, a semi-automated, Fourier-based method can provide highly reproducible CBO measurements in four different histopathological techniques. Masson’s trichrome tends to provide more randomly oriented CBO index values, probably due to non-specific visualization of non-collagenous structures. However, optimization of Masson’s trichrome microphotographs to remove non-collagenous components provides an almost perfect comparability between this technique, Picrosirius red and H&E-confocal.
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Affiliation(s)
- Víctor Marcos-Garcés
- Department of Cardiology, Hospital Clínico Universitario de Valencia, Valencia, Spain.,INCLIVA Health Research Institute, Valencia, Spain
| | | | - Fabián Gómez-Torres
- Universidad Industrial de Santander, Escuela de Medicina, Bucaramanga, Colombia
| | - Jose Gavara
- INCLIVA Health Research Institute, Valencia, Spain
| | - Elena de Dios
- Center for Networked Biomedical Research-Cardiovascular (CIBER-CV), Madrid, Spain
| | - Ana Diaz
- Central Unit for Research in Medicine (UCIM), University of Valencia, Valencia, Spain
| | - Gema Miñana
- Department of Cardiology, Hospital Clínico Universitario de Valencia, Valencia, Spain.,INCLIVA Health Research Institute, Valencia, Spain.,Department of Medicine, University of Valencia, Valencia, Spain
| | - Francisco Javier Chorro
- Department of Cardiology, Hospital Clínico Universitario de Valencia, Valencia, Spain.,INCLIVA Health Research Institute, Valencia, Spain.,Center for Networked Biomedical Research-Cardiovascular (CIBER-CV), Madrid, Spain.,Department of Medicine, University of Valencia, Valencia, Spain
| | - Vicente Bodi
- Department of Cardiology, Hospital Clínico Universitario de Valencia, Valencia, Spain. .,INCLIVA Health Research Institute, Valencia, Spain. .,Center for Networked Biomedical Research-Cardiovascular (CIBER-CV), Madrid, Spain. .,Department of Medicine, University of Valencia, Valencia, Spain. .,Department of Cardiology, Hospital Clínico Universitario de Valencia, Valencia, Spain Instituto de Investigación Sanitaria del Hospital Clínico Universitario de Valencia (INCLIVA), Valencia, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBER-CV), Madrid, Spain. .,Department of Medicine, Faculty of Medicine and Odontology, University of Valencia, Blasco Ibanez 17, 46010, Valencia, Spain.
| | - Amparo Ruiz-Sauri
- INCLIVA Health Research Institute, Valencia, Spain. .,Department of Pathology, University of Valencia, Valencia, Spain. .,Departamento de Patología, Facultad de Medicina y Odontología, Universitat de València, Avda/Blasco Ibáñez nº15, 46010, València, Spain.
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Garoffolo G, Casaburo M, Amadeo F, Salvi M, Bernava G, Piacentini L, Chimenti I, Zaccagnini G, Milcovich G, Zuccolo E, Agrifoglio M, Ragazzini S, Baasansuren O, Cozzolino C, Chiesa M, Ferrari S, Carbonaro D, Santoro R, Manzoni M, Casalis L, Raucci A, Molinari F, Menicanti L, Pagano F, Ohashi T, Martelli F, Massai D, Colombo GI, Messina E, Morbiducci U, Pesce M. Reduction of Cardiac Fibrosis by Interference With YAP-Dependent Transactivation. Circ Res 2022; 131:239-257. [PMID: 35770662 DOI: 10.1161/circresaha.121.319373] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Conversion of cardiac stromal cells into myofibroblasts is typically associated with hypoxia conditions, metabolic insults, and/or inflammation, all of which are predisposing factors to cardiac fibrosis and heart failure. We hypothesized that this conversion could be also mediated by response of these cells to mechanical cues through activation of the Hippo transcriptional pathway. The objective of the present study was to assess the role of cellular/nuclear straining forces acting in myofibroblast differentiation of cardiac stromal cells under the control of YAP (yes-associated protein) transcription factor and to validate this finding using a pharmacological agent that interferes with the interactions of the YAP/TAZ (transcriptional coactivator with PDZ-binding motif) complex with their cognate transcription factors TEADs (TEA domain transcription factors), under high-strain and profibrotic stimulation. METHODS We employed high content imaging, 2-dimensional/3-dimensional culture, atomic force microscopy mapping, and molecular methods to prove the role of cell/nuclear straining in YAP-dependent fibrotic programming in a mouse model of ischemia-dependent cardiac fibrosis and in human-derived primitive cardiac stromal cells. We also tested treatment of cells with Verteporfin, a drug known to prevent the association of the YAP/TAZ complex with their cognate transcription factors TEADs. RESULTS Our experiments suggested that pharmacologically targeting the YAP-dependent pathway overrides the profibrotic activation of cardiac stromal cells by mechanical cues in vitro, and that this occurs even in the presence of profibrotic signaling mediated by TGF-β1 (transforming growth factor beta-1). In vivo administration of Verteporfin in mice with permanent cardiac ischemia reduced significantly fibrosis and morphometric remodeling but did not improve cardiac performance. CONCLUSIONS Our study indicates that preventing molecular translation of mechanical cues in cardiac stromal cells reduces the impact of cardiac maladaptive remodeling with a positive effect on fibrosis.
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Affiliation(s)
- Gloria Garoffolo
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Manuel Casaburo
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Francesco Amadeo
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Massimo Salvi
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy (M.S., D.C., F. Molinari, D.M., U.M.)
| | - Giacomo Bernava
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Luca Piacentini
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Isotta Chimenti
- Department of Medical Surgical Science and Biotechnology, Sapienza University of Rome (I.C., C.C.).,Mediterranea Cardiocentro, Napoli (I.C.)
| | | | | | - Estella Zuccolo
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Marco Agrifoglio
- Dipartimento di Scienze Biomediche, Chirurgiche ed Odontoiatriche, Università di Milano, Milan, Italy (M.A.)
| | - Sara Ragazzini
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Otgon Baasansuren
- Faculty of Engineering, Hokkaido University, Sapporo, Japan (O.B., T.O.)
| | - Claudia Cozzolino
- Department of Medical Surgical Science and Biotechnology, Sapienza University of Rome (I.C., C.C.)
| | - Mattia Chiesa
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Silvia Ferrari
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Dario Carbonaro
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy (M.S., D.C., F. Molinari, D.M., U.M.)
| | - Rosaria Santoro
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Martina Manzoni
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | | | - Angela Raucci
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Filippo Molinari
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy (M.S., D.C., F. Molinari, D.M., U.M.)
| | | | - Francesca Pagano
- Institute of Biochemistry and Cell Biology, National Council of Research (IBBC-CNR), Monterotondo, Italy (F.P.)
| | - Toshiro Ohashi
- Faculty of Engineering, Hokkaido University, Sapporo, Japan (O.B., T.O.)
| | | | - Diana Massai
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy (M.S., D.C., F. Molinari, D.M., U.M.)
| | - Gualtiero I Colombo
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
| | - Elisa Messina
- Department of Pediatrics and Infant Neuropsychiatry. Policlinico Umberto I, Sapienza University of Rome (E.M.)
| | - Umberto Morbiducci
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy (M.S., D.C., F. Molinari, D.M., U.M.)
| | - Maurizio Pesce
- Centro Cardiologico Monzino, IRCCS, Milan, Italy (G.G., M.C., F.A., G.B., L.P., E.Z., S.R., M.C., S.F., R.S., M.M., A.R., G.I.C., M.P.)
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Rogers JD, Richardson WJ. Fibroblast mechanotransduction network predicts targets for mechano-adaptive infarct therapies. eLife 2022; 11:e62856. [PMID: 35138248 PMCID: PMC8849334 DOI: 10.7554/elife.62856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 02/08/2022] [Indexed: 11/13/2022] Open
Abstract
Regional control of fibrosis after myocardial infarction is critical for maintaining structural integrity in the infarct while preventing collagen accumulation in non-infarcted areas. Cardiac fibroblasts modulate matrix turnover in response to biochemical and biomechanical cues, but the complex interactions between signaling pathways confound efforts to develop therapies for regional scar formation. We employed a logic-based ordinary differential equation model of fibroblast mechano-chemo signal transduction to predict matrix protein expression in response to canonical biochemical stimuli and mechanical tension. Functional analysis of mechano-chemo interactions showed extensive pathway crosstalk with tension amplifying, dampening, or reversing responses to biochemical stimuli. Comprehensive drug target screens identified 13 mechano-adaptive therapies that promote matrix accumulation in regions where it is needed and reduce matrix levels in regions where it is not needed. Our predictions suggest that mechano-chemo interactions likely mediate cell behavior across many tissues and demonstrate the utility of multi-pathway signaling networks in discovering therapies for context-specific disease states.
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Affiliation(s)
- Jesse D Rogers
- Department of Bioengineering; Clemson UniversityClemsonUnited States
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7
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Volumetric growth of soft tissues evaluated in the current configuration. Biomech Model Mechanobiol 2022; 21:569-588. [PMID: 35044527 PMCID: PMC8940838 DOI: 10.1007/s10237-021-01549-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 12/17/2021] [Indexed: 11/02/2022]
Abstract
AbstractThe growth and remodelling of soft tissues plays a significant role in many physiological applications, particularly in understanding and managing many diseases. A commonly used approach for soft tissue growth and remodelling is volumetric growth theory, introduced in the framework of finite elasticity. In such an approach, the total deformation gradient tensor is decomposed so that the elastic and growth tensors can be studied separately. A critical element in this approach is to determine the growth tensor and its evolution with time. Most existing volumetric growth theories define the growth tensor in the reference (natural) configuration, which does not reflect the continuous adaptation processes of soft tissues under the current configuration. In a few studies where growth from a loaded configuration was considered, simplifying assumptions, such as compatible deformation or geometric symmetries, were introduced. In this work, we propose a new volumetric growth law that depends on fields evaluated in the current configuration, which is residually stressed and loaded, without any geometrical restrictions. We illustrate our idea using a simplified left ventricle model, which admits inhomogeneous growth in the current configuration. We compare the residual stress distribution of our approach with the traditional volumetric growth theory, that assumes growth occurring from the natural reference configuration. We show that the proposed framework leads to qualitative agreements with experimental measurements. Furthermore, using a cylindrical model, we find an incompatibility index that explains the differences between the two approaches in more depth. We also demonstrate that results from both approaches reach the same steady solution published previously at the limit of a saturated growth. Although we used a left ventricle model as an example, our theory is applicable in modelling the volumetric growth of general soft tissues.
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8
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Potter MJ, Richardson WJ. Fabrication and characterization methods for investigating cell-matrix interactions in environments possessing spatial orientation heterogeneity. Acta Biomater 2021; 136:420-428. [PMID: 34601105 PMCID: PMC8627456 DOI: 10.1016/j.actbio.2021.09.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 11/29/2022]
Abstract
Fibrillar collagen is a ubiquitous structural protein that plays a significant role in determining the mechanical properties of various tissues. The constituent collagen architecture can give direct insight into the respective functional role of the tissue due to the strong structure-function relationship that is exhibited. In such tissues, matrix structure can vary across local subregions contributing to mechanical heterogeneity which can be implicated in tissue function or failure. The post-myocardial infarction scar environment is an example of note where mechanically insufficient collagen can result in impaired cardiac function and possibly tissue rupture due to post-MI cellular response and matrix interactions. In order to further develop the understanding of cell-matrix interactions within heterogeneous environments, we developed a method of heterogeneous collagen gel fabrication which produces a region of randomly oriented fibers directly adjacent to an interconnected region of anisotropic alignment. To fully capture and evaluate the degree of alignment and spatial orientation heterogeneity, several image processing and automated analysis methods were employed. Our analysis revealed the successful fabrication of an interconnected spatially heterogeneous collagen gel possessing distinct regions of random or preferential alignment. Additionally, embedded cell populations were observed to recognize and reorient with their underlying and surrounding architectures through our cell-centric analysis techniques. STATEMENT OF SIGNIFICANCE: Fibrillar collagen is a structural protein that contributes to the architecture-function relationship exhibited by various tissues where mechanically insufficient collagen architecture can lead to tissue failure. One environment where this can occur is the post-myocardial infarction scar environment where too much or too little collagen accumulation coupled with spatial fiber orientation heterogeneity can lead to environments incapable of normal mechanical functionality. While there are methodologies capable of generating aligned constructs, they do so with varying degrees of control and complexity with many producing uniform construct alignment. The presented platform is simple and produces continuous constructs possessing inherent spatial orientation heterogeneity. Coupling this with image processing and automated analysis methods enables the probing of fundamental cell-matrix interactions within heterogeneous environments.
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Affiliation(s)
- Michael J Potter
- Department of Bioengineering, 301 Rhodes Research Center Clemson University, Clemson, SC, USA.
| | - William J Richardson
- Department of Bioengineering, 301 Rhodes Research Center Clemson University, Clemson, SC, USA; Biomedical Data Science & Informatics Program, Clemson University, Clemson, SC, USA.
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9
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Ghasemi M, Johnston RD, Lally C. Development of a Collagen Fibre Remodelling Rupture Risk Metric for Potentially Vulnerable Carotid Artery Atherosclerotic Plaques. Front Physiol 2021; 12:718470. [PMID: 34776999 PMCID: PMC8586512 DOI: 10.3389/fphys.2021.718470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/22/2021] [Indexed: 11/24/2022] Open
Abstract
Atherosclerotic plaque rupture in carotid arteries can lead to stroke which is one of the leading causes of death or disability worldwide. The accumulation of atherosclerotic plaque in an artery changes the mechanical properties of the vessel. Whilst healthy arteries can continuously adapt to mechanical loads by remodelling their internal structure, particularly the load-bearing collagen fibres, diseased vessels may have limited remodelling capabilities. In this study, a local stress modulated remodelling algorithm is proposed to explore the mechanical response of arterial tissue to the remodelling of collagen fibres. This stress driven remodelling algorithm is used to predict the optimum distribution of fibres in healthy and diseased human carotid bifurcations obtained using Magnetic Resonance Imaging (MRI). In the models, healthy geometries were segmented into two layers: media and adventitia and diseased into four components: adventitia, media, plaque atheroma and lipid pool (when present in the MRI images). A novel meshing technique for hexahedral meshing of these geometries is also demonstrated. Using the remodelling algorithm, the optimum fibre patterns in various patient specific plaques are identified and the role that deviations from these fibre configurations in plaque vulnerability is shown. This study provides critical insights into the collagen fibre patterns required in carotid artery and plaque tissue to maintain plaque stability.
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Affiliation(s)
- Milad Ghasemi
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland
- Department of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
| | - Robert D. Johnston
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland
- Department of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
| | - Caitríona Lally
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland
- Department of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
- Advanced Materials and Bioengineering Research Centre (AMBER), Royal College of Surgeons in Ireland and Trinity College Dublin, Dublin, Ireland
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10
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Montgomery J, Richardson WJ, Marsh S, Rhett JM, Bustos F, Degen K, Ghatnekar GS, Grek CL, Jourdan LJ, Holmes JW, Gourdie RG. The connexin 43 carboxyl terminal mimetic peptide αCT1 prompts differentiation of a collagen scar matrix in humans resembling unwounded skin. FASEB J 2021; 35:e21762. [PMID: 34246197 DOI: 10.1096/fj.202001881r] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 06/02/2021] [Accepted: 06/14/2021] [Indexed: 12/12/2022]
Abstract
Phase II clinical trials have reported that acute treatment of surgical skin wounds with the therapeutic peptide alpha Connexin Carboxy-Terminus 1 (αCT1) improves cutaneous scar appearance by 47% 9-month postsurgery. While Cx43 and ZO-1 have been identified as molecular targets of αCT1, the mode-of-action of the peptide in scar mitigation at cellular and tissue levels remains to be further characterized. Scar histoarchitecture in αCT1 and vehicle-control treated skin wounds within the same patient were compared using biopsies from a Phase I clinical trial at 29-day postwounding. The sole effect on scar structure of a range of epidermal and dermal variables examined was that αCT1-treated scars had less alignment of collagen fibers relative to control wounds-a characteristic that resembles unwounded skin. The with-in subject effect of αCT1 on scar collagen order observed in Phase I testing in humans was recapitulated in Sprague-Dawley rats and the IAF hairless guinea pig. Transient increase in histologic collagen density in response to αCT1 was also observed in both animal models. Mouse NIH 3T3 fibroblasts and primary human dermal fibroblasts treated with αCT1 in vitro showed more rapid closure in scratch wound assays, with individual cells showing decreased directionality in movement. An agent-based computational model parameterized with fibroblast motility data predicted collagen alignments in simulated scars consistent with that observed experimentally in human and the animal models. In conclusion, αCT1 prompts decreased directionality of fibroblast movement and the generation of a 3D collagen matrix postwounding that is similar to unwounded skin-changes that correlate with long-term improvement in scar appearance.
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Affiliation(s)
- Jade Montgomery
- Fralin Biomedical Research Institute, Center for Vascular and Heart Research, Virginia Tech Carilion, Roanoke, VA, USA.,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, USA
| | | | - Spencer Marsh
- Fralin Biomedical Research Institute, Center for Vascular and Heart Research, Virginia Tech Carilion, Roanoke, VA, USA
| | - J Matthew Rhett
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
| | - Francis Bustos
- Fralin Biomedical Research Institute, Center for Vascular and Heart Research, Virginia Tech Carilion, Roanoke, VA, USA.,Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
| | - Katherine Degen
- Fralin Biomedical Research Institute, Center for Vascular and Heart Research, Virginia Tech Carilion, Roanoke, VA, USA.,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, USA
| | | | | | - L Jane Jourdan
- Fralin Biomedical Research Institute, Center for Vascular and Heart Research, Virginia Tech Carilion, Roanoke, VA, USA
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Robert G Gourdie
- Fralin Biomedical Research Institute, Center for Vascular and Heart Research, Virginia Tech Carilion, Roanoke, VA, USA.,Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA, USA.,Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
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11
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Lafci Büyükkahraman M, Sabine GK, Kojouharov HV, Chen-Charpentier BM, McMahan SR, Liao J. Using models to advance medicine: mathematical modeling of post-myocardial infarction left ventricular remodeling. Comput Methods Biomech Biomed Engin 2021; 25:298-307. [PMID: 34266318 DOI: 10.1080/10255842.2021.1953487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The heart is an organ with limited capacity for regeneration and repair. The irreversible cell death and corresponding diminished ability of the heart to repair after myocardial infarction (MI), is a leading cause of morbidity and mortality worldwide. In this paper, a new mathematical model is presented to study the left ventricular (LV) remodeling and associated events after MI. The model accurately describes and predicts the interactions among heart cells and the immune system post-MI in the absence of medical interventions. The resulting system of nonlinear ordinary differential equations is studied both analytically and numerically in order to demonstrate the functionality and performance of the new model. To the best of our knowledge, this model is the only one of its kind to consider and correctly apply all of the known factors in diseased heart LV modeling. This model has the potential to provide researchers with a predictive computational tool to better understand the MI pathology and develop various cell-based treatment options, with benefits of lowering the cost and reducing the development time.
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Affiliation(s)
- Mehtap Lafci Büyükkahraman
- Department of Mathematics, The University of Texas at Arlington, Arlington, TX, USA.,Department of Mathematics, Uşak University, Uşak, Turkey
| | - Gavin K Sabine
- Department of Mathematics, The University of Texas at Arlington, Arlington, TX, USA
| | - Hristo V Kojouharov
- Department of Mathematics, The University of Texas at Arlington, Arlington, TX, USA
| | | | - Sara R McMahan
- Department of Bioengineering, The University of Texas at Arlington, Arlington, TX, USA
| | - Jun Liao
- Department of Bioengineering, The University of Texas at Arlington, Arlington, TX, USA
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12
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McGee OM, Nolan DR, Mathieu PS, Lally C. An in-silico Investigation Into the Role of Strain and Structure on Vascular Smooth Muscle Cell Growth. Front Bioeng Biotechnol 2021; 9:641794. [PMID: 33959595 PMCID: PMC8093633 DOI: 10.3389/fbioe.2021.641794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 03/25/2021] [Indexed: 11/15/2022] Open
Abstract
The orientation of vascular cells can greatly influence the in vivo mechanical properties and functionality of soft vascular tissues. How cell orientation mediates the growth response of cells is of critical importance in understanding the response of soft tissues to mechanical stimuli or injury. To date, considerable evidence has shown that cells align with structural cues such as collagen fibers. However, in the presence of uniaxial cyclic strain on unstructured substrates, cells generally align themselves perpendicularly to the mechanical stimulus, such as strain, a phenomenon known as “strain avoidance.” The cellular response to this interplay between structural cues and a mechanical stimulus is poorly understood. A recent in vitro experimental study in our lab has investigated both the individual and collective response of rat aortic smooth muscle cells (RASMC) to structural (collagenous aligned constructs) and mechanical (cyclic strain) cues. In this study, a 2D agent-based model (ABM) is developed to simulate the collective response of RASMC to varying amplitudes of cyclic strain (0–10%, 2–8%, 4–6%) when seeded on unstructured (PDMS) and structured (decellularized collagenous tissue) constructs. An ABM is presented that is fit to the experimental outcomes in terms of cellular alignment and cell growth on PDMS substrates, under cyclic strain amplitudes of (4–6%, 2–8%, 0–10%) at 24 and 72 h timepoints. Furthermore, the ABM can predict RASMC alignment and change in cell number on a structured construct at a cyclic strain amplitude of 0–10% after 10 days. The ABM suggests that strain avoidance behavior observed in cells is dominated by selective cell proliferation and apoptosis at these early time points, as opposed to cell re-orientation, i.e., cells perpendicular to the strain increase their rate of proliferation, whilst the rate of apoptosis simultaneously increases in cells parallel to the strain direction. The development of in-silico modeling platforms, such as that presented here, allow for further understanding of the response of cells to changes in their mechanical environment. Such models offer an efficient and robust means to design and optimize the compliance and topological structure of implantable devices and could be used to aid the design of next-generation vascular grafts and stents.
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Affiliation(s)
- Orla M McGee
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Trinity Biomedical Sciences Institute, Dublin, Ireland.,Department of Mechanical, Manufacturing & Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
| | - David R Nolan
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Trinity Biomedical Sciences Institute, Dublin, Ireland.,Department of Mechanical, Manufacturing & Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
| | - Pattie S Mathieu
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Trinity Biomedical Sciences Institute, Dublin, Ireland.,Department of Mechanical, Manufacturing & Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
| | - Caitríona Lally
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Trinity Biomedical Sciences Institute, Dublin, Ireland.,Department of Mechanical, Manufacturing & Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland.,Advanced Materials and Bioengineering Research Centre (AMBER), Royal College of Surgeons in Ireland & Trinity College Dublin, Dublin, Ireland
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13
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Bugg D, Bretherton R, Kim P, Olszewski E, Nagle A, Schumacher AE, Chu N, Gunaje J, DeForest CA, Stevens K, Kim DH, Davis J. Infarct Collagen Topography Regulates Fibroblast Fate via p38-Yes-Associated Protein Transcriptional Enhanced Associate Domain Signals. Circ Res 2020; 127:1306-1322. [PMID: 32883176 DOI: 10.1161/circresaha.119.316162] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
RATIONALE Myocardial infarction causes spatial variation in collagen organization and phenotypic diversity in fibroblasts, which regulate the heart's ECM (extracellular matrix). The relationship between collagen structure and fibroblast phenotype is poorly understood but could provide insights regarding the mechanistic basis for myofibroblast heterogeneity in the injured heart. OBJECTIVE To investigate the role of collagen organization in cardiac fibroblast fate determination. METHODS AND RESULTS Biomimetic topographies were nanofabricated to recapitulate differential collagen organization in the infarcted mouse heart. Here, adult cardiac fibroblasts were freshly isolated and cultured on ECM topographical mimetics for 72 hours. Aligned mimetics caused cardiac fibroblasts to elongate while randomly organized topographies induced circular morphology similar to the disparate myofibroblast morphologies measured in vivo. Alignment cues also induced myofibroblast differentiation, as >60% of fibroblasts formed αSMA (α-smooth muscle actin) stress fibers and expressed myofibroblast-specific ECM genes like Postn (periostin). By contrast, random organization caused 38% of cardiac fibroblasts to express αSMA albeit with downregulated myofibroblast-specific ECM genes. Coupling topographical cues with the profibrotic agonist, TGFβ (transforming growth factor beta), additively upregulated myofibroblast-specific ECM genes independent of topography, but only fibroblasts on flat and randomly oriented mimetics had increased percentages of fibroblasts with αSMA stress fibers. Increased tension sensation at focal adhesions induced myofibroblast differentiation on aligned mimetics. These signals were transduced by p38-YAP (yes-associated protein)-TEAD (transcriptional enhanced associate domain) interactions, in which both p38 and YAP-TEAD (yes-associated protein transcriptional enhanced associate domain) binding were required for myofibroblast differentiation. By contrast, randomly oriented mimetics did not change focal adhesion tension sensation or enrich for p38-YAP-TEAD interactions, which explains the topography-dependent diversity in fibroblast phenotypes observed here. CONCLUSIONS Spatial variations in collagen organization regulate cardiac fibroblast phenotype through mechanical activation of p38-YAP-TEAD signaling, which likely contribute to myofibroblast heterogeneity in the infarcted myocardium.
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Affiliation(s)
- Darrian Bugg
- Pathology (D.B., J.G., K.S., J.D.), University of Washington, Seattle.,Center for Cardiovascular Biology (D.B., R.B., E.O., A.N., J.G., K.S., J.D.), University of Washington, Seattle
| | - Ross Bretherton
- Bioengineering (R.B., P.K., E.O., A.N., N.C., C.A.D., K.S., J.D.), University of Washington, Seattle.,Center for Cardiovascular Biology (D.B., R.B., E.O., A.N., J.G., K.S., J.D.), University of Washington, Seattle
| | - Peter Kim
- Bioengineering (R.B., P.K., E.O., A.N., N.C., C.A.D., K.S., J.D.), University of Washington, Seattle
| | - Emily Olszewski
- Bioengineering (R.B., P.K., E.O., A.N., N.C., C.A.D., K.S., J.D.), University of Washington, Seattle.,Center for Cardiovascular Biology (D.B., R.B., E.O., A.N., J.G., K.S., J.D.), University of Washington, Seattle
| | - Abigail Nagle
- Bioengineering (R.B., P.K., E.O., A.N., N.C., C.A.D., K.S., J.D.), University of Washington, Seattle.,Center for Cardiovascular Biology (D.B., R.B., E.O., A.N., J.G., K.S., J.D.), University of Washington, Seattle
| | | | - Nick Chu
- Bioengineering (R.B., P.K., E.O., A.N., N.C., C.A.D., K.S., J.D.), University of Washington, Seattle
| | - Jagadambika Gunaje
- Pathology (D.B., J.G., K.S., J.D.), University of Washington, Seattle.,Center for Cardiovascular Biology (D.B., R.B., E.O., A.N., J.G., K.S., J.D.), University of Washington, Seattle
| | - Cole A DeForest
- Bioengineering (R.B., P.K., E.O., A.N., N.C., C.A.D., K.S., J.D.), University of Washington, Seattle.,Institute for Stem Cell and Regenerative Medicine (C.A.D., K.S., J.D.), University of Washington, Seattle.,Chemical Engineering (C.A.D.), University of Washington, Seattle
| | - Kelly Stevens
- Bioengineering (R.B., P.K., E.O., A.N., N.C., C.A.D., K.S., J.D.), University of Washington, Seattle.,Pathology (D.B., J.G., K.S., J.D.), University of Washington, Seattle.,Institute for Stem Cell and Regenerative Medicine (C.A.D., K.S., J.D.), University of Washington, Seattle.,Center for Cardiovascular Biology (D.B., R.B., E.O., A.N., J.G., K.S., J.D.), University of Washington, Seattle
| | - Deok-Ho Kim
- Biomedical Engineering, Johns Hopkins University, Baltimore, MD (D.-H.K.).,Medicine, Johns Hopkins School of Medicine, Baltimore, MD (D.-H.K.)
| | - Jennifer Davis
- Center for Cardiovascular Biology (D.B., R.B., E.O., A.N., J.G., K.S., J.D.), University of Washington, Seattle
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14
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Li W. Biomechanics of infarcted left ventricle: a review of modelling. Biomed Eng Lett 2020; 10:387-417. [PMID: 32864174 DOI: 10.1007/s13534-020-00159-4] [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: 02/22/2020] [Revised: 05/06/2020] [Accepted: 05/26/2020] [Indexed: 11/26/2022] Open
Abstract
Mathematical modelling in biomechanics of infarcted left ventricle (LV) serves as an indispensable tool for remodelling mechanism exploration, LV biomechanical property estimation and therapy assessment after myocardial infarction (MI). However, a review of mathematical modelling after MI has not been seen in the literature so far. In the paper, a systematic review of mathematical models in biomechanics of infarcted LV was established. The models include comprehensive cardiovascular system model, essential LV pressure-volume and stress-stretch models, constitutive laws for passive myocardium and scars, tension models for active myocardium, collagen fibre orientation optimization models, fibroblast and collagen fibre growth/degradation models and integrated growth-electro-mechanical model after MI. The primary idea, unique characteristics and key equations of each model were identified and extracted. Discussions on the models were provided and followed research issues on them were addressed. Considerable improvements in the cardiovascular system model, LV aneurysm model, coupled agent-based models and integrated electro-mechanical-growth LV model are encouraged. Substantial attention should be paid to new constitutive laws with respect to stress-stretch curve and strain energy function for infarcted passive myocardium, collagen fibre orientation optimization in scar, cardiac rupture and tissue damage and viscoelastic effect post-MI in the future.
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Affiliation(s)
- Wenguang Li
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ UK
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15
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Fischer NA, Kahook MY, Abdullah S, Porteous E, Ammar DA, Patnaik JL, SooHoo JR. Effect of Novel Design Modifications on Fibrotic Encapsulation: An In Vivo Glaucoma Drainage Device Study in a Rabbit Model. Ophthalmol Ther 2020; 9:279-291. [PMID: 32152939 PMCID: PMC7196114 DOI: 10.1007/s40123-020-00242-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Indexed: 02/07/2023] Open
Abstract
Purpose To quantify the effects of modified Ahmed glaucoma valves® (AGV) with anti-fibrotic plate coatings or a plate surface micro-pattern on outflow resistance and tissue response. Methods Twelve New Zealand rabbits were divided into four groups: commercially available AGV implants (n = 3), AGV with hydrophilic coating (n = 3), AGV with heparin coating (n = 3), and AGV with a plate surface micro-pattern (n = 3). After 6 weeks, the anterior chamber silicone tube was cannulated in situ and perfused with 2.5 μL/min of saline. The pressures were recorded with a perfusion system to measure outflow resistance. The rabbits were then euthanized followed by enucleation of all eyes for bleb histological analyses. Results Hydrostatic pressures were significantly lower in AGVs with the hydrophilic plate coating (mean difference −9.6 mm Hg; p < 0.001), heparin-coated plates (mean difference −4.4 mm Hg; p < 0.001), and micro-patterned plates (mean difference −18.6 mm Hg, p < 0.001), indicating lower outflow resistance compared to control AGV models. Fibrotic encapsulation was lower in hydrophilic plate coating (84.2 μm; mean difference −6.2 μm, p = 0.425), micro-patterned surface (63.7 μm; mean difference −26.7 μm, p = 0.003), and heparin plate coating (49.3 μm; mean difference −41.1 μm, p = 0.006) when compared to control AGV models. Conclusions Modified AGVs with plate coatings and AGVs with micro-patterned plates both appear to reduce postoperative fibrotic encapsulation and aqueous outflow resistance by altering the tissue response to implanted materials. Further studies are needed to characterize the safety and role of plate surface modifications on glaucoma drainage devices.
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Affiliation(s)
- Nathan A Fischer
- Department of Ophthalmology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Malik Y Kahook
- Department of Ophthalmology, University of Colorado School of Medicine, Aurora, CO, USA
| | | | | | - David A Ammar
- Lions Eye Institute for Transplant and Research, Tampa, FL, USA
| | - Jennifer L Patnaik
- Department of Ophthalmology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Jeffrey R SooHoo
- Department of Ophthalmology, University of Colorado School of Medicine, Aurora, CO, USA.
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16
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Rikard SM, Athey TL, Nelson AR, Christiansen SLM, Lee JJ, Holmes JW, Peirce SM, Saucerman JJ. Multiscale Coupling of an Agent-Based Model of Tissue Fibrosis and a Logic-Based Model of Intracellular Signaling. Front Physiol 2019; 10:1481. [PMID: 31920691 PMCID: PMC6928129 DOI: 10.3389/fphys.2019.01481] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 11/18/2019] [Indexed: 12/14/2022] Open
Abstract
Wound healing and fibrosis following myocardial infarction (MI) is a dynamic process involving many cell types, extracellular matrix (ECM), and inflammatory cues. As both incidence and survival rates for MI increase, management of post-MI recovery and associated complications are an increasingly important focus. Complexity of the wound healing process and the need for improved therapeutics necessitate a better understanding of the biochemical cues that drive fibrosis. To study the progression of cardiac fibrosis across spatial and temporal scales, we developed a novel hybrid multiscale model that couples a logic-based differential equation (LDE) model of the fibroblast intracellular signaling network with an agent-based model (ABM) of multi-cellular tissue remodeling. The ABM computes information about cytokine and growth factor levels in the environment including TGFβ, TNFα, IL-1β, and IL-6, which are passed as inputs to the LDE model. The LDE model then computes the network signaling state of individual cardiac fibroblasts within the ABM. Based on the current network state, fibroblasts make decisions regarding cytokine secretion and deposition and degradation of collagen. Simulated fibroblasts respond dynamically to rapidly changing extracellular environments and contribute to spatial heterogeneity in model predicted fibrosis, which is governed by many parameters including cell density, cell migration speeds, and cytokine levels. Verification tests confirmed that predictions of the coupled model and network model alone were consistent in response to constant cytokine inputs and furthermore, a subset of coupled model predictions were validated with in vitro experiments with human cardiac fibroblasts. This multiscale framework for cardiac fibrosis will allow for systematic screening of the effects of molecular perturbations in fibroblast signaling on tissue-scale extracellular matrix composition and organization.
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Affiliation(s)
- S Michaela Rikard
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States
| | - Thomas L Athey
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Anders R Nelson
- Department of Pharmacology, University of Virginia, Charlottesville, VA, United States
| | - Steven L M Christiansen
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States
| | - Jia-Jye Lee
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, United States.,Department of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Shayn M Peirce
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, United States
| | - Jeffrey J Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, United States
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17
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Zhan H, Zhang J, Jiao A, Wang Q. Stretch-activated current in human atrial myocytes and Na + current and mechano-gated channels' current in myofibroblasts alter myocyte mechanical behavior: a computational study. Biomed Eng Online 2019; 18:104. [PMID: 31653259 PMCID: PMC6814973 DOI: 10.1186/s12938-019-0723-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 10/16/2019] [Indexed: 12/19/2022] Open
Abstract
Background The activation of stretch-activated channels (SACs) in cardiac myocytes, which changes the phases of action potential repolarization, is proven to be highly efficient for the conversion of atrial fibrillation. The expression of Na+ current in myofibroblasts (Mfbs) regenerates myocytes’ action potentials, suggesting that Mfbs play an active role in triggering cardiac rhythm disturbances. Moreover, the excitation of mechano-gated channels (MGCs) in Mfbs depolarizes their membrane potential and contributes to the increased risk of post-infarct arrhythmia. Although these electrophysiological mechanisms have been largely known, the roles of these currents in cardiac mechanics are still debated. In this study, we aimed to investigate the mechanical influence of these currents via mathematical modeling. A novel mathematical model was developed by integrating models of human atrial myocyte (including the stretch-activated current, Ca2+–force relation, and mechanical behavior of a single segment) and Mfb (including our formulation of Na+ current and mechano-gated channels’ current). The effects of the changes in basic cycle length, number of coupled Mfbs and intercellular coupling conductance on myocyte mechanical properties were compared. Results Our results indicated that these three currents significantly regulated myocyte mechanical parameters. In isosarcometric contraction, these currents increased segment force by 13.8–36.6% and dropped element length by 12.1–31.5%. In isotonic contraction, there are 2.7–5.9% growth and 0.9–24% reduction. Effects of these currents on the extremum of myocyte mechanical parameters become more significant with the increase of basic cycle length, number of coupled Mfbs and intercellular coupling conductance. Conclusions The results demonstrated that stretch-activated current in myocytes and Na+ current and mechano-gated channels’ current in Mfbs significantly influenced myocyte mechanical behavior and should be considered in future cardiac mechanical mathematical modeling.
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Affiliation(s)
- Heqing Zhan
- College of Medical Information, Hainan Medical University, Haikou, 571199, China.
| | - Jingtao Zhang
- Cardiac Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Beijing, 100037, China
| | - Anquan Jiao
- College of Medical Information, Hainan Medical University, Haikou, 571199, China
| | - Qin Wang
- College of Medical Information, Hainan Medical University, Haikou, 571199, China
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18
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Multiscale modeling of ventricular–vascular dysfunction in pulmonary arterial hypertension. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2019. [DOI: 10.1016/j.cobme.2019.09.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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19
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Korenczuk CE, Barocas VH, Richardson WJ. Effects of Collagen Heterogeneity on Myocardial Infarct Mechanics in a Multiscale Fiber Network Model. J Biomech Eng 2019; 141:091015. [PMID: 31141605 PMCID: PMC6807994 DOI: 10.1115/1.4043865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/23/2019] [Indexed: 01/14/2023]
Abstract
The scar that forms after a myocardial infarction is often characterized by a highly disordered architecture but generally exhibits some degree of collagen fiber orientation, with a resulting mechanical anisotropy. When viewed in finer detail, however, the heterogeneity of the sample is clear, with different subregions exhibiting different fiber orientations. In this work, we used a multiscale finite element model to explore the consequences of the heterogeneity in terms of mechanical behavior. To do so, we used previously obtained fiber alignment maps of rat myocardial scar slices (n = 15) to generate scar-specific finite element meshes that were populated with fiber models based on the local alignment state. These models were then compared to isotropic models with the same sample shape and fiber density, and to homogeneous models with the same sample shape, fiber density, and average fiber alignment as the scar-specific models. All simulations involved equibiaxial extension of the sample with free motion in the third dimension. We found that heterogeneity led to a lower degree of mechanical anisotropy and a higher level of local stress concentration than the corresponding homogeneous model, and also that fibers failed in the heterogeneous model at much lower macroscopic strains than in the isotropic and homogeneous models. Taken together, these results suggest that scar heterogeneity may impair myocardial mechanical function both in terms of anisotropy and strength, and that individual variations in scar heterogeneity could be an important consideration for understanding scar remodeling and designing therapeutic interventions for patients after myocardial infarction.
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Affiliation(s)
- Christopher E Korenczuk
- Department of Biomedical Engineering,University of Minnesota,7-105 Nils Hasselmo Hall,312 Church Street SE,Minneapolis, MN 55455e-mail:
| | - Victor H Barocas
- Department of Biomedical Engineering,University of Minnesota,7-105 Nils Hasselmo Hall,312 Church Street SE,Minneapolis, MN 55455e-mail:
| | - William J Richardson
- Department of Bioengineering,Clemson University,401-3 Rhodes Engineering Research Center,118 Engineering Service Drive,Clemson, SC 29631e-mail:
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20
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Torres M, Wang J, Yannie PJ, Ghosh S, Segal RA, Reynolds AM. Identifying important parameters in the inflammatory process with a mathematical model of immune cell influx and macrophage polarization. PLoS Comput Biol 2019; 15:e1007172. [PMID: 31365522 PMCID: PMC6690555 DOI: 10.1371/journal.pcbi.1007172] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 08/12/2019] [Accepted: 06/07/2019] [Indexed: 02/08/2023] Open
Abstract
In an inflammatory setting, macrophages can be polarized to an inflammatory M1 phenotype or to an anti-inflammatory M2 phenotype, as well as existing on a spectrum between these two extremes. Dysfunction of this phenotypic switch can result in a population imbalance that leads to chronic wounds or disease due to unresolved inflammation. Therapeutic interventions that target macrophages have therefore been proposed and implemented in diseases that feature chronic inflammation such as diabetes mellitus and atherosclerosis. We have developed a model for the sequential influx of immune cells in the peritoneal cavity in response to a bacterial stimulus that includes macrophage polarization, with the simplifying assumption that macrophages can be classified as M1 or M2. With this model, we were able to reproduce the expected timing of sequential influx of immune cells and mediators in a general inflammatory setting. We then fit this model to in vivo experimental data obtained from a mouse peritonitis model of inflammation, which is widely used to evaluate endogenous processes in response to an inflammatory stimulus. Model robustness is explored with local structural and practical identifiability of the proposed model a posteriori. Additionally, we perform sensitivity analysis that identifies the population of apoptotic neutrophils as a key driver of the inflammatory process. Finally, we simulate a selection of proposed therapies including points of intervention in the case of delayed neutrophil apoptosis, which our model predicts will result in a sustained inflammatory response. Our model can therefore provide hypothesis testing for therapeutic interventions that target macrophage phenotype and predict outcomes to be validated by subsequent experimentation. Using experimental data and mathematical analysis, we develop a model for the inflammatory response that includes macrophage polarization between M1 and M2 phenotypes. Dysfunction of this phenotypic switch can disrupt the timely influx and egress of immune cells during the healing process and lead to chronic wounds or disease. The modulation of macrophage population has been suggested as a strategy to dampen inflammation in diseases that feature chronic inflammation, such as diabetes and atherosclerosis. It is therefore important that we learn more about which components of the system drive the population level switch in phenotype. Our model is able to reproduce the expected timing of sequential influx of neutrophils and macrophages in response to an inflammatory stimulus. Model parameters were estimated with weighted least squares fitting to in vivo experimental data from a mouse model of peritonitis while considering identifiability of parameter sets. We perform sensitivity analysis that identifies primary drivers of the system, and predict the effects of variations in these key parameters on immune cell populations.
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Affiliation(s)
- Marcella Torres
- Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Jing Wang
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Paul J. Yannie
- Hunter Holmes McGuire VA Medical Center, Richmond, Virginia, United States of America
| | - Shobha Ghosh
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Hunter Holmes McGuire VA Medical Center, Richmond, Virginia, United States of America
| | - Rebecca A. Segal
- Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Angela M. Reynolds
- Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Victoria Johnson Center for Lung Disease Research, Virginia Commonwealth University, Richmond, Virginia, United States of America
- * E-mail:
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21
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Zhang F, Xie Y, Celik H, Akkus O, Bernacki SH, King MW. Engineering small-caliber vascular grafts from collagen filaments and nanofibers with comparable mechanical properties to native vessels. Biofabrication 2019; 11:035020. [PMID: 30943452 DOI: 10.1088/1758-5090/ab15ce] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
At the present time, there is no successful synthetic, off-the-shelf small-caliber vascular graft (<6 mm) for the repair or bypass of the coronary or carotid arteries. This stimulates on-going investigations to fabricate an artificial vascular graft that has both sufficient mechanical properties as well as superior biological performance. Collagen has long been considered as a viable material to encourage cell recruitment, tissue regeneration, and revascularization, but its use has been limited by its inferior mechanical properties. In this study, novel electrochemically aligned collagen filaments were used to engineer a bilayer small-caliber vascular graft, by circular knitting the collagen filaments and electrospinning collagen nanofibers. The collagen prototype grafts showed significantly greater bursting strength under dry and hydrated conditions to that of autografts such as the human internal mammary artery and the saphenous vein (SV). The suture retention strength was sufficient under dry condition, but that under hydrated condition needs to be further improved. The radial dynamic compliance of the collagen grafts was similar to that of the human SV. During in vitro cell culture assays with human umbilical vein endothelial cells, the prototype collagen grafts also encouraged cell adhesion and promoted cell proliferation compared to the synthetic poly(lactic acid) grafts. In conclusion, this study demonstrated the feasibility of the use of novel collagen filaments for fabricating small caliber tissue-engineered vascular grafts that provide both sufficient mechanical properties and superior biological performance.
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Affiliation(s)
- Fan Zhang
- Wilson College of Textiles, North Carolina State University, Raleigh, United States of America
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22
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Lee JJ, Talman L, Peirce SM, Holmes JW. Spatial scaling in multiscale models: methods for coupling agent-based and finite-element models of wound healing. Biomech Model Mechanobiol 2019; 18:1297-1309. [PMID: 30968216 DOI: 10.1007/s10237-019-01145-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 03/26/2019] [Indexed: 11/27/2022]
Abstract
Multiscale models that couple agent-based modeling (ABM) and finite-element modeling (FEM) allow the dynamic simulation of tissue remodeling and wound healing, with mechanical environment influencing cellular behaviors even as tissue remodeling modifies mechanics. One of the challenges in coupling ABM to FEM is that these two domains typically employ grid or element sizes that differ by several orders of magnitude. Here, we develop and demonstrate an interpolation-based method for mapping between ABM and FEM domains of different resolutions that is suitable for linear and nonlinear FEM meshes and balances accuracy with computational demands. We then explore the effects of refining the FEM mesh and the ABM grid in the setting of a fully coupled model. ABM grid refinement studies showed unexpected effects of grid size whenever cells were present at a high enough density for crowding to affect proliferation and migration. In contrast to an FE-only model, refining the FE mesh in the coupled model increased strain differences between adjacent finite elements. Allowing strain-dependent feedback on collagen turnover magnified the effects of regional heterogeneity, producing highly nonlinear spatial and temporal responses. Our results suggest that the choice of both ABM grid and FEM mesh density in coupled models must be guided by experimental data and accompanied by careful grid and mesh refinement studies in the individual domains as well as the fully coupled model.
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Affiliation(s)
- Jia-Jye Lee
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Lee Talman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Shayn M Peirce
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, USA
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA.
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, USA.
- Department of Medicine, University of Virginia, Charlottesville, VA, USA.
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23
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Holmes JW. Model First and Ask Questions Later: Confessions of a Reformed Experimentalist. J Biomech Eng 2019; 141:2730665. [PMID: 30958518 PMCID: PMC6611345 DOI: 10.1115/1.4043432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 03/28/2019] [Indexed: 12/26/2022]
Abstract
This paper is an invited perspective written in association with the awarding of the 2018 American Society of Mechanical Engineers Van C. Mow Medal. Inspired by Professor Mow's collaboration with Professor Michael Lai and the role mathematical modeling played in their work on cartilage biomechanics, this article uses our group's work on myocardial infarct healing as an example of the potential value of models in modern experimental biomechanics. Focusing more on the thought process and lessons learned from our studies on infarct mechanics than on the details of the science, this article argues that the complexity of current research questions and the wealth of information already available about almost any cell, tissue, or organ should change how we approach problems and design experiments. In particular, this paper proposes that constructing a mathematical or computational model is now in many cases a critical prerequisite to designing scientifically useful, informative experiments.
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Affiliation(s)
- Jeffrey W. Holmes
- Departments of Biomedical
Engineering and Medicine,
Robert M. Berne Cardiovascular
Research Center, and Center for
Engineering in Medicine,
University of Virginia,
P.O. Box 800759,
Charlottesville, VA 22908
e-mail:
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24
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French BA, Holmes JW. Implications of scar structure and mechanics for post-infarction cardiac repair and regeneration. Exp Cell Res 2019; 376:98-103. [PMID: 30610848 DOI: 10.1016/j.yexcr.2019.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 12/21/2018] [Accepted: 01/01/2019] [Indexed: 01/14/2023]
Abstract
Regenerating cardiac muscle lost during a heart attack is a topic of broad interest and enormous potential impact. One promising approach is to regenerate or re-engineer new myocardium in situ, at the site of damage, by injecting cells, growth factors, and other materials, or by reprogramming aspects of the normal wound healing process. A wide variety of strategies have been explored, from promoting angiogenesis to injection of a variety of different progenitor cell types, to re-engineering resident cells to produce key growth factors or even transdifferentiate into myocytes. Despite substantial progress and continued promise, clinical impact of this work has fallen short of expectations. One contributing factor may be that many efforts focus primarily on generating cardiomyocytes, with less attention to re-engineering the extracellular matrix (ECM). Yet the role of the ECM is particularly crucial to consider following myocardial infarction, which leads to rapid formation of a collagen-rich scar. This review combines a brief summary of current efforts to regenerate cardiomyocytes with what is currently known about the structure and mechanics of post-infarction scar, with the goal of identifying principles that can guide efforts to produce new myocytes embedded in an extracellular environment that facilitates their differentiation, maintenance, and function.
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Affiliation(s)
- Brent A French
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA; Department of Radiology, University of Virginia, Charlottesville, VA, USA; Department of Medicine, University of Virginia, Charlottesville, VA, USA; Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, USA
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA; Department of Medicine, University of Virginia, Charlottesville, VA, USA; Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, USA.
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25
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Zhuan X, Luo X, Gao H, Ogden RW. Coupled agent-based and hyperelastic modelling of the left ventricle post-myocardial infarction. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3155. [PMID: 30253447 PMCID: PMC6492033 DOI: 10.1002/cnm.3155] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 07/24/2018] [Accepted: 09/09/2018] [Indexed: 05/29/2023]
Abstract
Understanding the healing and remodelling processes induced by myocardial infarction (MI) of the heart is important, and the mechanical properties of the myocardium post-MI can be indicative for effective treatments aimed at avoiding eventual heart failure. MI remodelling is a multiscale feedback process between the mechanical loading and cellular adaptation. In this paper, we use an agent-based model to describe collagen remodelling by fibroblasts regulated by chemical and mechanical cues after acute MI, and upscale into a finite element 3D left ventricular model. We model the dispersed collagen fibre structure using the angular integration method and have incorporated a collagen fibre tension-compression switch in the left ventricle (LV) model. This enables us to study the scar healing (collagen deposition, degradation, and reorientation) of a rat heart post-MI. Our results, in terms of collagen accumulation and alignment, compare well with published experimental data. In addition, we show that different shapes of the MI region can affect the collagen remodelling, and in particular, the mechanical cue plays an important role in the healing process.
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Affiliation(s)
- Xin Zhuan
- School of Mathematics and StatisticsUniversity of GlasgowGlasgowUK
| | - Xiaoyu Luo
- School of Mathematics and StatisticsUniversity of GlasgowGlasgowUK
| | - Hao Gao
- School of Mathematics and StatisticsUniversity of GlasgowGlasgowUK
| | - Ray W. Ogden
- School of Mathematics and StatisticsUniversity of GlasgowGlasgowUK
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26
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Chen K, Hu X, Blemker SS, Holmes JW. Multiscale computational model of Achilles tendon wound healing: Untangling the effects of repair and loading. PLoS Comput Biol 2018; 14:e1006652. [PMID: 30550566 PMCID: PMC6310293 DOI: 10.1371/journal.pcbi.1006652] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/28/2018] [Accepted: 11/15/2018] [Indexed: 12/11/2022] Open
Abstract
Mechanical stimulation of the healing tendon is thought to regulate scar anisotropy and strength and is relatively easy to modulate through physical therapy. However, in vivo studies of various loading protocols in animal models have produced mixed results. To integrate and better understand the available data, we developed a multiscale model of rat Achilles tendon healing that incorporates the effect of changes in the mechanical environment on fibroblast behavior, collagen deposition, and scar formation. We modified an OpenSim model of the rat right hindlimb to estimate physiologic strains in the lateral/medial gastrocnemius and soleus musculo-tendon units during loading and unloading conditions. We used the tendon strains as inputs to a thermodynamic model of stress fiber dynamics that predicts fibroblast alignment, and to determine local collagen synthesis rates according to a response curve derived from in vitro studies. We then used an agent-based model (ABM) of scar formation to integrate these cell-level responses and predict tissue-level collagen alignment and content. We compared our model predictions to experimental data from ten different studies. We found that a single set of cellular response curves can explain features of observed tendon healing across a wide array of reported experiments in rats–including the paradoxical finding that repairing transected tendon reverses the effect of loading on alignment–without fitting model parameters to any data from those experiments. The key to these successful predictions was simulating the specific loading and surgical protocols to predict tissue-level strains, which then guided cellular behaviors according to response curves based on in vitro experiments. Our model results provide a potential explanation for the highly variable responses to mechanical loading reported in the tendon healing literature and may be useful in guiding the design of future experiments and interventions. Tendons and ligaments transmit force between muscles and bones throughout the body and are comprised of highly aligned collagen fibers that help bear high loads. The Achilles tendon is exposed to exceptionally high loads and is prone to rupture. When damaged Achilles tendons heal, they typically have reduced strength and stiffness, and while most believe that appropriate physical therapy can help improve these mechanical properties, both clinical and animal studies of mechanical loading following injury have produced highly variable and somewhat disappointing results. To help better understand the effects of mechanical loading on tendon healing and potentially guide future therapies, we developed a computational model of rat Achilles tendon healing and showed that we could predict the main effects of different mechanical loading and surgical repair conditions reported across a wide range of published studies. Our model offers potential explanations for some surprising findings of prior studies and for the high variability observed in those studies and may prove useful in designing future therapies or experiments to test new therapies.
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Affiliation(s)
- Kellen Chen
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States of America
| | - Xiao Hu
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States of America
| | - Silvia S. Blemker
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States of America
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, United States of America
- Department of Orthopaedic Surgery, University of Virginia, Charlottesville, VA, United States of America
| | - Jeffrey W. Holmes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States of America
- Department of Medicine, University of Virginia, Charlottesville, VA, United States of America
- * E-mail:
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27
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Pham QL, Rodrigues LN, Maximov MA, Chandran VD, Bi C, Chege D, Dijamco T, Stein E, Tong NAN, Basuray S, Voronov RS. Cell Sequence and Mitosis Affect Fibroblast Directional Decision-Making During Chemotaxis in Microfluidic Mazes. Cell Mol Bioeng 2018; 11:483-494. [PMID: 31719895 DOI: 10.1007/s12195-018-0551-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 08/21/2018] [Indexed: 01/25/2023] Open
Abstract
Introduction Directed fibroblast migration is central to highly proliferative processes in regenerative medicine and developmental biology. However, the mechanisms by which single fibroblasts affect each other's directional decisions, while chemotaxing in microscopic pores, are not well understood. Methods We explored effects of cell sequence and mitosis on fibroblast platelet-derived growth factor-BB (PDGF-BB)-induced migration in microfluidic mazes with two possible through paths: short and long. Additionally, image-based modeling of the chemoattractant's diffusion, consumption and decay, was used to explain the experimental observations. Results It both cases, the cells displayed behavior that is contradictory to expectation based on the global chemoattractant gradient pre-established in the maze. In case of the sequence, the cells tend to alternate when faced with a bifurcation: if a leading cell takes the shorter (steeper gradient) path, the cell following it chooses the longer (weaker gradient) path, and vice versa. Image-based modeling of the process showed that the local PDGF-BB consumption by the individual fibroblasts may be responsible for this phenomenon. Additionally, it was found that when a mother cell divides, its two daughters go in opposite directions (even if it means migrating against the chemoattractant gradient and overcoming on-going cell traffic). Conclusions It is apparent that micro-confined fibroblasts modify each other's directional decisions in a manner that is counter-intuitive to what is expected from classical chemotaxis theory. Consequently, accounting for these effects could lead to a better understanding of tissue generation in vivo, and result in more advanced engineered tissue products in vitro.
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Affiliation(s)
- Quang Long Pham
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Lydia N Rodrigues
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Max A Maximov
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Vishnu Deep Chandran
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Cheng Bi
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - David Chege
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Timothy Dijamco
- Computer Science Dept., New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Elisabeth Stein
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Nhat Anh Nguyen Tong
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Sagnik Basuray
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
| | - Roman S Voronov
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA
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28
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Torii R, Velliou RI, Hodgson D, Mudera V. Modelling multi-scale cell-tissue interaction of tissue-engineered muscle constructs. J Tissue Eng 2018; 9:2041731418787141. [PMID: 30128109 PMCID: PMC6090492 DOI: 10.1177/2041731418787141] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 06/12/2018] [Indexed: 01/21/2023] Open
Abstract
Expectation on engineered tissue substitute continues to grow, and for an effective development of a functional tissue and to control its quality, cellular mechanoresponse plays a key role. Although the mechanoresponse – in terms of cell–tissue interaction across scales – has been understood better in recent years, there are still technical limitations to quantitatively monitor the processes involved in the development of both native and engineered tissues. Computational (in silico) studies have been utilised to complement the experimental limitations and successfully applied to the prediction of tissue growth. We here review recent activities in the area of combined experimental and computational analyses of tissue growth, especially in the tissue engineering context, and highlight the advantages of such an approach for the future of the tissue engineering, using our own case study of predicting musculoskeletal tissue engineering construct development.
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Affiliation(s)
- Ryo Torii
- Department of Mechanical Engineering, University College London, London, UK
| | | | - David Hodgson
- Centre for Computation, Mathematics and Physics in the Life Sciences and Experimental Biology (COMPLEX), University College London, London, UK.,Clinical Operational Research Unit, Department of Mathematics, University College London, London, UK
| | - Vivek Mudera
- Division of Surgery and Interventional Science, University College London, London, UK
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29
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Virgilio KM, Martin KS, Peirce SM, Blemker SS. Agent-based model illustrates the role of the microenvironment in regeneration in healthy and mdx skeletal muscle. J Appl Physiol (1985) 2018; 125:1424-1439. [PMID: 30070607 DOI: 10.1152/japplphysiol.00379.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease with no effective treatment. Multiple mechanisms are thought to contribute to muscle wasting, including increased susceptibility to contraction-induced damage, chronic inflammation, fibrosis, altered satellite stem cell (SSC) dynamics, and impaired regenerative capacity. The goals of this project were to 1) develop an agent-based model of skeletal muscle that predicts the dynamic regenerative response of muscle cells, fibroblasts, SSCs, and inflammatory cells as a result of contraction-induced injury, 2) calibrate and validate the model parameters based on comparisons with published experimental measurements, and 3) use the model to investigate how changing isolated and combined factors known to be associated with DMD (e.g., altered fibroblast or SSC behaviors) influence muscle regeneration. Our predictions revealed that the percent of injured muscle that recovered 28 days after injury was dependent on the peak SSC counts following injury. In simulations with near-full cross-sectional area recovery (healthy, 4-wk mdx, 3-mo mdx), the SSC counts correlated with the extent of initial injury; however, in simulations with impaired regeneration (9-mo mdx), the peak SSC counts were suppressed relative to initial injury. The differences in SSC counts between these groups were emergent predictions dependent on altered microenvironment factors known to be associated with DMD. Multiple cell types influenced the peak number of SSCs, but no individual parameter predicted the differences in SSC counts. This finding suggests that interventions to target the microenvironment rather than SSCs directly could be an effective method for improving regeneration in impaired muscle. NEW & NOTEWORTHY A computational model predicted that satellite stem cell (SSC) counts are correlated with muscle cross-sectional area (CSA) recovery following injury. In simulations with impaired CSA recovery, SSC counts are suppressed relative to healthy muscle. The suppressed SSC counts were an emergent model prediction, because all simulations had equal initial SSC counts. Fibroblast and anti-inflammatory macrophage counts influenced SSC counts, but no single factor was able to predict the pathological differences in SSC counts that lead to impaired regeneration.
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Affiliation(s)
- Kelley M Virgilio
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia
| | - Kyle S Martin
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia
| | - Shayn M Peirce
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia
| | - Silvia S Blemker
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia.,Department of Orthopaedic Surgery, University of Virginia , Charlottesville, Virginia.,Department of Mechanical and Aerospace Engineering, University of Virginia , Charlottesville, Virginia
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30
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Caggiano LR, Lee JJ, Holmes JW. Surgical reinforcement alters collagen alignment and turnover in healing myocardial infarcts. Am J Physiol Heart Circ Physiol 2018; 315:H1041-H1050. [PMID: 30028201 DOI: 10.1152/ajpheart.00088.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies have suggested that the composition and global mechanical properties of the scar tissue that forms after a myocardial infarction (MI) are key determinants of long-term survival, and emerging therapies such as biomaterial injection are designed in part to alter those mechanical properties. However, recent evidence suggests that local mechanics regulate scar formation post-MI, so that perturbing infarct mechanics could have unexpected consequences. We therefore tested the effect of changes in local mechanical environment on scar collagen turnover, accumulation, and alignment in 77 Sprague-Dawley rats at 1, 2, 3 and 6 wk post-MI by sewing a Dacron patch to the epicardium to eliminate circumferential strain while permitting continued longitudinal stretching with each heart beat. We found that collagen in healing infarcts aligned parallel to regional strain and perpendicular to the preinfarction muscle and collagen fiber direction, strongly supporting our hypothesis that mechanical environment is the primary determinant of scar collagen alignment. Mechanical reinforcement reduced levels of carboxy-terminal propeptide of type I procollagen (PICP; a biomarker for collagen synthesis) in samples collected by microdialysis significantly, particularly in the first 2 wk. Reinforcement also reduced carboxy-terminal telopeptide of type I collagen (ICTP; a biomarker for collagen degradation), particularly at later time points. These alterations in collagen turnover produced no change in collagen area fraction as measured by histology but significantly reduced wall thickness in the reinforced scars compared with untreated controls. Our findings confirm the importance of regional mechanics in regulating scar formation after infarction and highlight the potential for therapies that reduce stretch to also reduce wall thickness in healing infarcts. NEW & NOTEWORTHY This study shows that therapies such as surgical reinforcement, which reduce stretch in healing infarcts, can also reduce collagen synthesis and wall thickness and modify collagen alignment in postinfarction scars.
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Affiliation(s)
- Laura R Caggiano
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia
| | - Jia-Jye Lee
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia.,Department of Medicine, University of Virginia , Charlottesville, Virginia
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31
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Richardson WJ, Kegerreis B, Thomopoulos S, Holmes JW. Potential strain-dependent mechanisms defining matrix alignment in healing tendons. Biomech Model Mechanobiol 2018; 17:1569-1580. [PMID: 30003433 DOI: 10.1007/s10237-018-1044-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 06/18/2018] [Indexed: 12/13/2022]
Abstract
Tendon mechanical function after injury and healing is largely determined by its underlying collagen structure, which in turn is dependent on the degree of mechanical loading experienced during healing. Experimental studies have shown seemingly conflicting outcomes: although collagen content steadily increases with increasing loads, collagen alignment peaks at an intermediate load. Herein, we explored potential collagen remodeling mechanisms that could give rise to this structural divergence in response to strain. We adapted an established agent-based model of collagen remodeling in order to simulate various strain-dependent cell and collagen interactions that govern long-term collagen content and fiber alignment. Our simulation results show two collagen remodeling mechanisms that give rise to divergent collagen content and alignment in healing tendons: (1) strain-induced collagen fiber damage in concert with increased rates of deposition at higher strains, or (2) strain-dependent rates of enzymatic degradation. These model predictions identify critical future experiments needed to isolate each mechanism's specific contribution to the structure of healing tendons.
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Affiliation(s)
- William J Richardson
- Department of Bioengineering, Clemson University, Clemson, SC, USA
- Institute for Biological Interfaces of Engineering, Clemson University, Clemson, SC, USA
| | - Brian Kegerreis
- Department of Biomedical Engineering, University of Virginia, Box 800759, Charlottesville, VA, 22908, USA
| | - Stavros Thomopoulos
- Department of Orthopedic Surgery, Columbia University, New York, NY, USA
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Box 800759, Charlottesville, VA, 22908, USA.
- Department of Medicine, University of Virginia, Charlottesville, VA, USA.
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, USA.
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Modelling The Combined Effects Of Collagen and Cyclic Strain On Cellular Orientation In Collagenous Tissues. Sci Rep 2018; 8:8518. [PMID: 29867153 PMCID: PMC5986791 DOI: 10.1038/s41598-018-26989-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 05/17/2018] [Indexed: 01/13/2023] Open
Abstract
Adherent cells are generally able to reorient in response to cyclic strain. In three-dimensional tissues, however, extracellular collagen can affect this cellular response. In this study, a computational model able to predict the combined effects of mechanical stimuli and collagen on cellular (re)orientation was developed. In particular, a recently proposed computational model (which only accounts for mechanical stimuli) was extended by considering two hypotheses on how collagen influences cellular (re)orientation: collagen contributes to cell alignment by providing topographical cues (contact guidance); or collagen causes a spatial obstruction for cellular reorientation (steric hindrance). In addition, we developed an evolution law to predict cell-induced collagen realignment. The hypotheses were tested by simulating bi- or uniaxially constrained cell-populated collagen gels with different collagen densities, subjected to immediate or delayed uniaxial cyclic strain with varying strain amplitudes. The simulation outcomes are in agreement with previous experimental reports. Taken together, our computational approach is a promising tool to understand and predict the remodeling of collagenous tissues, such as native or tissue-engineered arteries and heart valves.
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Shi Y, Yan W, Lin Q, Wang W. Icariin influences cardiac remodeling following myocardial infarction by regulating the CD147/MMP-9 pathway. J Int Med Res 2018; 46:2371-2385. [PMID: 29734850 PMCID: PMC6023067 DOI: 10.1177/0300060518762060] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Objective We investigated the protective effect of icariin on myocardial infarction-induced cardiac remodeling. Methods A cardiac remodeling model was constructed by ligating rats’ coronary artery. Different icariin and CD147 concentrations were administered in the model group, and echocardiography was used to detect systolic function, screening out ideal experimental concentrations. The ventricular systolic function, myocardial apoptosis rate, and expression of collagen type I (Col I), Col III, CD147, matrix metalloproteinase 9 (MMP-9), and tissue inhibitor of metalloproteinase 1 (TIMP-1) were detected by hematoxylin–eosin staining, TUNEL assay, and western blot. MMP-9 activity was evaluated by gelatin zymography. Results The expression of Col I, Col III, CD147, and MMP-9 was higher, the expression of TIMP-1 was lower, and the maximal rates of left ventricular pressure rise and fall (+dp/dtmax and −dp/dtmax, respectively) were lower in model than control rats. The expression of CD147, MMP-9, Col I, and Col III was lower, the expression of TIMP-1 was higher, and the +dp/dtmax and −dp/dtmax were higher in the icariin than model group. The apoptosis rate was lower in the icariin and icariin + CD147 groups than control group. Conclusion Icariin attenuated myocardial apoptosis following myocardial infarction by apoptosis rate reduction and CD147/MMP-9 pathway inhibition.
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Affiliation(s)
- Yu Shi
- 1 Department of Cardiology, the Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
| | - Weihong Yan
- 1 Department of Cardiology, the Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
| | - Qiaoyan Lin
- 1 Department of Cardiology, the Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
| | - Weimin Wang
- 2 Department of Electrocardiogram, the Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
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Nguyen CT, Dawkins J, Bi X, Marbán E, Li D. Diffusion Tensor Cardiac Magnetic Resonance Reveals Exosomes From Cardiosphere-Derived Cells Preserve Myocardial Fiber Architecture After Myocardial Infarction. JACC Basic Transl Sci 2018; 3:97-109. [PMID: 29600288 PMCID: PMC5869026 DOI: 10.1016/j.jacbts.2017.09.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/11/2017] [Accepted: 09/12/2017] [Indexed: 12/15/2022]
Abstract
The object of the study was to reveal the fiber microstructural response with diffusion tensor cardiac magnetic resonance after intramyocardial exosomes secreted by cardiosphere-derived cells (CDCEXO) in chronic porcine myocardial infarction. Porcine with myocardial infarction underwent intramyocardial delivery of human CDCEXO and placebo in a randomized placebo-controlled study. Four weeks after injection, viability improved in the CDCEXO group, whereas myocardial fiber architecture and cardiac function were preserved. In the placebo group, fiber architecture and cardiac function declined. Myocardial regeneration by CDCEXO is not tumor-like; instead, details of tissue architecture are faithfully preserved, which may foster physiological excitation and contraction.
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Affiliation(s)
- Christopher T. Nguyen
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California
- Cardiovascular Research Center, Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts
| | - James Dawkins
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | - Xiaoming Bi
- MR R&D, Siemens Healthcare, Los Angeles, California
| | - Eduardo Marbán
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | - Debiao Li
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California
- Departments of Medicine and Bioengineering, University of California Los Angeles, Los Angeles, California
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35
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Kim P, Chu N, Davis J, Kim DH. Mechanoregulation of Myofibroblast Fate and Cardiac Fibrosis. ADVANCED BIOSYSTEMS 2018; 2:1700172. [PMID: 31406913 PMCID: PMC6690497 DOI: 10.1002/adbi.201700172] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
During myocardial infarction, myocytes die and are replaced by a specialized fibrotic extracellular matrix, otherwise known as scarring. Fibrotic scarring presents a tremendous hemodynamic burden on the heart, as it creates a stiff substrate, which resists diastolic filling. Fibrotic mechanisms result in permanent scarring which often leads to hypertrophy, arrhythmias, and a rapid progression to failure. Despite the deep understanding of fibrosis in other tissues, acquired through previous investigations, the mechanisms of cardiac fibrosis remain unclear. Recent studies suggest that biochemical cues as well as mechanical cues regulate cells in myocardium. However, the steps in myofibroblast transdifferentiation, as well as the molecular mechanisms of such transdifferentiation in vivo, are poorly understood. This review is focused on defining myofibroblast physiology, scar mechanics, and examining current findings of myofibroblast regulation by mechanical stress, stiffness, and topography for understanding fibrotic disease dynamics.
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Affiliation(s)
- Peter Kim
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Nick Chu
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Jennifer Davis
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
| | - Deok-Ho Kim
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
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36
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Janes KA, Chandran PL, Ford RM, Lazzara MJ, Papin JA, Peirce SM, Saucerman JJ, Lauffenburger DA. An engineering design approach to systems biology. Integr Biol (Camb) 2017; 9:574-583. [PMID: 28590470 PMCID: PMC6534349 DOI: 10.1039/c7ib00014f] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Measuring and modeling the integrated behavior of biomolecular-cellular networks is central to systems biology. Over several decades, systems biology has been shaped by quantitative biologists, physicists, mathematicians, and engineers in different ways. However, the basic and applied versions of systems biology are not typically distinguished, which blurs the separate aspirations of the field and its potential for real-world impact. Here, we articulate an engineering approach to systems biology, which applies educational philosophy, engineering design, and predictive models to solve contemporary problems in an age of biomedical Big Data. A concerted effort to train systems bioengineers will provide a versatile workforce capable of tackling the diverse challenges faced by the biotechnological and pharmaceutical sectors in a modern, information-dense economy.
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Affiliation(s)
- Kevin A Janes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA.
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37
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Richardson WJ, Holmes JW. Emergence of Collagen Orientation Heterogeneity in Healing Infarcts and an Agent-Based Model. Biophys J 2017; 110:2266-77. [PMID: 27224491 DOI: 10.1016/j.bpj.2016.04.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/30/2015] [Accepted: 04/07/2016] [Indexed: 01/01/2023] Open
Abstract
Spatial heterogeneity of matrix structure can be an important determinant of tissue function. Although bulk properties of collagen structure in healing myocardial infarcts have been characterized previously, regional heterogeneity in infarct structure has received minimal attention. Herein, we quantified regional variations of collagen and nuclear orientations over the initial weeks of healing after infarction in rats, and employed a computational model of infarct remodeling to test potential explanations for the heterogeneity we observed in vivo. Fiber and cell orientation maps were generated from infarct samples acquired previously at 1, 2, 3, and 6 weeks postinfarction in a rat ligation model. We analyzed heterogeneity by calculating the dot product of each fiber or cell orientation vector with every other fiber or cell orientation vector, and plotting that dot product versus distance between the fibers or cells. This analysis revealed prominent regional heterogeneity, with alignment of both fibers and cell nuclei in local pockets far exceeding the global average. Using an agent-based model of fibroblast-mediated collagen remodeling, we found that similar levels of heterogeneity can spontaneously emerge from initially isotropic matrix via locally reinforcing cell-matrix interactions. Specifically, cells that sensed fiber orientation at a distance or remodeled fibers at a distance by traction-mediated reorientation or aligned deposition gave rise to regionally heterogeneous structures. However, only the simulations in which cells deposited collagen fibers aligned with their own orientation reproduced experimentally measured patterns of heterogeneity across all time points. These predictions warrant experimental follow-up to test the role of such mechanisms in vivo and identify opportunities to control heterogeneity for therapeutic benefit.
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Affiliation(s)
- William J Richardson
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia; Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia; Department of Medicine, University of Virginia, Charlottesville, Virginia; Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia.
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38
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Romito E, Shazly T, Spinale FG. In vivo assessment of regional mechanics post-myocardial infarction: A focus on the road ahead. J Appl Physiol (1985) 2017; 123:728-745. [PMID: 28235858 DOI: 10.1152/japplphysiol.00589.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 01/13/2017] [Accepted: 02/18/2017] [Indexed: 12/21/2022] Open
Abstract
Cardiovascular disease, particularly the occurrence of myocardial infarction (MI), remains a leading cause of morbidity and mortality (Go et al., Circulation 127: e6-e245, 2013; Go et al. Circulation 129: e28-e292, 2014). There is growing recognition that a key factor for post-MI outcomes is adverse remodeling and changes in the regional structure, composition, and mechanical properties of the MI region itself. However, in vivo assessment of regional mechanics post-MI can be confounded by the species, temporal aspects of MI healing, as well as size, location, and extent of infarction across myocardial wall. Moreover, MI regional mechanics have been assessed over varying phases of the cardiac cycle, and thus, uniform conclusions regarding the material properties of the MI region can be difficult. This review assesses past studies that have performed in vivo measures of MI mechanics and attempts to provide coalescence on key points from these studies, as well as offer potential recommendations for unifying approaches in terms of regional post-MI mechanics. A uniform approach to biophysical measures of import will allow comparisons across studies, as well as provide a basis for potential therapeutic markers.
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Affiliation(s)
- Eva Romito
- University of South Carolina School of Engineering and Computing, Columbia, South Carolina; .,Cardiovascular Translational Research Center, University of South Carolina School of Medicine, Columbia, South Carolina
| | - Tarek Shazly
- University of South Carolina School of Engineering and Computing, Columbia, South Carolina
| | - Francis G Spinale
- University of South Carolina School of Engineering and Computing, Columbia, South Carolina.,Cardiovascular Translational Research Center, University of South Carolina School of Medicine, Columbia, South Carolina.,Department of Cell Biology and Anatomy, University of South Carolina School of Medicine, Columbia, South Carolina; and.,William Jennings Bryan Dorn Veteran Affairs Medical Center, Columbia, South Carolina
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39
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Cai L, Xiong X, Kong X, Xie J. The Role of the Lysyl Oxidases in Tissue Repair and Remodeling: A Concise Review. Tissue Eng Regen Med 2017; 14:15-30. [PMID: 30603458 DOI: 10.1007/s13770-016-0007-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 04/01/2016] [Accepted: 04/17/2016] [Indexed: 02/05/2023] Open
Abstract
Tissue injury provokes a series of events containing inflammation, new tissue formation and tissue remodeling which are regulated by the spatially and temporally coordinated organization. It is an evolutionarily conserved, multi-cellular, multi-molecular process via complex signalling network. Tissue injury disorders present grievous clinical problems and are likely to increase since they are generally associated with the prevailing diseases such as diabetes, hypertension and obesity. Although these dynamic responses vary not only for the different types of trauma but also for the different organs, a balancing act between the tissue degradation and tissue synthesis is the same. In this process, the degradation of old extracellular matrix (ECM) elements and new ones' synthesis and deposition play an essential role, especially collagens. Lysyl oxidase (LOX) and four lysyl oxidase-like proteins are a group of enzymes capable of catalyzing cross-linking reaction of collagen and elastin, thus initiating the formation of covalent cross-links that insolubilize ECM proteins. In this way, LOX facilitates ECM stabilization through ECM formation, development, maturation and remodeling. This ability determines its potential role in tissue repair and regeneration. In this review, based on the current in vitro, animal and human in vivo studies which have shown the significant role of the LOXs in tissue repair, e.g., tendon regeneration, ligament healing, cutaneous wound healing, and cartilage remodeling, we focused on the role of the LOXs in inflammation phase, proliferation phase, and tissue remodeling phase of the repair process. By summarizing its healing role, we hope to shed light on the understanding of its potential in tissue repair and provide up to date therapeutic strategies towards related injuries.
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Affiliation(s)
- Linyi Cai
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041 People's Republic of China
| | - Xin Xiong
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041 People's Republic of China
| | - Xiangli Kong
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041 People's Republic of China
| | - Jing Xie
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041 People's Republic of China
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40
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Ongstad EL, Gourdie RG. Can heart function lost to disease be regenerated by therapeutic targeting of cardiac scar tissue? Semin Cell Dev Biol 2016; 58:41-54. [PMID: 27234380 DOI: 10.1016/j.semcdb.2016.05.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/18/2016] [Accepted: 05/23/2016] [Indexed: 01/14/2023]
Abstract
Myocardial infarction results in scar tissue that cannot actively contribute to heart mechanical function and frequently causes lethal arrhythmias. The healing response after infarction involves inflammation, biochemical signaling, changes in cellular phenotype, activity, and organization, and alterations in electrical conduction due to variations in cell and tissue geometry and alterations in protein expression, organization, and function - particularly in membrane channels. The intensive research focus on regeneration of myocardial tissues has, as of yet, only met with modest success, with no near-term prospect of improving standard-of-care for patients with heart disease. An alternative concept for novel therapeutic approach is the rejuvenation of cardiac electrical and mechanical properties through the modification of scar tissue. Several peptide therapeutics, locally applied genetic therapies, or delivery of genetically modified cells have shown promise in improving the characteristics of the fibrous scar and post-myocardial infarction prognosis in experimental models. This review highlights several factors that contribute to arrhythmogenesis in scar formation and how these might be targeted to regenerate some of the electrical and mechanical function of the post-MI scar.
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Affiliation(s)
- Emily L Ongstad
- Center for Heart and Regenerative Medicine Research, Virginia Tech Carilion Research Institute, 2 Riverside Circle, Roanoke, VA 24016, USA.
| | - Robert G Gourdie
- Center for Heart and Regenerative Medicine Research, Virginia Tech Carilion Research Institute, 2 Riverside Circle, Roanoke, VA 24016, USA; Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences, 317 Kelly Hall, Stanger Street, Blacksburg, VA 24061, USA; Department of Emergency Medicine, Carilion Clinic, 1906 Belleview Avenue, Roanoke VA 24014, USA.
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41
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Zeigler AC, Richardson WJ, Holmes JW, Saucerman JJ. Computational modeling of cardiac fibroblasts and fibrosis. J Mol Cell Cardiol 2016; 93:73-83. [PMID: 26608708 PMCID: PMC4846515 DOI: 10.1016/j.yjmcc.2015.11.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/18/2015] [Accepted: 11/18/2015] [Indexed: 12/31/2022]
Abstract
Altered fibroblast behavior can lead to pathologic changes in the heart such as arrhythmia, diastolic dysfunction, and systolic dysfunction. Computational models are increasingly used as a tool to identify potential mechanisms driving a phenotype or potential therapeutic targets against an unwanted phenotype. Here we review how computational models incorporating cardiac fibroblasts have clarified the role for these cells in electrical conduction and tissue remodeling in the heart. Models of fibroblast signaling networks have primarily focused on fibroblast cell lines or fibroblasts from other tissues rather than cardiac fibroblasts, specifically, but they are useful for understanding how fundamental signaling pathways control fibroblast phenotype. In the future, modeling cardiac fibroblast signaling, incorporating -omics and drug-interaction data into signaling network models, and utilizing multi-scale models will improve the ability of in silico studies to predict potential therapeutic targets against adverse cardiac fibroblast activity.
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Affiliation(s)
- Angela C Zeigler
- University of Virginia, Biomedical Engineering Department, 415 Lane Road, Charlottesville, VA 22903, USA.
| | - William J Richardson
- University of Virginia, Biomedical Engineering Department, 415 Lane Road, Charlottesville, VA 22903, USA.
| | - Jeffrey W Holmes
- University of Virginia, Biomedical Engineering Department, 415 Lane Road, Charlottesville, VA 22903, USA.
| | - Jeffrey J Saucerman
- University of Virginia, Biomedical Engineering Department, 415 Lane Road, Charlottesville, VA 22903, USA.
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42
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Holmes JW, Laksman Z, Gepstein L. Making better scar: Emerging approaches for modifying mechanical and electrical properties following infarction and ablation. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:134-48. [PMID: 26615948 DOI: 10.1016/j.pbiomolbio.2015.11.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/13/2015] [Accepted: 11/20/2015] [Indexed: 12/31/2022]
Abstract
Following myocardial infarction (MI), damaged myocytes are replaced by collagenous scar tissue, which serves an important mechanical function - maintaining integrity of the heart wall against enormous mechanical forces - but also disrupts electrical function as structural and electrical remodeling in the infarct and borderzone predispose to re-entry and ventricular tachycardia. Novel emerging regenerative approaches aim to replace this scar tissue with viable myocytes. Yet an alternative strategy of therapeutically modifying selected scar properties may also prove important, and in some cases may offer similar benefits with lower risk or regulatory complexity. Here, we review potential goals for such modifications as well as recent proof-of-concept studies employing specific modifications, including gene therapy to locally increase conduction velocity or prolong the refractory period in and around the infarct scar, and modification of scar anisotropy to improve regional mechanics and pump function. Another advantage of scar modification techniques is that they have applications well beyond MI. In particular, ablation treats electrical abnormalities of the heart by intentionally generating scar to block aberrant conduction pathways. Yet in diseases such as atrial fibrillation (AF) where ablation can be extensive, treating the electrical disorder can significantly impair mechanical function. Creating smaller, denser scars that more effectively block conduction, and choosing the location of those lesions by balancing their electrical and mechanical impacts, could significantly improve outcomes for AF patients. We review some recent advances in this area, including the use of computational models to predict the mechanical effects of specific lesion sets and gene therapy for functional ablation. Overall, emerging techniques for modifying scar properties represents a potentially important set of tools for improving patient outcomes across a range of heart diseases, whether used in place of or as an adjunct to regenerative approaches.
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Affiliation(s)
- Jeffrey W Holmes
- Departments of Biomedical Engineering and Medicine, Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, United States.
| | - Zachary Laksman
- Cardiac Electrophysiology, University of British Columbia, Vancouver, BC, Canada
| | - Lior Gepstein
- Departments of Cardiology (Ramban Health Care Campus) and Physiology, The Rappaport Faculty of Medicine and Research Institute, Technion - Israel Institute of Technology, Haifa, Israel
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43
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Abstract
The heart pumps blood to maintain circulation and ensure the delivery of oxygenated blood to all the organs of the body. Mechanics play a critical role in governing and regulating heart function under both normal and pathological conditions. Biological processes and mechanical stress are coupled together in regulating myocyte function and extracellular matrix structure thus controlling heart function. Here, we offer a brief introduction to the biomechanics of left ventricular function and then summarize recent progress in the study of the effects of mechanical stress on ventricular wall remodeling and cardiac function as well as the effects of wall mechanical properties on cardiac function in normal and dysfunctional hearts. Various mechanical models to determine wall stress and cardiac function in normal and diseased hearts with both systolic and diastolic dysfunction are discussed. The results of these studies have enhanced our understanding of the biomechanical mechanism in the development and remodeling of normal and dysfunctional hearts. Biomechanics provide a tool to understand the mechanism of left ventricular remodeling in diastolic and systolic dysfunction and guidance in designing and developing new treatments.
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Affiliation(s)
- Andrew P. Voorhees
- Department of Mechanical Engineering, The University of Texas at San Antonio, Biomedical Engineering Program, UTSA-UTHSCSA
| | - Hai-Chao Han
- Department of Mechanical Engineering, The University of Texas at San Antonio, Biomedical Engineering Program, UTSA-UTHSCSA
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44
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Richardson WJ, Clarke SA, Quinn TA, Holmes JW. Physiological Implications of Myocardial Scar Structure. Compr Physiol 2015; 5:1877-909. [PMID: 26426470 DOI: 10.1002/cphy.c140067] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Once myocardium dies during a heart attack, it is replaced by scar tissue over the course of several weeks. The size, location, composition, structure, and mechanical properties of the healing scar are all critical determinants of the fate of patients who survive the initial infarction. While the central importance of scar structure in determining pump function and remodeling has long been recognized, it has proven remarkably difficult to design therapies that improve heart function or limit remodeling by modifying scar structure. Many exciting new therapies are under development, but predicting their long-term effects requires a detailed understanding of how infarct scar forms, how its properties impact left ventricular function and remodeling, and how changes in scar structure and properties feed back to affect not only heart mechanics but also electrical conduction, reflex hemodynamic compensations, and the ongoing process of scar formation itself. In this article, we outline the scar formation process following a myocardial infarction, discuss interpretation of standard measures of heart function in the setting of a healing infarct, then present implications of infarct scar geometry and structure for both mechanical and electrical function of the heart and summarize experiences to date with therapeutic interventions that aim to modify scar geometry and structure. One important conclusion that emerges from the studies reviewed here is that computational modeling is an essential tool for integrating the wealth of information required to understand this complex system and predict the impact of novel therapies on scar healing, heart function, and remodeling following myocardial infarction.
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Affiliation(s)
- William J Richardson
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
| | - Samantha A Clarke
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA.,Department of Medicine, University of Virginia, Charlottesville, Virginia, USA.,Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA
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45
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Voorhees AP, DeLeon-Pennell KY, Ma Y, Halade GV, Yabluchanskiy A, Iyer RP, Flynn E, Cates CA, Lindsey ML, Han HC. Building a better infarct: Modulation of collagen cross-linking to increase infarct stiffness and reduce left ventricular dilation post-myocardial infarction. J Mol Cell Cardiol 2015; 85:229-39. [PMID: 26080361 PMCID: PMC4530076 DOI: 10.1016/j.yjmcc.2015.06.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 11/29/2022]
Abstract
Matrix metalloproteinase-9 (MMP-9) deletion attenuates collagen accumulation and dilation of the left ventricle (LV) post-myocardial infarction (MI); however the biomechanical mechanisms underlying the improved outcome are poorly understood. The aim of this study was to determine the mechanisms whereby MMP-9 deletion alters collagen network composition and assembly in the LV post-MI to modulate the mechanical properties of myocardial scar tissue. Adult C57BL/6J wild-type (WT; n=88) and MMP-9 null (MMP-9(-/-); n=92) mice of both sexes underwent permanent coronary artery ligation and were compared to day 0 controls (n=42). At day 7 post-MI, WT LVs displayed a 3-fold increase in end-diastolic volume, while MMP-9(-/-) showed only a 2-fold increase (p<0.05). Biaxial mechanical testing revealed that MMP-9(-/-) infarcts were stiffer than WT infarcts, as indicated by a 1.3-fold reduction in predicted in vivo circumferential stretch (p<0.05). Paradoxically, MMP-9(-/-) infarcts had a 1.8-fold reduction in collagen deposition (p<0.05). This apparent contradiction was explained by a 3.1-fold increase in lysyl oxidase (p<0.05) in MMP-9(-/-) infarcts, indicating that MMP-9 deletion increased collagen cross-linking activity. Furthermore, MMP-9 deletion led to a 3.0-fold increase in bone morphogenetic protein-1, the metalloproteinase that cleaves pro-collagen and pro-lysyl oxidase (p<0.05) and reduced fibronectin fragmentation by 49% (p<0.05) to enhance lysyl oxidase activity. We conclude that MMP-9 deletion increases infarct stiffness and prevents LV dilation by reducing collagen degradation and facilitating collagen assembly and cross-linking through preservation of the fibronectin network and activation of lysyl oxidase.
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Affiliation(s)
- Andrew P Voorhees
- Department of Mechanical Engineering, The University of Texas at San Antonio, USA; Joint Biomedical Engineering Program, UTSA-UTHSCSA, USA; San Antonio Cardiovascular Proteomics Center, USA
| | - Kristine Y DeLeon-Pennell
- San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Yonggang Ma
- San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Ganesh V Halade
- San Antonio Cardiovascular Proteomics Center, USA; Division of Cardiovascular Disease, Department of Medicine, The University of Alabama at Birmingham, USA
| | - Andriy Yabluchanskiy
- San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA; Research Service, G.V. (Sonny) Montgomery Veterans Affairs Medical Center, USA
| | - Rugmani Padmanabhan Iyer
- San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Elizabeth Flynn
- Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Courtney A Cates
- Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Merry L Lindsey
- Joint Biomedical Engineering Program, UTSA-UTHSCSA, USA; San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA; Research Service, G.V. (Sonny) Montgomery Veterans Affairs Medical Center, USA
| | - Hai-Chao Han
- Department of Mechanical Engineering, The University of Texas at San Antonio, USA; Joint Biomedical Engineering Program, UTSA-UTHSCSA, USA; San Antonio Cardiovascular Proteomics Center, USA.
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Clarke SA, Goodman NC, Ailawadi G, Holmes JW. Effect of Scar Compaction on the Therapeutic Efficacy of Anisotropic Reinforcement Following Myocardial Infarction in the Dog. J Cardiovasc Transl Res 2015; 8:353-61. [PMID: 26077797 DOI: 10.1007/s12265-015-9637-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 05/27/2015] [Indexed: 04/21/2023]
Abstract
Cardiac restraint devices have been used following myocardial infarction (MI) to limit left ventricular (LV) dilation, although isotropic restraints have not been shown to improve post-MI LV function. We have previously shown that anisotropic reinforcement of acute infarcts dramatically improves LV function. This study examined the effects of chronic, anisotropic infarct restraint on LV function and remodeling. Hemodynamics, infarct scar structure, and LV volumes were measured in 28 infarcted dogs (14 reinforced, 14 control). Longitudinal restraint reduced 48-h LV volumes, but no differences in LV volume, function, or infarct scar structure were observed after 8 weeks of healing. All scars underwent substantial compaction during healing; we hypothesize that compaction negated the effects of restraint therapy by mechanically unloading the restraint device. Our results lend support to the concept of adjustable restraint devices and suggest that scar compaction may explain some of the variability in published studies of local infarct restraint.
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Affiliation(s)
- Samantha A Clarke
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
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Buganza Tepole A, Kuhl E. Computational modeling of chemo-bio-mechanical coupling: a systems-biology approach toward wound healing. Comput Methods Biomech Biomed Engin 2014; 19:13-30. [DOI: 10.1080/10255842.2014.980821] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Mechanical boundary conditions bias fibroblast invasion in a collagen-fibrin wound model. Biophys J 2014; 106:932-43. [PMID: 24559996 DOI: 10.1016/j.bpj.2013.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 11/17/2013] [Accepted: 12/02/2013] [Indexed: 11/22/2022] Open
Abstract
Because fibroblasts deposit the collagen matrix that determines the mechanical integrity of scar tissue, altering fibroblast invasion could alter wound healing outcomes. Anisotropic mechanical boundary conditions (restraint, stretch, or tension) could affect the rate of fibroblast invasion, but their importance relative to the prototypical drivers of fibroblast infiltration during wound healing--cell and chemokine concentration gradients--is unknown. We tested whether anisotropic mechanical boundary conditions affected the directionality and speed of fibroblasts migrating into a three-dimensional model wound, which could simultaneously expose fibroblasts to mechanical, structural, steric, and chemical guidance cues. We created fibrin-filled slits in fibroblast-populated collagen gels and applied uniaxial mechanical restraint along the short or long axis of the fibrin wounds. Anisotropic mechanical conditions increased the efficiency of fibroblast invasion by guiding fibroblasts without increasing their migration speed. The migration behavior could be modeled as a biased random walk, where the bias due to multiple guidance cues was accounted for in the shape of a displacement orientation probability distribution. Taken together, modeling and experiments suggested an effect of strain anisotropy, rather than strain-induced fiber alignment, on fibroblast invasion.
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Estimating passive mechanical properties in a myocardial infarction using MRI and finite element simulations. Biomech Model Mechanobiol 2014. [PMID: 25315521 DOI: 10.1007/s10237‐014‐0627‐z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2022]
Abstract
Myocardial infarction (MI) triggers a series of maladaptive events that lead to structural and functional changes in the left ventricle. It is crucial to better understand the progression of adverse remodeling, in order to develop effective treatment. In addition, being able to assess changes in vivo would be a powerful tool in the clinic. The goal of the current study is to quantify the in vivo material properties of infarcted and remote myocardium 1 week after MI, as well as the orientation of collagen fibers in the infarct. This will be accomplished by using a combination of magnetic resonance imaging (MRI), catheterization, finite element modeling, and numerical optimization to analyze a porcine model ([Formula: see text]) of posterolateral myocardial infarction. Specifically, properties will be determined by minimizing the difference between in vivo strains and volume calculated from MRI and finite element model predicted strains and volume. The results indicate that the infarct region is stiffer than the remote region and that the infarct collagen fibers become more circumferentially oriented 1 week post-MI. These findings are consistent with previous studies, which employed ex vivo techniques. The proposed methodology will ultimately provide a means of predicting remote and infarct mechanical properties in vivo at any time point post-MI.
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50
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Estimating passive mechanical properties in a myocardial infarction using MRI and finite element simulations. Biomech Model Mechanobiol 2014; 14:633-47. [PMID: 25315521 DOI: 10.1007/s10237-014-0627-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 10/06/2014] [Indexed: 10/24/2022]
Abstract
Myocardial infarction (MI) triggers a series of maladaptive events that lead to structural and functional changes in the left ventricle. It is crucial to better understand the progression of adverse remodeling, in order to develop effective treatment. In addition, being able to assess changes in vivo would be a powerful tool in the clinic. The goal of the current study is to quantify the in vivo material properties of infarcted and remote myocardium 1 week after MI, as well as the orientation of collagen fibers in the infarct. This will be accomplished by using a combination of magnetic resonance imaging (MRI), catheterization, finite element modeling, and numerical optimization to analyze a porcine model ([Formula: see text]) of posterolateral myocardial infarction. Specifically, properties will be determined by minimizing the difference between in vivo strains and volume calculated from MRI and finite element model predicted strains and volume. The results indicate that the infarct region is stiffer than the remote region and that the infarct collagen fibers become more circumferentially oriented 1 week post-MI. These findings are consistent with previous studies, which employed ex vivo techniques. The proposed methodology will ultimately provide a means of predicting remote and infarct mechanical properties in vivo at any time point post-MI.
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