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Jacho D, Yildirim-Ayan E. Mechanome-Guided Strategies in Regenerative Rehabilitation. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2024; 29:100516. [PMID: 38586151 PMCID: PMC10993906 DOI: 10.1016/j.cobme.2023.100516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Regenerative Rehabilitation represents a multifaceted approach that merges mechanobiology with therapeutic intervention to harness the body's intrinsic tissue repair and regeneration capacity. This review delves into the intricate interplay between mechanical loading and cellular responses in the context of musculoskeletal tissue healing. It emphasizes the importance of understanding the phases involved in translating mechanical forces into biochemical responses at the cellular level. The review paper also covers the mechanosensitivity of macrophages, fibroblasts, and mesenchymal stem cells, which play a crucial role during regenerative rehabilitation since these cells exhibit unique mechanoresponsiveness during different stages of the tissue healing process. Understanding how mechanical loading amplitude and frequency applied during regenerative rehabilitation influences macrophage polarization, fibroblast-to-myofibroblast transition (FMT), and mesenchymal stem cell differentiation is crucial for developing effective therapies for musculoskeletal tissues. In conclusion, this review underscores the significance of mechanome-guided strategies in regenerative rehabilitation. By exploring the mechanosensitivity of different cell types and their responses to mechanical loading, this field offers promising avenues for accelerating tissue healing and functional recovery, ultimately enhancing the quality of life for individuals with musculoskeletal injuries and degenerative diseases.
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Affiliation(s)
- Diego Jacho
- Department of Bioengineering, University of Toledo, 2801 W. Bancroft Street, Toledo, OH, USA
| | - Eda Yildirim-Ayan
- Department of Bioengineering, University of Toledo, 2801 W. Bancroft Street, Toledo, OH, USA
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2
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Schetzsle S, Lin WWC, Purushothaman P, Ding J, Kwan P, Tredget EE. Serial Casting as an Effective Method for Burn Scar Contracture Rehabilitation: A Case Series. J Burn Care Res 2023; 44:1062-1072. [PMID: 37254900 DOI: 10.1093/jbcr/irad078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Indexed: 06/01/2023]
Abstract
Guidelines and protocols for orthoses in burn scar contracture rehabilitation are limited. The current study aims to determine the optimal frequency of casting, potentially facilitating the development of a serial casting protocol. Previous literature supporting casting has low generalizability due to methodology limitations. Seven patients with burn scar contracted joints, who did not respond to traditional therapy, were recruited in this study. Patients were serially casted once, three times, or five times a week. Joint range of motion was maximized with stretching and exercise techniques before every new cast application. Across all patients, active range of motion increased from 65.8 ± 27.8° to 108.1 ± 23.3° with casting; or from 57.8 ± 16.2% to 96.7 ± 2.9% of normal. Similarly, scars improved from 9.5 ± 1.5 to 4.9 ± 1.4 on the Modified Vancouver Scar Scale score. This therapeutic effect was achieved within an average of 8.5 ± 3.7 d and 4.0 ± 2.2 new cast applications. Given the study findings, the procedures outlined could be used to develop a standardized serial casting protocol for burn scar contracture rehabilitation.
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Affiliation(s)
- Stephanie Schetzsle
- Department of Surgery, Firefighters Burn Treatment Unit, University of Alberta Hospital, Edmonton, AB, CanadaT6G 2B7
| | - Weber Wei Chiang Lin
- Wound Healing Research Group, Department of Surgery, University of Alberta, Division of Plastic and Reconstructive Surgery and Critical Care, Department of Surgery, University of Alberta, Edmonton, AB, CanadaT6G 2S2
| | - Prabhu Purushothaman
- Department of Surgery, Firefighters Burn Treatment Unit, University of Alberta Hospital, Edmonton, AB, CanadaT6G 2B7
| | - Jie Ding
- Wound Healing Research Group, Department of Surgery, University of Alberta, Division of Plastic and Reconstructive Surgery and Critical Care, Department of Surgery, University of Alberta, Edmonton, AB, CanadaT6G 2S2
| | - Peter Kwan
- Wound Healing Research Group, Department of Surgery, University of Alberta, Division of Plastic and Reconstructive Surgery and Critical Care, Department of Surgery, University of Alberta, Edmonton, AB, CanadaT6G 2S2
| | - Edward E Tredget
- Wound Healing Research Group, Department of Surgery, University of Alberta, Division of Plastic and Reconstructive Surgery and Critical Care, Department of Surgery, University of Alberta, Edmonton, AB, CanadaT6G 2S2
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Koller T, Meier P, Pasquale C, Rüegg C. [Physiotherapeutic Scar Therapy for Large Scars]. PRAXIS 2022; 111:927-938. [PMID: 36475363 DOI: 10.1024/1661-8157/a003951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Physiotherapeutic Scar Therapy for Large Scars Abstract. Deep dermal defects can result from burns, necrotizing fasciitis, and severe soft tissue trauma. Physiological scar restriction during wound healing becomes increasingly relevant in proportion to the area affected. It is massively restrictive for the general mobility of patients. External mechanical influences (activity or immobilization in everyday life) can cause pronounced scar strands and adhesions to form. Overloading ends in a renewed inflammatory reaction and thus in further restriction. Adequate mechanical stimuli can positively influence the scar tissue. The current state of research does not allow a direct transfer to the clinical treatment of large-area scars. However, the continuous clinical implementation of study results regarding the mechanosensitivity of isolated fibroblasts and the constant adaptation of manual techniques have resulted in an evidence-based foundation for manual scar therapy. Early manual treatment in combination with appropriate compression therapy is important.
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Affiliation(s)
- Thomas Koller
- Orthopädische und Handchirurgische Rehabilitation, Rehaklinik Bellikon, Bellikon, Schweiz
| | - Patrick Meier
- Orthopädische und Handchirurgische Rehabilitation, Rehaklinik Bellikon, Bellikon, Schweiz
| | - Caterina Pasquale
- Physiotherapie Ergotherapie, Universitätsspital Zürich, Zürich, Schweiz
| | - Christine Rüegg
- Orthopädische und Handchirurgische Rehabilitation, Rehaklinik Bellikon, Bellikon, Schweiz
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Rizzi S, Ragazzini S, Pesce M. Engineering Efforts to Refine Compatibility and Duration of Aortic Valve Replacements: An Overview of Previous Expectations and New Promises. Front Cardiovasc Med 2022; 9:863136. [PMID: 35509271 PMCID: PMC9058060 DOI: 10.3389/fcvm.2022.863136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 03/28/2022] [Indexed: 01/18/2023] Open
Abstract
The absence of pharmacological treatments to reduce or retard the progression of cardiac valve diseases makes replacement with artificial prostheses (mechanical or bio-prosthetic) essential. Given the increasing incidence of cardiac valve pathologies, there is always a more stringent need for valve replacements that offer enhanced performance and durability. Unfortunately, surgical valve replacement with mechanical or biological substitutes still leads to disadvantages over time. In fact, mechanical valves require a lifetime anticoagulation therapy that leads to a rise in thromboembolic complications, while biological valves are still manufactured with non-living tissue, consisting of aldehyde-treated xenograft material (e.g., bovine pericardium) whose integration into the host fails in the mid- to long-term due to unresolved issues regarding immune-compatibility. While various solutions to these shortcomings are currently under scrutiny, the possibility to implant fully biologically compatible valve replacements remains elusive, at least for large-scale deployment. In this regard, the failure in translation of most of the designed tissue engineered heart valves (TEHVs) to a viable clinical solution has played a major role. In this review, we present a comprehensive overview of the TEHVs developed until now, and critically analyze their strengths and limitations emerging from basic research and clinical trials. Starting from these aspects, we will also discuss strategies currently under investigation to produce valve replacements endowed with a true ability to self-repair, remodel and regenerate. We will discuss these new developments not only considering the scientific/technical framework inherent to the design of novel valve prostheses, but also economical and regulatory aspects, which may be crucial for the success of these novel designs.
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Affiliation(s)
- Stefano Rizzi
- Tissue Engineering Unit, Centro Cardiologico Monzino, Istituto di ricovero e cura a carattere scientifico (IRCCS), Milan, Italy
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milan, Italy
- Stefano Rizzi
| | - Sara Ragazzini
- Tissue Engineering Unit, Centro Cardiologico Monzino, Istituto di ricovero e cura a carattere scientifico (IRCCS), Milan, Italy
| | - Maurizio Pesce
- Tissue Engineering Unit, Centro Cardiologico Monzino, Istituto di ricovero e cura a carattere scientifico (IRCCS), Milan, Italy
- *Correspondence: Maurizio Pesce
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5
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Guo Y, Calve S, Tepole AB. Multiscale mechanobiology: Coupling models of adhesion kinetics and nonlinear tissue mechanics. Biophys J 2022; 121:525-539. [PMID: 35074393 PMCID: PMC8874030 DOI: 10.1016/j.bpj.2022.01.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 12/13/2021] [Accepted: 01/18/2022] [Indexed: 11/25/2022] Open
Abstract
The mechanical behavior of tissues at the macroscale is tightly coupled to cellular activity at the microscale. Dermal wound healing is a prominent example of a complex system in which multiscale mechanics regulate restoration of tissue form and function. In cutaneous wound healing, a fibrin matrix is populated by fibroblasts migrating in from a surrounding tissue made mostly out of collagen. Fibroblasts both respond to mechanical cues, such as fiber alignment and stiffness, as well as exert active stresses needed for wound closure. Here, we develop a multiscale model with a two-way coupling between a microscale cell adhesion model and a macroscale tissue mechanics model. Starting from the well-known model of adhesion kinetics proposed by Bell, we extend the formulation to account for nonlinear mechanics of fibrin and collagen and show how this nonlinear response naturally captures stretch-driven mechanosensing. We then embed the new nonlinear adhesion model into a custom finite element implementation of tissue mechanical equilibrium. Strains and stresses at the tissue level are coupled with the solution of the microscale adhesion model at each integration point of the finite element mesh. In addition, solution of the adhesion model is coupled with the active contractile stress of the cell population. The multiscale model successfully captures the mechanical response of biopolymer fibers and gels, contractile stresses generated by fibroblasts, and stress-strain contours observed during wound healing. We anticipate that this framework will not only increase our understanding of how mechanical cues guide cellular behavior in cutaneous wound healing, but will also be helpful in the study of mechanobiology, growth, and remodeling in other tissues.
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Affiliation(s)
- Yifan Guo
- School of Mechanical Engineering, Purdue University, West Lafayette
| | - Sarah Calve
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette,Paul M. Rady Department of Mechanical Engineering, University of Colorado - Boulder, Boulder
| | - Adrian Buganza Tepole
- School of Mechanical Engineering, Purdue University, West Lafayette; Weldon School of Biomedical Engineering, Purdue University, West Lafayette.
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6
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Khalil NN, McCain ML. Engineering the Cellular Microenvironment of Post-infarct Myocardium on a Chip. Front Cardiovasc Med 2021; 8:709871. [PMID: 34336962 PMCID: PMC8316619 DOI: 10.3389/fcvm.2021.709871] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 06/14/2021] [Indexed: 01/02/2023] Open
Abstract
Myocardial infarctions are one of the most common forms of cardiac injury and death worldwide. Infarctions cause immediate necrosis in a localized region of the myocardium, which is followed by a repair process with inflammatory, proliferative, and maturation phases. This repair process culminates in the formation of scar tissue, which often leads to heart failure in the months or years after the initial injury. In each reparative phase, the infarct microenvironment is characterized by distinct biochemical, physical, and mechanical features, such as inflammatory cytokine production, localized hypoxia, and tissue stiffening, which likely each contribute to physiological and pathological tissue remodeling by mechanisms that are incompletely understood. Traditionally, simplified two-dimensional cell culture systems or animal models have been implemented to elucidate basic pathophysiological mechanisms or predict drug responses following myocardial infarction. However, these conventional approaches offer limited spatiotemporal control over relevant features of the post-infarct cellular microenvironment. To address these gaps, Organ on a Chip models of post-infarct myocardium have recently emerged as new paradigms for dissecting the highly complex, heterogeneous, and dynamic post-infarct microenvironment. In this review, we describe recent Organ on a Chip models of post-infarct myocardium, including their limitations and future opportunities in disease modeling and drug screening.
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Affiliation(s)
- Natalie N Khalil
- Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States
| | - Megan L McCain
- Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA, United States.,Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States
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7
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Zhang W, Huang G, Xu F. Engineering Biomaterials and Approaches for Mechanical Stretching of Cells in Three Dimensions. Front Bioeng Biotechnol 2020; 8:589590. [PMID: 33154967 PMCID: PMC7591716 DOI: 10.3389/fbioe.2020.589590] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/09/2020] [Indexed: 12/21/2022] Open
Abstract
Mechanical stretch is widely experienced by cells of different tissues in the human body and plays critical roles in regulating their behaviors. Numerous studies have been devoted to investigating the responses of cells to mechanical stretch, providing us with fruitful findings. However, these findings have been mostly observed from two-dimensional studies and increasing evidence suggests that cells in three dimensions may behave more closely to their in vivo behaviors. While significant efforts and progresses have been made in the engineering of biomaterials and approaches for mechanical stretching of cells in three dimensions, much work remains to be done. Here, we briefly review the state-of-the-art researches in this area, with focus on discussing biomaterial considerations and stretching approaches. We envision that with the development of advanced biomaterials, actuators and microengineering technologies, more versatile and predictive three-dimensional cell stretching models would be available soon for extensive applications in such fields as mechanobiology, tissue engineering, and drug screening.
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Affiliation(s)
- Weiwei Zhang
- Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan, China
| | - Guoyou Huang
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing University, Chongqing, China
- Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan, China
| | - Feng Xu
- Bioinspired Engineering and Biomechanics Center, Xi’an Jiaotong University, Xi’an, China
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Sciences and Technology, Xi’an Jiaotong University, Xi’an, China
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8
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Mechanosensitive Aspects of Cell Biology in Manual Scar Therapy for Deep Dermal Defects. Int J Mol Sci 2020; 21:ijms21062055. [PMID: 32192136 PMCID: PMC7139679 DOI: 10.3390/ijms21062055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/06/2020] [Accepted: 03/10/2020] [Indexed: 01/06/2023] Open
Abstract
Deep dermal defects can result from burns, necrotizing fasciitis and severe soft tissue trauma. Physiological scar restriction during wound healing becomes increasingly relevant in proportion to the affected area. This massively restricts the general mobility of patients. External mechanical influences (activity or immobilization in everyday life) can lead to the formation of marked scar strands and adhesions. Overloading results in a renewed inflammatory reaction and thus in further restriction. Appropriate mechanical stimuli can have a positive influence on the scar tissue. “Use determines function,” and even minimal external forces are sufficient to cause functional alignment (mechanotransduction). The first and second remarkable increases in connective tissue resistance (R1 and R2) seem to be relevant clinical indications of adequate dosage in the proliferation and remodulation phase, making it possible to counteract potential overdosage in deep dermal defects. The current state of research does not allow a direct transfer to the clinical treatment of large scars. However, the continuous clinical implementation of study results with regard to the mechanosensitivity of isolated fibroblasts, and the constant adaptation of manual techniques, has nevertheless created an evidence-base for manual scar therapy. The manual dosages are adapted to tissue physiology and to respective wound healing phases. Clinical observations show improved mobility of the affected regions and fewer relapses into the inflammatory phase due to mechanical overload.
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9
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McEvoy E, Deshpande VS, McGarry P. Transient active force generation and stress fibre remodelling in cells under cyclic loading. Biomech Model Mechanobiol 2019; 18:921-937. [PMID: 30783833 DOI: 10.1007/s10237-019-01121-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/21/2019] [Indexed: 12/27/2022]
Abstract
The active cytoskeleton is known to play an important mechanistic role in cellular structure, spreading, and contractility. Contractility is actively generated by stress fibres (SF), which continuously remodel in response to physiological dynamic loading conditions. The influence of actin-myosin cross-bridge cycling on SF remodelling under dynamic loading conditions has not previously been uncovered. In this study, a novel SF cross-bridge cycling model is developed to predict transient active force generation in cells subjected to dynamic loading. Rates of formation of cross-bridges within SFs are governed by the chemical potentials of attached and unattached myosin heads. This transient cross-bridge cycling model is coupled with a thermodynamically motivated framework for SF remodelling to analyse the influence of transient force generation on cytoskeletal evolution. A 1D implementation of the model is shown to correctly predict complex patterns of active cell force generation under a range of dynamic loading conditions, as reported in previous experimental studies.
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Affiliation(s)
- Eoin McEvoy
- Discipline of Biomedical Engineering, National University of Ireland Galway, Galway, Ireland
| | | | - Patrick McGarry
- Discipline of Biomedical Engineering, National University of Ireland Galway, Galway, Ireland.
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10
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Kong M, Lee J, Yazdi IK, Miri AK, Lin YD, Seo J, Zhang YS, Khademhosseini A, Shin SR. Cardiac Fibrotic Remodeling on a Chip with Dynamic Mechanical Stimulation. Adv Healthc Mater 2019; 8:e1801146. [PMID: 30609312 PMCID: PMC6546425 DOI: 10.1002/adhm.201801146] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 11/07/2018] [Indexed: 12/19/2022]
Abstract
Cardiac tissue is characterized by being dynamic and contractile, imparting the important role of biomechanical cues in the regulation of normal physiological activity or pathological remodeling. However, the dynamic mechanical tension ability also varies due to extracellular matrix remodeling in fibrosis, accompanied with the phenotypic transition from cardiac fibroblasts (CFs) to myofibroblasts. It is hypothesized that the dynamic mechanical tension ability regulates cardiac phenotypic transition within fibrosis in a strain-mediated manner. In this study, a microdevice that is able to simultaneously and accurately mimic the biomechanical properties of the cardiac physiological and pathological microenvironment is developed. The microdevice can apply cyclic compressions with gradient magnitudes (5-20%) and tunable frequency onto gelatin methacryloyl (GelMA) hydrogels laden with CFs, and also enables the integration of cytokines. The strain-response correlations between mechanical compression and CFs spreading, and proliferation and fibrotic phenotype remolding, are investigated. Results reveal that mechanical compression plays a crucial role in the CFs phenotypic transition, depending on the strain of mechanical load and myofibroblast maturity of CFs encapsulated in GelMA hydrogels. The results provide evidence regarding the strain-response correlation of mechanical stimulation in CFs phenotypic remodeling, which can be used to develop new preventive or therapeutic strategies for cardiac fibrosis.
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Affiliation(s)
- Ming Kong
- College of Marine Life Science, Ocean University of China, Yushan Road, Qingdao, Shandong Province 266003, China
- Department of Medicine, Division of Engineering in Medicine, Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Junmin Lee
- Department of Medicine, Division of Engineering in Medicine, Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
- Department of Bioengineering, Department of Chemical and Biomolecular Engineering, Henry Samueli School of Engineering and Applied Sciences, University of California-Los Angeles, Los Angeles, CA90095, USA
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, Los Angeles, CA90095, USA
- California NanoSystems Institute (CNSI), University of California-Los Angeles, Los Angeles, CA90095, USA
| | - Iman K. Yazdi
- Department of Medicine, Division of Engineering in Medicine, Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Amir K. Miri
- Department of Medicine, Division of Engineering in Medicine, Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yi-Dong Lin
- Divisions of Genetics and Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA02115, USA
| | - Jungmok Seo
- Department of Medicine, Division of Engineering in Medicine, Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science and Technology, 14 Hwarang-ro, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Yu Shrike Zhang
- Department of Medicine, Division of Engineering in Medicine, Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ali Khademhosseini
- Department of Medicine, Division of Engineering in Medicine, Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Bioengineering, Department of Chemical and Biomolecular Engineering, Henry Samueli School of Engineering and Applied Sciences, University of California-Los Angeles, Los Angeles, CA90095, USA
- Department of Radiology, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA90095, USA
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, Los Angeles, CA90095, USA
- California NanoSystems Institute (CNSI), University of California-Los Angeles, Los Angeles, CA90095, USA
- Department of Bioindustrial Technologies, College of Animal Bioscience and Technology, Konkuk University, Hwayang-dong, Gwangjin-gu, Seoul 05029, Republic of Korea
| | - Su Ryon Shin
- Department of Medicine, Division of Engineering in Medicine, Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA 02139, USA
- Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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11
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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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12
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Cho N, Razipour SE, McCain ML. Featured Article: TGF-β1 dominates extracellular matrix rigidity for inducing differentiation of human cardiac fibroblasts to myofibroblasts. Exp Biol Med (Maywood) 2018; 243:601-612. [PMID: 29504479 DOI: 10.1177/1535370218761628] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cardiac fibroblasts and their activated derivatives, myofibroblasts, play a critical role in wound healing after myocardial injury and often contribute to long-term pathological outcomes, such as excessive fibrosis. Thus, defining the microenvironmental factors that regulate the phenotype of cardiac fibroblasts and myofibroblasts could lead to new therapeutic strategies. Both chemical and biomechanical cues have previously been shown to induce myofibroblast differentiation in many organs and species. For example, transforming growth factor beta 1, a cytokine secreted by neutrophils, and rigid extracellular matrix environments have both been shown to promote differentiation. However, the relative contributions of transforming growth factor beta 1 and extracellular matrix rigidity, two hallmark cues in many pathological myocardial microenvironments, to the phenotype of human cardiac fibroblasts are unclear. We hypothesized that transforming growth factor beta 1 and rigid extracellular matrix environments would potentially have a synergistic effect on the differentiation of human cardiac fibroblasts to myofibroblasts. To test this, we seeded primary human adult cardiac fibroblasts onto coverslips coated with polydimethylsiloxane of various elastic moduli, introduced transforming growth factor beta 1, and longitudinally quantified cell phenotype by measuring expression of α-smooth muscle actin, the most robust indicator of myofibroblasts. Our data indicate that, although extracellular matrix rigidity influenced differentiation after one day of transforming growth factor beta 1 treatment, ultimately transforming growth factor beta 1 superseded extracellular matrix rigidity as the primary regulator of myofibroblast differentiation. We also measured expression of POSTN, FAP, and FSP1, proposed secondary indicators of fibroblast/myofibroblast phenotypes. Although these genes partially trended with α-smooth muscle actin expression, they were relatively inconsistent. Finally, we demonstrated that activated myofibroblasts incompletely revert to a fibroblast phenotype after they are re-plated onto new surfaces without transforming growth factor beta 1, suggesting differentiation is partially reversible. Our results provide new insights into how microenvironmental cues affect human cardiac fibroblast differentiation in the context of myocardial pathology, which is important for identifying effective therapeutic targets and dictating supporting cell phenotypes for engineered human cardiac disease models. Impact statement Heart disease is the leading cause of death worldwide. Many forms of heart disease are associated with fibrosis, which increases extracellular matrix (ECM) rigidity and compromises cardiac output. Fibrotic tissue is synthesized primarily by myofibroblasts differentiated from fibroblasts. Thus, defining the cues that regulate myofibroblast differentiation is important for understanding the mechanisms of fibrosis. However, previous studies have focused on non-human cardiac fibroblasts and have not tested combinations of chemical and mechanical cues. We tested the effects of TGF-β1, a cytokine secreted by immune cells after injury, and ECM rigidity on the differentiation of human cardiac fibroblasts to myofibroblasts. Our results indicate that differentiation is initially influenced by ECM rigidity, but is ultimately superseded by TGF-β1. This suggests that targeting TGF-β signaling pathways in cardiac fibroblasts may have therapeutic potential for attenuating fibrosis, even in rigid microenvironments. Additionally, our approach can be leveraged to engineer more precise multi-cellular human cardiac tissue models.
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Affiliation(s)
- Nathan Cho
- 1 Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Shadi E Razipour
- 1 Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Megan L McCain
- 1 Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA.,2 Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA 90033, USA
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Çoban G, Çelebi MS. A novel computational remodelling algorithm for the probabilistic evolution of collagen fibre dispersion in biaxially strained vascular tissue. MATHEMATICAL MEDICINE AND BIOLOGY : A JOURNAL OF THE IMA 2017; 34:433-467. [PMID: 27614761 DOI: 10.1093/imammb/dqw012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 08/02/2016] [Indexed: 06/06/2023]
Abstract
In this work, we constructed a novel collagen fibre remodelling algorithm that incorporates the complex nature of random evolution acting on single fibres causing macroscopic fibre dispersion. The proposed framework is different from the existing remodelling algorithms, in that the microscopic random force on cellular scales causing a rotational-type Brownian motion alone is considered as an aspect of vascular tissue remodelling. A continuum mechanical framework for the evolution of local dispersion and how it could be used for modeling the evolution of internal radius of biaxially strained artery structures under constant internal blood pressure are presented. A linear evolution form for the statistical fibre dispersion is employed in the model. The random force component of the evolution, which depends on the mechanical stress stimuli, is described by a single parameter. Although the mathematical form of the proposed model is simple, there is a strong link between the microscopic evolution of collagen dispersion on the cellular level and its effects on the macroscopic visible world through mechanical variables. We believe that the proposed algorithm utilizes a better understanding of the relationship between the evolution rates of mean fibre direction and fibre dispersion. The predictive capability of the algorithm is presented using experimental data. The model has been simulated by solving a single-layered axisymmetric artery (adventitia) deformation problem. The algorithm performed well for estimating the quantitative features of experimental anisotropy, the mean fibre direction vector and the dispersion (κ) measurements under strain-dependent evolution assumptions.
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Affiliation(s)
- Gürsan Çoban
- Department of Computational Science & Engineering, Informatics Institute, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey
| | - M Serdar Çelebi
- Department of Computational Science & Engineering, Informatics Institute, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey
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14
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Huang AH, Balestrini JL, Udelsman BV, Zhou KC, Zhao L, Ferruzzi J, Starcher BC, Levene MJ, Humphrey JD, Niklason LE. Biaxial Stretch Improves Elastic Fiber Maturation, Collagen Arrangement, and Mechanical Properties in Engineered Arteries. Tissue Eng Part C Methods 2017; 22:524-33. [PMID: 27108525 DOI: 10.1089/ten.tec.2015.0309] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Tissue-engineered blood vessels (TEVs) are typically produced using the pulsatile, uniaxial circumferential stretch to mechanically condition and strengthen the arterial grafts. Despite improvements in the mechanical integrity of TEVs after uniaxial conditioning, these tissues fail to achieve critical properties of native arteries such as matrix content, collagen fiber orientation, and mechanical strength. As a result, uniaxially loaded TEVs can result in mechanical failure, thrombus, or stenosis on implantation. In planar tissue equivalents such as artificial skin, biaxial loading has been shown to improve matrix production and mechanical properties. To date however, multiaxial loading has not been examined as a means to improve mechanical and biochemical properties of TEVs during culture. Therefore, we developed a novel bioreactor that utilizes both circumferential and axial stretch that more closely simulates loading conditions in native arteries, and we examined the suture strength, matrix production, fiber orientation, and cell proliferation. After 3 months of biaxial loading, TEVs developed a formation of mature elastic fibers that consisted of elastin cores and microfibril sheaths. Furthermore, the distinctive features of collagen undulation and crimp in the biaxial TEVs were absent in both uniaxial and static TEVs. Relative to the uniaxially loaded TEVs, tissues that underwent biaxial loading remodeled and realigned collagen fibers toward a more physiologic, native-like organization. The biaxial TEVs also showed increased mechanical strength (suture retention load of 303 ± 14.53 g, with a wall thickness of 0.76 ± 0.028 mm) and increased compliance. The increase in compliance was due to combinatorial effects of mature elastic fibers, undulated collagen fibers, and collagen matrix orientation. In conclusion, biaxial stretching is a potential means to regenerate TEVs with improved matrix production, collagen organization, and mechanical properties.
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Affiliation(s)
- Angela H Huang
- 1 Department of Biomedical Engineering, School of Engineering and Applied Science, Yale University , New Haven, Connecticut
| | - Jenna L Balestrini
- 1 Department of Biomedical Engineering, School of Engineering and Applied Science, Yale University , New Haven, Connecticut
| | | | - Kevin C Zhou
- 1 Department of Biomedical Engineering, School of Engineering and Applied Science, Yale University , New Haven, Connecticut
| | - Liping Zhao
- 2 School of Medicine, Yale University , New Haven, Connecticut
| | - Jacopo Ferruzzi
- 1 Department of Biomedical Engineering, School of Engineering and Applied Science, Yale University , New Haven, Connecticut
| | - Barry C Starcher
- 3 Department of Biochemistry, The University of Texas Health Science Center at Tyler , Tyler, Texas
| | - Michael J Levene
- 1 Department of Biomedical Engineering, School of Engineering and Applied Science, Yale University , New Haven, Connecticut
| | - Jay D Humphrey
- 1 Department of Biomedical Engineering, School of Engineering and Applied Science, Yale University , New Haven, Connecticut
| | - Laura E Niklason
- 1 Department of Biomedical Engineering, School of Engineering and Applied Science, Yale University , New Haven, Connecticut.,2 School of Medicine, Yale University , New Haven, Connecticut
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15
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Abstract
PURPOSE OF REVIEW The objectives of this review are to evaluate the current evidence-based literature and concepts surrounding rehabilitation in patients with anterior shoulder instability injuries and surgical repair. RECENT FINDINGS The current literature evidence for shoulder rehabilitation for anterior shoulder instability and labral repair is limited. As a result, there are variations among surgeons and physical therapists in rehabilitation protocols after anterior shoulder instability injuries and repair. While general consensus on certain rehabilitation parameters exists, the evidence for the importance of rehabilitation and functional performance test for return to sport in future injury prevention is still lacking in literature. Rehabilitation after anterior shoulder instability injury and anterior labral repair is paramount in the injured or post-operative shoulder. Restoration of soft tissue mobility, dynamic glenohumeral joint stability, and balance and strength around the shoulder not only protect healing of injured or repaired soft tissues but also potentially minimizes future re-injury or recurrence risk.
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van Loosdregt IAEW, Dekker S, Alford PW, Oomens CWJ, Loerakker S, Bouten CVC. Intrinsic Cell Stress is Independent of Organization in Engineered Cell Sheets. Cardiovasc Eng Technol 2016; 9:181-192. [PMID: 27778297 PMCID: PMC5988777 DOI: 10.1007/s13239-016-0283-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 10/11/2016] [Indexed: 11/27/2022]
Abstract
Understanding cell contractility is of fundamental importance for cardiovascular tissue engineering, due to its major impact on the tissue’s mechanical properties as well as the development of permanent dimensional changes, e.g., by contraction or dilatation of the tissue. Previous attempts to quantify contractile cellular stresses mostly used strongly aligned monolayers of cells, which might not represent the actual organization in engineered cardiovascular tissues such as heart valves. In the present study, therefore, we investigated whether differences in organization affect the magnitude of intrinsic stress generated by individual myofibroblasts, a frequently used cell source for in vitro engineered heart valves. Four different monolayer organizations were created via micro-contact printing of fibronectin lines on thin PDMS films, ranging from strongly anisotropic to isotropic. Thin film curvature, cell density, and actin stress fiber distribution were quantified, and subsequently, intrinsic stress and contractility of the monolayers were determined by incorporating these data into sample-specific finite element models. Our data indicate that the intrinsic stress exerted by the monolayers in each group correlates with cell density. Additionally, after normalizing for cell density and accounting for differences in alignment, no consistent differences in intrinsic contractility were found between the different monolayer organizations, suggesting that the intrinsic stress exerted by individual myofibroblasts is independent of the organization. Consequently, this study emphasizes the importance of choosing proper architectural properties for scaffolds in cardiovascular tissue engineering, as these directly affect the stresses in the tissue, which play a crucial role in both the functionality and remodeling of (engineered) cardiovascular tissues.
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Affiliation(s)
- Inge A E W van Loosdregt
- Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Sylvia Dekker
- Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Cees W J Oomens
- Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Sandra Loerakker
- Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands.
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands.
| | - Carlijn V C Bouten
- Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
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17
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Moortgat P, Anthonissen M, Meirte J, Van Daele U, Maertens K. The physical and physiological effects of vacuum massage on the different skin layers: a current status of the literature. BURNS & TRAUMA 2016; 4:34. [PMID: 27660766 PMCID: PMC5027633 DOI: 10.1186/s41038-016-0053-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 06/23/2016] [Indexed: 11/10/2022]
Abstract
Vacuum massage is a non-invasive mechanical massage technique performed with a mechanical device that lifts the skin by means of suction, creates a skin fold and mobilises that skin fold. In the late 1970s, this therapy was introduced to treat traumatic or burn scars. Although vacuum massage was invented to treat burns and scars, one can find very little literature on the effects of this intervention. Therefore, the aim of this review is to present an overview of the available literature on the physical and physiological effects of vacuum massage on epidermal and dermal skin structures in order to find the underlying working mechanisms that could benefit the healing of burns and scars. The discussion contains translational analysis of the results and provides recommendations for future research on the topic. An extended search for publications was performed using PubMed, Web of Science and Google Scholar. Two authors independently identified and checked each study against the inclusion criteria. Nineteen articles were included in the qualitative synthesis. The two most reported physical effects of vacuum massage were improvement of the tissue hardness and the elasticity of the skin. Besides physical effects, a variety of physiological effects are reported in literature, for example, an increased number of fibroblasts and collagen fibres accompanied by an alteration of fibroblast phenotype and collagen orientation. Little information was found on the decrease of pain and itch due to vacuum massage. Although vacuum massage initially had been developed for the treatment of burn scars, this literature review found little evidence for the efficacy of this treatment. Variations in duration, amplitude or frequency of the treatment have a substantial influence on collagen restructuring and reorientation, thus implying possible beneficial influences on the healing potential by mechanotransduction pathways. Vacuum massage may release the mechanical tension associated with scar retraction and thus induce apoptosis of myofibroblasts. Suggestions for future research include upscaling the study design, investigating the molecular pathways and dose dependency, comparing effects in different stages of repair, including evolutive parameters and the use of more objective assessment tools.
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Affiliation(s)
- Peter Moortgat
- OSCARE, Organisation for Burns, Scar After-care and Research, Van Roiestraat 18, B-2170 Antwerp, Belgium
| | - Mieke Anthonissen
- OSCARE, Organisation for Burns, Scar After-care and Research, Van Roiestraat 18, B-2170 Antwerp, Belgium ; Department of Rehabilitation Sciences, KU Leuven, Tervuursevest 101, box 1500, 3001 Heverlee, Belgium
| | - Jill Meirte
- OSCARE, Organisation for Burns, Scar After-care and Research, Van Roiestraat 18, B-2170 Antwerp, Belgium ; Department of Rehabilitation Sciences and Physiotherapy, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
| | - Ulrike Van Daele
- Department of Rehabilitation Sciences and Physiotherapy, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
| | - Koen Maertens
- OSCARE, Organisation for Burns, Scar After-care and Research, Van Roiestraat 18, B-2170 Antwerp, Belgium ; Department of Clinical and Lifespan Psychology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
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18
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Balestrini JL, Gard AL, Gerhold KA, Wilcox EC, Liu A, Schwan J, Le AV, Baevova P, Dimitrievska S, Zhao L, Sundaram S, Sun H, Rittié L, Dyal R, Broekelmann TJ, Mecham RP, Schwartz MA, Niklason LE, White ES. Comparative biology of decellularized lung matrix: Implications of species mismatch in regenerative medicine. Biomaterials 2016; 102:220-30. [PMID: 27344365 DOI: 10.1016/j.biomaterials.2016.06.025] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 06/03/2016] [Accepted: 06/12/2016] [Indexed: 01/14/2023]
Abstract
Lung engineering is a promising technology, relying on re-seeding of either human or xenographic decellularized matrices with patient-derived pulmonary cells. Little is known about the species-specificity of decellularization in various models of lung regeneration, or if species dependent cell-matrix interactions exist within these systems. Therefore decellularized scaffolds were produced from rat, pig, primate and human lungs, and assessed by measuring residual DNA, mechanical properties, and key matrix proteins (collagen, elastin, glycosaminoglycans). To study intrinsic matrix biologic cues, human endothelial cells were seeded onto acellular slices and analyzed for markers of cell health and inflammation. Despite similar levels of collagen after decellularization, human and primate lungs were stiffer, contained more elastin, and retained fewer glycosaminoglycans than pig or rat lung scaffolds. Human endothelial cells seeded onto human and primate lung tissue demonstrated less expression of vascular cell adhesion molecule and activation of nuclear factor-κB compared to those seeded onto rodent or porcine tissue. Adhesion of endothelial cells was markedly enhanced on human and primate tissues. Our work suggests that species-dependent biologic cues intrinsic to lung extracellular matrix could have profound effects on attempts at lung regeneration.
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Affiliation(s)
- Jenna L Balestrini
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Department of Anesthesiolgy, Yale University, New Haven, CT, USA
| | - Ashley L Gard
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | | | - Elise C Wilcox
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Angela Liu
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Jonas Schwan
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Andrew V Le
- Department of Anesthesiolgy, Yale University, New Haven, CT, USA
| | - Pavlina Baevova
- Department of Anesthesiolgy, Yale University, New Haven, CT, USA
| | | | - Liping Zhao
- Department of Anesthesiolgy, Yale University, New Haven, CT, USA
| | - Sumati Sundaram
- Department of Anesthesiolgy, Yale University, New Haven, CT, USA
| | - Huanxing Sun
- Department of Internal Medicine, Yale University, New Haven, CT, USA
| | - Laure Rittié
- Department of Dermatology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Rachel Dyal
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Tom J Broekelmann
- Department of Cell Biology and Physiology, Washington University St. Louis, St. Louis, MO, USA
| | - Robert P Mecham
- Department of Cell Biology and Physiology, Washington University St. Louis, St. Louis, MO, USA
| | - Martin A Schwartz
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Department of Cell Biology, Yale University, New Haven, CT, USA
| | - Laura E Niklason
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Department of Anesthesiolgy, Yale University, New Haven, CT, USA
| | - Eric S White
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA.
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19
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van Putten S, Shafieyan Y, Hinz B. Mechanical control of cardiac myofibroblasts. J Mol Cell Cardiol 2015; 93:133-42. [PMID: 26620422 DOI: 10.1016/j.yjmcc.2015.11.025] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 12/17/2022]
Abstract
Fibroblasts produce and turn over collagenous extracellular matrix as part of the normal adaptive response to increased mechanical load in the heart, e.g. during prolonged exercise. However, chronic overload as a consequence of hypertension or myocardial injury trigger a repair program that culminates in the formation of myofibroblasts. Myofibroblasts are opportunistically activated from various precursor cells that all acquire a phenotype promoting excessive collagen secretion and contraction of the neo-matrix into stiff scar tissue. Stiff fibrotic tissue reduces heart distensibility, impedes pumping and valve function, contributes to diastolic and systolic dysfunction, and affects myocardial electrical transmission, potentially leading to arrhythmia and heart failure. Here, we discuss how mechanical factors, such as matrix stiffness and strain, are feeding back and cooperate with cytokine signals to drive myofibroblast activation. We elaborate on the importance of considering the mechanical boundary conditions in the heart to generate better cell culture models for mechanistic studies of cardiac fibroblast function. Elements of the force transmission and mechanoperception apparatus acting in myofibroblasts are presented as potential therapeutic targets to treat fibrosis.
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Affiliation(s)
- Sander van Putten
- Laboratory of Tissue Repair and Regeneration, Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 3E2, Canada
| | - Yousef Shafieyan
- Laboratory of Tissue Repair and Regeneration, Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 3E2, Canada
| | - Boris Hinz
- Laboratory of Tissue Repair and Regeneration, Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 3E2, Canada.
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20
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Single cell active force generation under dynamic loading - Part I: AFM experiments. Acta Biomater 2015; 27:236-250. [PMID: 26360596 DOI: 10.1016/j.actbio.2015.09.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/14/2015] [Accepted: 09/06/2015] [Indexed: 12/27/2022]
Abstract
A novel series of experiments are performed on single cells using a bespoke AFM system where the response of cells to dynamic loading at physiologically relevant frequencies is uncovered. Measured forces for the untreated cells are dramatically different to cytochalasin-D (cyto-D) treated cells, indicating that the contractile actin cytoskeleton plays a critical role in the response of cells to dynamic loading. Following a change in applied strain magnitude, while maintaining a constant applied strain rate, the compression force for contractile cells recovers to 88.9±7.8% of the steady state force. In contrast, cyto-D cell compression forces recover to only 38.0±6.7% of the steady state force. Additionally, untreated cells exhibit strongly negative (pulling) forces during unloading half-cycles when the probe is retracted. In comparison, negligible pulling forces are measured for cyto-D cells during probe retraction. The current study demonstrates that active contractile forces, generated by actin-myosin cross-bridge cycling, dominate the response of single cells to dynamic loading. Such active force generation is shown to be independent of applied strain magnitude. Passive forces generated by the applied deformation are shown to be of secondary importance, exhibiting a high dependence on applied strain magnitude, in contrast to the active forces in untreated cells. STATEMENT OF SIGNIFICANCE A novel series of experiments are performed on single cells using a bespoke AFM system where the response of cells to dynamic loading at physiologically relevant frequencies is uncovered. Contractile cells, which contain the active force generation machinery of the actin cytoskeleton, are shown to be insensitive to applied strain magnitude, exhibiting high resistance to dynamic compression and stretching. Such trends are not observed for cells in which the actin cytoskeleton has been chemically disrupted. These biomechanical insights have not been previously reported. This detailed characterisation of single cell active and passive stress during dynamic loading has important implications for tissue engineering strategies, where applied deformation has been reported to significantly affect cell mechanotransduction and matrix synthesis.
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21
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Zein-Hammoud M, Standley PR. Modeled Osteopathic Manipulative Treatments: A Review of Their in Vitro Effects on Fibroblast Tissue Preparations. J Osteopath Med 2015. [DOI: 10.7556/jaoa.2015.103] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
A key osteopathic tenet involves the body’s ability to self-heal. Osteopathic manipulative treatment (OMT) has been evolved to improve this healing capacity. The authors' in vitro work has focused on modeling 2 common OMT modalities: myofascial release (MFR) and counterstrain. Their studies have evaluated the effects of these modalities on wound healing, cytokine secretion, and muscle repair. The key components of the host response to mechanical forces are fibroblasts, which are the main fascial cells that respond to different types of strain by secreting anti-inflammatory chemicals and growth factors, thus improving wound healing and muscle repair processes. The purpose of this review is to discuss the cellular and molecular mechanisms by which MFR and other OMT modalities work, in particular, the role of strained fibroblasts in inflammation, wound healing, and muscle repair and regeneration. Changing MFR parameters, such as magnitude, duration, direction, and frequency of strain, might uniquely affect the physiologic response of fibroblasts, muscle contraction, and wound healing. If such results are clinically translatable, the mechanisms underlying the clinical outcomes of OMT modalities will be better understood, and these treatments will be more widely accepted as evidence-based, first-line therapies.
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22
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Cardwell RD, Kluge JA, Thayer PS, Guelcher SA, Dahlgren LA, Kaplan DL, Goldstein AS. Static and cyclic mechanical loading of mesenchymal stem cells on elastomeric, electrospun polyurethane meshes. J Biomech Eng 2015; 137:2279318. [PMID: 25902471 DOI: 10.1115/1.4030404] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Indexed: 11/08/2022]
Abstract
Biomaterial substrates composed of semi-aligned electrospun fibers are attractive supports for the regeneration of connective tissues because the fibers are durable under cyclic tensile loads and can guide cell adhesion, orientation, and gene expression. Previous studies on supported electrospun substrates have shown that both fiber diameter and mechanical deformation can independently influence cell morphology and gene expression. However, no studies have examined the effect of mechanical deformation and fiber diameter on unsupported meshes. Semi-aligned large (1.75 μm) and small (0.60 μm) diameter fiber meshes were prepared from degradable elastomeric poly(esterurethane urea) (PEUUR) meshes and characterized by tensile testing and scanning electron microscopy (SEM). Next, unsupported meshes were aligned between custom grips (with the stretch axis oriented parallel to axis of fiber alignment), seeded with C3H10T1/2 cells, and subjected to a static load (50 mN, adjusted daily), a cyclic load (4% strain at 0.25 Hz for 30 min, followed by a static tensile loading of 50 mN, daily), or no load. After 3 days of mechanical stimulation, confocal imaging was used to characterize cell shape, while measurements of deoxyribonucleic acid (DNA) content and messenger ribonucleic acid (mRNA) expression were used to characterize cell retention on unsupported meshes and expression of the connective tissue phenotype. Mechanical testing confirmed that these materials deform elastically to at least 10%. Cells adhered to unsupported meshes under all conditions and aligned with the direction of fiber orientation. Application of static and cyclic loads increased cell alignment. Cell density and mRNA expression of connective tissue proteins were not statistically different between experimental groups. However, on large diameter fiber meshes, static loading slightly elevated tenomodulin expression relative to the no load group, and tenascin-C and tenomodulin expression relative to the cyclic load group. These results demonstrate the feasibility of maintaining cell adhesion and alignment on semi-aligned fibrous elastomeric substrates under different mechanical conditions. The study confirms that cell morphology is sensitive to the mechanical environment and suggests that expression of select connective tissue genes may be enhanced on large diameter fiber meshes under static tensile loads.
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23
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Park S, Seawright A, Park S, Craig Dutton J, Grinnell F, Han B. Preservation of tissue microstructure and functionality during freezing by modulation of cytoskeletal structure. J Mech Behav Biomed Mater 2015; 45:32-44. [PMID: 25679482 DOI: 10.1016/j.jmbbm.2015.01.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 01/13/2015] [Accepted: 01/16/2015] [Indexed: 02/06/2023]
Abstract
Cryopreservation is one of the key enabling technologies for tissue engineering and regenerative medicine, which can provide reliable long-term storage of engineered tissues (ETs) without losing their functionality. However, it is still extremely difficult to design and develop cryopreservation protocols guaranteeing the post-thaw tissue functionality. One of the major challenges in cryopreservation is associated with the difficulty of identifying effective and less toxic cryoprotective agents (CPAs) to guarantee the post-thaw tissue functionality. In this study, thus, a hypothesis was tested that the modulation of the cytoskeletal structure of cells embedded in the extracellular matrix (ECM) can mitigate the freezing-induced changes of the functionality and can reduce the amount of CPA necessary to preserve the functionality of ETs during cryopreservation. In order to test this hypothesis, we prepared dermal equivalents by seeding fibroblasts in type I collagen matrices resulting in three different cytoskeletal structures. These ETs were exposed to various freeze/thaw (F/T) conditions with and without CPAs. The freezing-induced cell-fluid-matrix interactions and subsequent functional properties of the ETs were assessed. The results showed that the cytoskeletal structure and the use of CPA were strongly correlated to the preservation of the post-thaw functional properties. As the cytoskeletal structure became stronger via stress fiber formation, the ET's functionality was preserved better. It also reduced the necessary CPA concentration to preserve the post-thaw functionality. However, if the extent of the freezing-induced cell-fluid-matrix interaction was too excessive, the cytoskeletal structure was completely destroyed and the beneficial effects became minimal.
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Affiliation(s)
- Seungman Park
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
| | - Angela Seawright
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
| | - Sinwook Park
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
| | - J Craig Dutton
- Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Frederick Grinnell
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bumsoo Han
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA; Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA.
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24
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Wilson CJ, Pearcy MJ, Epari DR. Mechanical tension as a driver of connective tissue growth in vitro. Med Hypotheses 2014; 83:111-5. [DOI: 10.1016/j.mehy.2014.03.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 03/27/2014] [Indexed: 10/25/2022]
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25
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Aghvami M, Barocas VH, Sander EA. Multiscale mechanical simulations of cell compacted collagen gels. J Biomech Eng 2014; 135:71004. [PMID: 23720151 DOI: 10.1115/1.4024460] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 05/08/2013] [Indexed: 01/17/2023]
Abstract
Engineered tissues are commonly stretched or compressed (i.e., conditioned) during culture to stimulate extracellular matrix (ECM) production and to improve the mechanical properties of the growing construct. The relationships between mechanical stimulation and ECM remodeling, however, are complex, interdependent, and dynamic. Thus, theoretical models are required for understanding the underlying phenomena so that the conditioning process can be optimized to produce functional engineered tissues. Here, we continue our development of multiscale mechanical models by simulating the effect of cell tractions on developing isometric tension and redistributing forces in the surrounding fibers of a collagen gel embedded with explants. The model predicted patterns of fiber reorganization that were similar to those observed experimentally. Furthermore, the inclusion of cell compaction also changed the distribution of fiber strains in the gel compared to the acellular case, particularly in the regions around the cells where the highest strains were found.
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Affiliation(s)
- Maziar Aghvami
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
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van Loosdregt IAEW, Argento G, Driessen-Mol A, Oomens CWJ, Baaijens FPT. Cell-mediated retraction versus hemodynamic loading - A delicate balance in tissue-engineered heart valves. J Biomech 2013; 47:2064-9. [PMID: 24268314 DOI: 10.1016/j.jbiomech.2013.10.049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 10/29/2013] [Accepted: 10/31/2013] [Indexed: 02/05/2023]
Abstract
Preclinical studies of tissue-engineered heart valves (TEHVs) showed retraction of the heart valve leaflets as major failure of function mechanism. This retraction is caused by both passive and active cell stress and passive matrix stress. Cell-mediated retraction induces leaflet shortening that may be counteracted by the hemodynamic loading of the leaflets during diastole. To get insight into this stress balance, the amount and duration of stress generation in engineered heart valve tissue and the stress imposed by physiological hemodynamic loading are quantified via an experimental and a computational approach, respectively. Stress generation by cells was measured using an earlier described in vitro model system, mimicking the culture process of TEHVs. The stress imposed by the blood pressure during diastole on a valve leaflet was determined using finite element modeling. Results show that for both pulmonary and systemic pressure, the stress imposed on the TEHV leaflets is comparable to the stress generated in the leaflets. As the stresses are of similar magnitude, it is likely that the imposed stress cannot counteract the generated stress, in particular when taking into account that hemodynamic loading is only imposed during diastole. This study provides a rational explanation for the retraction found in preclinical studies of TEHVs and represents an important step towards understanding the retraction process seen in TEHVs by a combined experimental and computational approach.
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Affiliation(s)
- Inge A E W van Loosdregt
- Soft Tissue Biomechanics and Engineering, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - Giulia Argento
- Soft Tissue Biomechanics and Engineering, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Anita Driessen-Mol
- Soft Tissue Biomechanics and Engineering, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Cees W J Oomens
- Soft Tissue Biomechanics and Engineering, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Frank P T Baaijens
- Soft Tissue Biomechanics and Engineering, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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27
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Kural MH, Billiar KL. Regulating tension in three-dimensional culture environments. Exp Cell Res 2013; 319:2447-59. [PMID: 23850829 DOI: 10.1016/j.yexcr.2013.06.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/21/2013] [Accepted: 06/25/2013] [Indexed: 01/13/2023]
Abstract
The processes of development, repair, and remodeling of virtually all tissues and organs, are dependent upon mechanical signals including external loading, cell-generated tension, and tissue stiffness. Over the past few decades, much has been learned about mechanotransduction pathways in specialized two-dimensional culture systems; however, it has also become clear that cells behave very differently in two- and three-dimensional (3D) environments. Three-dimensional in vitro models bring the ability to simulate the in vivo matrix environment and the complexity of cell-matrix interactions together. In this review, we describe the role of tension in regulating cell behavior in three-dimensional collagen and fibrin matrices with a focus on the effective use of global boundary conditions to modulate the tension generated by populations of cells acting in concert. The ability to control and measure the tension in these 3D culture systems has the potential to increase our understanding of mechanobiology and facilitate development of new ways to treat diseased tissues and to direct cell fate in regenerative medicine and tissue engineering applications.
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Affiliation(s)
- Mehmet Hamdi Kural
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA
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28
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van Vlimmeren MA, Driessen-Mol A, Oomens CW, Baaijens FP. The Potential of Prolonged Tissue Culture to Reduce Stress Generation and Retraction in Engineered Heart Valve Tissues. Tissue Eng Part C Methods 2013; 19:205-15. [DOI: 10.1089/ten.tec.2012.0100] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
| | - Anita Driessen-Mol
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Cees W.J. Oomens
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Frank P.T. Baaijens
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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29
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Strain-induced Collagen Organization at the Micro-level in Fibrin-based Engineered Tissue Constructs. Ann Biomed Eng 2012. [DOI: 10.1007/s10439-012-0704-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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30
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Richards JM, Farrar EJ, Kornreich BG, Moïse NS, Butcher JT. The mechanobiology of mitral valve function, degeneration, and repair. J Vet Cardiol 2012; 14:47-58. [PMID: 22366572 PMCID: PMC3586284 DOI: 10.1016/j.jvc.2012.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 12/24/2011] [Accepted: 01/17/2012] [Indexed: 12/28/2022]
Abstract
In degenerative valve disease, the highly organized mitral valve leaflet matrix stratification is progressively destroyed and replaced with proteoglycan rich, mechanically inadequate tissue. This is driven by the actions of originally quiescent valve interstitial cells that become active contractile and migratory myofibroblasts. While treatment for myxomatous mitral valve disease in humans ranges from repair to total replacement, therapies in dogs focus on treating the consequences of the resulting mitral regurgitation. The fundamental gap in our understanding is how the resident valve cells respond to altered mechanical signals to drive tissue remodeling. Despite the pathological similarities and high clinical occurrence, surprisingly little mechanistic insight has been gleaned from the dog. This review presents what is known about mitral valve mechanobiology from clinical, in vivo, and in vitro data. There are a number of experimental strategies already available to pursue this significant opportunity, but success requires the collaboration between veterinary clinicians, scientists, and engineers.
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Affiliation(s)
| | - Emily J. Farrar
- Department of Biomedical Engineering, Cornell University, Ithaca NY, USA
| | - Bruce G. Kornreich
- Department of Clinical Sciences, Section of Cardiology, College of Veterinary Medicine, Cornell University, Ithaca NY, USA
| | - N. Sydney Moïse
- Department of Clinical Sciences, Section of Cardiology, College of Veterinary Medicine, Cornell University, Ithaca NY, USA
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31
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Effects of Diabetes on Matrix Protein Expression and Response to Cyclic Strain by Cardiac Fibroblasts. Cell Mol Bioeng 2012. [DOI: 10.1007/s12195-012-0222-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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32
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van Vlimmeren MAA, Driessen-Mol A, Oomens CWJ, Baaijens FPT. Passive and active contributions to generated force and retraction in heart valve tissue engineering. Biomech Model Mechanobiol 2012; 11:1015-27. [PMID: 22246054 DOI: 10.1007/s10237-011-0370-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 12/27/2011] [Indexed: 01/13/2023]
Abstract
In tissue engineered heart valves, cell-mediated stress development during culture results in leaflet retraction at time of implantation. This tissue retraction is partly active due to traction forces exerted by the cells and partly passive due to release of residual stress in the extracellular matrix and the cells. Within this study, we unraveled the passive and active contributions of cells and matrix to generated force and retraction in engineered heart valve tissues. Tissue engineered rectangular strips, fabricated from PGA/P4HB scaffolds and seeded with human myofibroblasts, were cultured for 4 weeks, after which the cellular contribution was changed at different levels. Elimination of the active cellular traction forces was achieved with Cytochalasin D and inhibition of the Rho-associated kinase pathway. Both active and passive cellular contributions were eliminated by lysation and/or decellularization of the tissue. Maximum cell activity was reached by increasing the fetal bovine serum concentration to 50%. The generated force decreased ~20% after elimination of the active cellular component, ~25% when the passive cellular component was removed as well and remained unaffected by increased serum concentrations. Passive retraction accounted for ~60% of total retraction, of which ~15% was residual stress in the matrix and ~45% was passive cell retraction. Cell traction forces accounted for the remainder ~40% of the retraction. Full activation of the cells increased retraction by ~45%. These results illustrate the importance of the cells in the process of tissue retraction, not only actively retracting the tissue, but also in a passive manner to a large extent.
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Affiliation(s)
- Marijke A A van Vlimmeren
- Department of Biomedical Engineering, WH4.12, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands.
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33
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Paxton JZ, Hagerty P, Andrick JJ, Baar K. Optimizing an intermittent stretch paradigm using ERK1/2 phosphorylation results in increased collagen synthesis in engineered ligaments. Tissue Eng Part A 2011; 18:277-84. [PMID: 21902469 DOI: 10.1089/ten.tea.2011.0336] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Dynamic mechanical input is believed to play a critical role in the development of functional musculoskeletal tissues. To study this phenomenon, cyclic uniaxial mechanical stretch was applied to engineered ligaments using a custom-built bioreactor and the effects of different stretch frequency, amplitude, and duration were determined. Stretch acutely increased the phosphorylation of p38 (3.5±0.74-fold), S6K1 (3.9±0.19-fold), and ERK1/2 (2.45±0.32-fold). The phosphorylation of ERK1/2 was dependent on time, rather than on frequency or amplitude, within these constructs. ERK1/2 phosphorylation was similar following stretch at frequencies from 0.1 to 1 Hz and amplitudes from 2.5% to 15%, whereas phosphorylation reached maximal levels at 10 min of stretch and returned toward basal within 60 min of stretch. Following a single 10-min bout of cyclic stretch, the cells remained refractory to a second stretch for up to 6 h. Using the phosphorylation of ERK1/2 as a guide, the optimum stretch paradigm was hypothesized to be 10 min of stretch at 2.5% of resting length repeated every 6 h. Consistent with this hypothesis, 7 days of stretch using this optimized intermittent stretch program increased the collagen content of the grafts more than a continuous stretch program (CTL=3.1%±0.44%; CONT=4.8%±0.30%; and INT=5.9%±0.56%). These results suggest that short infrequent bouts of loading are optimal for improving engineered tendon and ligament physiology.
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Affiliation(s)
- Jennifer Z Paxton
- Division of Molecular Physiology, University of Dundee, Dundee, Scotland
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34
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van Vlimmeren MAA, Driessen-Mol A, Oomens CWJ, Baaijens FPT. An in vitro model system to quantify stress generation, compaction, and retraction in engineered heart valve tissue. Tissue Eng Part C Methods 2011; 17:983-91. [PMID: 21609192 DOI: 10.1089/ten.tec.2011.0070] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Autologous heart valve tissue engineering relies on extracellular matrix production by cells seeded into a degrading scaffold material. The cells naturally exert traction forces to their surroundings, and due to an imbalance between scaffold, tissue, and these traction forces, stress is generated within the tissue. This stress results in compaction during culture and retraction of the leaflets at release of constraints, causing shape loss of the heart valve leaflets. In the present study, an in vitro model system has been developed to quantify stress generation, compaction, and retraction during culture and after release of constraints. Tissue-engineered (TE) constructs based on polyglycolic acid/poly-4-hydroxybutyrate scaffolds seeded with human vascular-derived cells were cultured for 4 weeks. Compaction in width was measured during culture, stress generation was measured during culture and after release of constraints at week 4, and contraction was measured after release of constraints at week 4. Both compaction and stress generation started after 2 weeks of culture and continued up to week 4. TE constructs compacted up to half of their original width and reached an internal stress of 6-8 kPa at week 4, which resulted in a retraction of 36%. The model system has provided a useful tool to unravel and optimize the balance between the different aspects of TE constructs to develop functional TE leaflets.
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Affiliation(s)
- Marijke A A van Vlimmeren
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
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35
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Kroon M. Modeling of fibroblast-controlled strengthening and remodeling of uniaxially constrained collagen gels. J Biomech Eng 2010; 132:111008. [PMID: 21034149 DOI: 10.1115/1.4002666] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A theoretical model for the remodeling of collagen gels is proposed. The collagen fabric is modeled as a network of collagen fibers, which in turn are composed of collagen fibrils. In the model, the strengthening of collagen fabric is accomplished by fibroblasts, which continuously recruit and attach more collagen fibrils to existing collagen fibers. The fibroblasts also accomplish a reorientation of collagen fibers. Fibroblasts are assumed to reorient collagen fibers toward the direction of maximum material stiffness. The proposed model is applied to experiments in which fibroblasts were inserted into a collagen gel. The model is able to predict the force-strain curves for the experimental collagen gels, and the final distribution of collagen fibers also agrees qualitatively with the experiments.
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Affiliation(s)
- Martin Kroon
- Department of Solid Mechanics, Royal Institute of Technology, Stockholm, Sweden.
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36
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Sander EA, Barocas VH, Tranquillo RT. Initial fiber alignment pattern alters extracellular matrix synthesis in fibroblast-populated fibrin gel cruciforms and correlates with predicted tension. Ann Biomed Eng 2010; 39:714-29. [PMID: 21046467 DOI: 10.1007/s10439-010-0192-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 10/13/2010] [Indexed: 11/25/2022]
Abstract
Human dermal fibroblasts entrapped in fibrin gels cast in cross-shaped (cruciform) geometries with 1:1 and 1:0.5 ratios of arm widths were studied to assess whether tension and alignment of the cells and fibrils affected ECM deposition. The cruciforms of contrasting geometry (symmetric vs. asymmetric), which developed different fiber alignment patterns, were harvested at 2, 5, and 10 weeks of culture. Cruciforms were subjected to planar biaxial testing, polarimetric imaging, DNA and biochemical analyses, histological staining, and SEM imaging. As the cruciforms compacted and developed fiber alignment, fibrin was degraded, and elastin and collagen were produced in a geometry-dependent manner. Using a continuum mechanical model that accounts for direction-dependent stress due to cell traction forces and cell contact guidance with aligned fibers that occurs in the cruciforms, the mechanical stress environment was concluded to influence collagen deposition, with deposition being the greatest in the narrow arms of the asymmetric cruciform where stress was predicted to be the largest.
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Affiliation(s)
- E A Sander
- Department of Biomedical Engineering, University of Minnesota, 312 Church St. SE, Minneapolis, MN 55455, USA.
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37
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On the correlation between continuum mechanics entities and cell activity in biological soft tissues: Assessment of three possible criteria for cell-controlled fibre reorientation in collagen gels and collagenous tissues. J Theor Biol 2010; 264:66-76. [DOI: 10.1016/j.jtbi.2009.12.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 12/22/2009] [Accepted: 12/24/2009] [Indexed: 11/17/2022]
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38
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Applying controlled non-uniform deformation for in vitro studies of cell mechanobiology. Biomech Model Mechanobiol 2010; 9:329-44. [PMID: 20169395 DOI: 10.1007/s10237-009-0179-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 11/05/2009] [Indexed: 10/19/2022]
Abstract
Cells within connective tissues routinely experience a wide range of non-uniform mechanical loads that regulate many cell behaviors. In this study, we developed an experimental system to produce complex strain patterns for the study of strain magnitude, anisotropy, and gradient effects on cells in culture. A standard equibiaxial cell stretching system was modified by affixing glass coverslips (5, 10, or 15 mm diameter) to the center of 35 mm diameter flexible-bottomed culture wells. Ring inserts were utilized to limit applied strain to different levels in each individual well at a given vacuum pressure thus enabling parallel experiments at different strain levels. Deformation fields were measured using high-density mapping for up to 6% applied strain. The addition of the rigid inclusion creates strong circumferential and radial strain gradients, with a continuous range of stretch anisotropy ranging from strip biaxial to equibiaxial strain and radial strains up to 24% near the inclusion. Dermal fibroblasts seeded within our 2D system (5 mm inclusions; 2% applied strain for 2 days at 0.2 Hz) demonstrated the characteristic orientation perpendicular to the direction of principal strain. Dermal fibroblasts seeded within fibrin gels (5 mm inclusions; 6% applied strain for 8 days at 0.2 Hz) oriented themselves similarly and compacted their surrounding matrix to an increasing extent with local strain magnitude. This study verifies how inhomogeneous strain fields can be produced in a tunable and simply constructed system and demonstrates the potential utility for studying gradients with a continuous spectrum of strain magnitudes and anisotropies.
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39
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Chan MWC, Hinz B, McCulloch CA. Mechanical induction of gene expression in connective tissue cells. Methods Cell Biol 2010; 98:178-205. [PMID: 20816235 DOI: 10.1016/s0091-679x(10)98008-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The extracellular matrices of mammals undergo coordinated synthesis and degradation, dynamic remodeling processes that enable tissue adaptations to a broad range of environmental factors, including applied mechanical forces. The soft and mineralized connective tissues of mammals also exhibit a wide repertoire of mechanical properties, which enable their tissue-specific functions and modulate cellular responses to forces. The expression of genes in response to applied forces are important for maintaining the support, attachment, and function of various organs including kidney, heart, liver, lung, joint, and periodontium. Several high-prevalence diseases of extracellular matrices including arthritis, heart failure, and periodontal diseases involve pathological levels of mechanical forces that impact the gene expression repertoires and function of bone, cartilage, and soft connective tissues. Recent work on the application of mechanical forces to cultured connective tissue cells and various in vivo force models have enabled study of the regulatory networks that control mechanically induced gene expression in connective tissue cells. In addition to the influence of mechanical forces on the expression of type 1 collagen, which is the most abundant protein of mammals, new work has shown that the expression of a wide range of matrix, signaling, and cytoskeletal proteins are regulated by exogenous mechanical forces and by the forces generated by cells themselves. In this chapter, we first discuss the fundamental nature of the extracellular matrix in health and the impact of mechanical forces. Next we consider the utilization of several, widely employed model systems for mechanical stimulation of cells. Finally, we consider in detail how application of tensile forces to cultured cardiac fibroblasts can be used for the characterization of the signaling systems by which mechanical forces regulate myofibroblast differentiation that is seen in cardiac pressure overload.
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Affiliation(s)
- Matthew W C Chan
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Fitzgerald Building, Toronto, ON, Canada M5S 3E2
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40
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Tang D, Yang C, Kobayashi S, Zheng J, Woodard PK, Teng Z, Billiar K, Bach R, Ku DN. 3D MRI-based anisotropic FSI models with cyclic bending for human coronary atherosclerotic plaque mechanical analysis. J Biomech Eng 2009; 131:061010. [PMID: 19449964 DOI: 10.1115/1.3127253] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Heart attack and stroke are often caused by atherosclerotic plaque rupture, which happens without warning most of the time. Magnetic resonance imaging (MRI)-based atherosclerotic plaque models with fluid-structure interactions (FSIs) have been introduced to perform flow and stress/strain analysis and identify possible mechanical and morphological indices for accurate plaque vulnerability assessment. For coronary arteries, cyclic bending associated with heart motion and anisotropy of the vessel walls may have significant influence on flow and stress/strain distributions in the plaque. FSI models with cyclic bending and anisotropic vessel properties for coronary plaques are lacking in the current literature. In this paper, cyclic bending and anisotropic vessel properties were added to 3D FSI coronary plaque models so that the models would be more realistic for more accurate computational flow and stress/strain predictions. Six computational models using one ex vivo MRI human coronary plaque specimen data were constructed to assess the effects of cyclic bending, anisotropic vessel properties, pulsating pressure, plaque structure, and axial stretch on plaque stress/strain distributions. Our results indicate that cyclic bending and anisotropic properties may cause 50-800% increase in maximum principal stress (Stress-P1) values at selected locations. The stress increase varies with location and is higher when bending is coupled with axial stretch, nonsmooth plaque structure, and resonant pressure conditions (zero phase angle shift). Effects of cyclic bending on flow behaviors are more modest (9.8% decrease in maximum velocity, 2.5% decrease in flow rate, 15% increase in maximum flow shear stress). Inclusion of cyclic bending, anisotropic vessel material properties, accurate plaque structure, and axial stretch in computational FSI models should lead to a considerable improvement of accuracy of computational stress/strain predictions for coronary plaque vulnerability assessment. Further studies incorporating additional mechanical property data and in vivo MRI data are needed to obtain more complete and accurate knowledge about flow and stress/strain behaviors in coronary plaques and to identify critical indicators for better plaque assessment and possible rupture predictions.
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Affiliation(s)
- Dalin Tang
- Department of Mathematical Sciences, Worcester Polytechnic Institute, Worcester, MA 01609, USA.
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41
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Yang C, Bach RG, Zheng J, Naqa IE, Woodard PK, Teng Z, Billiar K, Tang D. In vivo IVUS-based 3-D fluid-structure interaction models with cyclic bending and anisotropic vessel properties for human atherosclerotic coronary plaque mechanical analysis. IEEE Trans Biomed Eng 2009; 56:2420-8. [PMID: 19567341 DOI: 10.1109/tbme.2009.2025658] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this paper, a modeling approach combining in vivo intravascular ultrasound (IVUS) imaging, computational modeling, angiography, and mechanical testing is proposed to perform mechanical analysis for human coronary atherosclerotic plaques for potential more accurate plaque vulnerability assessment. A 44-slice in vivo IVUS dataset of a coronary plaque was acquired from one patient, and four 3-D models with fluid-structure interactions (FSIs) based on the data were constructed to quantify effects of anisotropic vessel properties and cyclic bending of the coronary plaque on flow and plaque stress/strain conditions. Compared to the isotropic model (model 1, no bending, no axial stretch), maximum stress- P(1) (maximum principal stress) values on the cut surface with maximum bending (where applicable) from model 2 (anisotropic, no bending, no stretch), model 3 (anisotropic, with bending, no stretch), and model 4 (anisotropic with bending and stretch) were, respectively, 63%, 126%, and 345% higher than that from model 1. Effects of cyclic bending on flow behaviors were modest (5%-15%). Our preliminary results indicated that in vivo IVUS-based FSI models with cyclic bending and anisotropic material properties could improve the accuracies of plaque stress/strain predictions and plaque vulnerability assessment. Large-scale patient studies are needed to further validate our findings.
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Affiliation(s)
- Chun Yang
- School of Mathematics, Beijing Normal University, Beijing 100875, China.
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