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Dwyer KD, Coulombe KL. Cardiac mechanostructure: Using mechanics and anisotropy as inspiration for developing epicardial therapies in treating myocardial infarction. Bioact Mater 2021; 6:2198-2220. [PMID: 33553810 PMCID: PMC7822956 DOI: 10.1016/j.bioactmat.2020.12.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 12/14/2022] Open
Abstract
The mechanical environment and anisotropic structure of the heart modulate cardiac function at the cellular, tissue and organ levels. During myocardial infarction (MI) and subsequent healing, however, this landscape changes significantly. In order to engineer cardiac biomaterials with the appropriate properties to enhance function after MI, the changes in the myocardium induced by MI must be clearly identified. In this review, we focus on the mechanical and structural properties of the healthy and infarcted myocardium in order to gain insight about the environment in which biomaterial-based cardiac therapies are expected to perform and the functional deficiencies caused by MI that the therapy must address. From this understanding, we discuss epicardial therapies for MI inspired by the mechanics and anisotropy of the heart focusing on passive devices, which feature a biomaterials approach, and active devices, which feature robotic and cellular components. Through this review, a detailed analysis is provided in order to inspire further development and translation of epicardial therapies for MI.
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Affiliation(s)
- Kiera D. Dwyer
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA
| | - Kareen L.K. Coulombe
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA
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2
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He H, Zhou R, Zou Y, Huang X, Li J. A Comprehensive Method for Accurate Strain Distribution Measurement of Cell Substrate Subjected to Large Deformation. JOURNAL OF HEALTHCARE ENGINEERING 2018; 2018:8504273. [PMID: 29599957 PMCID: PMC5823413 DOI: 10.1155/2018/8504273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/11/2017] [Accepted: 10/23/2017] [Indexed: 11/21/2022]
Abstract
Cell mechanical stretching in vitro is a fundamental technique commonly used in cardiovascular mechanobiology research. Accordingly, it is crucial to measure the accurate strain field of cell substrate under different strains. Digital image correlation (DIC) is a widely used measurement technique, which is able to obtain the accurate displacement and strain distribution. However, the traditional DIC algorithm used in digital image correlation engine (DICe) cannot obtain accurate result when utilized in large strain measurement. In this paper, an improved method aiming to acquire accurate strain distribution of substrate in large deformation was proposed, to evaluate the effect and accuracy, based on numerical experiments. The results showed that this method was effective and highly accurate. Then, we carried out uniaxial substrate stretching experiments and applied our method to measure strain distribution of the substrate. The proposed method could obtain accurate strain distribution of substrate film during large stretching, which would allow researchers to adequately describe the response of cells to different strains of substrate.
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Affiliation(s)
- Hong He
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Rong Zhou
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Yuanwen Zou
- College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China
| | - Xuejin Huang
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China
| | - Jinchuan Li
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China
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Yang H, Schmidt LP, Wang Z, Yang X, Shao Y, Borg TK, Markwald R, Runyan R, Gao BZ. Dynamic Myofibrillar Remodeling in Live Cardiomyocytes under Static Stretch. Sci Rep 2016; 6:20674. [PMID: 26861590 PMCID: PMC4748238 DOI: 10.1038/srep20674] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/11/2016] [Indexed: 12/21/2022] Open
Abstract
An increase in mechanical load in the heart causes cardiac hypertrophy, either physiologically (heart development, exercise and pregnancy) or pathologically (high blood pressure and heart-valve regurgitation). Understanding cardiac hypertrophy is critical to comprehending the mechanisms of heart development and treatment of heart disease. However, the major molecular event that occurs during physiological or pathological hypertrophy is the dynamic process of sarcomeric addition, and it has not been observed. In this study, a custom-built second harmonic generation (SHG) confocal microscope was used to study dynamic sarcomeric addition in single neonatal CMs in a 3D culture system under acute, uniaxial, static, sustained stretch. Here we report, for the first time, live-cell observations of various modes of dynamic sarcomeric addition (and how these real-time images compare to static images from hypertrophic hearts reported in the literature): 1) Insertion in the mid-region or addition at the end of a myofibril; 2) Sequential addition with an existing myofibril as a template; and 3) Longitudinal splitting of an existing myofibril. The 3D cell culture system developed on a deformable substrate affixed to a stretcher and the SHG live-cell imaging technique are unique tools for real-time analysis of cultured models of hypertrophy.
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Affiliation(s)
- Huaxiao Yang
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - Lucas P Schmidt
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - Zhonghai Wang
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - Xiaoqi Yang
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - Yonghong Shao
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Thomas K Borg
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA
| | - Roger Markwald
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA
| | - Raymond Runyan
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Bruce Z Gao
- Department of Bioengineering, Clemson University, Clemson, SC, USA
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Stoppel WL, Kaplan DL, Black LD. Electrical and mechanical stimulation of cardiac cells and tissue constructs. Adv Drug Deliv Rev 2016; 96:135-55. [PMID: 26232525 DOI: 10.1016/j.addr.2015.07.009] [Citation(s) in RCA: 157] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 07/16/2015] [Accepted: 07/25/2015] [Indexed: 12/19/2022]
Abstract
The field of cardiac tissue engineering has made significant strides over the last few decades, highlighted by the development of human cell derived constructs that have shown increasing functional maturity over time, particularly using bioreactor systems to stimulate the constructs. However, the functionality of these tissues is still unable to match that of native cardiac tissue and many of the stem-cell derived cardiomyocytes display an immature, fetal like phenotype. In this review, we seek to elucidate the biological underpinnings of both mechanical and electrical signaling, as identified via studies related to cardiac development and those related to an evaluation of cardiac disease progression. Next, we review the different types of bioreactors developed to individually deliver electrical and mechanical stimulation to cardiomyocytes in vitro in both two and three-dimensional tissue platforms. Reactors and culture conditions that promote functional cardiomyogenesis in vitro are also highlighted. We then cover the more recent work in the development of bioreactors that combine electrical and mechanical stimulation in order to mimic the complex signaling environment present in vivo. We conclude by offering our impressions on the important next steps for physiologically relevant mechanical and electrical stimulation of cardiac cells and engineered tissue in vitro.
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Bullard TA, Hastings JL, Davis JM, Borg TK, Price RL. Altered PKC expression and phosphorylation in response to the nature, direction, and magnitude of mechanical stretch. Can J Physiol Pharmacol 2007; 85:243-50. [PMID: 17487266 DOI: 10.1139/y07-023] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Protein kinase C (PKC) isozymes have been shown to play a role in mechanotransduction in a variety of cell types. We sought to identify the PKC isozymes involved in transducing mechanical (cyclic vs. static), direction and intensity of stretch by examining changes in protein expression and phosphorylation. We used a 3-dimensional culture system with aligned neonatal rat cardiac myocytes on silastic membranes. Myocytes were subjected to either cyclic stretch at 5 cycles/min or static stretch for a period of 24 h at intensities of 0%, 2.5%, 5%, or 10% of full membrane length. Stretch was applied in perpendicular or parallel directions to myocyte alignment. PKC delta was most sensitive to stretch applied perpendicular to myocyte alignment regardless of the nature of stretch, while phospho PKC delta T505 increased in response to static-perpendicular stretch. PKC epsilon expression was altered by cyclic stretch but not static stretch, while phospho PKC epsilon S719 remained unchanged. PKC alpha expression was not altered by stretch; however, phospho PKC alpha S657 increased in a dose-dependent manner following cyclic-perpendicular stretch. Our results indicate that changes in PKC expression and phosphorylation state may be a mechanism for cardiac myocytes to discriminate between the nature, direction, and intensity of mechanical stretch.
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Affiliation(s)
- Tara A Bullard
- Department of Cell and Developmental Biology and Anatomy, University of South Carolina, School of Medicine, 6439 Garners Ferry Road, Columbia, SC 29209, USA.
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Li H, Cook JD, Terry M, Spitzer NC, Ferrari MB. Calcium transients regulate patterned actin assembly during myofibrillogenesis. Dev Dyn 2004; 229:231-42. [PMID: 14745949 DOI: 10.1002/dvdy.10428] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The highly ordered arrangement of sarcomeric myosin during striated muscle development requires spontaneous calcium (Ca(2+)) transients. Here, we show that blocking transients also compromises patterned assembly of actin thin filaments, titin, and capZ. Because a conserved temporal assembly pattern has been described for these proteins, selective inhibitors of either thick or thin filament formation were used to determine their relative temporal interdependencies. For example, inhibition of myosin light chain kinase (MLCK) by application of a specific inhibitory peptide or phorbol myistate acetate (PMA) disrupts myosin assembly without significantly affecting formation of actin bands. The MLCK inhibitor ML-7, however, disrupted actin as well as myosin. Surprisingly, agents that interfere with actin dynamics, such as cytochalasin D, produced only minor organizational disruptions in actin, capZ, and titin staining. However, cytochalasin D and other actin disrupting compounds significantly perturbed myosin organization. The results indicate that (1) Ca(2+) transients regulate one or more of the earliest steps in sarcomere formation, (2) mature actin filaments can assemble independently of myosin band formation, and (3) myosin thick filament assembly is extremely sensitive to disruption of either the actin or titin filament systems.
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Affiliation(s)
- Hongyan Li
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, USA
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Gopalan SM, Flaim C, Bhatia SN, Hoshijima M, Knoell R, Chien KR, Omens JH, McCulloch AD. Anisotropic stretch-induced hypertrophy in neonatal ventricular myocytes micropatterned on deformable elastomers. Biotechnol Bioeng 2003; 81:578-87. [PMID: 12514807 DOI: 10.1002/bit.10506] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Because cell shape and alignment, cell-matrix adhesion, and cell-cell contact can all affect growth, and because mechanical strains in vivo are multiaxial and anisotropic, we developed an in vitro system for engineering aligned, rod-shaped, neonatal cardiac myocyte cultures. Photolithographic and microfluidic techniques were used to micropattern extracellular matrices in parallel lines on deformable silicone elastomers. Confluent, elongated, aligned myocytes were produced by varying the micropattern line width and collagen density. An elliptical cell stretcher applied 2:1 anisotropic strain statically to the elastic substrate, with the axis of greatest stretch (10%) either parallel or transverse to the myofibrils. After 24 h, the principal strain parallel to myocytes did not significantly alter myofibril accumulation or expression of atrial natriuretic factor (ANF), connexin-43 (Cx-43), or N-cadherin (by indirect immunofluorescent antibody labeling and immunoblotting) compared with unstretched controls. In contrast, 10% transverse principal strain resulted in continuous staining of actin filaments (rhodamine phalloidin); increased immunofluorescent labeling of ANF, Cx-43, and N-cadherin; and upregulation of protein signal intensity by western blotting. By using microfabrication and microfluidics to control cell shape and alignment on an elastic substrate, we found greater effects for transverse than for longitudinal stretch in regulating sarcomere organization, hypertrophy, and cell-to-cell junctions.
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Affiliation(s)
- Sindhu M Gopalan
- Department of Bioengineering, Whitaker Institute for Biomedical Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0412, USA
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Martineau LC, Gardiner PF. Skeletal muscle is sensitive to the tension-time integral but not to the rate of change of tension, as assessed by mechanically induced signaling. J Biomech 2002; 35:657-63. [PMID: 11955505 DOI: 10.1016/s0021-9290(01)00249-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mechanical forces regulate many cellular processes. Mechanotransduction, however, is poorly understood. In skeletal muscle, mechanical forces have a major impact on the regulation of cellular volume, yet the nature of the mechanical stimulation to which muscle is most sensitive is unknown. It was recently demonstrated that activation of the mechanically-sensitive kinase p54 jun-N-terminal-kinase (JNK), is a quantitative marker of mechanical stimulation in skeletal muscle. This marker was shown to be more sensitive to peak tension than to other tension-related parameters such as the tension-time integral (TTI) and the rate of change of tension (dT/dt). The purpose of the present study was to parcel out the contribution of TTI and dT/dt to mechanical stimulation of muscle under conditions of constant peak tension. The rat medial gastrocnemius in situ was subjected to one of four 5-min passive stretch protocols consisting of equal length excursions, but differing in displacement-time integral (4%, 40%, or 100%) and/or rate of stretch (0, 3, or 30 mm/s), and the resulting p54-JNK phosphorylation was assessed. A linear relationship between TTI and p54-JNK signaling was observed. However, no effect of dT/dt was observed. It is concluded that peak tension and TTI are necessary parameters for modeling the mechanical stimulus-response of muscle. Additionally, the mechanism of mechanotransduction is sensitive to peak tension and TTI, but not to dT/dt, and thus exhibits spring-like behavior. These findings may contribute to the refinement of disuse atrophy countermeasures.
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Affiliation(s)
- Louis C Martineau
- Department of Kinesiology, Neuromuscular Plasticity Laboratory, Université de Montréal, P.O. Box 6128, Centre-Ville, Montreal, Quebec, Canada H3C 3J7
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Nikcevic G, Perhonen M, Boateng SY, Russell B. Translation is regulated via the 3' untranslated region of alpha-myosin heavy chain mRNA by calcium but not by its localization. J Muscle Res Cell Motil 2001; 21:599-607. [PMID: 11206137 DOI: 10.1023/a:1026507727700] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Posttranscriptional regulation plays an important role in alpha-myosin heavy chain (alpha-MyHC) protein synthesis in cardiac muscle cells. In the present study, we test the effects of calcium and mRNA mislocalization on alpha-MyHC translation in order to determine the mechanism(s) contributing to translational block via the 3' untranslated region (3'UTR). Neonatal rat cardiac myocytes were treated for 6 h with L-isoproterenol (10 microM) to enhance beating, with 10 microM verapamil to block beating and mislocalize mRNA, or with 3 microM colchicine to enhance beating but mislocalize mRNA by depolymerization of the microtubules. In order to determine whether translation is regulated by the 3'UTR, either a control (SV40 3'UTR) or the experimental (alpha-MyHC 3'UTR) was placed after a luciferase reporter gene and transfected into the myocytes. The amount of luciferase protein only decreased significantly in verapamil arrested cells transfected with the alpha-MyHC 3'UTR construct (P < 0.01). To control for the possibility that pharmacological treatments might affect transcription or message stability, we analyzed neomycin and luciferase mRNA levels transcribed from the same transfected plasmid. No significant changes were found with an RNase protection assay. These results suggest that calcium but not mRNA localization regulates protein synthesis and further, this is mediated by the 3' untranslated region of alpha-MyHC.
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Affiliation(s)
- G Nikcevic
- Department of Physiology and Biophysics, University of Illinois at Chicago, 60612-7342, USA
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Omens JH. Stress and strain as regulators of myocardial growth. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1998; 69:559-72. [PMID: 9785956 DOI: 10.1016/s0079-6107(98)00025-x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The response of the heart to altered hemodynamic loading is growth or remodeling of myocytes and the extracellular matrix. In order to describe and mathematically model this dynamic and complex system of growing and resorbing tissue, the stimulating factor for tissue growth must be found, and up to now is not known. Most evidence, both in tissue and at the cellular level, points to a mechanical factor as the stimulus, and most likely a deformation signal is transduced to initiate protein synthesis. At the cellular level mechanotransduction likely takes place at the cellular membrane, although multiple biochemical and mechanical pathways have been proposed which induce transcription in the nucleus and eventual protein upregulation. The results of a recent mathematical analysis based on experimental data suggest that end-diastolic fiber strain at the tissue level may be the stimulus to one mode of tissue growth: volume-overload hypertrophy. This is the only mechanical factor that we found to be normalized after volume overload hypertrophy. But other studies do not agree with this result, and other modes of hypertrophy may be regulated by different factors or combinations of factors.
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Affiliation(s)
- J H Omens
- Department of Medicine, University of California, San Diego, La Jolla 92093-0613, USA.
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Lee AA, McCulloch AD. Multiaxial myocardial mechanics and extracellular matrix remodeling: mechanochemical regulation of cardiac fibroblast function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 430:227-40. [PMID: 9330732 DOI: 10.1007/978-1-4615-5959-7_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Substantial evidence suggests that not only does the structure of the cardiac extracellular matrix affect the mechanical properties of myocardium, but that mechanical loading affects the synthesis of the extracellular matrix. However, loading conditions in vivo are nonhomogeneous and multiaxial. An experimental approach that combines mechanics and cell biology is used to examine the mechanisms of extracellular matrix remodeling in the heart. The results indicate that differential biological responses in adult cardiac fibroblasts can be correlated with specific physical signals, such as the magnitude and two dimensional (2D) pattern of strain. Some effects of flow-function relations are discussed.
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Affiliation(s)
- A A Lee
- Department of Bioengineering, University of California San Diego, La Jolla, USA
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Lee AA, Delhaas T, Waldman LK, MacKenna DA, Villarreal FJ, McCulloch AD. An equibiaxial strain system for cultured cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:C1400-8. [PMID: 8897847 DOI: 10.1152/ajpcell.1996.271.4.c1400] [Citation(s) in RCA: 134] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We developed a device that applies homogeneous equibiaxial strains of 0-10% to a cell culture substrate and quantitatively verified transmission of substrate deformation to cultured cardiac cells. Clamped elastic membranes in both single-well and multiwell versions of the device are uniformly stretched by indentation with a plastic ring, resulting in strain that is directly proportional to the pitch-to-radius ratio. Two-dimensional deformations were measured by tracking fluorescent microspheres attached to the substrate and to cultured adult rat cardiac fibroblasts. For nominal stretches up to 18%, strains along circumferential and radial axes were equal in magnitude and homogeneously distributed with negligible shear. For 5% stretch, circumferential and radial strains in the substrate were 0.046 +/- 0.005 and 0.048 +/- 0.004 [not significant (NS)], respectively, and shear strain was 0.001 +/- 0.003 (NS). Calibration of both single-well and multiwell versions permits strain selection by device rotation. The reproducible application and quantification of homogeneous equibiaxial strain in cultured cells provides a quantitative approach for correlating mechanical stimuli to cellular transduction mechanisms.
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Affiliation(s)
- A A Lee
- Department of Bioengineering and Medicine, University of California at San Diego, USA
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Price RL, Chintanowonges C, Shiraishi I, Borg TK, Terracio L. Local and regional variations in myofibrillar patterns in looping rat hearts. Anat Rec (Hoboken) 1996; 245:83-93. [PMID: 8731044 DOI: 10.1002/(sici)1097-0185(199605)245:1<83::aid-ar13>3.0.co;2-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND In chickens, cytodifferentiation, right side dominance in myofibril development, and variations in myofibrillar patterns in different areas and layers of the myocardial wall exist which have been implicated in the process of heart looping. Little comparable information is available for developing myofibrillar patterns in the early development of mammalian hearts. METHODS We have used transmission electron microscopy (TEM), confocal scanning laser microscopy (CSLM), and 3-D reconstruction techniques also present in the looping hearts of embryonic day (ED) 9.5 to 11.5 rat hearts. RESULTS Local and regional variations and right side dominance in myofibrillar patterns were shown during looping in 9.5 through 11.5 days of development in embryonic rat heart. At 9.5 days of development, myofibrils near the lumen of the myocardial wall were primarily in circumferential bands while near the pericardial surface they were primarily in longitudinal bands. In older embryos, regional variations in myofibrillar organization was found in areas associated with the cardiac cushions, trabeculae, and myocardial wall of the developing heart chambers. Based on sarcomeric structure, myofibrils in the ventricle and outflow tract were more advanced than those found in the atrial wall. CONCLUSIONS The local and regional patterns of myofibrils in looping rat hearts are similar to those which have been found in developing chicken hearts. This study and others indicate cytodifferentiation and development of the contractile apparatus has a crucial role in the process of heart looping.
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Affiliation(s)
- R L Price
- Department of Developmental Biology and Anatomy, School of Medicine, University of South Carolina, Columbia 29208, USA
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