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Quansah E, Shaik TA, Çevik E, Wang X, Höppener C, Meyer-Zedler T, Deckert V, Schmitt M, Popp J, Krafft C. Investigating biochemical and structural changes of glycated collagen using multimodal multiphoton imaging, Raman spectroscopy, and atomic force microscopy. Anal Bioanal Chem 2023; 415:6257-6267. [PMID: 37640827 PMCID: PMC10558391 DOI: 10.1007/s00216-023-04902-5] [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] [Received: 06/07/2023] [Revised: 07/31/2023] [Accepted: 08/03/2023] [Indexed: 08/31/2023]
Abstract
Advanced glycation end products (AGEs) form extracellular crosslinking with collagenous proteins, which contributes to the development of diabetic complications. In this study, AGEs-related pentosidine (PENT) crosslinks-induced structural and biochemical changes are studied using multimodal multiphoton imaging, Raman spectroscopy and atomic force microscopy (AFM). Decellularized equine pericardium (EP) was glycated with four ribose concentrations ranging between 5 and 200 mM and monitored for up to 30 days. Two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) microscopic imaging probed elastin and collagen fibers, respectively. The glycated EP showed a decrease in the SHG intensities associated with loss of non-centrosymmetry of collagen and an increase of TPEF intensities associated with PENT crosslinks upon glycation. TPEF signals from elastin fibers were unaffected. A three-dimensional reconstruction with SHG + TPEF z-stack images visualized the distribution of collagen and elastin within the EP volume matrix. In addition, Raman spectroscopy (RS) detected changes in collagen-related bands and discriminated glycated from untreated EP. Furthermore, AFM scans showed that the roughness increases and the D-unit structure of fibers remained unchanged during glycation. The PENT crosslinked-induced changes are discussed in the context of previous studies of glutaraldehyde- and genipin-induced crosslinking and collagenase-induced digestion of collagen. We conclude that TPEF, SHG, RS, and AFM are effective, label-free, and non-destructive methods to investigate glycated tissues, differentiate crosslinking processes, and characterize general collagen-associated and disease-related changes, in particular by their RS fingerprints.
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Affiliation(s)
- Elsie Quansah
- Institute of Physical Chemistry and Abbe Center of Photonics (IPC), Member of the Leibniz Center for Photonics in Infectious Research (LPI), Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Tanveer Ahmed Shaik
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Ecehan Çevik
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Xinyue Wang
- Institute of Physical Chemistry and Abbe Center of Photonics (IPC), Member of the Leibniz Center for Photonics in Infectious Research (LPI), Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Christiane Höppener
- Institute of Physical Chemistry and Abbe Center of Photonics (IPC), Member of the Leibniz Center for Photonics in Infectious Research (LPI), Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Tobias Meyer-Zedler
- Institute of Physical Chemistry and Abbe Center of Photonics (IPC), Member of the Leibniz Center for Photonics in Infectious Research (LPI), Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Volker Deckert
- Institute of Physical Chemistry and Abbe Center of Photonics (IPC), Member of the Leibniz Center for Photonics in Infectious Research (LPI), Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Michael Schmitt
- Institute of Physical Chemistry and Abbe Center of Photonics (IPC), Member of the Leibniz Center for Photonics in Infectious Research (LPI), Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Jürgen Popp
- Institute of Physical Chemistry and Abbe Center of Photonics (IPC), Member of the Leibniz Center for Photonics in Infectious Research (LPI), Friedrich Schiller University Jena, Helmholtzweg 4, 07743, Jena, Germany
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Christoph Krafft
- Leibniz Institute of Photonic Technology (IPHT), Member of Leibniz Health Technologies, Member of the Leibniz Center for Photonics in Infectious Research (LPI), Albert-Einstein-Straße 9, 07745, Jena, Germany.
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Song J, Kang J, Kang U, Nam HS, Kim HJ, Kim RH, Kim JW, Yoo H. SNR enhanced high-speed two-photon microscopy using a pulse picker and time gating detection. Sci Rep 2023; 13:14244. [PMID: 37648768 PMCID: PMC10468500 DOI: 10.1038/s41598-023-41270-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 08/24/2023] [Indexed: 09/01/2023] Open
Abstract
Two-photon microscopy (TPM) is an attractive biomedical imaging method due to its large penetration depth and optical sectioning capability. In particular, label-free autofluorescence imaging offers various advantages for imaging biological samples. However, relatively low intensity of autofluorescence leads to low signal-to-noise ratio (SNR), causing practical challenges for imaging biological samples. In this study, we present TPM using a pulse picker to utilize low pulse repetition rate of femtosecond pulsed laser to increase the pulse peak power of the excitation source leading to higher emission of two-photon fluorescence with the same average illumination power. Stronger autofluorescence emission allowed us to obtain higher SNR images of arterial and liver tissues. In addition, by applying the time gating detection method to the pulse signals obtained by TPM, we were able to significantly reduce the background noise of two-photon images. As a result, our TPM system using the pulsed light source with a 19 times lower repetition rate allowed us to obtain the same SNR image more than 19 times faster with the same average power. Although high pulse energy can increase the photobleaching, we also observed that high-speed imaging with low total illumination energy can mitigate the photobleaching effect to a level similar to that of conventional illumination with a high repetition rate. We anticipate that this simple approach will provide guidance for SNR enhancement with high-speed imaging in TPM as well as other nonlinear microscopy.
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Affiliation(s)
- Jeonggeun Song
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Daejeon, 34141, South Korea
| | - Juehyung Kang
- Department of Biomedical Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul, 04763, Republic of Korea
| | - Ungyo Kang
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Daejeon, 34141, South Korea
| | - Hyeong Soo Nam
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Daejeon, 34141, South Korea
| | - Hyun Jung Kim
- Cardiovascular Center, Korea University Guro Hospital, 148 Gurodong-Ro, Seoul, 08308, South Korea
| | - Ryeong Hyeon Kim
- Cardiovascular Center, Korea University Guro Hospital, 148 Gurodong-Ro, Seoul, 08308, South Korea
| | - Jin Won Kim
- Cardiovascular Center, Korea University Guro Hospital, 148 Gurodong-Ro, Seoul, 08308, South Korea
| | - Hongki Yoo
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Daejeon, 34141, South Korea.
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3
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Pukaluk A, Wolinski H, Viertler C, Regitnig P, Holzapfel GA, Sommer G. Changes in the microstructure of the human aortic adventitia under biaxial loading investigated by multi-photon microscopy. Acta Biomater 2023; 161:154-169. [PMID: 36812954 DOI: 10.1016/j.actbio.2023.02.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 02/01/2023] [Accepted: 02/17/2023] [Indexed: 02/23/2023]
Abstract
Among the three layers of the aortic wall, the media is primarily responsible for its mechanical properties, but the adventitia prevents the aorta from overstretching and rupturing. The role of the adventitia is therefore crucial with regard to aortic wall failure, and understanding the load-induced changes in tissue microstructure is of high importance. Specifically, the focus of this study is on the changes in collagen and elastin microstructure in response to macroscopic equibiaxial loading applied to the aortic adventitia. To observe these changes, multi-photon microscopy imaging and biaxial extension tests were performed simultaneously. In particular, microscopy images were recorded at 0.02 stretch intervals. The microstructural changes of collagen fiber bundles and elastin fibers were quantified with the parameters of orientation, dispersion, diameter, and waviness. The results showed that the adventitial collagen was divided from one into two fiber families under equibiaxial loading conditions. The almost diagonal orientation of the adventitial collagen fiber bundles remained unchanged, but the dispersion was substantially reduced. No clear orientation of the adventitial elastin fibers was observed at any stretch level. The waviness of the adventitial collagen fiber bundles decreased under stretch, but the adventitial elastin fibers showed no change. These original findings highlight differences between the medial and adventitial layers and provide insight into the stretching process of the aortic wall. STATEMENT OF SIGNIFICANCE: To provide accurate and reliable material models, it is essential to understand the mechanical behavior of the material and its microstructure. Such understanding can be enhanced with tracking of the microstructural changes caused by mechanical loading of the tissue. This study provides therefore a unique dataset of structural parameters of the human aortic adventitia obtained under equibiaxial loading. The structural parameters describe orientation, dispersion, diameter, and waviness of collagen fiber bundles and elastin fibers. Eventually, the microstructural changes in the human aortic adventitia are compared with the microstructural changes in the human aortic media from a previous study. This comparison reveals the cutting-edge findings on the differences in the response to the loading between these two human aortic layers.
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Affiliation(s)
- Anna Pukaluk
- Institute of Biomechanics, Graz University of Technology, Austria
| | - Heimo Wolinski
- Institute of Molecular Biosciences, University of Graz, Austria; Field of Excellence BioHealth, University of Graz, Austria
| | - Christian Viertler
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Austria
| | - Peter Regitnig
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Austria
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Austria; Department of Structural Engineering (NTNU), Trondheim, Norway
| | - Gerhard Sommer
- Institute of Biomechanics, Graz University of Technology, Austria.
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Pineda-Castillo SA, Aparicio-Ruiz S, Burns MM, Laurence DW, Bradshaw E, Gu T, Holzapfel GA, Lee CH. Linking the region-specific tissue microstructure to the biaxial mechanical properties of the porcine left anterior descending artery. Acta Biomater 2022; 150:295-309. [PMID: 35905825 PMCID: PMC10230544 DOI: 10.1016/j.actbio.2022.07.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 07/14/2022] [Accepted: 07/20/2022] [Indexed: 11/16/2022]
Abstract
Coronary atherosclerosis is the main cause of death worldwide. Advancing the understanding of coronary microstructure-based mechanics is fundamental for the development of therapeutic tools and surgical procedures. Although the passive biaxial properties of the coronary arteries have been extensively explored, their regional differences and the relationship between tissue microstructure and mechanics have not been fully characterized. In this study, we characterized the passive biaxial mechanical properties and microstructural properties of the proximal, medial, and distal regions of the porcine left anterior descending artery (LADA). We also attempted to relate the biaxial stress-stretch response of the LADA and its respective birefringent responses to the polarized light for obtaining information about the load-dependent microstructural variations. We found that the LADA extensibility is reduced in the proximal-to-distal direction and that the medial region exhibits more heterogeneous mechanical behavior than the other two regions. We have also observed highly dynamic microstructural behavior where fiber families realign themselves depending on loading. In addition, we found that the microstructure of the distal region exhibited highly aligned fibers along the longitudinal axis of the artery. To verify this microstructural feature, we imaged the LADA specimens with multi-photon microscopy and observed that the adventitia microstructure transitioned from a random fiber network in the proximal region to highly aligned fibers in the distal region. Our findings could offer new perspectives for understanding coronary mechanics and aid in the development of tissue-engineered vascular grafts, which are currently limited due to their mismatch with native tissue in terms of mechanical properties and microstructural features. STATEMENT OF SIGNIFICANCE: The tissue biomechanics of coronary arteries is fundamental for the development of revascularization techniques such as coronary artery bypass. These therapeutics require a deep understanding of arterial mechanics, microstructure, and mechanobiology to prevent graft failure and reoperation. The present study characterizes the unique regional mechanical and microstructural properties of the porcine left anterior descending artery using biaxial testing, polarized-light imaging, and confocal microscopy. This comprehensive characterization provides an improved understanding of the collagen/elastin architecture in response to mechanical loads using a region-specific approach. The unique tissue properties obtained from this study will provide guidance for the selection of anastomotic sites in coronary artery bypass grafting and for the design of tissue-engineered vascular grafts.
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Affiliation(s)
- Sergio A Pineda-Castillo
- Biomechanics and Biomaterials Design Lab, School of Aerospace and Mechanical Engineering, The University of Oklahoma, USA; Stephenson School of Biomedical Engineering, The University of Oklahoma, USA
| | - Santiago Aparicio-Ruiz
- Biomechanics and Biomaterials Design Lab, School of Aerospace and Mechanical Engineering, The University of Oklahoma, USA
| | - Madison M Burns
- Biomechanics and Biomaterials Design Lab, School of Aerospace and Mechanical Engineering, The University of Oklahoma, USA
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Lab, School of Aerospace and Mechanical Engineering, The University of Oklahoma, USA
| | - Elizabeth Bradshaw
- Biomechanics and Biomaterials Design Lab, School of Aerospace and Mechanical Engineering, The University of Oklahoma, USA
| | - Tingting Gu
- Samuel Roberts Noble Microscopy Laboratory, The University of Oklahoma, USA
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Austria; Department of Structural Engineering, Norwegian University of Science and Technology, Norway
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Lab, School of Aerospace and Mechanical Engineering, The University of Oklahoma, USA.
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5
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Niestrawska JA, Pukaluk A, Babu AR, Holzapfel GA. Differences in Collagen Fiber Diameter and Waviness between Healthy and Aneurysmal Abdominal Aortas. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-15. [PMID: 35545876 DOI: 10.1017/s1431927622000629] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Collagen plays a key role in the strength of aortic walls, so studying micro-structural changes during disease development is critical to better understand collagen reorganization. Second-harmonic generation microscopy is used to obtain images of human aortic collagen in both healthy and diseased states. Methods are being developed in order to efficiently determine the waviness, that is, tortuosity and amplitude, as well as the diameter, orientation, and dispersion of collagen fibers, and bundles in healthy and aneurysmal tissues. The results show layer-specific differences in the collagen of healthy tissues, which decrease in samples of aneurysmal aortic walls. In healthy tissues, the thick collagen bundles of the adventitia are characterized by greater waviness, both in the tortuosity and in the amplitude, compared to the relatively thin and straighter collagen fibers of the media. In contrast, most aneurysmal tissues tend to have a more uniform structure of the aortic wall with no significant difference in collagen diameter between the luminal and abluminal layers. An increase in collagen tortuosity compared to the healthy media is also observed in the aneurysmal luminal layer. The data set provided can help improve related material and multiscale models of aortic walls and aneurysm formation.
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Affiliation(s)
- Justyna A Niestrawska
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16, 8010Graz, Austria
| | - Anna Pukaluk
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16, 8010Graz, Austria
| | - Anju R Babu
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16, 8010Graz, Austria
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16, 8010Graz, Austria
- Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), 7491Trondheim, Norway
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6
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An ultrastructural 3D reconstruction method for observing the arrangement of collagen fibrils and proteoglycans in the human aortic wall under mechanical load. Acta Biomater 2022; 141:300-314. [PMID: 35065266 DOI: 10.1016/j.actbio.2022.01.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 12/31/2022]
Abstract
An insight into changes of soft biological tissue ultrastructures under loading conditions is essential to understand their response to mechanical stimuli. Therefore, this study offers an approach to investigate the arrangement of collagen fibrils and proteoglycans (PGs), which are located within the mechanically loaded aortic wall. The human aortic samples were either fixed directly with glutaraldehyde in the load-free state or subjected to a planar biaxial extension test prior to fixation. The aortic ultrastructure was recorded using electron tomography. Collagen fibrils and PGs were segmented using convolutional neural networks, particularly the ESPNet model. The 3D ultrastructural reconstructions revealed a complex organization of collagen fibrils and PGs. In particular, we observed that not all PGs are attached to the collagen fibrils, but some fill the spaces between the fibrils with a clear distance to the collagen. The complex organization cannot be fully captured or can be severely misinterpreted in 2D. The approach developed opens up practical possibilities, including the quantification of the spatial relationship between collagen fibrils and PGs as a function of the mechanical load. Such quantification can also be used to compare tissues under different conditions, e.g., healthy and diseased, to improve or develop new material models. STATEMENT OF SIGNIFICANCE: The developed approach enables the 3D reconstruction of collagen fibrils and proteoglycans as they are embedded in the loaded human aortic wall. This methodological pipeline comprises the knowledge of arterial mechanics, imaging with transmission electron microscopy and electron tomography, segmentation of 3D image data sets with convolutional neural networks and finally offers a unique insight into the ultrastructural changes in the aortic tissue caused by mechanical stimuli.
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Athaide CE, Spronck B, Au JS. Physiological basis for longitudinal motion of the arterial wall. Am J Physiol Heart Circ Physiol 2022; 322:H689-H701. [PMID: 35213244 DOI: 10.1152/ajpheart.00567.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As opposed to arterial distension in the radial plane, longitudinal wall motion (LWM) is a multiphasic and bidirectional displacement of the arterial wall in the anterograde (i.e., in the direction of blood flow) and retrograde (i.e., opposing direction of blood flow) directions. While initially disregarded as imaging artifact, LWM has been consistently reported in ultrasound investigations in the last decade and is reproducible beat-to-beat, albeit with large inter-individual variability across healthy and diseased populations. Emerging literature has sought to examine the mechanistic control of LWM to explain the shape and variability of the motion pattern but lacks considerations for key foundational vascular principles at the level of the arterial wall ultrastructure. The purpose of this review is to summarize the potential factors that underpin the causes and control of arterial LWM, spanning considerations from the arterial extracellular matrix to systems-level integrative theories. First, an overview of LWM and relevant aspects wall composition will be discussed, including major features of the multiphasic pattern, arterial wall extracellular components, tunica fiber orientations, and arterial longitudinal pre-stretch. Second, current theories on the systems-level physiological mechanisms driving LWM will be discussed in the context of available evidence including experimental human research, porcine studies, and mathematical models. Throughout, we discuss implications of these observations with suggestions for future priority research areas.
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Affiliation(s)
- Chloe E Athaide
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Bart Spronck
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Jason S Au
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
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Sherlock B, Chen J, Mansfield J, Green E, Winlove C. Biophotonic tools for probing extracellular matrix mechanics. Matrix Biol Plus 2021; 12:100093. [PMID: 34934939 PMCID: PMC8661043 DOI: 10.1016/j.mbplus.2021.100093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 11/07/2021] [Accepted: 11/11/2021] [Indexed: 12/11/2022] Open
Abstract
The complex, hierarchical and heterogeneous biomechanics of the extracellular matrix (ECM) are central to the health of multicellular organisms. Characterising the distribution, dynamics and above all else origins of ECM biomechanics are challenges that have captivated researchers for decades. Recently, a suite of biophotonics techniques have emerged as powerful new tools to investigate ECM biomechanics. In this mini-review, we discuss how the non-destructive, sub-micron resolution imaging capabilities of Raman spectroscopy and nonlinear microscopy are being used to interrogate the biomechanics of thick, living tissues. These high speed, label-free techniques are implemented during mechanical testing, providing unprecedented insight into the compositional and structural response of the ECM to changes in the mechanical environment.
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Affiliation(s)
- B.E. Sherlock
- College of Medicine and Health, University of Exeter, Exeter EX1 2LU, United Kingdom
| | - J. Chen
- College of Engineering, Mathematical and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom
| | - J.C. Mansfield
- College of Engineering, Mathematical and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom
| | - E. Green
- College of Engineering, Mathematical and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom
| | - C.P. Winlove
- College of Engineering, Mathematical and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom
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Feng Y, Wang X, Zhao Y, Li L, Niu P, Huang Y, Han Y, Tan W, Huo Y. A comparison of passive and active wall mechanics between elastic and muscular arteries of juvenile and adult rats. J Biomech 2021; 126:110642. [PMID: 34325121 DOI: 10.1016/j.jbiomech.2021.110642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 05/26/2021] [Accepted: 06/18/2021] [Indexed: 02/03/2023]
Abstract
The elastic abdominal aorta and muscular femoral artery are susceptible to aneurysm and atherosclerosis, respectively. The vessel wall mechanics should be an important element for the difference. The objective of the study is to demonstrate a comparison of vessel wall mechanics between elastic and muscular arteries of juvenile and adult rats to show the changes of mechanical properties relevant to aging. The passive and active mechanical tests, theoretical analysis, and histological evaluation were carried out to investigate mechanical properties of vessel walls in the abdominal aorta and carotid and femoral arteries of young and adult rats. There are stiffening femoral artery, unchanged carotid artery, and distensible abdominal aorta in adult rats as compared with the young. The opening angle has values of 54 ± 13°, 82 ± 13°, and 94 ± 13° in the abdominal aorta and carotid and femoral arteries of adult rats, respectively, as well as 80 ± 22°, 93 ± 19°, and 100 ± 23° in the young. The findings are explained by the significantly reduced width of collagen fibers in the abdominal aorta, relatively unchanged width in the carotid artery, and significantly increased width in the femoral artery of adult rats as compared with the young. In conjunction with available literatures, we concluded that inconsistency for nonlinear age-related changes of artery wall mechanics occurs between arteries of different types, which may be a risk factor for the occurrence of abdominal aorta aneurysm and femoral artery atherosclerosis.
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Affiliation(s)
- Yundi Feng
- PKU-HKUST Shenzhen-Hongkong Institution, Shenzhen, China
| | - Xuan Wang
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
| | - Yiyang Zhao
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
| | - Li Li
- Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
| | - Pei Niu
- PKU-HKUST Shenzhen-Hongkong Institution, Shenzhen, China
| | - Yufan Huang
- College of Medicine, Hebei University, Baoding, China
| | - Yue Han
- Institute of Mechanobiology & Medical Engineering, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
| | - Wenchang Tan
- PKU-HKUST Shenzhen-Hongkong Institution, Shenzhen, China; Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
| | - Yunlong Huo
- Institute of Mechanobiology & Medical Engineering, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
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10
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Wertheimer S, Sharabi M, Shelah O, Lesman A, Haj-Ali R. Bio-composites reinforced with unique coral collagen fibers: Towards biomimetic-based small diameter vascular grafts. J Mech Behav Biomed Mater 2021; 119:104526. [PMID: 33894525 DOI: 10.1016/j.jmbbm.2021.104526] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 03/15/2021] [Accepted: 04/09/2021] [Indexed: 01/01/2023]
Abstract
Cardiovascular Diseases (CVDs) are the leading cause of death worldwide. Approximately 31% of all global deaths are caused by CVDs, of which 42% are attributable to coronary artery disease (CAD). CAD is characterized by a narrowing of arteries that restricts the normal blood flow. Over time, surgical intervention is required in severe cases of occlusions and includes implantation of autologous vessels. Today synthetic grafts are used successfully as replacements for blood vessels with a diameter larger than 6 mm. However, they often fail as small-diameter blood vessel replacements. This study introduces a new biocomposite material system consisting of unique and long (cm-scale) collagen fibers derived from soft corals embedded within an alginate hydrogel matrix. The new biocomposite layers were used to fabricate grafts, towards developing a new class of tissue-engineered small-diameter blood vessels. These constructs consisted of both circumferentially and longitudinally oriented collagen fibers. The mechanical properties of the grafts were investigated via a new experimental setup constructed in our lab for this purpose, which applied internal pressure levels of 0-300 mmHg. Similar to native coronary arteries, the biocomposite tubes demonstrated a compliance of 4.88 ± 0.99%/100 mmHg for a physiologic pressure range of 80-120 mmHg. Furthermore, a numerical finite element simulation model is proposed to generate the overall mechanical response of the construct. It is composed of axial and circumferential fibers embedded within the continuum alginate elements. Good prediction is demonstrated when compared with the measured pressure-strain response. Moreover, we examined biocompatibility and cell growth on the collagen fibers. Fibroblast cells proliferated during the experiment that lasted for 32 days and showed aligned configuration with the collagen fiber orientation. The novelty of this study is manifested in the use of naturally derived coral-based long collagen fibers for the development of a new class of tissue-engineered grafts. The proposed novel biocomposite graft demonstrated both mechanical and biological compatibility and can be further developed for small-diameter blood-vessel replacement.
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Affiliation(s)
- Shir Wertheimer
- The Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Mirit Sharabi
- The Faculty of Engineering, Ariel University, Ariel, 407000, Israel
| | - Ortal Shelah
- The Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Ayelet Lesman
- The Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Rami Haj-Ali
- The Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel.
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11
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Giudici A, Wilkinson IB, Khir AW. Review of the Techniques Used for Investigating the Role Elastin and Collagen Play in Arterial Wall Mechanics. IEEE Rev Biomed Eng 2021; 14:256-269. [PMID: 32746366 DOI: 10.1109/rbme.2020.3005448] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The arterial wall is characterised by a complex microstructure that impacts the mechanical properties of the vascular tissue. The main components consist of collagen and elastin fibres, proteoglycans, Vascular Smooth Muscle Cells (VSMCs) and ground matrix. While VSMCs play a key role in the active mechanical response of arteries, collagen and elastin determine the passive mechanics. Several experimental methods have been designed to investigate the role of these structural proteins in determining the passive mechanics of the arterial wall. Microscopy imaging of load-free or fixed samples provides useful information on the structure-function coupling of the vascular tissue, and mechanical testing provides information on the mechanical role of collagen and elastin networks. However, when these techniques are used separately, they fail to provide a full picture of the arterial micromechanics. More recently, advances in imaging techniques have allowed combining both methods, thus dynamically imaging the sample while loaded in a pseudo-physiological way, and overcoming the limitation of using either of the two methods separately. The present review aims at describing the techniques currently available to researchers for the investigation of the arterial wall micromechanics. This review also aims to elucidate the current understanding of arterial mechanics and identify some research gaps.
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12
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Sigaeva T, Polzer S, Vitásek R, Di Martino ES. Effect of testing conditions on the mechanical response of aortic tissues from planar biaxial experiments: Loading protocol and specimen side. J Mech Behav Biomed Mater 2020; 111:103882. [DOI: 10.1016/j.jmbbm.2020.103882] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 05/22/2020] [Accepted: 05/23/2020] [Indexed: 01/15/2023]
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13
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Geith MA, Nothdurfter L, Heiml M, Agrafiotis E, Gruber M, Sommer G, Schratzenstaller TG, Holzapfel GA. Quantifying stent-induced damage in coronary arteries by investigating mechanical and structural alterations. Acta Biomater 2020; 116:285-301. [PMID: 32858190 DOI: 10.1016/j.actbio.2020.08.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/28/2020] [Accepted: 08/12/2020] [Indexed: 11/18/2022]
Abstract
Vascular damage develops with diverging severity during and after percutaneous coronary intervention with stent placement and is the prevailing stimulus for in-stent restenosis. Previous work has failed to link mechanical data obtained in a realistic in vivo or in vitro environment with data collected during imaging processes. We investigated whether specimens of porcine right coronary arteries soften when indented with a stent strut shaped structure, and if the softening results from damage mechanisms inside the fibrillar collagen structure. To simulate the multiaxial loading scenario of a stented coronary artery, we developed the testing device 'LAESIO' that can measure differences in the stress-stretch behavior of the arterial wall before and after the indentation of a strut-like stamp. The testing protocol was optimized according to preliminary experiments, more specifically equilibrium and relaxation tests. After chemical fixation of the specimens and subsequent tissue clearing, we performed three-dimensional surface and second-harmonic generation scans on the deformed specimens. We analyzed and correlated the mechanical response with structural parameters of high-affected tissue located next to the stamp indentation and low-affected tissue beyond the injured area. The results reveal that damage mechanisms, like tissue compression as well as softening, fiber dispersion, and the lesion extent, are direction-dependent, and the severity of them is linked to the strut orientation, indentation pressure, and position. The findings highlight the need for further investigations by applying the proposed methods to human coronary arteries. Additional data and insights might help to incorporate the observed damage mechanisms into material models for finite element analyses to perform more accurate simulations of stent-implantations.
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Affiliation(s)
- Markus A Geith
- Institute of Biomechanics, Graz University of Technology, Graz, Austria; Biomedical Engineering Department, King's College London, London, United Kingdom
| | | | - Manuel Heiml
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
| | | | | | - Gerhard Sommer
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
| | - Thomas G Schratzenstaller
- Medical Device Laboratory, Regensburg Center of Biomedical Engineering, Technical University of Applied Sciences Regensburg, Regensburg, Germany
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria; Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim, Norway.
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14
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Madurska MJ, Franklin C, Richmond M, Adnan SM, Stansby GP, White JM, Morrison JJ. Improving the safety of resuscitative endovascular balloon occlusion of the aorta - Compliant versus semi-compliant balloon systems. Vascular 2020; 28:612-618. [PMID: 32356682 DOI: 10.1177/1708538120922106] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVES Resuscitative endovascular balloon occlusion of the aorta is an alternative to resuscitative thoracotomy in non-compressible torso haemorrhage. Low-profile, compliant balloon catheter systems have been developed, which can be deployed without the need for fluoroscopy. However, concern exists for over inflation and aortic injury, especially as compliant balloon material can stretch reducing syringe feedback and limiting the effectiveness of a safety valve. An alternative material would be a semi-compliant balloon material, but its performance is unknown. The aim of this study was to compare the inflation characteristics of compliant versus semi-compliant balloon systems and to determine whether a pressure relief safety valve can be practically applied to a semi-compliant balloon catheter as a safety device. METHODS This was an ex vivo study using porcine segments of thoracic aorta. The study consisted of two phases. The first phase involved intermittent inflation of six compliant balloon and six semi-compliant balloon balloons until balloon or aortic rupture. In the second phase, six semi-compliant balloons with the pressure-relief valve set at 0.45 atmospheres were inflated in the aortas until the valve release, followed by injection with additional 30 mL. Data including pressure, volume, balloon working length, diameter and circumferential stretch ratio were collected. RESULTS At failure, mean balloon volume was almost double in compliant balloon group vs semi-compliant balloon group - 49.83 mL (±23.25) and 25.16 mL (±8.93), respectively (p = 0.004), with 36% increase in working length in the compliant balloon group - 81.17 mm (±19.11) vs 59.49 (±4.86) for semi-compliant balloon (p = 0.023). When plotted, the relationship pattern between volume and pressure fit a linear model for the compliant balloon, and a quadratic model for the semi-compliant balloon. Following attempted over inflation with the pressure valve, there was no change in parameters before and after attempted over inflation. CONCLUSIONS The inflation profile differs between balloon designs. In contrast to semi-compliant balloons, compliant balloons will accommodate more volume to mitigate increase in pressure. This does not completely eliminate the risk of over inflation. The inflation characteristics of the semi-compliant balloon permit pairing it with a safety valve, which could lead to a development of a safer balloon technology in the future.
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Affiliation(s)
- Marta J Madurska
- R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD, USA
| | | | - Michael Richmond
- R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD, USA
| | - Sakib M Adnan
- Department of Surgery, Albert Einstein Healthcare Network, Philadelphia, PA, USA
| | - Gerard P Stansby
- Department of Vascular Surgery, Freeman Hospital, Newcastle upon Tyne, UK
| | - Joseph M White
- Division of Vascular Surgery, The Department of Surgery at the Uniformed Services University of the Health Sciences & the Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Jonathan J Morrison
- R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD, USA
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15
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Bou Jawde S, Takahashi A, Bates JHT, Suki B. An Analytical Model for Estimating Alveolar Wall Elastic Moduli From Lung Tissue Uniaxial Stress-Strain Curves. Front Physiol 2020; 11:121. [PMID: 32158400 PMCID: PMC7052331 DOI: 10.3389/fphys.2020.00121] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 02/03/2020] [Indexed: 12/17/2022] Open
Abstract
The non-linear stress-strain behavior of uniaxially-stretched lung parenchyma is thought to be an emergent phenomenon arising from the ensemble behavior of its microscopic constituents. Such behavior includes the alignment and elongation of randomly oriented alveolar walls with initially flaccid fibers in the direction of strain. To account for the link between microscopic wall behavior and the macroscopic stress-strain curve, we developed an analytical model that represents both alignment and elongation of alveolar walls during uniaxial stretching. The model includes the kinetics and mechanical behavior of randomly oriented elastic alveolar walls that have a bending stiffness at their intersections. The alignment and stretch of the walls following incremental stretch of the tissue were determined based on energy minimization, and the total stress was obtained by differentiating the total energy density with respect to strain. The stress-strain curves predicted by the model were comparable to curves generated by a previously published numerical alveolar network model. The model was also fit to experimentally measured stress-strain curves in parenchymal strips obtained from mice with decreased lung collagen content, and from young and aged mice. This yielded estimates for the elastic modulus of an alveolar wall, which increased with age from 4.4 to 5.9 kPa (p = 0.043), and for the elastic modulus of fibers within the wall, which increased with age from 311 to 620 kPa (p = 0.001). This demonstrates the possibility of estimating alveolar wall mechanical properties in biological soft tissue from its macroscopic behavior given appropriate assumptions about tissue structure.
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Affiliation(s)
- Samer Bou Jawde
- Biomedical Engineering, Boston University, Boston, MA, United States
| | - Ayuko Takahashi
- Biomedical Engineering, Boston University, Boston, MA, United States
| | - Jason H T Bates
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, VT, United States
| | - Béla Suki
- Biomedical Engineering, Boston University, Boston, MA, United States
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16
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On the uniform stress/uniform stretch states of prestressed arteries. J Theor Biol 2020; 486:110100. [DOI: 10.1016/j.jtbi.2019.110100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 11/10/2019] [Accepted: 11/28/2019] [Indexed: 11/18/2022]
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17
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Cavinato C, Badel P, Krasny W, Avril S, Morin C. Experimental Characterization of Adventitial Collagen Fiber Kinematics Using Second-Harmonic Generation Imaging Microscopy: Similarities and Differences Across Arteries, Species and Testing Conditions. MULTI-SCALE EXTRACELLULAR MATRIX MECHANICS AND MECHANOBIOLOGY 2020. [DOI: 10.1007/978-3-030-20182-1_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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18
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Tinajero MG, Gotlieb AI. Recent Developments in Vascular Adventitial Pathobiology: The Dynamic Adventitia as a Complex Regulator of Vascular Disease. THE AMERICAN JOURNAL OF PATHOLOGY 2019; 190:520-534. [PMID: 31866347 DOI: 10.1016/j.ajpath.2019.10.021] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 12/20/2022]
Abstract
The adventitia, the outer layer of the blood vessel wall, may be the most complex layer of the wall and may be the master regulator of wall physiology and pathobiology. This review proposes a major shift in thinking to apply a functional lens to the adventitia rather than only a structural lens. Human and experimental in vivo and in vitro studies show that the adventitia is a dynamic microenvironment in which adventitial and perivascular adipose tissue cells initiate and regulate important vascular functions in disease, especially intimal hyperplasia and atherosclerosis. Although well away from the blood-wall interface, where much pathology has been identified, the adventitia has a profound influence on the population of intimal and medial endothelial, macrophage, and smooth muscle cell function. Vascular injury and dysfunction of the perivascular adipose tissue promote expansion of the vasa vasorum, activation of fibroblasts, and differentiation of myofibroblasts. This regulates further biologic processes, including fibroblast and myofibroblast migration and proliferation, inflammation, immunity, stem cell activation and regulation, extracellular matrix remodeling, and angiogenesis. A debate exists as to whether the adventitia initiates disease or is just an important participant. We describe a mechanistic model of adventitial function that brings together current knowledge and guides the design of future investigations to test specific hypotheses on adventitial pathobiology.
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Affiliation(s)
- Maria G Tinajero
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Avrum I Gotlieb
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
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19
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The status and challenges of replicating the mechanical properties of connective tissues using additive manufacturing. J Mech Behav Biomed Mater 2019; 103:103544. [PMID: 32090944 DOI: 10.1016/j.jmbbm.2019.103544] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 10/29/2019] [Accepted: 11/16/2019] [Indexed: 01/23/2023]
Abstract
The ability to fabricate complex structures via precise and heterogeneous deposition of biomaterials makes additive manufacturing (AM) a leading technology in the creation of implants and tissue engineered scaffolds. Connective tissues (CTs) remain attractive targets for manufacturing due to their "simple" tissue compositions that, in theory, are replicable through choice of biomaterial(s) and implant microarchitecture. Nevertheless, characterisation of the mechanical and biological functions of 3D printed constructs with respect to their host tissues is often limited and remains a restriction towards their translation into clinical practice. This review aims to provide an update on the current status of AM to mimic the mechanical properties of CTs, with focus on arterial tissue, articular cartilage and bone, from the perspective of printing platforms, biomaterial properties, and topological design. Furthermore, the grand challenges associated with the AM of CT replacements and their subsequent regulatory requirements are discussed to aid further development of reliable and effective implants.
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20
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Clark GL, Pokutta-Paskaleva AP, Lawrence DJ, Lindsey SH, Desrosiers L, Knoepp LR, Bayer CL, Gleason RL, Miller KS. Smooth muscle regional contribution to vaginal wall function. Interface Focus 2019; 9:20190025. [PMID: 31263538 PMCID: PMC6597518 DOI: 10.1098/rsfs.2019.0025] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2019] [Indexed: 12/16/2022] Open
Abstract
Pelvic organ prolapse is characterized as the descent of the pelvic organs into the vaginal canal. In the USA, there is a 12% lifetime risk for requiring surgical intervention. Although vaginal childbirth is a well-established risk factor for prolapse, the underlying mechanisms are not fully understood. Decreased smooth muscle organization, composition and maximum muscle tone are characteristics of prolapsed vaginal tissue. Maximum muscle tone of the vaginal wall was previously investigated in the circumferential or axial direction under uniaxial loading; however, the vaginal wall is subjected to multiaxial loads. Further, the contribution of vaginal smooth muscle basal (resting) tone to mechanical function remains undetermined. The objectives of this study were to determine the contribution of smooth muscle basal and maximum tone to the regional biaxial mechanical behaviour of the murine vagina. Vaginal tissue from C57BL/6 mice was subjected to extension-inflation protocols (n = 10) with and without basal smooth muscle tone. Maximum tone was induced with KCl under various circumferential (n = 5) and axial (n = 5) loading conditions. The microstructure was visualized with multiphoton microscopy (n = 1), multiaxial histology (n = 4) and multiaxial immunohistochemistry (n = 4). Smooth muscle basal tone decreased material stiffness and increased anisotropy. In addition, maximum vaginal tone was decreased with increasing intraluminal pressures. This study demonstrated that vaginal muscle tone contributed to the biaxial mechanical response of murine vaginal tissue. This may be important in further elucidating the underlying mechanisms of prolapse, in order to improve current preventative and treatment strategies.
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Affiliation(s)
- Gabrielle L. Clark
- Department of Biomedical Engineering, Tulane University, 6823 St Charles Avenue, New Orleans, LA 70118, USA
| | - Anastassia P. Pokutta-Paskaleva
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, 801 Ferst Drive NW, Atlanta, GA 30332, USA
| | - Dylan J. Lawrence
- Department of Biomedical Engineering, Tulane University, 6823 St Charles Avenue, New Orleans, LA 70118, USA
| | - Sarah H. Lindsey
- Department of Pharmacology, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA
| | - Laurephile Desrosiers
- Department of Female Pelvic Medicine and Reconstructive Surgery, University of Queensland Ochsner Clinical School, 1514 Jefferson Highway, New Orleans, LA 70121, USA
| | - Leise R. Knoepp
- Department of Female Pelvic Medicine and Reconstructive Surgery, University of Queensland Ochsner Clinical School, 1514 Jefferson Highway, New Orleans, LA 70121, USA
| | - Carolyn L. Bayer
- Department of Biomedical Engineering, Tulane University, 6823 St Charles Avenue, New Orleans, LA 70118, USA
| | - Rudolph L. Gleason
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, 801 Ferst Drive NW, Atlanta, GA 30332, USA
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Kristin S. Miller
- Department of Biomedical Engineering, Tulane University, 6823 St Charles Avenue, New Orleans, LA 70118, USA
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21
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Akentjew TL, Terraza C, Suazo C, Maksimcuka J, Wilkens CA, Vargas F, Zavala G, Ocaña M, Enrione J, García-Herrera CM, Valenzuela LM, Blaker JJ, Khoury M, Acevedo JP. Rapid fabrication of reinforced and cell-laden vascular grafts structurally inspired by human coronary arteries. Nat Commun 2019; 10:3098. [PMID: 31308369 PMCID: PMC6629634 DOI: 10.1038/s41467-019-11090-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 06/20/2019] [Indexed: 12/19/2022] Open
Abstract
Design strategies for small diameter vascular grafts are converging toward native-inspired tissue engineered grafts. A new automated technology is presented that combines a dip-spinning methodology for depositioning concentric cell-laden hydrogel layers, with an adapted solution blow spinning (SBS) device for intercalated placement of aligned reinforcement nanofibres. This additive manufacture approach allows the assembly of bio-inspired structural configurations of concentric cell patterns with fibres at specific angles and wavy arrangements. The middle and outer layers were tuned to structurally mimic the media and adventitia layers of native arteries, enabling the fabrication of small bore grafts that exhibit the J-shape mechanical response and compliance of human coronary arteries. This scalable automated system can fabricate cellularized multilayer grafts within 30 min. Grafts were evaluated by hemocompatibility studies and a preliminary in vivo carotid rabbit model. The dip-spinning-SBS technology generates constructs with native mechanical properties and cell-derived biological activities, critical for clinical bypass applications.
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Affiliation(s)
- Tamara L Akentjew
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de los Andes, San Carlos de Apoquindo 2200, Las Condes, Santiago, 7620001, Chile
- Cells for Cells, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
- Consorcio Regenero, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
- Department of Chemical and Bioprocess Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Avda. Vicuña Mackenna 4860, Macul, Santiago, 7820436, Chile
| | - Claudia Terraza
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de los Andes, San Carlos de Apoquindo 2200, Las Condes, Santiago, 7620001, Chile
- Cells for Cells, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
| | - Cristian Suazo
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de los Andes, San Carlos de Apoquindo 2200, Las Condes, Santiago, 7620001, Chile
- Cells for Cells, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
| | - Jekaterina Maksimcuka
- School of Materials, MSS Tower, The University of Manchester, Manchester, M13 9PL, UK
| | - Camila A Wilkens
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de los Andes, San Carlos de Apoquindo 2200, Las Condes, Santiago, 7620001, Chile
- Cells for Cells, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
- Consorcio Regenero, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
| | - Francisco Vargas
- Departamento de Cirugía Vascular y Endovascular, Pontificia Universidad Católica de Chile, Avda. Libertador Bernando O'Higgins 340, Santiago, 8331150, Chile
| | - Gabriela Zavala
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de los Andes, San Carlos de Apoquindo 2200, Las Condes, Santiago, 7620001, Chile
- Cells for Cells, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
| | - Macarena Ocaña
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de los Andes, San Carlos de Apoquindo 2200, Las Condes, Santiago, 7620001, Chile
- Cells for Cells, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
| | - Javier Enrione
- Biopolymer Research and Engineering Lab (BiopREL), School of Nutrition and Dietetics, Faculty of Medicine, Universidad de los Andes, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
| | - Claudio M García-Herrera
- Departmento de Ingeniería Mecánica, Universidad de Santiago de Chile, Avda. Libertador Bernando O'Higgins 3363, Estación Central, Santiago, 9170022, Chile
| | - Loreto M Valenzuela
- Department of Chemical and Bioprocess Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Avda. Vicuña Mackenna 4860, Macul, Santiago, 7820436, Chile
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological Sciences, Pontificia Universidad Católica de Chile, Libertador Bernando O'Higgins 340, Macul, Santiago, 7820436, Chile
- Center of Nanotechnology Research and Advanced Materials "CIEN -UC", Pontificia Universidad Católica de Chile, Avda. Libertador Bernando O'Higgins 340, Macul, Santiago, 7820436, Chile
| | - Jonny J Blaker
- Bio-Active Materials Group, School of Materials, MSS Tower, The University of Manchester, Manchester, M13 9PL, UK
| | - Maroun Khoury
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de los Andes, San Carlos de Apoquindo 2200, Las Condes, Santiago, 7620001, Chile
- Cells for Cells, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
- Consorcio Regenero, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile
| | - Juan Pablo Acevedo
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de los Andes, San Carlos de Apoquindo 2200, Las Condes, Santiago, 7620001, Chile.
- Cells for Cells, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile.
- Consorcio Regenero, Avda. Plaza 2501, Las Condes, Santiago, 7620157, Chile.
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22
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Trachet B, Ferraro M, Lovric G, Aslanidou L, Logghe G, Segers P, Stergiopulos N. Synchrotron-based visualization and segmentation of elastic lamellae in the mouse carotid artery during quasi-static pressure inflation. J R Soc Interface 2019; 16:20190179. [PMID: 31238834 DOI: 10.1098/rsif.2019.0179] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In computational aortic biomechanics, aortic and arterial tissue are typically modelled as a homogeneous layer, making abstraction not only of the layered structure of intima, media and adventitia but also of the microstructure that exists within these layers. Here, we present a novel method to visualize the microstructure of the tunica media along the entire circumference of the vessel. To that end, we developed a pressure-inflation device that is compatible with synchrotron-based phase-contrast imaging. Using freshly excised left common carotid arteries from n = 12 mice, we visualized how the lamellae and interlamellar layers inflate as the luminal pressure is increased from 0 to 120 mm Hg in quasi-static steps. A graph-based segmentation algorithm subsequently allowed us to automatically segment each of the three lamellae, resulting in a three-dimensional geometry that represents lamellae, interlamellar layers and adventitia at nine different pressure levels. Our results demonstrate that the three elastic lamellae unfold and stretch simultaneously as luminal pressure is increased. In the long term, we believe that the results presented in this work can be a first step towards a better understanding of the mechanics of the arterial microstructure.
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Affiliation(s)
- Bram Trachet
- 1 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland.,2 IBiTech-bioMMeda , Ghent University, Ghent , Belgium
| | - Mauro Ferraro
- 1 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland
| | - Goran Lovric
- 3 Centre d'Imagerie BioMédicale, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland.,4 Swiss Light Source, Paul Scherrer Institute , Villigen , Switzerland
| | - Lydia Aslanidou
- 1 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland
| | | | | | - Nikolaos Stergiopulos
- 1 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland
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23
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The Effect of Mechanical Overloading on Surface Roughness of the Coronary Arteries. Appl Bionics Biomech 2019; 2019:2784172. [PMID: 30809272 PMCID: PMC6364105 DOI: 10.1155/2019/2784172] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/29/2018] [Accepted: 01/01/2019] [Indexed: 01/03/2023] Open
Abstract
Background Surface roughness can be used to identify disease within biological tissues. Quantifying surface roughness in the coronary arteries aids in developing treatments for coronary heart disease. This study investigates the effect of extreme physiological loading on surface roughness, for example, due to a rupture of an artery. Methods The porcine left anterior descending (LAD) coronary arteries were dissected ex vivo. Mechanical overloading was applied to the arteries in the longitudinal direction to simulate extreme physiological loading. Surface roughness was calculated from three-dimensional reconstructed images. Surface roughness was measured before and after damage and after chemical processing to dehydrate tissue specimens. Results Control specimens confirmed that dehydration alone results in an increase of surface roughness in the circumferential direction only. No variation was noted between the hydrated healthy and damaged specimens, in both the longitudinal (0.91 ± 0.26 and 1.05 ± 0.25 μm) and circumferential (1.46 ± 0.38 and 1.47 ± 0.39 μm) directions. After dehydration, an increase in surface roughness was noted for damaged specimens in both the longitudinal (1.28 ± 0.33 μm) and circumferential (1.95 ± 0.56 μm) directions. Conclusions Mechanical overloading applied in the longitudinal direction did not significantly affect surface roughness. However, when combined with chemical processing, a significant increase in surface roughness was noted in both the circumferential and longitudinal directions. Mechanical overloading causes damage to the internal constituents of the arteries, which is significantly noticeable after dehydration of tissue.
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24
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Wang S, Tokgoz A, Huang Y, Zhang Y, Feng J, Sastry P, Sun C, Figg N, Lu Q, Sutcliffe MPF, Teng Z, Gillard JH. Bayesian Inference-Based Estimation of Normal Aortic, Aneurysmal and Atherosclerotic Tissue Mechanical Properties: From Material Testing, Modeling and Histology. IEEE Trans Biomed Eng 2019; 66:2269-2278. [PMID: 30703001 DOI: 10.1109/tbme.2018.2886681] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Mechanical properties of healthy, aneurysmal, and atherosclerotic arterial tissues are essential for assessing the risk of lesion development and rupture. Strain energy density function (SEDF) has been widely used to describe these properties, where material constants of the SEDF are traditionally determined using the ordinary least square (OLS) method. However, the material constants derived using OLS are usually dependent on initial guesses. METHODS To avoid such dependencies, Bayesian inference-based estimation was used to fit experimental stress-stretch curves of 312 tissue strips from 8 normal aortas, 19 aortic aneurysms, and 21 carotid atherosclerotic plaques to determine the constants, C1, D1, and D2 of the modified Mooney-Rivlin SEDF. RESULTS Compared with OLS, material constants varied much less with prior in the Bayesian inference-based estimation. Moreover, fitted material constants differed amongst distinct tissue types. Atherosclerotic tissues associated with the biggest D2, an indicator of the rate of increase in stress during stretching, followed by aneurysmal tissues and those from normal aortas. Histological analyses showed that C1 and D2 were associated with elastin content and details of the collagen configuration, specifically, waviness and dispersion, in the structure. CONCLUSION Bayesian inference-based estimation robustly determines material constants in the modified Mooney-Rivlin SEDF and these constants can reflect the inherent physiological and pathological features of the tissue structure. SIGNIFICANCE This study suggested a robust procedure to determine the material constants in SEDF and demonstrated that the obtained constants can be used to characterize tissues from different types of lesions, while associating with their inherent microstructures.
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Yu X, Turcotte R, Seta F, Zhang Y. Micromechanics of elastic lamellae: unravelling the role of structural inhomogeneity in multi-scale arterial mechanics. J R Soc Interface 2018; 15:rsif.2018.0492. [PMID: 30333250 DOI: 10.1098/rsif.2018.0492] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/20/2018] [Indexed: 01/15/2023] Open
Abstract
Microstructural deformation of elastic lamellae plays important roles in maintaining arterial tissue homeostasis and regulating vascular smooth muscle cell fate. Our study unravels the underlying microstructural origin that enables elastic lamellar layers to evenly distribute the stresses through the arterial wall caused by intraluminal distending pressure, a fundamental requirement for tissue and cellular function. A new experimental approach was developed to quantify the spatial organization and unfolding of elastic lamellar layers under pressurization in mouse carotid arteries by coupling physiological extension-inflation and multiphoton imaging. Tissue-level circumferential stretch was obtained from analysis of the deformation of a thick-walled cylinder. Our results show that the unfolding and extension of lamellar layers contribute simultaneously to tissue-level deformation. The inner lamellar layers are wavier and unfold more than the outer layers. This waviness gradient compensates the larger tissue circumferential stretch experienced at the inner surface, thus equalizing lamellar layer extension through the arterial wall. Discoveries from this study reveal the importance of structural inhomogeneity in maintaining tissue homeostasis through the arterial wall, and may have profound implications on vascular remodelling in aging and diseases, as well as in tissue engineering of functional blood vessels.
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Affiliation(s)
- Xunjie Yu
- Department of Mechanical Engineering, Boston University, Boston, MA, USA
| | | | - Francesca Seta
- Vascular Biology Section, Boston University School of Medicine, Boston, MA, USA
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA, USA .,Department of Biomedical Engineering, Boston University, Boston, MA, USA
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26
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Bloksgaard M, Thorsted B, Brewer JR, De Mey JGR. Assessing Collagen and Elastin Pressure-dependent Microarchitectures in Live, Human Resistance Arteries by Label-free Fluorescence Microscopy. J Vis Exp 2018. [PMID: 29683445 DOI: 10.3791/57451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The pathogenic contribution of resistance artery remodeling is documented in essential hypertension, diabetes and the metabolic syndrome. Investigations and development of microstructurally motivated mathematical models for understanding the mechanical properties of human resistance arteries in health and disease have the potential to aid understanding how disease and medical treatments affect the human microcirculation. To develop these mathematical models, it is essential to decipher the relationship between the mechanical and microarchitectural properties of the microvascular wall. In this work, we describe an ex vivo method for passive mechanical testing and simultaneous label-free three-dimensional imaging of the microarchitecture of elastin and collagen in the arterial wall of isolated human resistance arteries. The imaging protocol can be applied to resistance arteries of any species of interest. Image analyses are described for quantifying i) pressure-induced changes in internal elastic lamina branching angles and adventitial collagen straightness using Fiji and ii) collagen and elastin volume densities determined using Ilastik software. Preferably all mechanical and imaging measurements are performed on live, perfused arteries, however, an alternative approach using standard video-microscopy pressure myography in combination with post-fixation imaging of re-pressurized vessels is discussed. This alternative method provides users with different options for analysis approaches. The inclusion of the mechanical and imaging data in mathematical models of the arterial wall mechanics is discussed, and future development and additions to the protocol are proposed.
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Affiliation(s)
- Maria Bloksgaard
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark;
| | - Bjarne Thorsted
- Department of Biochemistry and Molecular Biology, University of Southern Denmark
| | - Jonathan R Brewer
- Department of Biochemistry and Molecular Biology, University of Southern Denmark
| | - Jo G R De Mey
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark; Department of Cardiac, Thoracic and Vascular Surgery, Odense University Hospital
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Chronic ET A antagonist reverses hypertension and impairment of structure and function of peripheral small arteries in aortic stiffening. Sci Rep 2018; 8:3076. [PMID: 29449619 PMCID: PMC5814460 DOI: 10.1038/s41598-018-20439-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 01/09/2018] [Indexed: 01/22/2023] Open
Abstract
Arterial stiffness may contribute to the pathogenesis of hypertension. The goal of this study is to elucidate the role of Endothelin-1 (ET-1) in aortic stiffening-induced hypertension through ETA receptor activation. An increase in aortic stiffness was created by use of a non-constrictive restraint, NCR on the abdominal aortic surface. A group of rats underwent aortic NCR or sham operation for 12 weeks and were then treated with ETA receptor antagonist BQ-123 for 3 weeks. We found that 12 weeks of aortic NCR significantly increased pulse and mean pressure and altered peripheral flow pattern, accompanied by an increased serum ET-1 level (p < 0.05). The increase in aortic stiffness (evidenced by an elevated pulse wave velocity) caused hypertrophic structural remodeling and decreased arterial compliance, along with an impaired endothelial function in peripheral small arteries. BQ-123 treatment only partially attenuated peripheral arterial hypertrophy and restored arterial compliance, but completely recovered endothelium function, and consequently restored local flow and lowered blood pressure. Our findings underscore the hemodynamic coupling between aortic stiffening and peripheral arterial vessels and flow dynamics through an ETA-dependent mechanism. ETA receptor blockade may have therapeutic potential for improving peripheral vessel structure and function in the treatment of aortic stiffness-induced hypertension.
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28
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Zhang D, Chen W, Chen H, Yu HQ, Kassab G, Cheng JX. Chemical imaging of fresh vascular smooth muscle cell response by epi-detected stimulated Raman scattering. JOURNAL OF BIOPHOTONICS 2018; 11:e201700005. [PMID: 28715124 DOI: 10.1002/jbio.201700005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 06/12/2017] [Accepted: 07/13/2017] [Indexed: 06/07/2023]
Abstract
An understanding of deformation of cardiovascular tissue under hemodynamic load is crucial for understanding the health and disease of blood vessels. In the present work, an epi-detected stimulated Raman scattering (epi-SRS) imaging platform was designed for in situ functional imaging of vascular smooth muscle cells (VMSCs) in fresh coronary arteries. For the first time, the pressure-induced morphological deformation of fresh VSMCs was imaged with no fixation and in a label-free manner. The relation between the loading pressure and the morphological parameters, including angle and length of the VSMCs, were apparent. The morphological responses of VMSCs to drug treatment were also explored, to demonstrate the capability of functional imaging for VSMCs by this method. The time-course imaging revealed the drug induced change in angle and length of VSMCs. The present study provides a better understanding of the biomechanical framework of blood vessels, as well as their responses to external stimulations, which are fundamental for developing new strategies for cardiovascular disease treatment.
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Affiliation(s)
- Delong Zhang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
| | - Wei Chen
- Department of Chemistry, University of Science and Technology of China, Hefei, P.R. China
| | - Huan Chen
- California Medical Innovations Institute, San Diego, California
| | - Han-Qing Yu
- Department of Chemistry, University of Science and Technology of China, Hefei, P.R. China
| | - Ghassan Kassab
- California Medical Innovations Institute, San Diego, California
| | - Ji-Xin Cheng
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
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29
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Wasicek PJ, Teeter WA, Brenner ML, Hoehn MR, Scalea TM, Morrison JJ. Resuscitative endovascular balloon occlusion of the aorta: rupture risk and implications for blind inflation. Trauma Surg Acute Care Open 2018; 3:e000141. [PMID: 29766130 PMCID: PMC5887780 DOI: 10.1136/tsaco-2017-000141] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/21/2017] [Accepted: 01/03/2018] [Indexed: 11/05/2022] Open
Abstract
Background Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a torso hemorrhage control technique. To expedite deployment, inflation is frequently performed as a blind technique with minimal imaging, which carries a theoretical risk of aortic injury. The objective of this study was to examine the relationship between balloon inflation, deformation and the risk of aortic rupture. Methods Compliant balloon catheters were incrementally inflated in segments of cadaveric swine aorta. Serial longitudinal and circumferential measurements were recorded, along with the incidence of aortic rupture. Results Fourteen cadaveric swine aorta segments were tested with mean (±SD) baseline aortic diameter (mm) of 14.2±3.4. Rupture occurred in three aortas. The mean baseline diameters (mm) of the aortic segments that were ruptured were significantly smaller than those that did not rupture (8.9±1.2 vs 15.6±1.9; P<0.001). The maximal circumferential stretch ratios were significantly higher in the aorta segments that ruptured compared with those that did not (1.9±0.1 vs 1.5±0.1; P<0.001). The maximal amount of balloon longitudinal deformation was 80 mm (116% longer than the intended working length). Conclusions Inflation of aortic balloon catheters carries an inherent risk of aortic injury, which may be minimized through an understanding of the intrinsic characteristics of the aorta and compliant balloons. Smaller diameter aortic segments undergoing overinflation, particularly beyond a circumferential stretch ratio of 1.8, are at risk of aortic rupture. Level of evidence Level II.
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Affiliation(s)
- Philip J Wasicek
- Program in Trauma/Critical Care, R Adam Cowley Shock Trauma Center, University of Maryland Medical System, Baltimore, Maryland, USA
| | - William A Teeter
- Program in Trauma/Critical Care, R Adam Cowley Shock Trauma Center, University of Maryland Medical System, Baltimore, Maryland, USA
| | - Megan L Brenner
- Program in Trauma/Critical Care, R Adam Cowley Shock Trauma Center, University of Maryland Medical System, Baltimore, Maryland, USA
| | - Melanie R Hoehn
- Program in Trauma/Critical Care, R Adam Cowley Shock Trauma Center, University of Maryland Medical System, Baltimore, Maryland, USA
| | - Thomas M Scalea
- Program in Trauma/Critical Care, R Adam Cowley Shock Trauma Center, University of Maryland Medical System, Baltimore, Maryland, USA
| | - Jonathan J Morrison
- Program in Trauma/Critical Care, R Adam Cowley Shock Trauma Center, University of Maryland Medical System, Baltimore, Maryland, USA
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30
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Kinematics of collagen fibers in carotid arteries under tension-inflation loading. J Mech Behav Biomed Mater 2018; 77:718-726. [DOI: 10.1016/j.jmbbm.2017.08.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/07/2017] [Accepted: 08/09/2017] [Indexed: 01/15/2023]
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31
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Georgiadis M, Müller R, Schneider P. Techniques to assess bone ultrastructure organization: orientation and arrangement of mineralized collagen fibrils. J R Soc Interface 2017; 13:rsif.2016.0088. [PMID: 27335222 DOI: 10.1098/rsif.2016.0088] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 05/18/2016] [Indexed: 12/13/2022] Open
Abstract
Bone's remarkable mechanical properties are a result of its hierarchical structure. The mineralized collagen fibrils, made up of collagen fibrils and crystal platelets, are bone's building blocks at an ultrastructural level. The organization of bone's ultrastructure with respect to the orientation and arrangement of mineralized collagen fibrils has been the matter of numerous studies based on a variety of imaging techniques in the past decades. These techniques either exploit physical principles, such as polarization, diffraction or scattering to examine bone ultrastructure orientation and arrangement, or directly image the fibrils at the sub-micrometre scale. They make use of diverse probes such as visible light, X-rays and electrons at different scales, from centimetres down to nanometres. They allow imaging of bone sections or surfaces in two dimensions or investigating bone tissue truly in three dimensions, in vivo or ex vivo, and sometimes in combination with in situ mechanical experiments. The purpose of this review is to summarize and discuss this broad range of imaging techniques and the different modalities of their use, in order to discuss their advantages and limitations for the assessment of bone ultrastructure organization with respect to the orientation and arrangement of mineralized collagen fibrils.
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Affiliation(s)
| | - Ralph Müller
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Philipp Schneider
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland Bioengineering Science Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
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32
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Resliced image space construction for coronary artery collagen fibers. PLoS One 2017; 12:e0184972. [PMID: 28953913 PMCID: PMC5617181 DOI: 10.1371/journal.pone.0184972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 09/05/2017] [Indexed: 11/19/2022] Open
Abstract
Collagen fibers play an important role in the biomechanics of the blood vessel wall. The objective of this study was to determine the 3D microstructure of collagen fibers in the media and adventitia of coronary arteries. We present a novel optimal angle consistence algorithm to reform image slices in the visualization and analysis of 3D collagen images. 3D geometry was reconstructed from resliced image space where the 3D skeleton was extracted as the primary feature for accurate reconstruction of geometrical parameters. Collagen fibers (range 80–200) were reconstructed from the porcine coronary artery wall for the measurement of various morphological parameters. Collagen waviness and diameters were 1.37 ± 0.19 and 2.61 ± 0.89 μm, respectively. The biaxial distributions of orientation had two different peaks at 110.7 ± 25.2° and 18.4 ± 19.3°. Results for width, waviness, and orientation were found to be in good agreement with manual measurements. In addition to accurately measuring 2D features more efficiently than the manual approach, the present method produced 3D features that could not be measured in the 2D manual approach. These additional parameters included the tilt angle (5.10 ± 2.95°) and cross-sectional area (CSA; 5.98 ± 3.79 μm2) of collagen fibers. These 3D collagen reconstructions provide accurate and reliable microstructure for biomechanical modeling of vessel wall mechanics.
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33
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Patel B, Chen H, Ahuja A, Krieger JF, Noblet J, Chambers S, Kassab GS. Constitutive modeling of the passive inflation-extension behavior of the swine colon. J Mech Behav Biomed Mater 2017; 77:176-186. [PMID: 28922650 DOI: 10.1016/j.jmbbm.2017.08.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/24/2017] [Accepted: 08/28/2017] [Indexed: 12/14/2022]
Abstract
In the present work, we propose the first structural constitutive model of the passive mechanical behavior of the swine colon that is validated against physiological inflation-extension tests, and accounts for residual strains. Sections from the spiral colon and the descending colon were considered to investigate potential regional variability. We found that the proposed constitutive model accurately captures the passive inflation-extension behavior of both regions of the swine colon (coefficient of determination R2=0.94±0.02). The model revealed that the circumferential muscle layer does not provide significant mechanical support under passive conditions and the circumferential load is actually carried by the submucosa layer. The stress analysis permitted by the model showed that the colon tissue can distend up to 30% radially without significant increase in the wall stresses suggesting a highly compliant behavior of the tissue. This is in-line with the requirement for the tissue to easily accommodate variable quantities of fecal matter. The analysis also showed that the descending colon is significantly more compliant than the spiral colon, which is relevant to the storage function of the descending colon. Histological analysis showed that the swine colon possesses a four-layer structure similar to the human colon, where the longitudinal muscle layer is organized into bands called taeniae, a typical feature of the human colon. The model and the estimated parameters can be used in a Finite Element framework to conduct simulations with realistic geometry of the swine colon. The resulting computational model will provide a foundation for virtual assessment of safe and effective devices for the treatment of colonic diseases.
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Affiliation(s)
- Bhavesh Patel
- California Medical Innovations Institute, 11107 Roselle st., San Diego, CA 92121, United States
| | - Huan Chen
- California Medical Innovations Institute, 11107 Roselle st., San Diego, CA 92121, United States
| | - Aashish Ahuja
- California Medical Innovations Institute, 11107 Roselle st., San Diego, CA 92121, United States
| | | | | | | | - Ghassan S Kassab
- California Medical Innovations Institute, 11107 Roselle st., San Diego, CA 92121, United States.
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34
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Chen H, Kassab GS. Microstructure-based constitutive model of coronary artery with active smooth muscle contraction. Sci Rep 2017; 7:9339. [PMID: 28839149 PMCID: PMC5571218 DOI: 10.1038/s41598-017-08748-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/18/2017] [Indexed: 12/27/2022] Open
Abstract
Currently, there is no full three-dimensional (3D) microstructural mechanical model of coronary artery based on measured microstructure including elastin, collagen and smooth muscle cells. Many structural models employ mean values of vessel microstructure, rather than continuous distributions of microstructure, to predict the mechanical properties of blood vessels. Although some models show good agreements on macroscopic vessel responses, they result in a lower elastin stiffness and earlier collagen recruitment. Hence, a full microstructural constitutive model is required for better understanding vascular biomechanics in health and disease. Here, a 3D microstructural model that accounts for all constituent microstructure is proposed to predict macroscopic and microscopic responses of coronary arteries. Coronary artery microstructural parameters were determined based on previous statistical measurements while mechanical testing of arteries (n = 5) were performed in this study to validate the computational predictions. The proposed model not only provides predictions of active and passive stress distributions of vessel wall, but also enables reliable estimations of material parameters of individual fibers and cells and thus predicts microstructural stresses. The validated microstructural model of coronary artery sheds light on vascular biomechanics and can be extend to diseased vessels for better understanding of initiation, progression and clinical treatment of vascular disease.
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Affiliation(s)
- H Chen
- California Medical Innovations Institute, Inc., San Diego, CA92121, USA
| | - G S Kassab
- California Medical Innovations Institute, Inc., San Diego, CA92121, USA.
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35
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Athanasiou D, Edgar LT, Jafarnejad M, Nixon K, Duarte D, Hawkins ED, Jamalian S, Cunnea P, Lo Celso C, Kobayashi S, Fotopoulou C, Moore JE. The passive biomechanics of human pelvic collecting lymphatic vessels. PLoS One 2017; 12:e0183222. [PMID: 28827843 PMCID: PMC5565099 DOI: 10.1371/journal.pone.0183222] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 08/01/2017] [Indexed: 11/19/2022] Open
Abstract
The lymphatic system has a major significance in the metastatic pathways in women's cancers. Lymphatic pumping depends on both extrinsic and intrinsic mechanisms, and the mechanical behavior of lymphatic vessels regulates the function of the system. However, data on the mechanical properties and function of human lymphatics are lacking. Our aim is to characterize, for the first time, the passive biomechanical behavior of human collecting lymphatic vessels removed at pelvic lymph node dissection during primary debulking surgeries for epithelial ovarian cancer. Isolated vessels were cannulated and then pressurized at varying levels of applied axial stretch in a calcium-free Krebs buffer. Pressurized vessels were then imaged using multi-photon microscopy for collagen-elastin structural composition and fiber orientation. Both pressure-diameter and force-elongation responses were highly nonlinear, and axial stretching of the vessel served to decrease diameter at constant pressure. Pressure-diameter behavior for the human vessels is very similar to data from rat mesenteric vessels, though the human vessels were approximately 10× larger than those from rats. Multiphoton microscopy revealed the vessels to be composed of an inner layer of elastin with an outer layer of aligned collagen fibers. This is the first study that successfully described the passive biomechanical response and composition of human lymphatic vessels in patients with ovarian cancer. Future work should expand on this knowledge base with investigations of vessels from other anatomical locations, contractile behavior, and the implications on metastatic cell transport.
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Affiliation(s)
- Dimitrios Athanasiou
- Department of Bioengineering, Imperial College, London, South Kensington Campus, London, United Kingdom
| | - Lowell T. Edgar
- Department of Bioengineering, Imperial College, London, South Kensington Campus, London, United Kingdom
- * E-mail:
| | - Mohammad Jafarnejad
- Department of Bioengineering, Imperial College, London, South Kensington Campus, London, United Kingdom
| | - Katherine Nixon
- Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London, Hammersmith Hospital, London, United Kingdom
| | - Delfim Duarte
- Department of Life Sciences and the Francis Crick Institute, Imperial College London, South Kensington Campus, London, United Kingdom
| | - Edwin D. Hawkins
- Immunology Division at the Walter and Eliza Hall, Institute of Medical Research, Department of Medical Biology, University of Melbourne, Victoria, Australia
| | - Samira Jamalian
- Department of Bioengineering, Imperial College, London, South Kensington Campus, London, United Kingdom
| | - Paula Cunnea
- Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London, Hammersmith Hospital, London, United Kingdom
| | - Cristina Lo Celso
- Department of Life Sciences and the Francis Crick Institute, Imperial College London, South Kensington Campus, London, United Kingdom
| | - Shunichi Kobayashi
- Department of Mechanical Engineering and Robotics, Shinshu University, Ueda, Nagano, Japan
| | - Christina Fotopoulou
- Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London, Hammersmith Hospital, London, United Kingdom
| | - James E. Moore
- Department of Bioengineering, Imperial College, London, South Kensington Campus, London, United Kingdom
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Krasny W, Morin C, Magoariec H, Avril S. A comprehensive study of layer-specific morphological changes in the microstructure of carotid arteries under uniaxial load. Acta Biomater 2017; 57:342-351. [PMID: 28499632 DOI: 10.1016/j.actbio.2017.04.033] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 02/20/2017] [Accepted: 04/19/2017] [Indexed: 10/19/2022]
Abstract
The load bearing properties of large blood vessels are principally conferred by collagen and elastin networks and their microstructural organization plays an important role in the outcomes of various arterial pathologies. In particular, these fibrous networks are able to rearrange and reorient spatially during mechanical deformations. In this study, we investigate for the first time whether these well-known morphological rearrangements are the same across the whole thickness of blood vessels, and subsequently if the underlying mechanisms that govern these rearrangements can be predicted using affine kinematics. To this aim, we submitted rabbit carotid samples to uniaxial load in three distinct deformation directions, while recording live images of the 3D microstructure using multiphoton microscopy. Our results show that the observed realignment of collagen and elastin in the media layer, along with elastin of the adventitia layer, remained limited to small angles that can be predicted by affine kinematics. We show also that collagen bundles of fibers in the adventitia layer behaved in significantly different fashion. They showed a remarkable capacity to realign in the direction of the load, whatever the loading direction. Measured reorientation angles of the fibers were significantly higher than affine predictions. This remarkable property of collagen bundles in the adventitia was never observed before, it shows that the medium surrounding collagen in the adventitia undergoes complex deformations challenging traditional hyperelastic models based on mixture theories. STATEMENT OF SIGNIFICANCE The biomechanical properties of arteries are conferred by the rearrangement under load of the collagen and elastin fibers making up the arterial microstructure. Their kinematics under deformation is not yet characterized for all fiber networks. In this respect we have submitted samples of arterial tissue to uniaxial tension, simultaneously to confocal imaging of their microstructure. Our method allowed identifying for the first time the remarkable ability of adventitial collagen fibers to reorient in the direction of the load, achieving reorientation rotations that exceeded those predicted by affine kinematics, while all other networks followed the affine kinematics. Our results highlight new properties of the microstructure, which might play a role in the outcomes of vascular pathologies like aneurysms.
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Bloksgaard M, Leurgans TM, Spronck B, Heusinkveld MHG, Thorsted B, Rosenstand K, Nissen I, Hansen UM, Brewer JR, Bagatolli LA, Rasmussen LM, Irmukhamedov A, Reesink KD, De Mey JGR. Imaging and modeling of acute pressure-induced changes of collagen and elastin microarchitectures in pig and human resistance arteries. Am J Physiol Heart Circ Physiol 2017; 313:H164-H178. [DOI: 10.1152/ajpheart.00110.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/30/2017] [Accepted: 04/14/2017] [Indexed: 01/15/2023]
Abstract
The impact of disease-related changes in the extracellular matrix (ECM) on the mechanical properties of human resistance arteries largely remains to be established. Resistance arteries from both pig and human parietal pericardium (PRA) display a different ECM microarchitecture compared with frequently used rodent mesenteric arteries. We hypothesized that the biaxial mechanics of PRA mirror pressure-induced changes in the ECM microarchitecture. This was tested using isolated pig PRA as a model system, integrating vital imaging, pressure myography, and mathematical modeling. Collagenase and elastase digestions were applied to evaluate the load-bearing roles of collagen and elastin, respectively. The incremental elastic modulus linearly related to the straightness of adventitial collagen fibers circumferentially and longitudinally (both R2 ≥ 0.99), whereas there was a nonlinear relationship to the internal elastic lamina elastin fiber branching angles. Mathematical modeling suggested a collagen recruitment strain (means ± SE) of 1.1 ± 0.2 circumferentially and 0.20 ± 0.01 longitudinally, corresponding to a pressure of ~40 mmHg, a finding supported by the vital imaging. The integrated method was tested on human PRA to confirm its validity. These showed limited circumferential distensibility and elongation and a collagen recruitment strain of 0.8 ± 0.1 circumferentially and 0.06 ± 0.02 longitudinally, reached at a distending pressure below 20 mmHg. This was confirmed by vital imaging showing negligible microarchitectural changes of elastin and collagen upon pressurization. In conclusion, we show here, for the first time in resistance arteries, a quantitative relationship between pressure-induced changes in the extracellular matrix and the arterial wall mechanics. The strength of the integrated methods invites for future detailed studies of microvascular pathologies. NEW & NOTEWORTHY This is the first study to quantitatively relate pressure-induced microstructural changes in resistance arteries to the mechanics of their wall. Principal findings using a pig model system were confirmed in human arteries. The combined methods provide a strong tool for future hypothesis-driven studies of microvascular pathologies.
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Affiliation(s)
- Maria Bloksgaard
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Thomas M. Leurgans
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Bart Spronck
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Maarten H. G. Heusinkveld
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Bjarne Thorsted
- MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark
| | - Kristoffer Rosenstand
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Inger Nissen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Ulla M. Hansen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Jonathan R. Brewer
- MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark
| | - Luis A. Bagatolli
- MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark
| | - Lars M. Rasmussen
- Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark; and
| | - Akhmadjon Irmukhamedov
- Department of Cardiac, Thoracic and Vascular Surgery, Odense University Hospital, Odense, Denmark
| | - Koen D. Reesink
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Jo G. R. De Mey
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
- Department of Cardiac, Thoracic and Vascular Surgery, Odense University Hospital, Odense, Denmark
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Chen Q, Wang Y, Li ZY. Re-examination of the mechanical anisotropy of porcine thoracic aorta by uniaxial tensile tests. Biomed Eng Online 2016; 15:167. [PMID: 28155705 PMCID: PMC5259859 DOI: 10.1186/s12938-016-0279-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Objective Considering past studies on the orthotropic anisotropy of arteries in the circumferential and axial directions, this work aims to experimentally study the anisotropic behaviour of arteries by tensioning multi-directional strips of porcine thoracic aorta. Methods Histology is first analyzed by staining arterial sections of three orthotropic (axial, circumferential, and radial) planes. 168 stripped samples from 21 aortas are categorized into three loading-rate groups to investigate the influence of loading rates on the Young’s modulus and ultimate stress. Basing on the Young’s modulus and ultimate stress, the degree of anisotropy is calculated. Moreover, 24 stripped samples from 3 aortas are tested to study the relaxation anisotropy of arteries by fitting the experimental data with a five-parameter Maxwell reduced relaxation function. Results Histological analysis shows the parallel orientation of crimpled collagen and elastin fibres. The Young’s modulus and ultimate stress reach the greatest in the circumferential direction, and the smallest in the axial direction, respectively, and the values in the other directions are in-between; moreover, the two parameters monotonously increase as the samples orientate from the axial to circumferential directions. The Young’s modulus is more sensitive to the loading rate than the ultimate stress. The degree of anisotropy calculated by the Young's modulus is similar to that by the ultimate stress, and it is independent of loading rates. Stress-relaxation also exhibits anisotropy, whose variation is consistent with those of the two parameters. Conclusions Due to the stress-growth rule, fibre preferably orientates in the circumferential direction, and the preferable orientation results in great mechanical parameters, anisotropy, and small relaxation behaviour of arteries. The work extends the studies on the arterial anisotropy instead of only the circumferential and axial directions, and could be useful to comprehensively understand the anisotropy of arteries.
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Affiliation(s)
- Qiang Chen
- Biomechanics Laboratory, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210096, People's Republic of China.
| | - Yan Wang
- Biomechanics Laboratory, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210096, People's Republic of China
| | - Zhi-Yong Li
- Biomechanics Laboratory, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210096, People's Republic of China. .,School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Australia.
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Luo T, Chen H, Kassab GS. 3D reconstruction of elastin fibres in coronary adventitia. J Microsc 2016; 265:121-131. [PMID: 27596327 DOI: 10.1111/jmi.12470] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 08/05/2016] [Accepted: 08/07/2016] [Indexed: 02/01/2023]
Abstract
A 3D reconstruction of individual fibres in vascular tissue is necessary to understand the microstructure properties of the vessel wall. The objective of this study is to determine the 3D microstructure of elastin fibres in the adventitia of coronary arteries. Quantification of fibre geometry is challenging due to the complex interwoven structure of the fibres. In particular, accurate linking of gaps remains a significant challenge, and complex features such as long gaps and interwoven fibres have not been adequately addressed by current fibre reconstruction algorithms. We use a novel line Laplacian deformation method, which better deals with fibre shape uncertainty to reconstruct elastin fibres in the coronary adventitia of five swine. A cost function, based on entropy and Euler Spiral, was used in the shortest path search. We find that mean diameter of elastin fibres is 1.67 ± 1.42 μm and fibre orientation is clustered around two major angles of 8.9˚ and 81.8˚. Comparing with CT-FIRE, we find that our method gives more accurate estimation of fibre width. To our knowledge, the measurements obtained using our algorithm represent the first investigation focused on the reconstruction of full elastin fibre length. Our data provide a foundation for a 3D microstructural model of the coronary adventitia to elucidate the structure-function relationship of elastin fibres.
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Affiliation(s)
- T Luo
- Department of Bioengineering, California Medical Innovations Institute, San Diego, California, U.S.A
| | - H Chen
- Department of Bioengineering, California Medical Innovations Institute, San Diego, California, U.S.A
| | - G S Kassab
- Department of Bioengineering, California Medical Innovations Institute, San Diego, California, U.S.A
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Chen H, Kassab GS. Microstructure-based biomechanics of coronary arteries in health and disease. J Biomech 2016; 49:2548-59. [PMID: 27086118 PMCID: PMC5028318 DOI: 10.1016/j.jbiomech.2016.03.023] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 03/16/2016] [Indexed: 12/27/2022]
Abstract
Coronary atherosclerosis is the major cause of mortality and disability in developed nations. A deeper understanding of mechanical properties of coronary arteries and hence their mechanical response to stress is significant for clinical prevention and treatment. Microstructure-based models of blood vessels can provide predictions of arterial mechanical response at the macro- and micro-mechanical level for each constituent structure. Such models must be based on quantitative data of structural parameters (constituent content, orientation angle and dimension) and mechanical properties of individual adventitia and media layers of normal arteries as well as change of structural and mechanical properties of atherosclerotic arteries. The microstructural constitutive models of healthy coronary arteries consist of three major mechanical components: collagen, elastin, and smooth muscle cells, while the models of atherosclerotic arteries should account for additional constituents including intima, fibrous plaque, lipid, calcification, etc. This review surveys the literature on morphology, mechanical properties, and microstructural constitutive models of normal and atherosclerotic coronary arteries. It also provides an overview of current gaps in knowledge that must be filed in order to advance this important area of research for understanding initiation, progression and clinical treatment of vascular disease. Patient-specific structural models are highlighted to provide diagnosis, virtual planning of therapy and prognosis when realistic patient-specific geometries and material properties of diseased vessels can be acquired by advanced imaging techniques.
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Affiliation(s)
- Huan Chen
- California Medical Innovations Institute, Inc., San Diego, CA 92121, United States
| | - Ghassan S Kassab
- California Medical Innovations Institute, Inc., San Diego, CA 92121, United States.
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Contribution of collagen and elastin fibers to the mechanical behavior of an abdominal connective tissue. J Mech Behav Biomed Mater 2016; 61:308-317. [DOI: 10.1016/j.jmbbm.2016.04.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 03/25/2016] [Accepted: 04/05/2016] [Indexed: 12/27/2022]
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Chen H, Guo X, Luo T, Kassab GS. A validated 3D microstructure-based constitutive model of coronary artery adventitia. J Appl Physiol (1985) 2016; 121:333-42. [PMID: 27174925 PMCID: PMC4967241 DOI: 10.1152/japplphysiol.00937.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 05/05/2016] [Indexed: 11/22/2022] Open
Abstract
A structure-based model that accurately predicts micro- or macromechanical behavior of blood vessels is necessary to understand vascular physiology. Based on recently measured microstructural data, we propose a three-dimensional microstructural model of coronary adventitia that incorporates the elastin and collagen distributions throughout the wall. The role of ground substance was found to be negligible under physiological axial stretch λz = 1.3, based on enzyme degradation of glycosaminoglycans in swine coronary adventitia (n = 5). The thick collagen bundles of outer adventitia (n = 4) were found to be undulated and unengaged at physiological loads, whereas the inner adventitia consisted of multiple sublayers of entangled fibers that bear the majority of load at higher pressures. The microstructural model was validated against biaxial (inflation and extension) experiments of coronary adventitia (n = 5). The model accurately predicted the nonlinear responses of the adventitia, even at high axial force (axial stretch ratio λz = 1.5). The model also enabled a reliable estimation of material parameters of individual fibers that were physically reasonable. A sensitivity analysis was performed to assess the effect of using mean values of the distributions for fiber orientation and waviness as opposed to the full distributions. The simplified mean analysis affects the fiber stress-strain relation, resulting in incorrect estimation of mechanical parameters, which underscores the need for measurements of fiber distribution for a rigorous analysis of fiber mechanics. The validated structure-based model of coronary adventitia provides a deeper understanding of vascular mechanics in health and can be extended to disease conditions.
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Affiliation(s)
- Huan Chen
- California Medical Innovations Institute, Incorporated, San Diego, California
| | - Xiaomei Guo
- California Medical Innovations Institute, Incorporated, San Diego, California
| | - Tong Luo
- California Medical Innovations Institute, Incorporated, San Diego, California
| | - Ghassan S Kassab
- California Medical Innovations Institute, Incorporated, San Diego, California
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Multi-scale Modeling of the Cardiovascular System: Disease Development, Progression, and Clinical Intervention. Ann Biomed Eng 2016; 44:2642-60. [PMID: 27138523 DOI: 10.1007/s10439-016-1628-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 04/22/2016] [Indexed: 12/19/2022]
Abstract
Cardiovascular diseases (CVDs) are the leading cause of death in the western world. With the current development of clinical diagnostics to more accurately measure the extent and specifics of CVDs, a laudable goal is a better understanding of the structure-function relation in the cardiovascular system. Much of this fundamental understanding comes from the development and study of models that integrate biology, medicine, imaging, and biomechanics. Information from these models provides guidance for developing diagnostics, and implementation of these diagnostics to the clinical setting, in turn, provides data for refining the models. In this review, we introduce multi-scale and multi-physical models for understanding disease development, progression, and designing clinical interventions. We begin with multi-scale models of cardiac electrophysiology and mechanics for diagnosis, clinical decision support, personalized and precision medicine in cardiology with examples in arrhythmia and heart failure. We then introduce computational models of vasculature mechanics and associated mechanical forces for understanding vascular disease progression, designing clinical interventions, and elucidating mechanisms that underlie diverse vascular conditions. We conclude with a discussion of barriers that must be overcome to provide enhanced insights, predictions, and decisions in pre-clinical and clinical applications.
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Chen H, Zhao X, Berwick ZC, Krieger JF, Chambers S, Kassab GS. Microstructure and Mechanical Property of Glutaraldehyde-Treated Porcine Pulmonary Ligament. J Biomech Eng 2016; 138:061003. [PMID: 27040732 DOI: 10.1115/1.4033300] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Indexed: 01/15/2023]
Abstract
There is a significant need for fixed biological tissues with desired structural and material constituents for tissue engineering applications. Here, we introduce the lung ligament as a fixed biological material that may have clinical utility for tissue engineering. To characterize the lung tissue for potential clinical applications, we studied glutaraldehyde-treated porcine pulmonary ligament (n = 11) with multiphoton microscopy (MPM) and conducted biaxial planar experiments to characterize the mechanical property of the tissue. The MPM imaging revealed that there are generally two families of collagen fibers distributed in two distinct layers: The first family largely aligns along the longitudinal direction with a mean angle of θ = 10.7 ± 9.3 deg, while the second one exhibits a random distribution with a mean θ = 36.6 ± 27.4. Elastin fibers appear in some intermediate sublayers with a random orientation distribution with a mean θ = 39.6 ± 23 deg. Based on the microstructural observation, a microstructure-based constitutive law was proposed to model the elastic property of the tissue. The material parameters were identified by fitting the model to the biaxial stress-strain data of specimens, and good fitting quality was achieved. The parameter e0 (which denotes the strain beyond which the collagen can withstand tension) of glutaraldehyde-treated tissues demonstrated low variability implying a relatively consistent collagen undulation in different samples, while the stiffness parameters for elastin and collagen fibers showed relatively greater variability. The fixed tissues presented a smaller e0 than that of fresh specimen, confirming that glutaraldehyde crosslinking increases the mechanical strength of collagen-based biomaterials. The present study sheds light on the biomechanics of glutaraldehyde-treated porcine pulmonary ligament that may be a candidate for tissue engineering.
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Chow MJ, Turcotte R, Lin CP, Zhang Y. Arterial extracellular matrix: a mechanobiological study of the contributions and interactions of elastin and collagen. Biophys J 2015; 106:2684-92. [PMID: 24940786 DOI: 10.1016/j.bpj.2014.05.014] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 03/04/2014] [Accepted: 05/05/2014] [Indexed: 01/01/2023] Open
Abstract
The complex network structure of elastin and collagen extracellular matrix (ECM) forms the primary load bearing components in the arterial wall. The structural and mechanobiological interactions between elastin and collagen are important for properly functioning arteries. Here, we examined the elastin and collagen organization, realignment, and recruitment by coupling mechanical loading and multiphoton imaging. Two-photon excitation fluorescence and second harmonic generation methods were performed with a multiphoton video-rate microscope to capture real time changes to the elastin and collagen structure during biaxial deformation. Enzymatic removal of elastin was performed to assess the structural changes of the remaining collagen structure. Quantitative analysis of the structural changes to elastin and collagen was made using a combination of two-dimensional fast Fourier transform and fractal analysis, which allows for a more complete understanding of structural changes. Our study provides new quantitative evidence, to our knowledge on the sequential engagement of different arterial ECM components in response to mechanical loading. The adventitial collagen exists as large wavy bundles of fibers that exhibit fiber engagement after 20% strain. The medial collagen is engaged throughout the stretching process, and prominent elastic fiber engagement is observed up to 20% strain after which the engagement plateaus. The fiber orientation distribution functions show remarkably different changes in the ECM structure in response to mechanical loading. The medial collagen shows an evident preferred circumferential distribution, however the fiber families of adventitial collagen are obscured by their waviness at no or low mechanical strains. Collagen fibers in both layers exhibit significant realignment in response to unequal biaxial loading. The elastic fibers are much more uniformly distributed and remained relatively unchanged due to loading. Removal of elastin produces similar structural changes in collagen as mechanical loading. Our study suggests that the elastic fibers are under tension and impart an intrinsic compressive stress on the collagen.
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Affiliation(s)
- Ming-Jay Chow
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts
| | - Raphaël Turcotte
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts; Center for Systems Biology, Advanced Microscopy Program, Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Charles P Lin
- Center for Systems Biology, Advanced Microscopy Program, Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, Boston, Massachusetts; Department of Biomedical Engineering, Boston University, Boston, Massachusetts.
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