1
|
Gorbenko N, Vaccaro JC, Fagan R, Cerro RA, Khorrami JM, Galindo L, Merna N. Perfusion Bioreactor Conditioning of Small-diameter Plant-based Vascular Grafts. Tissue Eng Regen Med 2024:10.1007/s13770-024-00670-0. [PMID: 39354262 DOI: 10.1007/s13770-024-00670-0] [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: 06/28/2024] [Revised: 08/21/2024] [Accepted: 08/26/2024] [Indexed: 10/03/2024] Open
Abstract
BACKGROUND Vascular grafts are mainly composed of synthetic materials, but are prone to thrombosis and intimal hyperplasia at small diameters. Decellularized plant scaffolds have emerged that provide promising alternatives for tissue engineering. We previously developed robust, endothelialized small-diameter vessels from decellularized leatherleaf viburnum. This is the first study to precondition and analyze plant-based vessels under physiological fluid flow and pressure waveforms. Using decellularized leatherleaf viburnum as tissue-engineered grafts for implantation can have profound impacts on healthcare due to their biocompatibility and cost-effective production. METHODS A novel perfusion bioreactor was designed, capable of accurately controlling fluid flow rate and pressure waveforms for preconditioning of small-diameter vascular grafts. A closed-loop system controlled pressure waveforms, mimicking physiological values of 50-120 mmHg at a frequency of 8.75 Hz for fluid flow reaching 5 mL/min. Plant-based vascular grafts were recellularized with endothelial and vascular smooth muscle cells and cultured for up to 3 weeks in this bioreactor. Cell density, scaffold structure and mechanics, thrombogenicity, and immunogenicity of grafts were evaluated. RESULTS Bioreactor treatment with fluid flow significantly increased luminal endothelial cell density, while pressure waveforms reduced thrombus formation and maintained viable vascular smooth muscle cells within inner layers of grafts compared to static controls. Suture retention of grafts met transplantation standards and white cell viability was suitable for vascular remodeling. CONCLUSION Low thrombogenicity of endothelialized leatherleaf viburnum holds great potential for vascular repair. This study provides insight into benefits of conditioning plant-based materials with hemodynamic forces at higher frequencies that have not previously been investigated.
Collapse
Affiliation(s)
- Nicole Gorbenko
- Bioengineering Program, Fred DeMatteis School of Engineering and Applied Science, Hofstra University, 229 Science and Innovation Center, Hempstead, NY, 11549, USA
| | - John C Vaccaro
- Mechanical Engineering Program, Fred DeMatteis School of Engineering and Applied Science, Hofstra University, 200B Weed Hall, Hempstead, NY, 11549, USA
| | - Ryan Fagan
- Bioengineering Program, Fred DeMatteis School of Engineering and Applied Science, Hofstra University, 229 Science and Innovation Center, Hempstead, NY, 11549, USA
| | - Robert A Cerro
- Fred DeMatteis School of Engineering and Applied Science, Hofstra University, 016 Adams Hall, Hempstead, NY, 11549, USA
| | - Jonah M Khorrami
- Bioengineering Program, Fred DeMatteis School of Engineering and Applied Science, Hofstra University, 229 Science and Innovation Center, Hempstead, NY, 11549, USA
| | - Lucia Galindo
- Bioengineering Program, Fred DeMatteis School of Engineering and Applied Science, Hofstra University, 229 Science and Innovation Center, Hempstead, NY, 11549, USA
| | - Nick Merna
- Bioengineering Program, Fred DeMatteis School of Engineering and Applied Science, Hofstra University, 229 Science and Innovation Center, Hempstead, NY, 11549, USA.
| |
Collapse
|
2
|
Patrawalla NY, Raj R, Nazar V, Kishore V. Magnetic Alignment of Collagen: Principles, Methods, Applications, and Fiber Alignment Analyses. TISSUE ENGINEERING. PART B, REVIEWS 2024; 30:405-422. [PMID: 38019048 PMCID: PMC11404687 DOI: 10.1089/ten.teb.2023.0222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
Anisotropically aligned collagen scaffolds mimic the microarchitectural properties of native tissue, possess superior mechanical properties, and provide the essential physicochemical cues to guide cell response. Biofabrication methodologies to align collagen fibers include mechanical, electrical, magnetic, and microfluidic approaches. Magnetic alignment of collagen was first published in 1983 but widespread use of this technique was hindered mainly due to the low diamagnetism of collagen molecules and the need for very strong tesla-order magnetic fields. Over the last decade, there is a renewed interest in the use of magnetic approaches that employ magnetic particles and low-level magnetic fields to align collagen fibers. In this review, the working principle, advantages, and limitations of different collagen alignment techniques with special emphasis on the magnetic alignment approach are detailed. Key findings from studies that employ high-strength magnetic fields and the magnetic particle-based approach to align collagen fibers are highlighted. In addition, the most common qualitative and quantitative image analyses methods to assess collagen alignment are discussed. Finally, current challenges and future directions are presented for further development and clinical translation of magnetically aligned collagen scaffolds.
Collapse
Affiliation(s)
- Nashaita Y Patrawalla
- Department of Biomedical Engineering and Sciences, Florida Institute of Technology, Melbourne, Florida, USA
| | - Ravi Raj
- Department of Biomedical Engineering and Sciences, Florida Institute of Technology, Melbourne, Florida, USA
| | - Vida Nazar
- Department of Bioengineering, Clemson University, Clemson, South Carolina, USA
| | - Vipuil Kishore
- Department of Chemistry and Chemical Engineering, Florida Institute of Technology, Melbourne, Florida, USA
| |
Collapse
|
3
|
Wang X, Li K, Yuan Y, Zhang N, Zou Z, Wang Y, Yan S, Li X, Zhao P, Li Q. Nonlinear Elasticity of Blood Vessels and Vascular Grafts. ACS Biomater Sci Eng 2024; 10:3631-3654. [PMID: 38815169 DOI: 10.1021/acsbiomaterials.4c00326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
The transplantation of vascular grafts has emerged as a prevailing approach to address vascular disorders. However, the development of small-diameter vascular grafts is still in progress, as they serve in a more complicated mechanical environment than their counterparts with larger diameters. The biocompatibility and functional characteristics of small-diameter vascular grafts have been well developed; however, mismatch in mechanical properties between the vascular grafts and native arteries has not been accomplished, which might facilitate the long-term patency of small-diameter vascular grafts. From a point of view in mechanics, mimicking the nonlinear elastic mechanical behavior exhibited by natural blood vessels might be the state-of-the-art in designing vascular grafts. This review centers on elucidating the nonlinear elastic behavior of natural blood vessels and vascular grafts. The biological functionality and limitations associated with as-reported vascular grafts are meticulously reviewed and the future trajectory for fabricating biomimetic small-diameter grafts is discussed. This review might provide a different insight from the traditional design and fabrication of artificial vascular grafts.
Collapse
Affiliation(s)
- Xiaofeng Wang
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
- The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, China
| | - Kecheng Li
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Yuan Yuan
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Ning Zhang
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Zifan Zou
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Yun Wang
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Shujie Yan
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Xiaomeng Li
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
| | - Peng Zhao
- The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310027, China
| | - Qian Li
- School of Mechanics and Safety Engineering, National Center for International Research of Micro-nano Molding Technology, Zhengzhou University, Zhengzhou 450001, China
| |
Collapse
|
4
|
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.
Collapse
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.
| |
Collapse
|
5
|
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.
Collapse
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.
| |
Collapse
|
6
|
Karimi A, Rahmati SM, Razaghi R, Crawford Downs J, Acott TS, Wang RK, Johnstone M. Biomechanics of human trabecular meshwork in healthy and glaucoma eyes via dynamic Schlemm's canal pressurization. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 221:106921. [PMID: 35660943 PMCID: PMC10424782 DOI: 10.1016/j.cmpb.2022.106921] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 05/17/2022] [Accepted: 05/26/2022] [Indexed: 05/27/2023]
Abstract
BACKGROUND AND OBJECTIVE The trabecular meshwork (TM) consists of extracellular matrix (ECM) with embedded collagen and elastin fibers providing its mechanical support. TM stiffness is considerably higher in glaucoma eyes. Emerging data indicates that the TM moves dynamically with transient intraocular pressure (IOP) fluctuations, implying the viscoelastic mechanical behavior of the TM. However, little is known about TM viscoelastic behavior. We calculated the viscoelastic mechanical properties of the TM in n = 2 healthy and n = 2 glaucoma eyes. METHODS A quadrant of the anterior segment was submerged in a saline bath, and a cannula connected to an adjustable saline reservoir was inserted into Schlemm's canal (SC). A spectral domain-OCT (SD-OCT) provided continuous cross-sectional B-scans of the TM/JCT/SC complex during pressure oscillation from 0 to 30 mmHg at two locations. The TM/JCT/SC complex boundaries were delineated to construct a 20-µm-thick volume finite element (FE) mesh. Pre-tensioned collagen and elastin fibrils were embedded in the model using a mesh-free penalty-based cable-in-solid algorithm. SC pressure was represented by a position- and time-dependent pressure boundary; floating boundary conditions were applied to the other cut edges of the model. An FE-optimization algorithm was used to adjust the ECM/fiber mechanical properties such that the TM/JCT/SC model and SD-OCT imaging data best matched over time. RESULTS Significantly larger short- and long-time ECM shear moduli (p = 0.0032), and collagen (1.82x) and elastin (2.72x) fibril elastic moduli (p = 0.0001), were found in the TM of glaucoma eyes compared to healthy controls. CONCLUSIONS These findings provide additional clarity on the mechanical property differences in healthy and glaucomatous outflow pathway under dynamic loading. Understanding the viscoelastic properties of the TM may serve as a new biomarker in early diagnosis of glaucoma.
Collapse
Affiliation(s)
- Alireza Karimi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA.
| | | | - Reza Razaghi
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - J Crawford Downs
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA.
| | - Ted S Acott
- Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA.
| | - Ruikang K Wang
- Department of Ophthalmology, University of Washington, Seattle, WA, USA; Department of Bioengineering, University of Washington, Seattle, WA, USA.
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, WA, USA.
| |
Collapse
|
7
|
Linka K, Cavinato C, Humphrey JD, Cyron CJ. Predicting and understanding arterial elasticity from key microstructural features by bidirectional deep learning. Acta Biomater 2022; 147:63-72. [PMID: 35643194 DOI: 10.1016/j.actbio.2022.05.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/19/2022] [Accepted: 05/19/2022] [Indexed: 01/15/2023]
Abstract
Microstructural features and mechanical properties are closely related in all soft biological tissues. Both yet exhibit considerable inter-individual differences and are affected by factors such as aging and disease and its progression. Histological analysis, modern in situ imaging, and biomechanical testing have deepened our understanding of these complex interrelations, yet two key questions remain: (1) Given the specific microstructure, can one predict the macroscopic mechanical properties without mechanical testing? (2) Can one quantify individual contributions of the different microstructural features to the macroscopic mechanical properties in an automated, systematic and largely unbiased way? Here we propose a bidirectional deep learning architecture to address these two questions. Our architecture uses data from standard histological analyses, two-photon microscopy and biaxial biomechanical testing. Its capabilities are demonstrated by predicting with high accuracy (R2=0.92) the evolving mechanical properties of the murine aorta during maturation and aging. Moreover, our architecture reveals that the extracellular matrix composition and organization are the most prominent factors governing the macroscopic mechanical properties of the tissues studied herein. STATEMENT OF SIGNIFICANCE: .
Collapse
Affiliation(s)
- Kevin Linka
- Institute for Continuum and Material Mechanics, Hamburg University of Technology, Hamburg, Germany
| | - Cristina Cavinato
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA
| | - Christian J Cyron
- Institute for Continuum and Material Mechanics, Hamburg University of Technology, Hamburg, Germany; Institute of Material Systems Modeling, Helmholtz-Zentrum Hereon, Geesthacht, Germany.
| |
Collapse
|
8
|
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: 9] [Impact Index Per Article: 4.5] [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.
Collapse
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
| |
Collapse
|
9
|
Tuttle TG, Lujan HL, Tykocki NR, DiCarlo SE, Roccabianca S. Remodeling of extracellular matrix in the urinary bladder of paraplegic rats results in increased compliance and delayed fiber recruitment 16 weeks after spinal cord injury. Acta Biomater 2022; 141:280-289. [PMID: 35032719 PMCID: PMC8898290 DOI: 10.1016/j.actbio.2022.01.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 12/17/2021] [Accepted: 01/07/2022] [Indexed: 01/21/2023]
Abstract
The ability of the urinary bladder to maintain low intravesical pressures while storing urine is key in ensuring proper organ function and highlights the key role that tissue mechanics plays in the lower urinary tract. Loss of supraspinal neuronal connections to the bladder after spinal cord injury can lead to remodeling of the structure of the bladder wall, which may alter its mechanical characteristics. In this study, we investigate if the morphology and mechanical properties of the bladder extracellular matrix are altered in rats 16 weeks after spinal cord injury as compared to animals who underwent sham surgery. We measured and quantified the changes in bladder geometry and mechanical behavior using histological analysis, tensile testing, and constitutive modeling. Our results suggest bladder compliance is increased in paraplegic animals 16 weeks post-injury. Furthermore, constitutive modeling showed that increased distensibility was driven by an increase in collagen fiber waviness, which altered the distribution of fiber recruitment during loading. STATEMENT OF SIGNIFICANCE: The ability of the urinary bladder to store urine under low pressure is key in ensuring proper organ function. This highlights the important role that mechanics plays in the lower urinary tract. Loss of control of neurologic connection to the bladder from spinal cord injury can lead to changes of the structure of the bladder wall, resulting in altered mechanical characteristics. We found that the bladder wall's microstructure in rats 16 weeks after spinal cord injury is more compliant than in healthy animals. This is significant since it is the longest time post-injury analyzed, to date. Understanding the extreme remodeling capabilities of the bladder in pathological conditions is key to inform new possible therapies.
Collapse
Affiliation(s)
- Tyler G Tuttle
- Michigan State University, Department of Mechanical Engineering, 428 S. Shaw Lane, Rm 2555, East Lansing, MI 48824, United States
| | - Heidi L Lujan
- Michigan State University, Department of Physiology, 567 Wilson Rd., Rm 2201, East Lansing, MI 48824, United States
| | - Nathan R Tykocki
- Michigan State University, Department of Pharmacology and Toxicology, 1355 Bogue St., B436 Life Science Building, East Lansing, MI 48824, United States
| | - Stephen E DiCarlo
- Michigan State University, Department of Physiology, 567 Wilson Rd., Rm 2201, East Lansing, MI 48824, United States
| | - Sara Roccabianca
- Michigan State University, Department of Mechanical Engineering, 428 S. Shaw Lane, Rm 2555, East Lansing, MI 48824, United States.
| |
Collapse
|
10
|
Tuttle TG, Morhardt DR, Poli AA, Park JM, Arruda EM, Roccabianca S. Investigation of Fiber-Driven Mechanical Behavior of Human and Porcine Bladder Tissue Tested Under Identical Conditions. J Biomech Eng 2021; 143:111007. [PMID: 34159357 DOI: 10.1115/1.4051525] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Indexed: 11/08/2022]
Abstract
The urinary bladder is a highly dynamic organ that undergoes large deformations several times per day. Mechanical characteristics of the tissue are crucial in determining the function and dysfunction of the organ. Yet, literature reporting on the mechanical properties of human bladder tissue is scarce and, at times, contradictory. In this study, we focused on mechanically testing tissue from both human and pig bladders using identical protocols to validate the use of pigs as a model for the human bladder. Furthermore, we tested the effect of two treatments on tissue mechanical properties. Namely, elastase to digest elastin fibers, and oxybutynin to reduce smooth muscle cell spasticity. Additionally, mechanical properties based on the anatomical direction of testing were evaluated. We implemented two different material models to aid in the interpretation of the experimental results. We found that human tissue behaves similarly to pig tissue at high deformations (collagen-dominated behavior) while we detected differences between the species at low deformations (amorphous matrix-dominated behavior). Our results also suggest that elastin could play a role in determining the behavior of the fiber network. Finally, we confirmed the anisotropy of the tissue, which reached higher stresses in the transverse direction when compared to the longitudinal direction.
Collapse
Affiliation(s)
- Tyler G Tuttle
- Mechanical Engineering Department, Michigan State University, 474 S. Shaw Lane, East Lansing, MI 48824
| | - Duncan R Morhardt
- Department of Urology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115
| | - Andrea A Poli
- Mechanical Engineering Department, University of Michigan, 2350 Hayward Street, Ann Arbor, MI 48109
| | - John M Park
- Department of Urology, Michigan Medicine, 1500 E. Medical Drive, Ann Arbor, MI 48019
| | - Ellen M Arruda
- Mechanical Engineering Department, University of Michigan, 2350 Hayward Street, Ann Arbor, MI 48109
| | - Sara Roccabianca
- Mechanical Engineering Department, Michigan State University, 474 S. Shaw Lane, East Lansing, MI 48824
| |
Collapse
|
11
|
Decellularized dermis extracellular matrix alloderm mechanically strengthens biological engineered tunica adventitia-based blood vessels. Sci Rep 2021; 11:11384. [PMID: 34059745 PMCID: PMC8166942 DOI: 10.1038/s41598-021-91005-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 05/20/2021] [Indexed: 11/29/2022] Open
Abstract
The ideal engineered vascular graft would utilize human-derived materials to minimize foreign body response and tissue rejection. Current biological engineered blood vessels (BEBVs) inherently lack the structure required for implantation. We hypothesized that an ECM material would provide the structure needed. Skin dermis ECM is commonly used in reconstructive surgeries, is commercially available and FDA-approved. We evaluated the commercially-available decellularized skin dermis ECM Alloderm for efficacy in providing structure to BEBVs. Alloderm was incorporated into our lab’s unique protocol for generating BEBVs, using fibroblasts to establish the adventitia. To assess structure, tissue mechanics were analyzed. Standard BEBVs without Alloderm exhibited a tensile strength of 67.9 ± 9.78 kPa, whereas Alloderm integrated BEBVs showed a significant increase in strength to 1500 ± 334 kPa. In comparison, native vessel strength is 1430 ± 604 kPa. Burst pressure reached 51.3 ± 2.19 mmHg. Total collagen and fiber maturity were significantly increased due to the presence of the Alloderm material. Vessels cultured for 4 weeks maintained mechanical and structural integrity. Low probability of thrombogenicity was confirmed with a negative platelet adhesion test. Vessels were able to be endothelialized. These results demonstrate the success of Alloderm to provide structure to BEBVs in an effective way.
Collapse
|
12
|
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.
Collapse
|
13
|
Kostelnik CJ, Crouse KJ, Carver W, Eberth JF. Longitudinal histomechanical heterogeneity of the internal thoracic artery. J Mech Behav Biomed Mater 2021; 116:104314. [PMID: 33476887 DOI: 10.1016/j.jmbbm.2021.104314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 12/10/2020] [Accepted: 01/03/2021] [Indexed: 11/16/2022]
Abstract
The internal thoracic artery (ITA) is the principal choice for coronary artery bypass grafting (CABG) due to its mechanical compatibility, histological composition, anti-thrombogenic lumen, and single anastomotic junction. Originating at the subclavian artery, traversing the thoracic cavity, and terminating at the superior epigastric and musculophrenic bifurcation, bilateral ITAs follow a protracted circuitous pathway. The physiological hemodynamics, anatomical configuration, and perivascular changes that occur throughout this length influence the tissue's microstructure and gross mechanical properties. Since histomechanics play a major role in premature graft failure we used inflation-extension testing to quantify the regional material and biaxial mechanical properties at four distinct locations along the left (L) and right (R) ITA and fit the results to a structurally-motivated constitutive model. Our comparative analysis of 44 vessel segments revealed a significant increase in the amount of collagen but not smooth muscle and a significant decrease in elastin and elastic lamellae present with distance from the heart. A subsequent decrease in the total deformation energy and isotropic contribution to the strain energy was present in the LITA but not RITA. Circumferential stress and compliance generally decreased along the length of the LITA while axial stress increased in the RITA. When comparing RITAs to LITAs, some morphological and histological differences were found in proximal sections while distal sections revealed differences predominantly in compliance and axial stress. Overall, this information can be used to better guide graft selection, graft preparation, and xenograft-based tissue-engineering strategies for CABG.
Collapse
Affiliation(s)
- Colton J Kostelnik
- Biomedical Engineering Program, University of South Carolina, Columbia, SC, USA
| | - Kiersten J Crouse
- Mechanical Engineering Department, University of South Carolina, Columbia, SC, USA
| | - Wayne Carver
- Cell Biology and Anatomy Department, University of South Carolina, Columbia, SC, USA
| | - John F Eberth
- Biomedical Engineering Program, University of South Carolina, Columbia, SC, USA; Cell Biology and Anatomy Department, University of South Carolina, Columbia, SC, USA.
| |
Collapse
|
14
|
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.
Collapse
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.
| |
Collapse
|
15
|
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]
|
16
|
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]
|
17
|
Li Y, McPhee IC, Lau MPH, Pease LF. Biomimetic surgical mesh to replace fascia with tunable force-displacement. J Theor Biol 2019; 486:110058. [PMID: 31678097 DOI: 10.1016/j.jtbi.2019.110058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 10/27/2019] [Accepted: 10/29/2019] [Indexed: 10/25/2022]
Abstract
Here we mimic the mechanical properties of native fascia to design surgical mesh for fascia replacement. Despite the widespread acceptance of synthetic materials as tissue scaffolds for pelvic floor disorders, mechanical property mismatch between mesh and adjacent native tissue drives fibrosis and erosion, leading the FDA to remove several surgical meshes from the market. However, autologous tissue does not induce either fibrosis or adjacent tissue erosion, suggesting the potential for biomimetic surgical mesh. In this study, we determined the design rules for mesh that mimics native fascia by mathematically modeling multi-component polymer networks, composed of elastin-like and collagen-like fibers, using a spring-network model. To validate the model, we measured the stress-strain curves of native bovine and nonhuman primate (Macaca mulatta) abdominal fascia in both toe and linear regions. We find that the stiffer collagen-like fibers must remain limp until the elastin-like fibers extend to the initial length of spanning collagen-like fibers under uniaxial tension. Comparing model results to experiment determines the product of fiber volume fraction and elastic modulus, a critical design parameter. Dual fiber mesh with mechanical properties that mimic fascia are feasible. These results have broad application to a wide range of soft tissue replacements including ~200,000 surgeries/year for pelvic floor disorders, because standard-of-care mesh contain only stiffer polymers that behave more like collagen than native tissue.
Collapse
Affiliation(s)
- Yuan Li
- Department of Chemical Engineering, College of Engineering, University of Utah, 50 S. Central Campus Drive, 3290 Merrill Engineering Building, Salt Lake City, UT 84112, USA
| | - Ian C McPhee
- Department of Chemical Engineering, College of Engineering, University of Utah, 50 S. Central Campus Drive, 3290 Merrill Engineering Building, Salt Lake City, UT 84112, USA
| | - Michael P H Lau
- Novo Contour, 7015 147th Street. SW, Edmonds, WA 98026, USA; Total Women's Health, 7500 212th Street. SW, Suite 214, Edmonds, WA 98026, USA
| | - Leonard F Pease
- Department of Chemical Engineering, College of Engineering, University of Utah, 50 S. Central Campus Drive, 3290 Merrill Engineering Building, Salt Lake City, UT 84112, USA; Novo Contour, 7015 147th Street. SW, Edmonds, WA 98026, USA; Department of Internal Medicine, Division of Gastroenterology, School of Medicine, University of Utah, 30 N. 1900 E., Salt Lake City, UT 84132, USA; Department of Pharmaceutics & Pharmaceutical Chemistry, College of Pharmacy, University of Utah, 30 S. 2000 E., Salt Lake City, UT 84112, USA.
| |
Collapse
|
18
|
Ayyalasomayajula V, Pierrat B, Badel P. A computational model for understanding the micro-mechanics of collagen fiber network in the tunica adventitia. Biomech Model Mechanobiol 2019; 18:1507-1528. [PMID: 31065952 PMCID: PMC6748894 DOI: 10.1007/s10237-019-01161-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 04/26/2019] [Indexed: 12/11/2022]
Abstract
Abdominal aortic aneurysm is a prevalent cardiovascular disease with high mortality rates. The mechanical response of the arterial wall relies on the organizational and structural behavior of its microstructural components, and thus, a detailed understanding of the microscopic mechanical response of the arterial wall layers at loads ranging up to rupture is necessary to improve diagnostic techniques and possibly treatments. Following the common notion that adventitia is the ultimate barrier at loads close to rupture, in the present study, a finite element model of adventitial collagen network was developed to study the mechanical state at the fiber level under uniaxial loading. Image stacks of the rabbit carotid adventitial tissue at rest and under uniaxial tension obtained using multi-photon microscopy were used in this study, as well as the force-displacement curves obtained from previously published experiments. Morphological parameters like fiber orientation distribution, waviness, and volume fraction were extracted for one sample from the confocal image stacks. An inverse random sampling approach combined with a random walk algorithm was employed to reconstruct the collagen network for numerical simulation. The model was then verified using experimental stress-stretch curves. The model shows the remarkable capacity of collagen fibers to uncrimp and reorient in the loading direction. These results further show that at high stretches, collagen network behaves in a highly non-affine manner, which was quantified for each sample. A comprehensive parameter study to understand the relationship between structural parameters and their influence on mechanical behavior is presented. Through this study, the model was used to conclude important structure-function relationships that control the mechanical response. Our results also show that at loads close to rupture, the probability of failure occurring at the fiber level is up to 2%. Uncertainties in usually employed rupture risk indicators and the stochastic nature of the event of rupture combined with limited knowledge on the microscopic determinants motivate the development of such an analysis. Moreover, this study will advance the study of coupling microscopic mechanisms to rupture of the artery as a whole.
Collapse
Affiliation(s)
- Venkat Ayyalasomayajula
- Mines Saint-Étienne, Univ Lyon, Univ Jean Monnet, INSERM, U1059 SAINBIOSE, Centre CIS, 42023, Saint-Étienne, France.
| | - Baptiste Pierrat
- Mines Saint-Étienne, Univ Lyon, Univ Jean Monnet, INSERM, U1059 SAINBIOSE, Centre CIS, 42023, Saint-Étienne, France
| | - Pierre Badel
- Mines Saint-Étienne, Univ Lyon, Univ Jean Monnet, INSERM, U1059 SAINBIOSE, Centre CIS, 42023, Saint-Étienne, France
| |
Collapse
|
19
|
Wells HC, Sizeland KH, Kirby N, Hawley A, Mudie S, Cunningham CW, Haverkamp RG. Measured collagen fibril response to arterial inflation using SAXS. Int J Biol Macromol 2019; 137:1020-1029. [DOI: 10.1016/j.ijbiomac.2019.07.061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 07/05/2019] [Accepted: 07/07/2019] [Indexed: 12/11/2022]
|
20
|
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.
Collapse
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
| |
Collapse
|
21
|
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.
Collapse
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.
| |
Collapse
|
22
|
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.
Collapse
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
| |
Collapse
|
23
|
Mredha MTI, Tran VT, Jeong SG, Seon JK, Jeon I. A diffusion-driven fabrication technique for anisotropic tubular hydrogels. SOFT MATTER 2018; 14:7706-7713. [PMID: 30187062 DOI: 10.1039/c8sm01235k] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A bio-inspired, simple, and versatile diffusion-driven method to fabricate complex tubular hydrogels is reported. The controlled diffusion of small ions from a pre-designed core hydrogel through a biopolymer reservoir solution causes the self-gelation of biopolymers with an anisotropic ordered structure on the surface of the core hydrogel. By controlling the concentration, diffusion time, and flow direction of the ions, as well as the size and shape of the core, various types of complex tubular-shaped hydrogels with well-defined 3D architectures were fabricated. The mechanical properties of the designed alginate-based tubular hydrogels were highly tunable and comparable to those of native blood vessels. The method was applied to form a living-cell encapsulated tubular hydrogel, which further strengthens its potential for biomedical applications. The method is suitable for biopolymer-based reaction-diffusion systems and available for further research on the fabrication of functional biomaterials with various biopolymers.
Collapse
Affiliation(s)
- Md Tariful Islam Mredha
- School of Mechanical Engineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 61186, Republic of Korea.
| | | | | | | | | |
Collapse
|
24
|
Marino M, Pontrelli G, Vairo G, Wriggers P. A chemo-mechano-biological formulation for the effects of biochemical alterations on arterial mechanics: the role of molecular transport and multiscale tissue remodelling. J R Soc Interface 2018; 14:rsif.2017.0615. [PMID: 29118114 DOI: 10.1098/rsif.2017.0615] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/11/2017] [Indexed: 12/21/2022] Open
Abstract
This paper presents a chemo-mechano-biological framework for arterial physiopathology. The model accounts for the fine remodelling in the multiscale hierarchical arrangement of tissue constituents and for the diffusion of molecular species involved in cell-cell signalling pathways. Effects in terms of alterations in arterial compliance are obtained. A simple instructive example is introduced. Although oversimplified with respect to realistic case studies, the proposed application mimics the biochemical activity of matrix metalloproteinases, transforming growth factors beta and interleukins on tissue remodelling. Effects of macrophage infiltration, of intimal thickening and of a healing phase are investigated, highlighting the corresponding influence on arterial compliance. The obtained results show that the present approach is able to capture changes in arterial mechanics as a consequence of the alterations in tissue biochemical environment and cellular activity, as well as to incorporate the protective role of both autoimmune responses and pharmacological treatments.
Collapse
Affiliation(s)
- Michele Marino
- Institut für Kontinuumsmechanik, Leibniz Universität Hannover, Hannover, Germany
| | - Giuseppe Pontrelli
- Istituto per le Applicazioni del Calcolo, National Research Council (CNR), Rome, Italy
| | - Giuseppe Vairo
- Dipartimento di Ingegneria Civile e Ingegneria Informatica, Università degli Studi di Roma 'Tor Vergata', Rome, Italy
| | - Peter Wriggers
- Institut für Kontinuumsmechanik, Leibniz Universität Hannover, Hannover, Germany
| |
Collapse
|
25
|
Frye JN, Sutterfield SL, Caldwell JT, Behnke BJ, Copp SW, Banister HR, Ade CJ. Vascular and autonomic changes in adult cancer patients receiving anticancer chemotherapy. J Appl Physiol (1985) 2018; 125:198-204. [PMID: 29565770 DOI: 10.1152/japplphysiol.00005.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Chemotherapy is associated with acute and long-term cardiotoxicity. To date, risk assessment has primarily focused on the heart; however, recent findings suggest that vascular and autonomic function may also be compromised. Whether this occurs during chemotherapy treatment remains unknown. Therefore, the present study evaluated carotid artery stiffness, cardiovagal baroreflex sensitivity (cBRS), and heart rate variability (HRV) in cancer patients currently being treated with adjuvant chemotherapy. Eleven current cancer patients receiving adjuvant chemotherapy and 11 matched (1:1) controls were studied. Carotid artery stiffness was assessed via two-dimensional ultrasonography. cBRS was assessed from the spontaneous changes in beat-to-beat time series of R-R interval and systolic blood pressure via the cross-correlation technique. HRV was assessed using the standard deviation of R-R intervals (SDNN) and low (LF) and high (HF) power frequencies. Carotid artery β-stiffness was significantly higher in the cancer patients compared with control participants (8.0 ± 0.8 vs. 6.3 ± 0.6 U, respectively; P = 0.02). cBRS was lower in the cancer patients compared with controls (4.3 ± 0.7 vs. 10.7 ± 1.9 ms/mmHg, respectively; P = 0.01), and all indices of HRV were lower in the cancer patients (SDNN, P = 0.02; LF, P = 0.01; HF, P = 0.02). There was no significant correlation between β-stiffness and cBRS ( P = 0.4). However, LF power was significantly correlated with cBRS (r = 0.66, P < 0.001). Compared with matched healthy controls, cancer patients undergoing chemotherapy demonstrated a significantly higher arterial stiffness and lower cBRS. The previously reported adverse effects of chemotherapy on the heart appear to also influence other aspects of cardiovascular health. NEW & NOTEWORTHY Patients treated with anticancer chemotherapy exhibit an impaired baroreflex control of arterial blood pressure and increased arterial stiffness. These findings hold significant value, in particular as part of a risk-stratification strategy in current cancer patients receiving chemotherapy. This is the first investigation, to our knowledge, to demonstrate an attenuated spontaneous baroreflex control of arterial blood pressure in cancer patients currently undergoing chemotherapy.
Collapse
Affiliation(s)
- Jacob N Frye
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | | | - Jacob T Caldwell
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | - Bradley J Behnke
- Department of Kinesiology, Kansas State University , Manhattan, Kansas.,Johnson Cancer Research Center, Kansas State University , Manhattan, Kansas
| | - Steven W Copp
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
| | | | - Carl J Ade
- Department of Kinesiology, Kansas State University , Manhattan, Kansas.,Johnson Cancer Research Center, Kansas State University , Manhattan, Kansas
| |
Collapse
|
26
|
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.
Collapse
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
| |
Collapse
|
27
|
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]
|
28
|
Collagen fibre characterisation in arterial tissue under load using SALS. J Mech Behav Biomed Mater 2017; 75:359-368. [DOI: 10.1016/j.jmbbm.2017.07.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 07/13/2017] [Accepted: 07/25/2017] [Indexed: 01/06/2023]
|
29
|
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.
Collapse
|
30
|
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.
Collapse
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.
| |
Collapse
|
31
|
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.
Collapse
|
32
|
Robinson KG, Scott RA, Hesek AM, Woodford EJ, Amir W, Planchon TA, Kiick KL, Akins RE. Reduced arterial elasticity due to surgical skeletonization is ameliorated by abluminal PEG hydrogel. Bioeng Transl Med 2017; 2:222-232. [PMID: 28932820 PMCID: PMC5579730 DOI: 10.1002/btm2.10060] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 02/15/2017] [Accepted: 03/06/2017] [Indexed: 12/17/2022] Open
Abstract
Arteries for bypass grafting are harvested either with neighboring tissue attached or as skeletonized vessels that are free of surrounding tissue. There are significant benefits to skeletonization, but reports suggest that skeletonized vessels may develop structural defects and are at risk for atherosclerosis. We investigated the specific short‐term effects of skeletonization on carotid artery biomechanics and microanatomy in a rabbit model. Six carotid arteries were surgically skeletonized. To support healing, three of these received polyethylene glycol hydrogel injected along their exterior surfaces. M‐mode ultrasonography was used to track circumferential cyclic strain in the skeletonized, hydrogel‐treated, and contralateral vessels. On day 21, the arteries were harvested, and vessel structure was assessed by histology, immunofluorescence microscopy, two‐photon elastin autofluorescence, and second harmonic generation (SHG) microscopy. Intimal‐medial thickness appeared unaffected by skeletonization, but the SHG signals indicated significant changes in collagen turnover in the adventitia. Skeletonized arteries also exhibited significantly decreased radial compliance (circumferential cyclic strain dropped ∼30%) and decreased numbers of elastic laminae (9.1 ± 2.0 to 2.3 ± 1.4). Hydrogel treatment protected against these effects with treated vessels maintaining normal mechanical properties. These results indicate that arterial skeletonization triggers immediate effects on vessel remodeling and reduced vessel compliance resulting in specific tissue alterations within 21 days, but that these effects can be attenuated by the placement of hydrogel on the exterior surface of the skeletonized vessel.
Collapse
Affiliation(s)
- Karyn G Robinson
- Nemours - Alfred I. duPont Hospital for Children Wilmington DE1 9803
| | - Rebecca A Scott
- Nemours - Alfred I. duPont Hospital for Children Wilmington DE1 9803.,Dept. of Materials Science & Engineering University of Delaware Newark DE 19716
| | - Anne M Hesek
- Nemours - Alfred I. duPont Hospital for Children Wilmington DE1 9803
| | - Edward J Woodford
- Nemours - Alfred I. duPont Hospital for Children Wilmington DE1 9803
| | - Wafa Amir
- Dept. of Physics and Engineering, Optical Science Center for Applied Research Delaware State University Dover DE 19901
| | - Thomas A Planchon
- Dept. of Physics and Engineering, Optical Science Center for Applied Research Delaware State University Dover DE 19901
| | - Kristi L Kiick
- Nemours - Alfred I. duPont Hospital for Children Wilmington DE1 9803.,Dept. of Materials Science & Engineering University of Delaware Newark DE 19716.,Dept. of Biomedical Engineering University of Delaware Newark DE 19716
| | - Robert E Akins
- Nemours - Alfred I. duPont Hospital for Children Wilmington DE1 9803.,Dept. of Materials Science & Engineering University of Delaware Newark DE 19716.,Dept. of Biomedical Engineering University of Delaware Newark DE 19716
| |
Collapse
|
33
|
An agent-based model of leukocyte transendothelial migration during atherogenesis. PLoS Comput Biol 2017; 13:e1005523. [PMID: 28542193 PMCID: PMC5444619 DOI: 10.1371/journal.pcbi.1005523] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 04/15/2017] [Indexed: 01/07/2023] Open
Abstract
A vast amount of work has been dedicated to the effects of hemodynamics and cytokines on leukocyte adhesion and trans-endothelial migration (TEM) and subsequent accumulation of leukocyte-derived foam cells in the artery wall. However, a comprehensive mechanobiological model to capture these spatiotemporal events and predict the growth and remodeling of an atherosclerotic artery is still lacking. Here, we present a multiscale model of leukocyte TEM and plaque evolution in the left anterior descending (LAD) coronary artery. The approach integrates cellular behaviors via agent-based modeling (ABM) and hemodynamic effects via computational fluid dynamics (CFD). In this computational framework, the ABM implements the diffusion kinetics of key biological proteins, namely Low Density Lipoprotein (LDL), Tissue Necrosis Factor alpha (TNF-α), Interlukin-10 (IL-10) and Interlukin-1 beta (IL-1β), to predict chemotactic driven leukocyte migration into and within the artery wall. The ABM also considers wall shear stress (WSS) dependent leukocyte TEM and compensatory arterial remodeling obeying Glagov's phenomenon. Interestingly, using fully developed steady blood flow does not result in a representative number of leukocyte TEM as compared to pulsatile flow, whereas passing WSS at peak systole of the pulsatile flow waveform does. Moreover, using the model, we have found leukocyte TEM increases monotonically with decreases in luminal volume. At critical plaque shapes the WSS changes rapidly resulting in sudden increases in leukocyte TEM suggesting lumen volumes that will give rise to rapid plaque growth rates if left untreated. Overall this multi-scale and multi-physics approach appropriately captures and integrates the spatiotemporal events occurring at the cellular level in order to predict leukocyte transmigration and plaque evolution.
Collapse
|
34
|
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.
Collapse
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
| |
Collapse
|
35
|
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.
Collapse
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.
| |
Collapse
|
36
|
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]
|
37
|
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.
Collapse
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
| |
Collapse
|
38
|
Tonniges JR, Albert B, Calomeni EP, Roy S, Lee J, Mo X, Cole SE, Agarwal G. Collagen Fibril Ultrastructure in Mice Lacking Discoidin Domain Receptor 1. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:599-611. [PMID: 27329311 PMCID: PMC5174982 DOI: 10.1017/s1431927616000787] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The quantity and quality of collagen fibrils in the extracellular matrix (ECM) have a pivotal role in dictating biological processes. Several collagen-binding proteins (CBPs) are known to modulate collagen deposition and fibril diameter. However, limited studies exist on alterations in the fibril ultrastructure by CBPs. In this study, we elucidate how the collagen receptor, discoidin domain receptor 1 (DDR1) regulates the collagen content and ultrastructure in the adventitia of DDR1 knock-out (KO) mice. DDR1 KO mice exhibit increased collagen deposition as observed using Masson's trichrome. Collagen ultrastructure was evaluated in situ using transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. Although the mean fibril diameter was not significantly different, DDR1 KO mice had a higher percentage of fibrils with larger diameter compared with their wild-type littermates. No significant differences were observed in the length of D-periods. In addition, collagen fibrils from DDR1 KO mice exhibited a small, but statistically significant, increase in the depth of the fibril D-periods. Consistent with these observations, a reduction in the depth of D-periods was observed in collagen fibrils reconstituted with recombinant DDR1-Fc. Our results elucidate how DDR1 modulates collagen fibril ultrastructure in vivo, which may have important consequences in the functional role(s) of the underlying ECM.
Collapse
Affiliation(s)
- Jeffrey R. Tonniges
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Benjamin Albert
- Biomedical Engineering Department, The Ohio State University, Columbus, OH 43210, USA
| | - Edward P. Calomeni
- Department of Pathology, The Ohio State University, Columbus, OH 43210, USA
| | - Shuvro Roy
- David Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Joan Lee
- David Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Xiaokui Mo
- Center for Biostatistics, The Ohio State University, Columbus, OH 43210, USA
| | - Susan E. Cole
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Gunjan Agarwal
- Biomedical Engineering Department, The Ohio State University, Columbus, OH 43210, USA
- David Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| |
Collapse
|
39
|
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.
Collapse
|
40
|
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.
Collapse
|
41
|
Platelets and physics: How platelets “feel” and respond to their mechanical microenvironment. Blood Rev 2015; 29:377-86. [DOI: 10.1016/j.blre.2015.05.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 05/04/2015] [Accepted: 05/04/2015] [Indexed: 01/08/2023]
|
42
|
Mansfield JC, Bell JS, Winlove CP. The micromechanics of the superficial zone of articular cartilage. Osteoarthritis Cartilage 2015; 23:1806-16. [PMID: 26050867 DOI: 10.1016/j.joca.2015.05.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 05/18/2015] [Accepted: 05/26/2015] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To investigate the relationships between the unique mechanical and structural properties of the superficial zone of articular cartilage on the microscopic scale. DESIGN Fresh unstained equine metacarpophalangeal cartilage samples were mounted on tensile and compressive loading rigs on the stage of a multiphoton microscope. Sequential image stacks were acquired under incremental loads together with simultaneous measurements of the applied stress and strain. Second harmonic generation was used to visualise the collagen fibre network, while two photon fluorescence was used to visualise elastin fibres and cells. The changes visualised by each modality were tracked between successive loads. RESULTS The deformation of the cartilage matrix was heterogeneous on the microscopic length scale. This was evident from local strain maps, which showed shearing between different regions of collagen under tensile strain, corrugations in the articular surface at higher tensile strains and a non-uniform distribution of compressive strain in the axial direction. Chondrocytes elongated and rotated under tensile strain and were compressed in the axial direction under compressive load. The magnitude of deformation varied between cells, indicating differences in either load transmission through the matrix or the mechanical properties of individual cells. Under tensile loading the reorganisation of the elastin network differed from a homogeneous elastic response, indicating that it forms a functional structure. CONCLUSIONS This study highlights the complexity of superficial zone mechanics and demonstrates that the response of the collagen matrix, elastin fibres and chondrocytes are all heterogeneous on the microscopic scale.
Collapse
Affiliation(s)
- J C Mansfield
- College of Engineering Mathematics and Physical Sciences, University of Exeter, UK.
| | - J S Bell
- College of Engineering Mathematics and Physical Sciences, University of Exeter, UK
| | - C P Winlove
- College of Engineering Mathematics and Physical Sciences, University of Exeter, UK
| |
Collapse
|
43
|
Chaparro FJ, Matusicky ME, Allen MJ, Lannutti JJ. Biomimetic microstructural reorganization during suture retention strength evaluation of electrospun vascular scaffolds. J Biomed Mater Res B Appl Biomater 2015; 104:1525-1534. [PMID: 26256447 DOI: 10.1002/jbm.b.33493] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 05/29/2015] [Accepted: 07/02/2015] [Indexed: 11/12/2022]
Abstract
Suture retention strength (SRS) is commonly used as a measure the ability of sutures to adhere implants to surrounding tissue. While SRS is widely employed, surprisingly its effects on graft microstructure have not been characterized. This is particularly germane to the broad utilization of electrospun implants in tissue engineering. These implants need to retain their initial nanoscale topography while simultaneously preserving clinically critical mechanical properties. We examined the suture-driven microstructural deformation of polycaprolactone electrospun to form both square and tubular SRS samples. The impact of fiber orientation (generally parallel or random orientation, orthogonally aligned) on the SRS of these vascular tissue equivalents was analyzed and compared to native and decellularized porcine vasculature. The initial state of the fiber clearly dictates the overall efficiency of scaffold utilization. SRS values for as-spun fibers at a thickness of 300 μm were found to be in the range of 1.59-4.78 N for the three orientations. Unexpectedly, random fibers provided the optimal SRS values based on both resistance to suture motion and the percentage of scaffold involvement. A "V-shaped" failure morphology is observed for both electrospun scaffolds and native tissue during SRS testing. Post-test fiber alignment in the tensile direction was visible in all initial fiber orientations similar to that of native tissue. These findings are significant as they allow us to employ new, counterintuitive biomimetic design criteria for nanofiber-based scaffolds in which reliable mechanical integration with the surrounding tissues via suture-based methods is important. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1525-1534, 2016.
Collapse
Affiliation(s)
- Francisco J Chaparro
- Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio, 43210.
| | - Michelle E Matusicky
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, Ohio, 43210
| | - Matthew J Allen
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - John J Lannutti
- Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio, 43210
| |
Collapse
|
44
|
Lanir Y, Namani R. Reliability of structure tensors in representing soft tissues structure. J Mech Behav Biomed Mater 2015; 46:222-8. [DOI: 10.1016/j.jmbbm.2015.02.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 02/16/2015] [Accepted: 02/18/2015] [Indexed: 11/16/2022]
|
45
|
Lee CH, Zhang W, Liao J, Carruthers CA, Sacks JI, Sacks MS. On the presence of affine fibril and fiber kinematics in the mitral valve anterior leaflet. Biophys J 2015; 108:2074-87. [PMID: 25902446 PMCID: PMC4407258 DOI: 10.1016/j.bpj.2015.03.019] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 02/07/2015] [Accepted: 03/10/2015] [Indexed: 11/21/2022] Open
Abstract
In this study, we evaluated the hypothesis that the constituent fibers follow an affine deformation kinematic model for planar collagenous tissues. Results from two experimental datasets were utilized, taken at two scales (nanometer and micrometer), using mitral valve anterior leaflet (MVAL) tissues as the representative tissue. We simulated MVAL collagen fiber network as an ensemble of undulated fibers under a generalized two-dimensional deformation state, by representing the collagen fibrils based on a planar sinusoidally shaped geometric model. The proposed approach accounted for collagen fibril amplitude, crimp period, and rotation with applied macroscopic tissue-level deformation. When compared to the small angle x-ray scattering measurements, the model fit the data well, with an r(2) = 0.976. This important finding suggests that, at the homogenized tissue-level scale of ∼1 mm, the collagen fiber network in the MVAL deforms according to an affine kinematics model. Moreover, with respect to understanding its function, affine kinematics suggests that the constituent fibers are largely noninteracting and deform in accordance with the bulk tissue. It also suggests that the collagen fibrils are tightly bounded and deform as a single fiber-level unit. This greatly simplifies the modeling efforts at the tissue and organ levels, because affine kinematics allows a straightforward connection between the macroscopic and local fiber strains. It also suggests that the collagen and elastin fiber networks act independently of each other, with the collagen and elastin forming long fiber networks that allow for free rotations. Such freedom of rotation can greatly facilitate the observed high degree of mechanical anisotropy in the MVAL and other heart valves, which is essential to heart valve function. These apparently novel findings support modeling efforts directed toward improving our fundamental understanding of tissue biomechanics in healthy and diseased conditions.
Collapse
Affiliation(s)
- Chung-Hao Lee
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas
| | - Will Zhang
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas
| | - Jun Liao
- Department of Agricultural and Biological Engineering, Mississippi State University, Mississippi State, Starkville, Mississippi
| | | | - Jacob I Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas
| | - Michael S Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas.
| |
Collapse
|
46
|
Kohn JC, Lampi MC, Reinhart-King CA. Age-related vascular stiffening: causes and consequences. Front Genet 2015; 6:112. [PMID: 25926844 PMCID: PMC4396535 DOI: 10.3389/fgene.2015.00112] [Citation(s) in RCA: 237] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 03/03/2015] [Indexed: 01/18/2023] Open
Abstract
Arterial stiffening occurs with age and is closely associated with the progression of cardiovascular disease. Stiffening is most often studied at the level of the whole vessel because increased stiffness of the large arteries can impose increased strain on the heart leading to heart failure. Interestingly, however, recent evidence suggests that the impact of increased vessel stiffening extends beyond the tissue scale and can also have deleterious microscale effects on cellular function. Altered extracellular matrix (ECM) architecture has been recognized as a key component of the pre-atherogenic state. Here, the underlying causes of age-related vessel stiffening are discussed, focusing on age-related crosslinking of the ECM proteins as well as through increased matrix deposition. Methods to measure vessel stiffening at both the macro- and microscale are described, spanning from the pulse wave velocity measurements performed clinically to microscale measurements performed largely in research laboratories. Additionally, recent work investigating how arterial stiffness and the changes in the ECM associated with stiffening contributed to endothelial dysfunction will be reviewed. We will highlight how changes in ECM protein composition contribute to atherosclerosis in the vessel wall. Lastly, we will discuss very recent work that demonstrates endothelial cells (ECs) are mechano-sensitive to arterial stiffening, where changes in stiffness can directly impact EC health. Overall, recent studies suggest that stiffening is an important clinical target not only because of potential deleterious effects on the heart but also because it promotes cellular level dysfunction in the vessel wall, contributing to a pathological atherosclerotic state.
Collapse
Affiliation(s)
- Julie C Kohn
- Department of Biomedical Engineering, Cornell University Ithaca, NY, USA
| | - Marsha C Lampi
- Department of Biomedical Engineering, Cornell University Ithaca, NY, USA
| | | |
Collapse
|
47
|
Mauri A, Ehret AE, Perrini M, Maake C, Ochsenbein-Kölble N, Ehrbar M, Oyen ML, Mazza E. Deformation mechanisms of human amnion: Quantitative studies based on second harmonic generation microscopy. J Biomech 2015; 48:1606-13. [PMID: 25805698 DOI: 10.1016/j.jbiomech.2015.01.045] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 01/31/2015] [Indexed: 11/15/2022]
Abstract
Multiphoton microscopy has proven to be a versatile tool to analyze the three-dimensional microstructure of the fetal membrane and the mechanisms of deformation on the length scale of cells and the collagen network. In the present contribution, dedicated microscopic tools for in situ mechanical characterization of tissue under applied mechanical loads and the related methods for data interpretation are presented with emphasis on new stepwise monotonic uniaxial experiments. The resulting microscopic parameters are consistent with previous ones quantified for cyclic and relaxation tests, underlining the reliability of these techniques. The thickness reduction and the substantial alignment of collagen fiber bundles in the compact and fibroblast layer starting at very small loads are highlighted, which challenges the definition of a reference configuration in terms of a force threshold. The findings presented in this paper intend to inform the development of models towards a better understanding of fetal membrane deformation and failure, and thus of related problems in obstetrics and other clinical conditions.
Collapse
Affiliation(s)
- Arabella Mauri
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland.
| | - Alexander E Ehret
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Michela Perrini
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; Department of Obstetrics, University Hospital Zürich, 8091 Zurich, Switzerland
| | - Caroline Maake
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland
| | | | - Martin Ehrbar
- Department of Obstetrics, University Hospital Zürich, 8091 Zurich, Switzerland
| | - Michelle L Oyen
- Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ, UK
| | - Edoardo Mazza
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland; Swiss Federal Laboratories for Materials Science and Technology, EMPA, 8600 Dübendorf, Switzerland
| |
Collapse
|
48
|
Sikora M, Scheiner D, Betschart C, Perucchini D, Mateos JM, di Natale A, Fink D, Maake C. Label-free, three-dimensional multiphoton microscopy of the connective tissue in the anterior vaginal wall. Int Urogynecol J 2014; 26:685-91. [PMID: 25421935 DOI: 10.1007/s00192-014-2571-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 11/04/2014] [Indexed: 11/27/2022]
Abstract
INTRODUCTION AND HYPOTHESIS Multiphoton microscopy (MPM) is a nonlinear, high-resolution laser scanning technique and a powerful approach for analyzing the spatial architecture within tissues. To demonstrate the potential of this technique for studying the extracellular matrix of the pelvic organs, we aimed to establish protocols for the detection of collagen and elastin in the vagina and to compare the MPM density of these fibers to fibers detected using standard histological methods. METHODS Samples of the anterior vaginal wall were obtained from nine patients undergoing a hysterectomy or cystocele repair. Samples were shock frozen, fixed with formaldehyde or Thiel's solution, or left untreated. Samples were imaged with MPM to quantify the amount of collagen and elastin via second harmonic generation and autofluorescence, respectively. In six patients, sample sections were also histologically stained and imaged with brightfield microscopy. The density of the fibers was quantified using the StereoInvestigator and Cavalieri software. RESULTS With MPM, collagen and elastin could be visualized to a depth of 100 μm, and no overlap of signals was detected. The different tissue processing protocols used did not result in significantly different fiber counts after MPM. MPM-based fiber quantifications are comparable to those based on conventional histological stains. However, MPM provided superior resolution, particularly of collagen fibers. CONCLUSIONS MPM is a robust, rapid, and label-free method that can be used to quantify the collagen and elastin content in thick specimens of the vagina. It is an excellent tool for future three-dimensional studies of the extracellular matrix in patients with pelvic organ prolapse.
Collapse
Affiliation(s)
- Michal Sikora
- Department of Gynecology, University Hospital Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland,
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Lipid crystals mechanically stimulate adjacent extracellular matrix in advanced atherosclerotic plaques. Atherosclerosis 2014; 237:769-76. [PMID: 25463119 DOI: 10.1016/j.atherosclerosis.2014.10.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 09/29/2014] [Accepted: 10/06/2014] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Although lipid crystals (LCs) have received attention as a causative factor of plaque rupture, the mechanisms by which they increase plaque vulnerability are unknown. We examined whether solid-state LCs physically affect the adjacent extracellular matrix (ECM) using a combination of multimodal nonlinear optical (MNLO) imaging and finite element analysis (FEA). METHODS The changes of ECMs affected by lipids in atherosclerotic arteries in apolipoprotein E-deficient mice (n = 32) fed a high-fat diet for 20-30 weeks were micro-anatomically visualized by a 3D MNLO imaging platform including CARS for lipids, TPEF for elastin, and SHG for collagen. RESULTS AND CONCLUSION The TPEF signal of elastin was increased at the peripheral regions of LCs (<10 μm) compared with foam cell regions. In order to confirm the increase of elastin, biochemical assay (western blot) was performed. The protein level of elastin was increased approximately 2.25-fold (p = 0.024) in LC-rich arteries. Under the hypothesis that the increase of elastin resulted from the mechanical stimulus from solid-state LCs, MNLO images were subjected to FEA to simulate the displacement according to the expanding magnitude of the vessel during cardiac cycles. We found that microscale focal stress was increased specifically around the LCs. These FEA results corresponded with the increase of elastin observed by TPEF. These data suggest that LCs mechanically stimulate the adjacent ECM to alter the composition of ECM and cause vessel remodeling. The combination of MNLO imaging and FEA has great potential to verify the mechanical predictions in cardiovascular diseases.
Collapse
|
50
|
Nierenberger M, Fargier G, Ahzi S, Rémond Y. Evolution of the three-dimensional collagen structure in vascular walls during deformation: an in situ mechanical testing under multiphoton microscopy observation. Biomech Model Mechanobiol 2014; 14:693-702. [DOI: 10.1007/s10237-014-0630-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 10/24/2014] [Indexed: 10/24/2022]
|