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Szafron JM, Heng EE, Boyd J, Humphrey JD, Marsden AL. Hemodynamics and Wall Mechanics of Vascular Graft Failure. Arterioscler Thromb Vasc Biol 2024; 44:1065-1085. [PMID: 38572650 PMCID: PMC11043008 DOI: 10.1161/atvbaha.123.318239] [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: 09/04/2023] [Accepted: 03/12/2024] [Indexed: 04/05/2024]
Abstract
Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.
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Affiliation(s)
- Jason M Szafron
- Departments of Pediatrics (J.M.S., A.L.M.), Stanford University, CA
| | - Elbert E Heng
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jack Boyd
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT (J.D.H.)
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2
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Liu P, Liu X, Yang L, Qian Y, Lu Q, Shi A, Wei S, Zhang X, Lv Y, Xiang J. Enhanced hemocompatibility and rapid magnetic anastomosis of electrospun small-diameter artificial vascular grafts. Front Bioeng Biotechnol 2024; 12:1331078. [PMID: 38328445 PMCID: PMC10847591 DOI: 10.3389/fbioe.2024.1331078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 01/15/2024] [Indexed: 02/09/2024] Open
Abstract
Background: Small-diameter (<6 mm) artificial vascular grafts (AVGs) are urgently required in vessel reconstructive surgery but constrained by suboptimal hemocompatibility and the complexity of anastomotic procedures. This study introduces coaxial electrospinning and magnetic anastomosis techniques to improve graft performance. Methods: Bilayer poly(lactide-co-caprolactone) (PLCL) grafts were fabricated by coaxial electrospinning to encapsulate heparin in the inner layer for anticoagulation. Magnetic rings were embedded at both ends of the nanofiber conduit to construct a magnetic anastomosis small-diameter AVG. Material properties were characterized by micromorphology, fourier transform infrared (FTIR) spectra, mechanical tests, in vitro heparin release and hemocompatibility. In vivo performance was evaluated in a rabbit model of inferior vena cava replacement. Results: Coaxial electrospinning produced PLCL/heparin grafts with sustained heparin release, lower platelet adhesion, prolonged clotting times, higher Young's modulus and tensile strength versus PLCL grafts. Magnetic anastomosis was significantly faster than suturing (3.65 ± 0.83 vs. 20.32 ± 3.45 min, p < 0.001) and with higher success rate (100% vs. 80%). Furthermore, magnetic AVG had higher short-term patency (2 days: 100% vs. 60%; 7 days: 40% vs. 0%) but similar long-term occlusion as sutured grafts. Conclusion: Coaxial electrospinning improved hemocompatibility and magnetic anastomosis enhanced implantability of small-diameter AVG. Short-term patency was excellent, but further optimization of anticoagulation is needed for long-term patency. This combinatorial approach holds promise for vascular graft engineering.
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Affiliation(s)
- Peng Liu
- Center for Regenerative and Reconstructive Medicine, Med-X Institute, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
- National Local Joint Engineering Research Center for Precision Surgery and Regenerative Medicine, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Xin Liu
- Department of Graduate School, Xi’an Medical University, Xi’an, Shaanxi, China
| | - Lifei Yang
- National Local Joint Engineering Research Center for Precision Surgery and Regenerative Medicine, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Yerong Qian
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Qiang Lu
- Department of Geriatric Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Aihua Shi
- National Local Joint Engineering Research Center for Precision Surgery and Regenerative Medicine, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Shasha Wei
- National Local Joint Engineering Research Center for Precision Surgery and Regenerative Medicine, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Xufeng Zhang
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Yi Lv
- Center for Regenerative and Reconstructive Medicine, Med-X Institute, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
- National Local Joint Engineering Research Center for Precision Surgery and Regenerative Medicine, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Junxi Xiang
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
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Hülsmann J, Fraune T, Dodawatta B, Reuter F, Beutner M, Beck V, Hackert-Oschätzchen M, Ohl CD, Bettenbrock K, Janiga G, Wippermann J, Wacker M. Integrated biophysical matching of bacterial nanocellulose coronary artery bypass grafts towards bioinspired artery typical functions. Sci Rep 2023; 13:18274. [PMID: 37880281 PMCID: PMC10600183 DOI: 10.1038/s41598-023-45451-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 10/19/2023] [Indexed: 10/27/2023] Open
Abstract
Revascularization via coronary artery bypass grafting (CABG) to treat cardiovascular disease is established as one of the most important lifesaving surgical techniques worldwide. But the shortage in functionally self-adaptive autologous arteries leads to circumstances where the clinical reality must deal with fighting pathologies coming from the mismatching biophysical functionality of more available venous grafts. Synthetic biomaterial-based CABG grafts did not make it to the market yet, what is mostly due to technical hurdles in matching biophysical properties to the complex demands of the CABG niche. But bacterial Nanocellulose (BNC) Hydrogels derived by growing biofilms hold a naturally integrative character in function-giving properties by its freedom in designing form and intrinsic fiber architecture. In this study we use this integral to combine impacts on the luminal fiber matrix, biomechanical properties and the reciprocal stimulation of microtopography and induced flow patterns, to investigate biomimetic and artificial designs on their bio-functional effects. Therefore, we produced tubular BNC-hydrogels at distinctive designs, characterized the structural and biomechanical properties and subjected them to in vitro endothelial colonization in bioreactor assisted perfusion cultivation. Results showed clearly improved functional properties and gave an indication of successfully realized stimulation by artery-typical helical flow patterns.
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Affiliation(s)
- Jörn Hülsmann
- Department for Cardiac Surgery, Medical Faculty, Otto von Guericke University, Magdeburg, Germany.
| | - Theresa Fraune
- Department for Cardiac Surgery, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Baratha Dodawatta
- Laboratory of Fluid Dynamics and Technical Flows, Otto von Guericke University, Magdeburg, Germany
| | - Fabian Reuter
- Department Soft Matter, Otto von Guericke University, Magdeburg, Germany
| | - Martin Beutner
- Chair of Manufacturing Technology with Focus Machining, Institute of Manufacturing Technology and Quality Management, Otto von Guericke University, Magdeburg, Germany
| | - Viktoria Beck
- Department for Cardiac Surgery, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Matthias Hackert-Oschätzchen
- Chair of Manufacturing Technology with Focus Machining, Institute of Manufacturing Technology and Quality Management, Otto von Guericke University, Magdeburg, Germany
| | - Claus Dieter Ohl
- Department Soft Matter, Otto von Guericke University, Magdeburg, Germany
| | - Katja Bettenbrock
- Max Plank Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Gabor Janiga
- Laboratory of Fluid Dynamics and Technical Flows, Otto von Guericke University, Magdeburg, Germany
| | - Jens Wippermann
- Department for Cardiac Surgery, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Max Wacker
- Department for Cardiac Surgery, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
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Rovas G, Bikia V, Stergiopulos N. Design and computational optimization of compliance-matching aortic grafts. Front Bioeng Biotechnol 2023; 11:1179174. [PMID: 37456727 PMCID: PMC10341153 DOI: 10.3389/fbioe.2023.1179174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 06/19/2023] [Indexed: 07/18/2023] Open
Abstract
Introduction: Synthetic vascular grafts have been widely used in clinical practice for aortic replacement surgery. Despite their high rates of surgical success, they remain significantly less compliant than the native aorta, resulting in a phenomenon called compliance mismatch. This incompatibility of elastic properties may cause serious post-operative complications, including hypertension and myocardial hypertrophy. Methods: To mitigate the risk for these complications, we designed a multi-layer compliance-matching stent-graft, that we optimized computationally using finite element analysis, and subsequently evaluated in vitro. Results: We found that our compliance-matching grafts attained the distensibility of healthy human aortas, including those of young adults, thereby significantly exceeding the distensibility of gold-standard grafts. The compliant grafts maintained their properties in a wide range of conditions that are expected after the implantation. Furthermore, the computational model predicted the graft radius with enough accuracy to allow computational optimization to be performed effectively. Conclusion: Compliance-matching grafts may offer a valuable improvement over existing prostheses and they could potentially mitigate the risk for post-operative complications attributed to excessive graft stiffness.
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Tan W, Boodagh P, Selvakumar PP, Keyser S. Strategies to counteract adverse remodeling of vascular graft: A 3D view of current graft innovations. Front Bioeng Biotechnol 2023; 10:1097334. [PMID: 36704297 PMCID: PMC9871289 DOI: 10.3389/fbioe.2022.1097334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 12/23/2022] [Indexed: 01/11/2023] Open
Abstract
Vascular grafts are widely used for vascular surgeries, to bypass a diseased artery or function as a vascular access for hemodialysis. Bioengineered or tissue-engineered vascular grafts have long been envisioned to take the place of bioinert synthetic grafts and even vein grafts under certain clinical circumstances. However, host responses to a graft device induce adverse remodeling, to varied degrees depending on the graft property and host's developmental and health conditions. This in turn leads to invention or failure. Herein, we have mapped out the relationship between the design constraints and outcomes for vascular grafts, by analyzing impairment factors involved in the adverse graft remodeling. Strategies to tackle these impairment factors and counteract adverse healing are then summarized by outlining the research landscape of graft innovations in three dimensions-cell technology, scaffold technology and graft translation. Such a comprehensive view of cell and scaffold technological innovations in the translational context may benefit the future advancements in vascular grafts. From this perspective, we conclude the review with recommendations for future design endeavors.
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Affiliation(s)
- Wei Tan
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, United States,*Correspondence: Wei Tan,
| | - Parnaz Boodagh
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | | | - Sean Keyser
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, United States
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6
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Wang X, Chan V, Corridon PR. Acellular Tissue-Engineered Vascular Grafts from Polymers: Methods, Achievements, Characterization, and Challenges. Polymers (Basel) 2022; 14:polym14224825. [PMID: 36432950 PMCID: PMC9695055 DOI: 10.3390/polym14224825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/03/2022] [Accepted: 11/03/2022] [Indexed: 11/11/2022] Open
Abstract
Extensive and permanent damage to the vasculature leading to different pathogenesis calls for developing innovative therapeutics, including drugs, medical devices, and cell therapies. Innovative strategies to engineer bioartificial/biomimetic vessels have been extensively exploited as an effective replacement for vessels that have seriously malfunctioned. However, further studies in polymer chemistry, additive manufacturing, and rapid prototyping are required to generate highly engineered vascular segments that can be effectively integrated into the existing vasculature of patients. One recently developed approach involves designing and fabricating acellular vessel equivalents from novel polymeric materials. This review aims to assess the design criteria, engineering factors, and innovative approaches for the fabrication and characterization of biomimetic macro- and micro-scale vessels. At the same time, the engineering correlation between the physical properties of the polymer and biological functionalities of multiscale acellular vascular segments are thoroughly elucidated. Moreover, several emerging characterization techniques for probing the mechanical properties of tissue-engineered vascular grafts are revealed. Finally, significant challenges to the clinical transformation of the highly promising engineered vessels derived from polymers are identified, and unique perspectives on future research directions are presented.
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Affiliation(s)
- Xinyu Wang
- Department of Biomedical Engineering and Healthcare Engineering Innovation Center, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Department of Immunology and Physiology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates
| | - Vincent Chan
- Department of Biomedical Engineering and Healthcare Engineering Innovation Center, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Correspondence: (V.C.); (P.R.C.)
| | - Peter R. Corridon
- Department of Biomedical Engineering and Healthcare Engineering Innovation Center, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Department of Immunology and Physiology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Center for Biotechnology, Khalifa University, Abu Dhabi P.O. Box 127788, United Arab Emirates
- Correspondence: (V.C.); (P.R.C.)
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7
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Latorre M, Szafron JM, Ramachandra AB, Humphrey JD. In vivo development of tissue engineered vascular grafts: a fluid-solid-growth model. Biomech Model Mechanobiol 2022; 21:827-848. [PMID: 35179675 PMCID: PMC9133046 DOI: 10.1007/s10237-022-01562-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 01/24/2022] [Indexed: 11/02/2022]
Abstract
Methods of tissue engineering continue to advance, and multiple clinical trials are underway evaluating tissue engineered vascular grafts (TEVGs). Whereas initial concerns focused on suture retention and burst pressure, there is now a pressing need to design grafts to have optimal performance, including an ability to grow and remodel in response to changing hemodynamic loads. Toward this end, there is similarly a need for computational methods that can describe and predict the evolution of TEVG geometry, composition, and material properties while accounting for changes in hemodynamics. Although the ultimate goal is a fluid-solid-growth (FSG) model incorporating fully 3D growth and remodeling and 3D hemodynamics, lower fidelity models having high computational efficiency promise to play important roles, especially in the design of candidate grafts. We introduce here an efficient FSG model of in vivo development of a TEVG based on two simplifying concepts: mechanobiologically equilibrated growth and remodeling of the graft and an embedded control volume analysis of the hemodynamics. Illustrative simulations for a model Fontan conduit reveal the utility of this approach, which promises to be particularly useful in initial design considerations involving formal methods of optimization which otherwise add considerably to the computational expense.
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Affiliation(s)
- Marcos Latorre
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520, USA.
- Center for Research and Innovation in Bioengineering, Universitat Politècnica de València, València, 46022, Spain.
| | - Jason M Szafron
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520, USA
- Departments of Pediatrics and Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Abhay B Ramachandra
- Department of Biomedical Engineering, Yale University, New Haven, CT, 06520, USA
| | - Jay D Humphrey
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, 06520, USA
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8
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Furdella KJ, Higuchi S, Kim K, Doetschman T, Wagner WR, Vande Geest JP. ACUTE ELUTION OF TGFβ2 AFFECTS THE SMOOTH MUSCLE CELLS IN A COMPLIANCE-MATCHED VASCULAR GRAFT. Tissue Eng Part A 2022; 28:640-650. [PMID: 35521649 DOI: 10.1089/ten.tea.2021.0161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Transforming growth factor beta 2 (TGFβ2) is a pleiotropic growth factor that plays a vital role in smooth muscle cell (SMC) function. Our prior in vitro work has shown that SMC response can be modulated with TGFβ2 stimulation in a dose dependent manner. In particular, we have shown that increasing concentrations of TGFβ2 shift SMCs from a migratory to a synthetic behavior. In this work, electrospun compliance-matched and hypocompliant TGFβ2-eluting TEVGs were implanted into Sprague Dawley rats for 5 days to observe SMC population and collagen production. TEVGs were fabricated using a combined computational and experimental approach that varied the ratio of gelatin:polycaprolactone to be either compliance-matched or twice as stiff as rat aorta (hypocompliant). TGFβ2 concentrations of 0, 10, 100 ng/mg were added to both graft types (n=3 in each group) and imaged in vivo using ultrasound. Histological markers (SMC, macrophage, collagen, and elastin) were evaluated following explantation at 5 days. In vivo ultrasound showed that compliance-matched TEVGs became stiffer as TGFβ2 increased (100 ng/mg TEVGS compared to rat aorta, p<0.01) while all hypocompliant grafts remained stiffer than control rat aorta. In vivo velocity and diameter were also not significantly different than control vessels. The compliance-matched 10 ng/mg group had an elevated SMC signal (myosin heavy chain) compared to the 0 and 100 ng/mg grafts (p=0.0009 & 0.0006 ). Compliance-matched TEVGs containing 100 ng/mg TGFβ2 had an increase in collagen production (p<0.01), general immune response (p<0.05), and a decrease in SMC population to the 0 and 10 ng/mg groups. All hypocompliant groups were found to be similar, suggesting a lower rate of TGFβ2 release in these TEVGs. Our results suggest that TGFβ2 can modulate in vivo SMC phenotype over an acute implantation period, which is consistent with our prior in vitro work. To the author's knowledge, this is first in vivo rat study that evaluates a TGFβ2-eluting TEVG.
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Affiliation(s)
- Kenneth John Furdella
- University of Pittsburgh Swanson School of Engineering, 110071, Bioengineering, Pittsburgh, Pennsylvania, United States;
| | - Shinichi Higuchi
- University of Pittsburgh Swanson School of Engineering, 110071, McGowan Institute for Regenerative Medicine, Pittsburgh, Pennsylvania, United States;
| | - Kang Kim
- University of Pittsburgh Swanson School of Engineering, 110071, Department of Bioengineering, Pittsburgh, Pennsylvania, United States;
| | - Tom Doetschman
- University of Arizona Biochemistry and Molecular and Cellular Biology program, 242717, Tucson, Arizona, United States;
| | - William R Wagner
- University of Pittsburgh, 6614, McGowan Institute for Regenerative Medicine, Pittsburgh, Pennsylvania, United States;
| | - Jonathan P Vande Geest
- University of Pittsburgh Swanson School of Engineering, 110071, Bioengineering, Pittsburgh, Pennsylvania, United States;
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9
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Bioengineering silk into blood vessels. Biochem Soc Trans 2021; 49:2271-2286. [PMID: 34495327 DOI: 10.1042/bst20210359] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/05/2021] [Accepted: 08/11/2021] [Indexed: 11/17/2022]
Abstract
The rising incidence of cardiovascular disease has increased the demand for small diameter (<6 mm) synthetic vascular grafts for use in bypass surgery. Clinically available synthetic grafts (polyethylene terephthalate and expanded polytetrafluorethylene) are incredibly strong, but also highly hydrophobic and inelastic, leading to high rates of failure when used for small diameter bypass. The poor clinical outcomes of commercial synthetic grafts in this setting have driven significant research in search of new materials that retain favourable mechanical properties but offer improved biocompatibility. Over the last several decades, silk fibroin derived from Bombyx mori silkworms has emerged as a promising biomaterial for use in vascular applications. Progress has been driven by advances in silk manufacturing practices which have allowed unprecedented control over silk strength, architecture, and the ensuing biological response. Silk can now be manufactured to mimic the mechanical properties of native arteries, rapidly recover the native endothelial cell layer lining vessels, and direct positive vascular remodelling through the regulation of local inflammatory responses. This review summarises the advances in silk purification, processing and functionalisation which have allowed the production of robust vascular grafts with promise for future clinical application.
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10
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Furdella KJ, Higuchi S, Behrangzade A, Kim K, Wagner WR, Vande Geest JP. In-vivo assessment of a tissue engineered vascular graft computationally optimized for target vessel compliance. Acta Biomater 2021; 123:298-311. [PMID: 33482362 DOI: 10.1016/j.actbio.2020.12.058] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 12/22/2020] [Accepted: 12/29/2020] [Indexed: 11/24/2022]
Abstract
Tissue engineered vascular grafts (TEVGs) have the ability to be tuned to match a target vessel's compliance, diameter, wall thickness, and thereby prevent compliance mismatch. In this work, TEVG compliance was manipulated by computationally tuning its layered composition or by manipulating a crosslinking agent (genipin). In particular, these three acelluluar TEVGs were compared: a compliance matched graft (CMgel - high gelatin content); a hypocompliant PCL graft (HYPOpcl - high polycaprolactone content); and a hypocompliant genipin graft (HYPOgen - equivalent composition as CMgel but hypocompliant via increased genipin crosslinking). All constructs were implanted interpositionally into the abdominal aorta of 21 Sprague Dawley rats (n=7, males=11, females=10) for 28 days, imaged in-vivo using ultrasound, explanted, and assessed for remodeling using immunofluorescence and two photon excitation fluorescence imaging. Compliance matched grafts remained compliance-matched in-vivo compared to the hypocompliant grafts through 4 weeks (p<0.05). Construct degradation and cellular infiltration was increased in the CMgel and HYPOgen TEVGs. Contractile smooth muscle cell markers in the proximal anastomosis of the graft were increased in the CMgel group compared to the HYPOpcl (p=0.007) and HYPOgen grafts (p=0.04). Both hypocompliant grafts also had an increased pro-inflammatory response (increased ratio of CD163 to CD86 in the mid-axial location) compared to the CMgel group. Our results suggest that compliance matching using a computational optimization approach leads to the improved acute (28 day) remodeling of TEVGs. To the authors' knowledge, this is the first in-vivo rat study investigating TEVGs that have been computationally optimized for target vessel compliance.
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11
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Zbinden JC, Blum KM, Berman AG, Ramachandra AB, Szafron JM, Kerr KE, Anderson JL, Sangha GS, Earl CC, Nigh NR, Mirhaidari GJM, Reinhardt JW, Chang Y, Yi T, Smalley R, Gabriele PD, Harris JJ, Humphrey JD, Goergen CJ, Breuer CK. Effects of Braiding Parameters on Tissue Engineered Vascular Graft Development. Adv Healthc Mater 2020; 9:e2001093. [PMID: 33063452 DOI: 10.1002/adhm.202001093] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/17/2020] [Indexed: 01/06/2023]
Abstract
Tissue engineered vascular grafts (TEVGs) using scaffolds fabricated from braided poly(glycolic acid) (PGA) fibers coated with poly(glycerol sebacate) (PGS) are developed. The approach relies on in vivo tissue engineering by which neotissue forms solely within the body after a scaffold has been implanted. Herein, the impact of altering scaffold braid design and scaffold coating on neotissue formation is investigated. Several combinations of braiding parameters are manufactured and evaluated in a Beige mouse model in the infrarenal abdominal aorta. Animals are followed with 4D ultrasound analysis, and 12 week explanted vessels are evaluated for biaxial mechanical properties as well as histological composition. Results show that scaffold parameters (i.e., braiding angle, braiding density, and presence of a PGS coating) have interdependent effects on the resulting graft performance, namely, alteration of these parameters influences levels of inflammation, extracellular matrix production, graft dilation, neovessel distensibility, and overall survival. Coupling carefully designed in vivo experimentation with regression analysis, critical relationships between the scaffold design and the resulting neotissue that enable induction of favorable cellular and extracellular composition in a controlled manner are uncovered. Such an approach provides a potential for fabricating scaffolds with a broad range of features and the potential to manufacture optimized TEVGs.
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Affiliation(s)
- Jacob C. Zbinden
- Nationwide Children's Hospital, Abagail Wexner Research Institute 575 Children's Crossroad Columbus OH 43215 USA
| | - Kevin M. Blum
- Nationwide Children's Hospital, Abagail Wexner Research Institute 575 Children's Crossroad Columbus OH 43215 USA
| | - Alycia G. Berman
- Weldon School of Biomedical Engineering, Purdue University 206 S Martin Jischke Drive West Lafayette IN 47907 USA
| | - Abhay B. Ramachandra
- Department of Biomedical Engineering, Yale University 55 Prospect Street New Haven CT 06520 USA
| | - Jason M. Szafron
- Department of Biomedical Engineering, Yale University 55 Prospect Street New Haven CT 06520 USA
| | - Katherine E. Kerr
- Weldon School of Biomedical Engineering, Purdue University 206 S Martin Jischke Drive West Lafayette IN 47907 USA
| | - Jennifer L. Anderson
- Weldon School of Biomedical Engineering, Purdue University 206 S Martin Jischke Drive West Lafayette IN 47907 USA
| | - Gurneet S. Sangha
- Weldon School of Biomedical Engineering, Purdue University 206 S Martin Jischke Drive West Lafayette IN 47907 USA
| | - Conner C. Earl
- Weldon School of Biomedical Engineering, Purdue University 206 S Martin Jischke Drive West Lafayette IN 47907 USA
| | - Noah R. Nigh
- Weldon School of Biomedical Engineering, Purdue University 206 S Martin Jischke Drive West Lafayette IN 47907 USA
| | - Gabriel J. M. Mirhaidari
- Nationwide Children's Hospital, Abagail Wexner Research Institute 575 Children's Crossroad Columbus OH 43215 USA
| | - James W. Reinhardt
- Nationwide Children's Hospital, Abagail Wexner Research Institute 575 Children's Crossroad Columbus OH 43215 USA
| | - Yu‐Chun Chang
- Nationwide Children's Hospital, Abagail Wexner Research Institute 575 Children's Crossroad Columbus OH 43215 USA
| | - Tai Yi
- Nationwide Children's Hospital, Abagail Wexner Research Institute 575 Children's Crossroad Columbus OH 43215 USA
| | - Ryan Smalley
- Secant Group, LLC 551 East Church Ave Telford PA 18969 USA
| | | | | | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University 55 Prospect Street New Haven CT 06520 USA
| | - Craig J. Goergen
- Weldon School of Biomedical Engineering, Purdue University 206 S Martin Jischke Drive West Lafayette IN 47907 USA
| | - Christopher K. Breuer
- Nationwide Children's Hospital, Abagail Wexner Research Institute 575 Children's Crossroad Columbus OH 43215 USA
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12
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Wu YL, Szafron JM, Blum KM, Zbinden JC, Khosravi R, Best CA, Reinhardt JW, Zeng Q, Yi T, Shinoka T, Humphrey JD, Breuer CK, Wang Y. Electrospun Tissue-Engineered Arterial Graft Thickness Affects Long-Term Composition and Mechanics. Tissue Eng Part A 2020; 27:593-603. [PMID: 32854586 DOI: 10.1089/ten.tea.2020.0166] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Wall stress is often lower in tissue-engineered constructs than in comparable native tissues due to the use of stiff polymeric materials having thicker walls. In this work, we sought to design a murine arterial graft having a more favorable local mechanical environment for the infiltrating cells; we used electrospinning to enclose a compliant inner core of poly(glycerol sebacate) with a stiffer sheath of poly(caprolactone) to reduce the potential for rupture. Two scaffolds were designed that differed in the thickness of the core as previous computational simulations found that circumferential wall stresses could be increased in the core toward native values by increasing the ratio of the core:sheath. Our modified electrospinning protocols reduced swelling of the core upon implantation and eliminated residual stresses in the sheath, both of which had contributed to the occlusion of implanted grafts during pilot studies. For both designs, a subset of implanted grafts occluded due to thrombosis or ruptured due to suspected point defects in the sheath. However, there were design-based differences in collagen content and mechanical behavior during early remodeling of the patent samples, with the thinner-core scaffolds having more collagen and a stiffer behavior after 12 weeks of implantation than the thicker-core scaffolds. By 24 weeks, the thicker-core scaffolds also became stiff, with similar amounts of collagen but increased smooth muscle cell and elastin content. These data suggest that increasing wall stress toward native values may provide a more favorable environment for normal arterial constituents to form despite the overall stiffness of the construct remaining elevated due to the absolute increase in load-bearing constituents.
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Affiliation(s)
- Yen-Lin Wu
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Jason M Szafron
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Kevin M Blum
- Center for Regenerative Medicine, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Jacob C Zbinden
- Center for Regenerative Medicine, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Ramak Khosravi
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Cameron A Best
- Center for Regenerative Medicine, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Biomedical Sciences Graduate Program, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - James W Reinhardt
- Center for Regenerative Medicine, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Qiang Zeng
- Center for Regenerative Medicine, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Tai Yi
- Center for Regenerative Medicine, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Toshiharu Shinoka
- Department of Cardiothoracic Surgery, Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Surgery, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA.,Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, Connecticut, USA
| | - Christopher K Breuer
- Center for Regenerative Medicine, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Cardiothoracic Surgery, Nationwide Children's Hospital, Columbus, Ohio, USA.,Department of Surgery, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Yadong Wang
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
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13
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Szafron JM, Ramachandra AB, Breuer CK, Marsden AL, Humphrey JD. Optimization of Tissue-Engineered Vascular Graft Design Using Computational Modeling. Tissue Eng Part C Methods 2019; 25:561-570. [PMID: 31218941 DOI: 10.1089/ten.tec.2019.0086] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Tissue-engineered vascular grafts hold great promise in many clinical applications, especially in pediatrics wherein growth potential is critical. A continuing challenge, however, is identification of optimal scaffold parameters for promoting favorable neovessel development. In particular, given the countless design parameters available, including those related to polymeric microstructure, material behavior, and degradation kinetics, the number of possible scaffold designs is almost limitless. Advances in computationally modeling the growth and remodeling of native blood vessels suggest that similar simulations could help reduce the search space for candidate scaffold designs in tissue engineering. In this study, we meld a computational model of in vivo neovessel formation with a surrogate management framework to identify optimal scaffold designs for use in the extracardiac Fontan circulation while comparing the utility of different objective functions. We show that evolving luminal radius and graft compliance can be matched to that of the native vein by the end of the simulation period with judicious combinations of scaffold parameters, although the inability to match these metrics at all times reveals constraints engendered by current materials. We emphasize further that there is yet a need to examine additional metrics, and combinations thereof, when seeking to optimize functionality and reduce the potential for adverse outcomes. Impact Statement Tissue-engineered vascular grafts have considerable promise for treating myriad conditions, and multiple designs are now in FDA-approved trials. Nevertheless, the search continues for the optimal design of the underlying polymeric scaffold. We present a novel melding of a computational model of vascular adaptation and a formal method of optimization that can aid in identifying optimal design parameters, with potential to save development time and costs while improving clinical outcomes.
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Affiliation(s)
- Jason M Szafron
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut
| | - Abhay B Ramachandra
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut
| | | | - Alison L Marsden
- Departments of Pediatrics and Bioengineering, Stanford University, Stanford, California
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut.,Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, Connecticut
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