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Sameti M, Shojaee M, Saleh BM, Moore LK, Bashur CA. Peritoneal pre-conditioning impacts long-term vascular graft patency and remodeling. BIOMATERIALS ADVANCES 2023; 148:213386. [PMID: 36948108 DOI: 10.1016/j.bioadv.2023.213386] [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] [Received: 11/14/2022] [Revised: 02/13/2023] [Accepted: 03/10/2023] [Indexed: 03/18/2023]
Abstract
There are questions about how well small-animal models for tissue-engineered vascular grafts (TEVGs) translate to clinical patients. Most TEVG studies used grafting times ≤6 months where conduits from generally biocompatible materials like poly(ε-caprolactone) (PCL) perform well. However, longer grafting times can result in significant intimal hyperplasia and calcification. This study tests the hypothesis that differences in pro-inflammatory response from pure PCL conduits will be consequential after long-term grafting. It also tests the long-term benefits of a peritoneal pre-implantation strategy on rodent outcomes. Electrospun conduits with and without peritoneal pre-implantation, and with 0 % and 10 % (w/w) collagen/PCL, were grafted into abdominal aortae of rats for 10 months. This study found that viability of control grafts without pre-implantation was reduced unlike prior studies with shorter grafting times, confirming the relevance of this model. Importantly, pre-implanted grafts had a 100 % patency rate. Further, pre-implantation reduced intimal hyperplasia within the graft. Differences in response between pure PCL and collagen/PCL conduits were observed (e.g., fewer CD80+ and CD3+ cells for collagen/PCL), but only pre-implantation had an effect on the overall graft viability. This study demonstrates how long-term grafting in rodent models can better evaluate viability of different TEVGs, and the benefits of the peritoneal pre-implantation step.
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Affiliation(s)
- Mahyar Sameti
- Department of Biomedical, Chemical Engineering, and Science, Florida Institute of Technology, Melbourne, FL 32901, United States
| | - Mozhgan Shojaee
- Department of Biomedical, Chemical Engineering, and Science, Florida Institute of Technology, Melbourne, FL 32901, United States
| | - Bayan M Saleh
- Department of Biomedical, Chemical Engineering, and Science, Florida Institute of Technology, Melbourne, FL 32901, United States
| | - Lisa K Moore
- Department of Biomedical, Chemical Engineering, and Science, Florida Institute of Technology, Melbourne, FL 32901, United States
| | - Chris A Bashur
- Department of Biomedical, Chemical Engineering, and Science, Florida Institute of Technology, Melbourne, FL 32901, United States.
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2
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Peritoneal Pre-conditioning Method for In Vivo Vascular Graft Maturation Utilizing a Porous Pouch. Methods Mol Biol 2021. [PMID: 34591301 DOI: 10.1007/978-1-0716-1708-3_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Tissue-engineered vascular grafts (TEVGs) require strategies to allow graft remodeling but avoid stenosis and loss of graft mechanics. A variety of promising biomaterials and methods to incorporate cells have been tested, but intimal hyperplasia and graft thrombosis are still concerning when grafting in small-diameter arteries. Here, we describe a strategy using the peritoneal cavity as an "in vivo" bioreactor to recruit autologous cells to electrospun conduits, which can improve the in vivo response after aortic grafting. We focus on the methods for a novel hydrogel pouch design to enclose the electrospun conduits that can avoid peritoneal adhesion but still allow infiltration of peritoneal fluid and cells needed to provide benefits when subsequently grafting in the aorta.
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3
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Whitaker R, Hernaez-Estrada B, Hernandez RM, Santos-Vizcaino E, Spiller KL. Immunomodulatory Biomaterials for Tissue Repair. Chem Rev 2021; 121:11305-11335. [PMID: 34415742 DOI: 10.1021/acs.chemrev.0c00895] [Citation(s) in RCA: 106] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
All implanted biomaterials are targets of the host's immune system. While the host inflammatory response was once considered a detrimental force to be blunted or avoided, in recent years, it has become a powerful force to be leveraged to augment biomaterial-tissue integration and tissue repair. In this review, we will discuss the major immune cells that mediate the inflammatory response to biomaterials, with a focus on how biomaterials can be designed to modulate immune cell behavior to promote biomaterial-tissue integration. In particular, the intentional activation of monocytes and macrophages with controlled timing, and modulation of their interactions with other cell types involved in wound healing, have emerged as key strategies to improve biomaterial efficacy. To this end, careful design of biomaterial structure and controlled release of immunomodulators can be employed to manipulate macrophage phenotype for the maximization of the wound healing response with enhanced tissue integration and repair, as opposed to a typical foreign body response characterized by fibrous encapsulation and implant isolation. We discuss current challenges in the clinical translation of immunomodulatory biomaterials, such as limitations in the use of in vitro studies and animal models to model the human immune response. Finally, we describe future directions and opportunities for understanding and controlling the biomaterial-immune system interface, including the application of new imaging tools, new animal models, the discovery of new cellular targets, and novel techniques for in situ immune cell reprogramming.
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Affiliation(s)
- Ricardo Whitaker
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Beatriz Hernaez-Estrada
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States.,NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz 01006, Spain
| | - Rosa Maria Hernandez
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz 01006, Spain.,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz 01006, Spain
| | - Edorta Santos-Vizcaino
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz 01006, Spain.,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz 01006, Spain
| | - Kara L Spiller
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States
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Shojaee M, Sameti M, Vuppuluri K, Ziff M, Carriero A, Bashur CA. Design and characterization of a porous pouch to prevent peritoneal adhesions during in vivo vascular graft maturation. J Mech Behav Biomed Mater 2020; 102:103461. [PMID: 31600667 DOI: 10.1016/j.jmbbm.2019.103461] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 09/09/2019] [Accepted: 09/29/2019] [Indexed: 11/24/2022]
Abstract
Vein grafts for coronary artery bypass are not available in more than 30% of patients due to prior use or systemic vascular diseases. Tissue engineered vascular grafts (TEVGs) have shown promise, but intimal hyperplasia and graft thrombosis are still concerns when grafted in small-diameter arteries. In this study, we utilized the peritoneal cavity as an "in vivo" bioreactor to recruit autologous cells to electrospun conduits enclosed within porous pouches to improve the response after grafting. Specifically, we designed a new poly (ethylene glycol)-based pouch to avoid adhesion to the peritoneal wall and still allow the necessary peritoneal fluid to reach the enclosed conduit. The pouch mechanics in compression and bending were determined through experiments and finite element simulations to optimize the pouch design. This included poly (ethylene glycol) concentration, pore density, and pouch size. We demonstrated that the optimized pouch was able to withstand the estimated forces applied in the rat peritoneal cavity and it allowed maturation of the enclosed electrospun conduit. This pouch significantly reduced peritoneal adhesion formation compared to polytetrafluoroethylene pouches that have been used previously, which overcomes this potential limitation to clinical translation. After aortic grafting of pre-conditioned conduits, patent grafts with limited intimal hyperplasia were observed. Overall, this study demonstrated a new pouch design that allows the in vivo bioreactor strategy to be used for vascular tissue engineering without the potential side effect of peritoneal adhesion formation.
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Affiliation(s)
- Mozhgan Shojaee
- Department of Biomedical, Chemical Engineering and Science, Florida Institute of Technology, Melbourne, FL, USA.
| | - Mahyar Sameti
- Department of Biomedical, Chemical Engineering and Science, Florida Institute of Technology, Melbourne, FL, USA.
| | - Kranthi Vuppuluri
- Department of Biomedical, Chemical Engineering and Science, Florida Institute of Technology, Melbourne, FL, USA.
| | - Matthew Ziff
- Department of Biomedical Engineering, Grove School of Engineering, The City College of New York, New York, NY, USA.
| | - Alessandra Carriero
- Department of Biomedical Engineering, Grove School of Engineering, The City College of New York, New York, NY, USA.
| | - Chris A Bashur
- Department of Biomedical, Chemical Engineering and Science, Florida Institute of Technology, Melbourne, FL, USA.
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5
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Johnson R, Ding Y, Nagiah N, Monnet E, Tan W. Coaxially-structured fibres with tailored material properties for vascular graft implant. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2018; 97:1-11. [PMID: 30678891 DOI: 10.1016/j.msec.2018.11.036] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 10/18/2018] [Accepted: 11/24/2018] [Indexed: 12/21/2022]
Abstract
Readily-available small-diameter arterial grafts require a great combination of materials properties, including high strength, compliance, suturability, blood sealing and anti-thrombogenicity, as well as anti-kinking property for those used in challenging anatomical situations. We have constructed grafts composed of coaxially-structured polycaprolactone (PCL)/gelatin nanofibres, and tailored the material structures to achieve high strength, compliance and kink resistance, as well as excellent water sealing and anti-thrombogenicity. Coaxially-structured fibres in the grafts provided mechanical stability through the core, while flexibility and cell adhesion through the sheath. Results showed that graft compliance increased while strength decreased with the concentration ratio between core and sheath polymers. Compared to pure PCL fibrous surfaces, coaxial PCL/gelatin fibrous surfaces potently inhibited platelet adhesion and activation, providing excellent anti-thrombogenicity. To render sufficient burst strength and suturability, an additional layer of pure PCL was necessary to cap the layer of coaxial PCL/gelatin fibres. The two-layered grafts with the wall thickness comparable to native arteries demonstrated artery-like compliance and kink resistance, properties important to arteries under complex mechanical loading. The in vivo evaluation was performed using the interposition carotid artery graft model in rabbits for three months. Interestingly, results from ultrasonic imaging and histological analysis demonstrated that the two-layered grafts with a thinner outer PCL layer, which possessed higher compliance and kink resistance, showed increased blood flow, minimal lumen reduction and fibrosis. All vascular grafts exhibited patency and induced limited cell infiltration. Together, we presented a facile and useful approach to fabricate vascular grafts with superior graft performances, biomechanical properties, and blood compatibility. Grafts with artery-like compliance and flexibility have demonstrated improved implantation outcomes.
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Affiliation(s)
- Richard Johnson
- Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, CO 80309, United States
| | - Yonghui Ding
- Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, CO 80309, United States
| | - Naveen Nagiah
- Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, CO 80309, United States
| | - Eric Monnet
- Department of Clinical Sciences, Colorado State University, Fort Colins, CO, United States
| | - Wei Tan
- Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, CO 80309, United States.
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Shojaee M, Swaminathan G, Bashur CA, Ramamurthi A. Temporal changes in peritoneal cell phenotype and neoelastic matrix induction with hyaluronan oligomers and TGF-β1 after implantation of engineered conduits. J Tissue Eng Regen Med 2018; 12:1420-1431. [PMID: 29701914 DOI: 10.1002/term.2674] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 01/19/2018] [Accepted: 04/12/2018] [Indexed: 12/26/2022]
Abstract
The neoassembly and maturation of elastic matrix is an important challenge for engineering small-diameter grafts for patients with peripheral artery disease. We have previously shown that hyaluronan oligomers and transforming growth factor-β (elastogenic factors or EFs) promote elastogenesis in smooth muscle cell (SMC) culture. However, their combined effects on macrophages and inflammatory cells in vivo are unknown. This information is needed to use the body (e.g., peritoneal cavity) as an "in vivo bioreactor" to recruit autologous cells to implanted EF-functionalized scaffolds. In this study, we determined if peritoneal fluid cells respond to EFs like smooth muscle cells and if these responses differ between cells sourced during different stages of inflammation triggered by scaffold implantation. Electrospun poly(ε-caprolactone)/collagen conduits were implanted in the peritoneal cavity prior to peritoneal fluid collection at 3-42 days postimplantation. Cells from the fluid were cultured in vitro with and without EFs to determine their response. Their phenotype/behaviour was assessed with a DNA assay, quantitative real-time PCR, and immunofluorescence. The EFs reduced peritoneal cell proliferation, maintained cell contractility, and unexpectedly did not exhibit proelastic effects, which we attributed to differences in cell density. We found the greatest elastin deposition in regions containing a high cell density. Further, we found that cells isolated from the peritoneal cavity at longer times after conduit implantation responded better to the EFs and exhibited more CD31 expression than cells at an earlier time point. Overall, this study provides information about the potential use of EFs in vivo and can guide the design of future tissue-engineered vascular grafts.
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Affiliation(s)
- Mozhgan Shojaee
- Department of Biomedical Engineering, Florida Institute of Technology, Melbourne, FL, USA
| | - Ganesh Swaminathan
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH, USA
| | - Chris A Bashur
- Department of Biomedical Engineering, Florida Institute of Technology, Melbourne, FL, USA
| | - Anand Ramamurthi
- Department of Biomedical Engineering, Cleveland Clinic, Cleveland, OH, USA
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7
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Washington KS, Bashur CA. Delivery of Antioxidant and Anti-inflammatory Agents for Tissue Engineered Vascular Grafts. Front Pharmacol 2017; 8:659. [PMID: 29033836 PMCID: PMC5627016 DOI: 10.3389/fphar.2017.00659] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 09/05/2017] [Indexed: 01/21/2023] Open
Abstract
The treatment of patients with severe coronary and peripheral artery disease represents a significant clinical need, especially for those patients that require a bypass graft and do not have viable veins for autologous grafting. Tissue engineering is being investigated to generate an alternative graft. While tissue engineering requires surgical intervention, the release of pharmacological agents is also an important part of many tissue engineering strategies. Delivery of these agents offers the potential to overcome the major concerns for graft patency and viability. These concerns are related to an extended inflammatory response and its impact on vascular cells such as endothelial cells. This review discusses the drugs that have been released from vascular tissue engineering scaffolds and some of the non-traditional ways that the drugs are presented to the cells. The impact of antioxidant compounds and gasotransmitters, such as nitric oxide and carbon monoxide, are discussed in detail. The application of tissue engineering and drug delivery principles to biodegradable stents is also briefly discussed. Overall, there are scaffold-based drug delivery techniques that have shown promise for vascular tissue engineering, but much of this work is in the early stages and there are still opportunities to incorporate additional drugs to modulate the inflammatory process.
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Affiliation(s)
| | - Chris A. Bashur
- Department of Biomedical Engineering, Florida Institute of Technology, MelbourneFL, United States
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8
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Shojaee M, Bashur CA. Compositions Including Synthetic and Natural Blends for Integration and Structural Integrity: Engineered for Different Vascular Graft Applications. Adv Healthc Mater 2017; 6. [PMID: 28371505 DOI: 10.1002/adhm.201700001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 02/13/2017] [Indexed: 11/07/2022]
Abstract
Tissue engineering approaches for small-diameter arteries require a scaffold that simultaneously maintains patency by preventing thrombosis and intimal hyperplasia, maintains its structural integrity after grafting, and allows integration. While synthetic and extracellular matrix-derived materials can provide some of these properties individually, developing a scaffold that provides the balanced properties needed for vascular graft survival in the clinic has been particularly challenging. After 30 years of research, there are now several scaffolds currently in clinical trials. However, these products are either being investigated for large-diameter applications or they require pre-seeding of endothelial cells. This progress report identifies important challenges unique to engineering vascular grafts for high pressure arteries less than 4 mm in diameter (e.g., coronary artery), and discusses limitations with the current usage of the term "small-diameter." Next, the composition and processing techniques used for generating tissue engineered vascular grafts (TEVGs) are discussed, with a focus on the benefits of blended materials. Other scaffolds for non-tissue engineering approaches and stents are also briefly mentioned for comparison. Overall, this progress report discusses the importance of defining the most critical challenges for small diameter TEVGs, developing new scaffolds to provide these properties, and determining acceptable benchmarks for scaffold responses in the body.
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Birthare K, Shojaee M, Jones CG, Brenner JR, Bashur CA. Collagen incorporation within electrospun conduits reduces lipid oxidation and impacts conduit mechanics. Biomed Mater 2016; 11:025019. [DOI: 10.1088/1748-6041/11/2/025019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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10
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Michael E, Abeyrathna N, Patel AV, Liao Y, Bashur CA. Incorporation of photo-carbon monoxide releasing materials into electrospun scaffolds for vascular tissue engineering. Biomed Mater 2016; 11:025009. [DOI: 10.1088/1748-6041/11/2/025009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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11
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Yau WWY, Long H, Gauthier NC, Chan JKY, Chew SY. The effects of nanofiber diameter and orientation on siRNA uptake and gene silencing. Biomaterials 2014; 37:94-106. [PMID: 25453941 DOI: 10.1016/j.biomaterials.2014.10.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/02/2014] [Indexed: 02/07/2023]
Abstract
While substrate topography influences cell behavior, RNA interference (RNAi) has also emerged as a potent method for understanding and directing cell fate. However, the effects of substrate topography on RNAi remain poorly understood. Here, we report the influence of nanofiber architecture on siRNA-mediated gene-silencing in human somatic and stem cells. The respective model cells, human dermal fibroblasts (HDFs) and mesenchymal stem cells (MSCs), were cultured onto aligned or randomly oriented electrospun poly(ε-caprolactone) fibers of different average diameters (300 nm, 700 nm and 1.3 μm). In HDFs, decreasing fiber diameter from 1.3 μm to 300 nm improved Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and Collagen-I silencing efficiencies by ∼ 3.8 and ∼4.4 folds respectively (p < 0.05) while the effective siRNA uptake pathway was altered from clathrin-dependent endocytosis to macropinocytosis. In MSCs, aligned fibers generated significantly higher level of gene silencing of RE-1 silencing transcription factor (REST) and green fluorescent protein (GFP) (∼1.6 and ∼1.5 folds respectively, p < 0.05), than randomly-oriented fibers. Aligned fiber topography facilitated functional siRNA uptake through clathrin-mediated endocytosis and membrane fusion. Taken together, our results demonstrated a promising role of three-dimensional fibrous scaffolds in modulating siRNA-mediated gene-silencing and established the critical synergistic role of these substrates in modulating cellular behavior by RNAi.
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Affiliation(s)
- Winifred Wing Yiu Yau
- Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
| | - Hongyan Long
- Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore
| | - Nils C Gauthier
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore
| | - Jerry Kok Yen Chan
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074, Singapore; Department of Reproductive Medicine, KK Women's and Children's Hospital, Singapore 229899, Singapore; Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore 169857, Singapore
| | - Sing Yian Chew
- Division of Chemical and Biomolecular Engineering, School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 308232, Singapore.
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12
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The effect of thick fibers and large pores of electrospun poly(ε-caprolactone) vascular grafts on macrophage polarization and arterial regeneration. Biomaterials 2014; 35:5700-10. [DOI: 10.1016/j.biomaterials.2014.03.078] [Citation(s) in RCA: 309] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 03/27/2014] [Indexed: 01/22/2023]
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13
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Fioretta ES, Simonet M, Smits AIPM, Baaijens FPT, Bouten CVC. Differential Response of Endothelial and Endothelial Colony Forming Cells on Electrospun Scaffolds with Distinct Microfiber Diameters. Biomacromolecules 2014; 15:821-9. [DOI: 10.1021/bm4016418] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Emanuela S. Fioretta
- Soft Tissue
Biomechanics and Tissue Engineering, Department of Biomedical
Engineering, and ‡Institute for Complex Molecular Systems, Eindhoven University of Technology,
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Marc Simonet
- Soft Tissue
Biomechanics and Tissue Engineering, Department of Biomedical
Engineering, and ‡Institute for Complex Molecular Systems, Eindhoven University of Technology,
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Anthal I. P. M. Smits
- Soft Tissue
Biomechanics and Tissue Engineering, Department of Biomedical
Engineering, and ‡Institute for Complex Molecular Systems, Eindhoven University of Technology,
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Frank P. T. Baaijens
- Soft Tissue
Biomechanics and Tissue Engineering, Department of Biomedical
Engineering, and ‡Institute for Complex Molecular Systems, Eindhoven University of Technology,
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Carlijn V. C. Bouten
- Soft Tissue
Biomechanics and Tissue Engineering, Department of Biomedical
Engineering, and ‡Institute for Complex Molecular Systems, Eindhoven University of Technology,
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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Venkataraman L, Bashur CA, Ramamurthi A. Impact of cyclic stretch on induced elastogenesis within collagenous conduits. Tissue Eng Part A 2014; 20:1403-15. [PMID: 24313750 DOI: 10.1089/ten.tea.2013.0294] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In vitro tissue engineering of vascular conduits requires a synergy between several external factors, including biochemical supplementation and mechanotranductive stimulation. The goal of this study was to improve adult human vascular smooth muscle cell orientation and elastic matrix synthesis within 3D tubular collagen gel constructs. We used a combination of elastogenic factors (EFs) previously tested in our lab, along with cyclic circumferential strains at low amplitude (2.5%) delivered at a range of frequencies (0.5, 1.5, and 3 Hz). After 21 days of culture, the constructs were analyzed for elastic matrix outcomes, activity of matrix metalloproteinases (MMPs)-2 and -9, cell densities and phenotype, and mechanical properties of constructs. While cell densities remained unaffected by the addition of stretch, contractile phenotypic markers were elevated in all stretched constructs relative to control. Constructs cultured with EFs stretched at 1.5 Hz exhibited the maximum elastin mRNA expression and total matrix elastin (over sixfold vs. the static EFs control). MMP-2 content was comparable in all treatment conditions, but MMP-9 levels were elevated at the higher frequencies (1.5 and 3 Hz). Minimal circumferential orientation was achieved and the mechanical properties remained comparable among the treatment conditions. Overall, constructs treated with EFs and stretched at 1.5 Hz exhibited the most elastogenic outcomes.
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15
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Bashur CA, Ramamurthi A. Composition of intraperitoneally implanted electrospun conduits modulates cellular elastic matrix generation. Acta Biomater 2014; 10:163-72. [PMID: 24016842 DOI: 10.1016/j.actbio.2013.08.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/07/2013] [Accepted: 08/29/2013] [Indexed: 12/28/2022]
Abstract
Improving elastic matrix generation is critical to developing functional tissue engineered vascular grafts. Therefore, this study pursued a strategy to grow autologous tissue in vivo by recruiting potentially more elastogenic cells to conduits implanted within the peritoneal cavity. The goal was to determine the impacts of electrospun conduit composition and hyaluronan oligomer (HA-o) modification on the recruitment of peritoneal cells, and their phenotype and ability to synthesize elastic matrix. These responses were assessed as a function of conduit intra-peritoneal implantation time. This study showed that the blending of collagen with poly(ε-caprolactone) (PCL) promotes a faster wound healing response, as assessed by trends in expression of macrophage and smooth muscle cell (SMC) contractile markers and in matrix deposition, compared to the more chronic response for PCL alone. This result, along with the increase in elastic matrix production, demonstrates the benefits of incorporating as little as 25% w/w collagen into the conduit. In addition, PCR analysis demonstrated the challenges in differentiating between a myofibroblast and an SMC using traditional phenotypic markers. Finally, the impact of the tethered HA-o is limited within the inflammatory environment, unlike the significant response found previously in vitro. In conclusion, these results demonstrate the importance of both careful control of implanted scaffold composition and the development of appropriate delivery methods for HA-o.
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