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Carbonaro D, Villa E, Gallo D, Morbiducci U, Audenino AL, Chiastra C. Designing the mechanical behavior of NiTi self-expandable vascular stents by tuning the heat treatment parameters. J Mech Behav Biomed Mater 2024; 158:106653. [PMID: 39074439 DOI: 10.1016/j.jmbbm.2024.106653] [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] [Received: 04/23/2024] [Revised: 06/14/2024] [Accepted: 07/06/2024] [Indexed: 07/31/2024]
Abstract
The remarkable mechanical properties of nickel-titanium (NiTi) shape memory alloy, particularly its super-elasticity, establish it as the material of choice for fabricating self-expanding vascular stents, including the metallic backbone of peripheral stents and the metallic frame of stent-grafts. The super-elastic nature of NiTi substantially influences the mechanical performance of vascular stents, thereby affecting their clinical effectiveness and safety. This property shows marked sensitivity to the primary parameters of the heat treatment process used in device fabrication, specifically temperature and processing time. In this context, this study integrates experimental and computational analyses to explore the potential of designing the mechanical characteristics of NiTi vascular stents by adjusting heat treatment parameters. To reach this aim, differently heat-treated NiTi wire samples were experimentally characterized using calorimetric and uniaxial tensile testing. Subsequently, the mechanical response of a stent-graft model featuring a metallic frame made of NiTi wire was assessed in terms of radial forces generated at various implantation diameters through finite element analysis. The stent-graft served as an illustrative case of NiTi vascular stent to investigate the impact of the heat treatment parameters on its mechanical response. From the study a strong linear relationship emerged between NiTi super-elastic parameters (i.e., austenite finish temperature, martensite elastic modulus, upper plateau stress, lower plateau stress and transformation strain) and heat treatment parameters (R2 > 0.79, p-value < 0.001) for the adopted ranges of temperature and processing time. Additionally, a strong linear relationship was observed between: (i) the radial force generated by the stent-graft during expansion and the heat treatment parameters (R2 > 0.82, p-value < 0.001); (ii) the radial force generated by the stent-graft during expansion and the lower plateau stress of NiTi (R2 > 0.93, p-value < 0.001). In conclusion, the findings of this study suggest that designing and optimizing the mechanical properties of NiTi vascular stents by finely tuning temperature and processing time of the heat treatment process is feasible.
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Affiliation(s)
- Dario Carbonaro
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Elena Villa
- National Research Council, Institute of Condensed Matter Chemistry and Technologies for Energy (CNR-ICMATE), Lecco, Italy
| | - Diego Gallo
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Umberto Morbiducci
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Alberto Luigi Audenino
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
| | - Claudio Chiastra
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
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Szczęsny G, Kopec M, Politis DJ, Kowalewski ZL, Łazarski A, Szolc T. A Review on Biomaterials for Orthopaedic Surgery and Traumatology: From Past to Present. MATERIALS 2022; 15:ma15103622. [PMID: 35629649 PMCID: PMC9145924 DOI: 10.3390/ma15103622] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/16/2022] [Accepted: 05/18/2022] [Indexed: 02/04/2023]
Abstract
The principal features essential for the success of an orthopaedic implant are its shape, dimensional accuracy, and adequate mechanical properties. Unlike other manufactured products, chemical stability and toxicity are of increased importance due to the need for biocompatibility over an implants life which could span several years. Thus, the combination of mechanical and biological properties determines the clinical usefulness of biomaterials in orthopaedic and musculoskeletal trauma surgery. Materials commonly used for these applications include stainless steel, cobalt-chromium and titanium alloys, ceramics, polyethylene, and poly(methyl methacrylate) (PMMA) bone cement. This study reviews the properties of commonly used materials and the advantages and disadvantages of each, with special emphasis on the sensitivity, toxicity, irritancy, and possible mutagenic and teratogenic capabilities. In addition, the production and final finishing processes of implants are discussed. Finally, potential directions for future implant development are discussed, with an emphasis on developing advanced personalised implants, according to a patient’s stature and physical requirements.
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Affiliation(s)
- Grzegorz Szczęsny
- Department of Orthopaedic Surgery and Traumatology, Medical University, 4 Lindleya Str., 02-005 Warsaw, Poland; (G.S.); (A.Ł.)
| | - Mateusz Kopec
- Institute of Fundamental Technological Research, Polish Academy of Sciences, 5B Pawińskiego Str., 02-106 Warsaw, Poland; (Z.L.K.); (T.S.)
- Correspondence:
| | - Denis J. Politis
- Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia 20537, Cyprus;
| | - Zbigniew L. Kowalewski
- Institute of Fundamental Technological Research, Polish Academy of Sciences, 5B Pawińskiego Str., 02-106 Warsaw, Poland; (Z.L.K.); (T.S.)
| | - Adam Łazarski
- Department of Orthopaedic Surgery and Traumatology, Medical University, 4 Lindleya Str., 02-005 Warsaw, Poland; (G.S.); (A.Ł.)
| | - Tomasz Szolc
- Institute of Fundamental Technological Research, Polish Academy of Sciences, 5B Pawińskiego Str., 02-106 Warsaw, Poland; (Z.L.K.); (T.S.)
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Park MH, Marin-Cuartas M, Imbrie-Moore AM, Wilkerson RJ, Pandya PK, Zhu Y, Wang H, Borger MA, Woo YJ. Biomechanical Analysis of Neochordal Repair Error from Diastolic Phase Inversion of Static Left Ventricular Pressurization. JTCVS Tech 2022; 12:54-64. [PMID: 35403058 PMCID: PMC8987390 DOI: 10.1016/j.xjtc.2022.01.009] [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: 07/27/2021] [Accepted: 01/12/2022] [Indexed: 11/30/2022] Open
Abstract
Objective Neochordal implantation is a common form of surgical mitral valve (MV) repair. However, neochord length is assessed using static left ventricular pressurization, leading surgeons to evaluate leaflet coaptation and valve competency when the left ventricle is dilating instead of contracting physiologically, referred to as diastolic phase inversion (DPI). We hypothesize that the difference in papillary muscle (PM) positioning between DPI and physiologic systole results in miscalculated neochord lengths, which might affect repair performance. Methods Porcine MVs (n = 6) were mounted in an ex vivo heart simulator and PMs were affixed to robots that accurately simulate PM motion. Baseline hemodynamic and chordal strain data were collected, after which P2 chordae were severed to simulate posterior leaflet prolapse from chordal rupture and subsequent mitral regurgitation. Neochord implantation was performed in the physiologic and DPI static configurations. Results Although both repairs successfully reduced mitral regurgitation, the DPI repair resulted in longer neochordae (2.19 ± 0.4 mm; P < .01). Furthermore, the hemodynamic performance was reduced for the DPI repair resulting in higher leakage volume (P = .01) and regurgitant fraction (P < .01). Peak chordal forces were reduced in the physiologic repair (0.57 ± 0.11 N) versus the DPI repair (0.68 ± 0.12 N; P < .01). Conclusions By leveraging advanced ex vivo technologies, we were able to quantify the effects of static pressurization on neochordal length determination. Our findings suggest that this post-repair assessment might slightly overestimate the neochordal length and that additional marginal shortening of neochordae might positively affect MV repair performance and durability by reducing load on surrounding native chordae.
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Affiliation(s)
- Matthew H. Park
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | - Mateo Marin-Cuartas
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Annabel M. Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | | | - Pearly K. Pandya
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Mechanical Engineering, Stanford University, Stanford, Calif
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Bioengineering, Stanford University, Stanford, Calif
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
| | - Michael A. Borger
- University Department of Cardiac Surgery, Leipzig Heart Center, Leipzig, Germany
| | - Y. Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif
- Department of Bioengineering, Stanford University, Stanford, Calif
- Address for reprints: Y. Joseph Woo, MD, Department of Cardiothoracic Surgery, Department of Bioengineering, Stanford University, Falk Cardiovascular Research Building CV-235, 300 Pasteur Drive, Stanford, CA 94305-5407.
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Mohd Radzali NA, Mohd Hidzir N, Abdul Rahman I, Mokhtar AK. Mechanical properties of polymeric biomaterials: Modified ePTFE using gamma irradiation. OPEN CHEM 2021. [DOI: 10.1515/chem-2021-0112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Evaluating the mechanical properties of expanded polytetrafluoroethylene (ePTFE) is essential to measure its resistance to permanent deformation from an applied force. These mechanical ePTFE properties must be comparable to the properties of real tissue. Various hydrophilic comonomers 2-hydroxyethyl methacrylate (HEMA), N-isopropylacrylamide (NIPAAM), and N-vinylcaprolactam were used individually for copolymerization with acrylic acid (AA) to be grafted onto ePTFE using the gamma irradiation-induced grafting method. After surface modification, the hydrophobic and mechanical properties of ePTFE were altered. The water uptake and contact angle measurement showed that the modified ePTFE was less hydrophobic (∼500%, θ < 90°) than the unmodified ePTFE (0%, θ = 140°). Moreover, the mechanical properties of ePTFE changed after the modification process due to the polymer grafted onto the ePTFE surface. The data from mechanical tests, such as Young’s modulus (74–121 MPa), ultimate tensile strength (5–9 MPa), and elongation at break (56–121%), obtained for the sample AA-co-HEMA and AA-co-NIPAAM remain within the ranges and are considered desirable for use as a biomaterial. The mechanical strength correlates well with the percentage of the grafting yield after the modification process and is dependent on the parameters used, such as irradiation dose and type of comonomer.
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Affiliation(s)
- Nur Ain Mohd Radzali
- Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia , 43600 Bangi , Selangor , Malaysia
- Nuclear Technology Research Centre, Faculty of Science and Technology, Universiti Kebangsaan Malaysia , 43600 Bangi , Selangor , Malaysia
| | - Norsyahidah Mohd Hidzir
- Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia , 43600 Bangi , Selangor , Malaysia
- Nuclear Technology Research Centre, Faculty of Science and Technology, Universiti Kebangsaan Malaysia , 43600 Bangi , Selangor , Malaysia
| | - Irman Abdul Rahman
- Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia , 43600 Bangi , Selangor , Malaysia
- Nuclear Technology Research Centre, Faculty of Science and Technology, Universiti Kebangsaan Malaysia , 43600 Bangi , Selangor , Malaysia
| | - Abdul Khaliq Mokhtar
- Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia , 43600 Bangi , Selangor , Malaysia
- Nuclear Technology Research Centre, Faculty of Science and Technology, Universiti Kebangsaan Malaysia , 43600 Bangi , Selangor , Malaysia
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Lin J, Nutley M, Li C, Douglas G, Du J, Zhang Z, Douville Y, Guidoin R, Wang L. Innovative textile structures designed to prevent type III endoleaks in endovascular stent-grafts. Artif Organs 2020; 45:278-288. [PMID: 32969519 DOI: 10.1111/aor.13819] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 08/20/2020] [Accepted: 09/07/2020] [Indexed: 12/14/2022]
Abstract
The damage caused to the fabric of endovascular stent-grafts most often occurs at the contact zones between the fabrics where they are attached to the apices of Z-shaped stents as a result of normal physiologic pulsatile movement within angulated vessels in vivo. Although design improvements were made over the years, the risks were not fully eliminated even with the newer M-shaped stent reconfiguration. In this study, we proposed to create and manufacture a novel fabric for stent-grafts with specifically designed reinforced zones to enhance resistance to fabric abrasion. These reinforced zones are set at the vicinity of the apices of the Z-shaped stents and between two adjacent Z-shaped stents where folding and pleating are commonly observed to occur in angulated vessels. Three innovative weaving structures with two different types of yarns and two controls were designed and prepared. Two commonly used commercial devices supported, respectively, with ringed stents, and Z-shaped stents were selected as the references for comparison. Textile structures including thickness, water permeability, mechanical properties, (more specifically tensile and bursting stress, as well as fatigue simulation) were tested on all fabrics. Compared to commercially available plain weaves, the fabrics with locally reinforced zones showed improved mechanical characteristics and fatigue resistant properties. A fabric designed with specifically reinforced zones has now clearly been shown to effectively reduce the abrasion caused by the apices of Z-shaped stents. However, further optimization may still be possible.
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Affiliation(s)
- Jing Lin
- Key Laboratory of Textile Science and Technology of Ministry of Education, Donghua University, Shanghai, China
| | - Mark Nutley
- Division of Vascular Surgery and Department of Diagnostic Imaging, Peter Lougheed Centre, University of Calgary, Calgary, AB, Canada
| | - Chaojing Li
- Key Laboratory of Textile Science and Technology of Ministry of Education, Donghua University, Shanghai, China
| | - Graeham Douglas
- Department of Engineering, University of Cambridge, Cambridge, UK
| | - Jia Du
- Key Laboratory of Textile Science and Technology of Ministry of Education, Donghua University, Shanghai, China
| | - Ze Zhang
- Department of Surgery, Université Laval, Centre de Recherche du CHU de Québec - Université Laval, Quebec, QC, Canada
| | - Yvan Douville
- Department of Surgery, Université Laval, Centre de Recherche du CHU de Québec - Université Laval, Quebec, QC, Canada
| | - Robert Guidoin
- Department of Surgery, Université Laval, Centre de Recherche du CHU de Québec - Université Laval, Quebec, QC, Canada
| | - Lu Wang
- Key Laboratory of Textile Science and Technology of Ministry of Education, Donghua University, Shanghai, China
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6
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Azakie A, Carney JP, Lahti MT, Seiberlich MK, Hiremath G, Moklyak Y, Bianco RW. Feasibility Study of Catheter-Based Interventions for Anisotropic Expanded Polytetrafluoroethylene Cardiovascular Conduits in a Growing Lamb Model. J INVEST SURG 2020; 34:1231-1237. [PMID: 32684061 DOI: 10.1080/08941939.2020.1795324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Cardiovascular repair in children often requires implant of conduits which do not have growth potential and will require reoperation. In the current study we sought to determine the feasibility of catheter-based interventions of anisotropic conduits inserted as interposition grafts in the main pulmonary artery (MPA) of growing lambs. METHODS Lambs underwent interpositional implant of either an anisotropic expanded polytetrafluoroethylene (ePTFE) (Test) conduit or conventional PTFE (Control) conduit. In the postoperative period, lambs were anesthetized and underwent catheter-based interventions consisting of hemodynamic and angiographic data collection, balloon dilation and/or stenting of the conduit at 3, 6 or 9 month postoperative time point. RESULTS At 3 months, control lambs showed significant increases in right ventricular pressures and trans-conduit gradients in comparison to test lambs. Test conduit diameters were significantly larger compared to controls due to spontaneous radial expansion of the anisotropic conduit. Balloon dilation of test conduits at 3 and 6 months showed a reduction in RV pressure and statistically significant improvement in the RV outflow tract gradient as well as significant increase in graft diameter, compared to both control and pre-dilation conditions. Furthermore, the test conduit diameter increased significantly compared to the pre-balloon and control conditions at each time point. Necropsy of test conduits showed no evidence of tears, perforations, or clot and smooth interiors with well-healed anastomoses. CONCLUSIONS Anisotropic conduits implanted as interposition grafts in the MPA show spontaneous expansion, and can safely and effectively undergo catheter-based interventions, with significant increases in graft diameter occurring after balloon dilation.
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Affiliation(s)
- Anthony Azakie
- Experimental Surgical Services Laboratory, Department of Surgery, University of Minnesota, Minneapolis, MN, USA.,Division of Pediatric Cardiac Surgery, Peyton Manning Children's Hospital, Ascension St. Vincent, Indianapolis, IN, USA
| | - John P Carney
- Experimental Surgical Services Laboratory, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Matthew T Lahti
- Experimental Surgical Services Laboratory, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Melissa K Seiberlich
- Experimental Surgical Services Laboratory, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Gurumurthy Hiremath
- Experimental Surgical Services Laboratory, Department of Surgery, University of Minnesota, Minneapolis, MN, USA.,Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA
| | - Yuriy Moklyak
- Experimental Surgical Services Laboratory, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Richard W Bianco
- Experimental Surgical Services Laboratory, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
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Lei Y, Chen X, Li Z, Zhang L, Sun W, Li L, Tang F. A new process for customized patient-specific aortic stent graft using 3D printing technique. Med Eng Phys 2020; 77:80-87. [PMID: 31937437 DOI: 10.1016/j.medengphy.2019.12.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 11/14/2019] [Accepted: 12/10/2019] [Indexed: 11/28/2022]
Abstract
Endovascular aneurysm repair (EVAR) is a popular and effective treatment for descending aortic disease. However, the majority of existing coating stents used in EVAR are of a standard design which may not meet the size or structural requirements of different patients. Therefore, in this paper, we propose using 3D printing and controlled deposition as a patient-specific aortic stent graft manufacturing technique. The methodology involves the use of a rapid prototyping study sacrificial core-coating forming (RPSC-CF) technique to develop an aortic stent graft that consists of a film and metallic stent. Polyether polyurethane and nickel-titanium alloys were chosen due to their shape memory properties and good biocompatibility. The resulting customized stent grafts meet the demands of personalized therapy and invasive surgery, and perform well as demonstrated from burst pressure testing and the degree of radial support provided and radial support force tests, laying the foundation for precise aortic dissection treatment.
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Affiliation(s)
- Yang Lei
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; Beijing Institute of Aeronautical Materials, Beijing 100095, China
| | - Xin Chen
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; China Electronics Technology Group Corporation, Beijing 100846, China
| | - Zhen Li
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Lei Zhang
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
| | - Wei Sun
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Lei Li
- The First Hospital of Tsinghua University, Beijing 100016, China
| | - Feng Tang
- The First Hospital of Tsinghua University, Beijing 100016, China
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8
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Quicken S, de Bruin Y, Mees B, Tordoir J, Delhaas T, Huberts W. Computational study on the haemodynamic and mechanical performance of electrospun polyurethane dialysis grafts. Biomech Model Mechanobiol 2019; 19:713-722. [PMID: 31679093 PMCID: PMC7105427 DOI: 10.1007/s10237-019-01242-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 10/18/2019] [Indexed: 11/29/2022]
Abstract
Compliance mismatch between an arteriovenous dialysis graft (AVG) and the connected vein is believed to result in disturbed haemodynamics around the graft–vein anastomosis and increased mechanical loading of the vein. Both phenomena are associated with neointimal hyperplasia development, which is the main reason for AVG patency loss. In this study, we use a patient-specific fluid structure interaction AVG model to assess whether AVG haemodynamics and mechanical loading can be optimised by using novel electrospun polyurethane (ePU) grafts, since their compliance can be better tuned to match that of the native veins, compared to gold standard, expanded polytetrafluoroethylene (ePTFE) grafts. It was observed that the magnitude of flow disturbances in the vein and the size of anastomotic areas exposed to highly oscillatory shear (\documentclass[12pt]{minimal}
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\begin{document}$$\hbox {OSI} >0.25$$\end{document}OSI>0.25) and very high wall shear stress (\documentclass[12pt]{minimal}
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\begin{document}$$>40 \hbox { Pa}$$\end{document}>40Pa) were largest for the ePTFE graft. Median strain and von Mises stress in the vein were similar for both graft types, whereas highest stress and strain were observed in the anastomosis of the ePU graft. Since haemodynamics were most favourable for the ePU graft simulation, AVG longevity might be improved by the use of ePU grafts.
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Affiliation(s)
- Sjeng Quicken
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, 6223ER, Maastricht, The Netherlands
| | - Yeshi de Bruin
- Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Barend Mees
- Department of Vascular Surgery, Maastricht University Medical Centre, PO Box 5800, 6229 HX, Maastricht, The Netherlands
| | - Jan Tordoir
- Department of Vascular Surgery, Maastricht University Medical Centre, PO Box 5800, 6229 HX, Maastricht, The Netherlands
| | - Tammo Delhaas
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, 6223ER, Maastricht, The Netherlands
| | - Wouter Huberts
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, 6223ER, Maastricht, The Netherlands.
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Imbrie-Moore AM, Paulsen MJ, Thakore AD, Wang H, Hironaka CE, Lucian HJ, Farry JM, Edwards BB, Bae JH, Cutkosky MR, Woo YJ. Ex Vivo Biomechanical Study of Apical Versus Papillary Neochord Anchoring for Mitral Regurgitation. Ann Thorac Surg 2019; 108:90-97. [PMID: 30836099 DOI: 10.1016/j.athoracsur.2019.01.053] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 01/07/2019] [Accepted: 01/21/2019] [Indexed: 11/27/2022]
Abstract
BACKGROUND Neochordoplasty is an important repair technique, but optimal anchoring position is unknown. Although typically anchored at papillary muscles, new percutaneous devices anchor the neochordae at or near the ventricular apex, which may have an effect on chordal forces and the long-term durability of the repair. METHODS Porcine mitral valves (n = 6) were mounted in a left heart simulator that generates physiologic pressure and flow through the valves, and chordal forces were measured with Fiber Bragg Grating strain gauge sensors. Isolated mitral regurgitation was induced by cutting P2 primary chordae, and the regurgitant valve was repaired with polytetrafluoroethylene neochord with apical anchoring, followed by papillary muscle fixation for comparison. In both situations, the neochord was anchored to a customized force-sensing post positioned to mimic the relevant in vivo placement. RESULTS Echocardiographic and hemodynamic data confirmed that the repairs restored physiologic hemodynamics. Forces on the chordae and neochord were lower for papillary fixation than for the apical fixation (p = 0.003). In addition, the maximum rate of change of force on the chordae and neochordae was higher for apical fixation than for papillary fixation (p = 0.028). CONCLUSIONS Apical neochord anchoring results in effective repair of mitral regurgitation, albeit with somewhat higher forces on the chordae and neochord suture, as well as an increased rate of loading on the neochord compared with the papillary muscle fixation. These results may guide strategies to reduce stresses on neochordae as well as aid optimal patient selection.
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Affiliation(s)
- Annabel M Imbrie-Moore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California; Department of Mechanical Engineering, Stanford University, Stanford, California
| | - Michael J Paulsen
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California
| | - Akshara D Thakore
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California
| | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California
| | - Camille E Hironaka
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California
| | - Haley J Lucian
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California
| | - Justin M Farry
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California
| | - Bryan B Edwards
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California
| | - Jung Hwa Bae
- Department of Mechanical Engineering, Stanford University, Stanford, California
| | - Mark R Cutkosky
- Department of Mechanical Engineering, Stanford University, Stanford, California
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, California; Department of Bioengineering, Stanford University, Stanford, California.
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10
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Rychter M, Milanowski B, Grześkowiak BF, Jarek M, Kempiński M, Coy EL, Borysiak S, Baranowska-Korczyc A, Lulek J. Cilostazol-loaded electrospun three-dimensional systems for potential cardiovascular application: Effect of fibers hydrophilization on drug release, and cytocompatibility. J Colloid Interface Sci 2019; 536:310-327. [DOI: 10.1016/j.jcis.2018.10.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 10/09/2018] [Accepted: 10/10/2018] [Indexed: 01/06/2023]
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11
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Nemoto K, Hanada Y. Etching-Assisted Ablation of the UV-Transparent Fluoropolymer CYTOP Using Various Laser Pulse Widths and Subsequent Microfluidic Applications. MICROMACHINES 2018; 9:E662. [PMID: 30558316 PMCID: PMC6316415 DOI: 10.3390/mi9120662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 11/17/2022]
Abstract
This work demonstrated the surface microfabrication of the UV-transparent fluoropolymer CYTOP (perfluoro 1-butenyl vinyl ether), by etching-assisted ablation using lasers with different pulse widths. In previous studies, we developed a technique for CYTOP microfluidic fabrication using laser ablation followed by etching and annealing. However, this technique was not suitable for some industrial applications due to the requirement for prolonged etching of the irradiated areas. The present work developed a faster etching-assisted ablation method in which the laser ablation of CYTOP took place in fluorinated etching solvent and investigated into the fabrication mechanism of ablated craters obtained from various pulse width lasers. The mechanism study revealed that the efficient CYTOP microfabrication can be achieved with a longer pulse width laser using this technique. Therefore, the rapid, high-quality surface microfabrication of CYTOP was demonstrated using a conventional nanosecond laser. Additionally, Microfluidic systems were produced on a CYTOP substrate via the new etching-assisted laser ablation process followed by annealing within 1 h, which is faster than the prior work of the microfluidic chip fabrication. Subsequently, CYTOP and polydimethylsiloxane substrates were bonded to create a 3D microfluidic chip that allowed for a clear microscopic image of the fluid boundary.
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Affiliation(s)
- Keisuke Nemoto
- Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 0368561, Japan.
| | - Yasutaka Hanada
- Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 0368561, Japan.
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Henry JJD, Yu J, Wang A, Lee R, Fang J, Li S. Engineering the mechanical and biological properties of nanofibrous vascular grafts for in situ vascular tissue engineering. Biofabrication 2017; 9:035007. [PMID: 28817384 PMCID: PMC5847368 DOI: 10.1088/1758-5090/aa834b] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Synthetic small diameter vascular grafts have a high failure rate, and endothelialization is critical for preventing thrombosis and graft occlusion. A promising approach is in situ tissue engineering, whereby an acellular scaffold is implanted and provides stimulatory cues to guide the in situ remodeling into a functional blood vessel. An ideal scaffold should have sufficient binding sites for biomolecule immobilization and a mechanical property similar to native tissue. Here we developed a novel method to blend low molecular weight (LMW) elastic polymer during electrospinning process to increase conjugation sites and to improve the mechanical property of vascular grafts. LMW elastic polymer improved the elasticity of the scaffolds, and significantly increased the amount of heparin conjugated to the micro/nanofibrous scaffolds, which in turn increased the loading capacity of vascular endothelial growth factor (VEGF) and prolonged the release of VEGF. Vascular grafts were implanted into the carotid artery of rats to evaluate the in vivo performance. VEGF treatment significantly enhanced endothelium formation and the overall patency of vascular grafts. Heparin coating also increased cell infiltration into the electrospun grafts, thus increasing the production of collagen and elastin within the graft wall. This work demonstrates that LMW elastic polymer blending is an approach to engineer the mechanical and biological property of micro/nanofibrous vascular grafts for in situ vascular tissue engineering.
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Affiliation(s)
- Jeffrey J. D. Henry
- Department of Bioengineering, University of California, Berkeley, CA 94720
- UC Berkeley and UCSF Bioengineering Graduate Program
| | - Jian Yu
- Department of Bioengineering, University of California, Berkeley, CA 94720
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China 200040
| | - Aijun Wang
- Department of Surgery, University of California, Davis, Sacramento, CA 95817
| | - Randall Lee
- UC Berkeley and UCSF Bioengineering Graduate Program
- Department of Medicine, University of California, San Francisco, CA 94143
| | - Jun Fang
- Department of Bioengineering and Medicine, University of California, Los Angeles, CA 90095
| | - Song Li
- Department of Bioengineering, University of California, Berkeley, CA 94720
- UC Berkeley and UCSF Bioengineering Graduate Program
- Department of Bioengineering and Medicine, University of California, Los Angeles, CA 90095
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13
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Gong W, Li S, Lei D, Huang P, Yuan Z, You Z, Ye X, Zhao Q. Tissue-engineered mitral valve chordae tendineae: Biomechanical and biological characterization of decellularized porcine chordae. J Mech Behav Biomed Mater 2015; 56:205-217. [PMID: 26708255 DOI: 10.1016/j.jmbbm.2015.11.008] [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: 06/24/2015] [Revised: 11/09/2015] [Accepted: 11/16/2015] [Indexed: 01/07/2023]
Abstract
Chordae tendineae are essential for maintaining mitral valve function. Chordae replacement is one of the valve repair procedures commonly used to treat mitral valve regurgitation. But current chordae alternatives (polytetrafluoroethylene, ePTFE) do not have the elastic and self-regenerative properties. Moreover, the ePTFE sutures sometimes fail due to degeneration, calcification and rupture. Tissue-engineered chordae tendineae may overcome these problems. The utility of xenogeneic chordae for tissue-engineered chordae tendineae has not yet been adequately explored. In this study, polyelectrolyte multilayers (PEM) film modified decellularized porcine mitral valve chordae (PEM-DPC) were developed to explore tissue-engineered chordae tendineae as neochordae substitutes. Fresh porcine mitral chordae were decellularized and reserved the major elastic fiber and collagen components. Decellularized chordae with a PEM film were produced with chitosan-heparin by a lay-by-lay technique. Mesenchymal stem cells and vascular endothelial cells could grow well on the surface of the PEM-DPC. The superior biomechanical properties of PEM-DPC were proved with good flexibility and strength both in vitro and in vivo. PEM-DPC can be developed for potential alternative mitral valve chordae graft.
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Affiliation(s)
- Wenhui Gong
- Department of Cardiac Surgery, Ruijin Hospital, Shanghai Jiaotong University, School of Medicine, Shanghai, PR China
| | - Sen Li
- Department of Cardiac Surgery, Ruijin Hospital, Shanghai Jiaotong University, School of Medicine, Shanghai, PR China
| | - Dong Lei
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, PR China
| | - Peng Huang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, PR China
| | - Zhize Yuan
- Department of Cardiac Surgery, Ruijin Hospital, Shanghai Jiaotong University, School of Medicine, Shanghai, PR China
| | - Zhengwei You
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, PR China
| | - Xiaofeng Ye
- Department of Cardiac Surgery, Ruijin Hospital, Shanghai Jiaotong University, School of Medicine, Shanghai, PR China.
| | - Qiang Zhao
- Department of Cardiac Surgery, Ruijin Hospital, Shanghai Jiaotong University, School of Medicine, Shanghai, PR China.
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Graft Durability and Fatigue after In Situ Fenestration of Endovascular Stent Grafts Using Radiofrequency Puncture and Balloon Dilatation. Eur J Vasc Endovasc Surg 2014; 47:501-8. [DOI: 10.1016/j.ejvs.2014.02.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 02/10/2014] [Indexed: 11/19/2022]
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15
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Cassady AI, Hidzir NM, Grøndahl L. Enhancing expanded poly(tetrafluoroethylene) (ePTFE) for biomaterials applications. J Appl Polym Sci 2014. [DOI: 10.1002/app.40533] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- A. Ian Cassady
- School of Medical Science; Griffith University; Gold Coast Queensland 4222 Australia
| | - Norsyahidah Mohd Hidzir
- School of Chemistry and Molecular Biosciences; University of Queensland; St Lucia Queensland 4072 Australia
- School of Applied Physics; Faculty of Science and Technology, Universiti Kebangsaan Malaysia; UKM Bangi Selangor 43600 Malaysia
| | - Lisbeth Grøndahl
- School of Chemistry and Molecular Biosciences; University of Queensland; St Lucia Queensland 4072 Australia
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16
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Kwon KA, Shipley RJ, Edirisinghe M, Ezra DG, Rose GE, Rayment AW, Best SM, Cameron RE. Microstructure and mechanical properties of synthetic brow-suspension materials. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2014; 35:220-30. [DOI: 10.1016/j.msec.2013.10.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/02/2013] [Accepted: 10/29/2013] [Indexed: 11/17/2022]
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17
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Demanget N, Duprey A, Badel P, Orgéas L, Avril S, Geindreau C, Albertini JN, Favre JP. Finite element analysis of the mechanical performances of 8 marketed aortic stent-grafts. J Endovasc Ther 2013; 20:523-35. [PMID: 23914862 DOI: 10.1583/12-4063.1] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE To assess numerically the flexibility and mechanical stresses undergone by stents and fabric of currently manufactured stent-grafts. METHODS Eight marketed stent-graft limbs (Aorfix, Anaconda, Endurant, Excluder, Talent, Zenith Flex, Zenith LP, and Zenith Spiral-Z) were modeled using finite element analysis. A numerical benchmark combining bending up to 180° and pressurization at 150 mmHg of the stent-grafts was performed. Stent-graft flexibility, assessed by the calculation of the luminal reduction rate, maximal stresses in stents, and maximal strains in fabric were assessed. RESULTS The luminal reduction rate at 90° was <20% except for the Talent stent-graft. The rate at 180° was higher for Z-stented models (Talent, Endurant, Zenith, and Zenith LP; range 39%-78%) than spiral (Aorfix, Excluder, and Zenith Spiral-Z) or circular-stented (Anaconda) devices (range 14%-26%). At 180°, maximal stress was higher for Z-stented stent-grafts (range 370-622 MPa) than spiral or circular-stented endografts (range 177-368 MPa). At 90° and 180°, strains in fabric were low and did not differ significantly among the polyester stent-grafts (range 0.5%-7%), while the expanded polytetrafluoroethylene fabric of the Excluder stent-graft underwent higher strains (range 11%-18%). CONCLUSION Stent design strongly influences mechanical performances of aortic stent-grafts. Spiral and circular stents provide greater flexibility, as well as lower stress values than Z-stents, and thus better durability.
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Mohd Hidzir N, Hill DJ, Taran E, Martin D, Grøndahl L. Argon plasma treatment-induced grafting of acrylic acid onto expanded poly(tetrafluoroethylene) membranes. POLYMER 2013. [DOI: 10.1016/j.polymer.2013.10.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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19
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Wong CS, Liu X, Xu Z, Lin T, Wang X. Elastin and collagen enhances electrospun aligned polyurethane as scaffolds for vascular graft. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2013; 24:1865-1874. [PMID: 23625321 DOI: 10.1007/s10856-013-4937-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/19/2013] [Indexed: 06/02/2023]
Abstract
Mismatch in mechanical properties between synthetic vascular graft and arteries contribute to graft failure. The viscoelastic properties of arteries are conferred by elastin and collagen. In this study, the mechanical properties and cellular interactions of aligned nanofibrous polyurethane (PU) scaffolds blended with elastin, collagen or a mixture of both proteins were examined. Elastin softened PU to a peak stress and strain of 7.86 MPa and 112.28 % respectively, which are similar to those observed in blood vessels. Collagen-blended PU increased in peak stress to 28.14 MPa. The growth of smooth muscle cells (SMCs) on both collagen-blended and elastin/collagen-blended scaffold increased by 283 and 224 % respectively when compared to PU. Smooth muscle myosin staining indicated that the cells are contractile SMCs which are favored in vascular tissue engineering. Elastin and collagen are beneficial for creating compliant synthetic vascular grafts as elastin provided the necessary viscoelastic properties while collagen enhanced the cellular interactions.
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MESH Headings
- Blood Vessel Prosthesis
- Cell Proliferation/drug effects
- Cells, Cultured
- Coated Materials, Biocompatible/chemistry
- Coated Materials, Biocompatible/metabolism
- Collagen/metabolism
- Collagen/pharmacology
- Coronary Vessels/cytology
- Elastin/metabolism
- Elastin/pharmacology
- Electroplating/methods
- Humans
- Materials Testing
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/physiology
- Polyurethanes/chemistry
- Tissue Scaffolds/chemistry
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Affiliation(s)
- Cynthia S Wong
- Institute for Frontier Materials, Deakin University, Geelong, VIC, 3217, Australia.
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20
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Dong-na Z, Kai-chang K, Yu Z, Qing-xin Z, Zhen-chao Z. Formation and structure of polytetrafluoroethylene fibrils. J Appl Polym Sci 2013. [DOI: 10.1002/app.39630] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Zhang Dong-na
- Key Laboratory of Macromolecular Science & Technology of Shaanxi Province; Northwestern Polytechnical University; Xi'an; 710129; China
| | - Kou Kai-chang
- Key Laboratory of Macromolecular Science & Technology of Shaanxi Province; Northwestern Polytechnical University; Xi'an; 710129; China
| | - Zhang Yu
- Key Laboratory of Macromolecular Science & Technology of Shaanxi Province; Northwestern Polytechnical University; Xi'an; 710129; China
| | - Zhao Qing-xin
- Key Laboratory of Macromolecular Science & Technology of Shaanxi Province; Northwestern Polytechnical University; Xi'an; 710129; China
| | - Zheng Zhen-chao
- Key Laboratory of Macromolecular Science & Technology of Shaanxi Province; Northwestern Polytechnical University; Xi'an; 710129; China
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21
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Gao F, Ueda H, Gang L, Okada H. Fluid structure interaction simulation in three-layered aortic aneurysm model under pulsatile flow: Comparison of wrapping and stenting. J Biomech 2013; 46:1335-42. [DOI: 10.1016/j.jbiomech.2013.02.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 01/12/2013] [Accepted: 02/05/2013] [Indexed: 11/26/2022]
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22
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Hidzir NM, Hill DJ, Martin D, Grøndahl L. Radiation-induced grafting of acrylic acid onto expanded poly(tetrafluoroethylene) membranes. POLYMER 2012. [DOI: 10.1016/j.polymer.2012.10.042] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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23
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Biomechanical properties and large strain deformation of artificial silicone devices with different forms of nanostructured carbon. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2012. [DOI: 10.1016/j.msec.2012.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Misra R, Depan D, Shah J. Structure-process-functional property relationship of nanostructured carbon mediated cellular response for soft-tissue reconstruction and replacement. Acta Biomater 2012; 8:1908-17. [PMID: 22342421 DOI: 10.1016/j.actbio.2012.01.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/15/2012] [Accepted: 01/24/2012] [Indexed: 10/14/2022]
Abstract
The flexible and ductile silicone is widely used as a soft-tissue substitute for joint reconstruction and replacement in situations including joint pain and loss of mobility caused by the congenital or acquired factors such as osteoarthritis. Although these artificial devices have an expected life span of 15 years or more, they can fragment prematurely. Explanations for such failure are low tensile strength and inadequate bone build-up around the device, as a result of which the device does not bind with the surrounding tissues. Thus, the continued challenge for materials in contact with the bone is the design of high-strength-at-break silicone with the ability to modulate cell-substrate interactions for promoting osseointegration and long-term stability. To this end, we have discovered exciting evidence that the introduction of a novel nanostructured carbon in the void space between the silicone chains combined with processing at elevated pressure favorably stimulate cellular functions and provide a high degree of cytocompatibility. Furthermore, the high strength-at-break and undiminished intrinsic elongation of silicone are retained. In this regard, we combine here materials science and engineering and cellular biology, to elucidate the mechanism of cell-substrate interactions and the molecular machinery controlling the cell response. This is accomplished by investigating cell attachment, proliferation, and morphology, including cytomorphometric evaluation and quantitative assessment of prominent proteins, actin, vinculin, and fibronectin that are sensitive to cell-substrate interactions. The study strengthens the foundation for utilizing the nano- or quantum-size effects of nanostructured biomaterials.
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25
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Yoon HJ, Kim SE, Kwon YK, Kim EJ, Lee JC, Lee YS. Synthesis of silver nanostructures on polytetrafluoroethylene (PTFE) using electron beam irradiation for antimicrobacterial effect. J IND ENG CHEM 2012. [DOI: 10.1016/j.jiec.2011.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Vad S, Eskinazi A, Corbett T, McGloughlin T, Vande Geest JP. Determination of coefficient of friction for self-expanding stent-grafts. J Biomech Eng 2011; 132:121007. [PMID: 21142321 DOI: 10.1115/1.4002798] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Migration of stent-grafts (SGs) after endovascular aneurysm repair of abdominal aortic aneurysms is a serious complication that may require secondary intervention. Experimental, analytical, and computational studies have been carried out in the past to understand the factors responsible for migration. In an experimental setting, it can be very challenging to correctly capture and understand the interaction between a SG and an artery. Quantities such as coefficient of friction (COF) and contact pressures that characterize this interaction are difficult to measure using an experimental approach. This behavior can be investigated with good accuracy using finite element modeling. Although finite element models are able to incorporate frictional behavior of SGs, the absence of reliable values of coefficient of friction make these simulations unreliable. The aim of this paper is to demonstrate a method for determining the coefficients of friction of a self-expanding endovascular stent-graft. The methodology is demonstrated by considering three commercially available self-expanding SGs, labeled as A, B, and C. The SGs were compressed, expanded, and pulled out of polymeric cylinders of varying diameters and the pullout force was recorded in each case. The SG geometries were recreated using computer-aided design modeling and the entire experiment was simulated in ABAQUS 6.8/STANDARD. An optimization procedure was carried out for each SG oversize configuration to determine the COF that generated a frictional force corresponding to that measured in the experiment. The experimental pullout force and analytically determined COF for SGs A, B, and C were in the range of 6-9 N, 3-12 N, and 3-9 N and 0.08-0.16, 0.22-0.46, and 0.012-0.018, respectively. The computational model predicted COFs in the range of 0.00025-0.0055, 0.025-0.07, and 0.00025-0.006 for SGs A, B, and C, respectively. Our results suggest that for SGs A and B, which are exoskeleton based devices, the pullout forces increase upto a particular oversize beyond which they plateau, while pullout forces showed a continuous increase with oversize for SG C, which is an endoskeleton based device. The COF decreased with oversizing for both types of SGs. The proposed methodology will be useful for determining the COF between self-expanding stent-grafts from pullout tests on human arterial tissue.
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Affiliation(s)
- Siddharth Vad
- Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721, USA
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27
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Ashton JH, Ayyalasomayajula A, Simon BR, Vande Geest JP. Wall stress reduction in abdominal aortic aneurysms as a result of polymeric endoaortic paving. Ann Biomed Eng 2011; 39:1680-9. [PMID: 21350892 DOI: 10.1007/s10439-011-0271-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 02/04/2011] [Indexed: 11/26/2022]
Abstract
Polymeric endoaortic paving (PEAP) may improve endovascular repair of abdominal aortic aneurysms (AAA) since it has the potential to treat patients with complex AAA geometries while reducing the incidence of migration and endoleak. Polycaprolactone (PCL)/polyurethane (PU) blends are proposed as PEAP materials due to their range of mechanical properties, thermoformability, and resistance to biodegradation. In this study, the reduction in AAA wall stress that can be achieved using PEAP was estimated and compared to that resulting from stent-grafts. This was accomplished by mechanically modeling the anisotropic response of PCL/PU blends and implementing these results into finite element model (FEM) simulations. We found that at the maximum diameter of the AAA, the 50/50 and 10/90 PCL/PU blends reduced wall stress by 99 and 98%, respectively, while a stent-graft reduced wall stress by 99%. Our results also show that wall stress reduction increases with increasing PEAP thickness and PCL content in the blend ratio. These results indicate that PEAP can reduce AAA wall stress as effectively as a stent-graft. As such, we propose that PEAP may provide an improved treatment alternative for AAA, since many of the limitations of stent-grafts have the potential to be solved using this approach.
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Affiliation(s)
- John H Ashton
- Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ, USA
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28
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Bacterial cellulose as a potential vascular graft: Mechanical characterization and constitutive model development. J Biomed Mater Res B Appl Biomater 2011; 97:105-13. [DOI: 10.1002/jbm.b.31791] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Revised: 07/22/2010] [Accepted: 10/13/2010] [Indexed: 11/07/2022]
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29
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Thein-Han WW, Shah J, Misra RDK. Superior in vitro biological response and mechanical properties of an implantable nanostructured biomaterial: Nanohydroxyapatite-silicone rubber composite. Acta Biomater 2009; 5:2668-79. [PMID: 19435616 DOI: 10.1016/j.actbio.2009.04.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 04/20/2009] [Accepted: 04/23/2009] [Indexed: 11/15/2022]
Abstract
A potential approach to achieving the objective of favorably modulating the biological response of implantable biopolymers combined with good mechanical properties is to consider compounding the biopolymer with a bioactive nanocrystalline ceramic biomimetic material with high surface area. The processing of silicone rubber (SR)-nanohydroxyapatite (nHA) composite involved uniform dispersion of nHA via shear mixing and ultrasonication, followed by compounding at sub-ambient temperature, and high-pressure solidification when the final curing reaction occurs. The high-pressure solidification approach enabled the elastomer to retain the high elongation of SR even in the presence of the reinforcement material, nHA. The biological response of the nanostructured composite in terms of initial cell attachment, cell viability and proliferation was consistently greater on SR-5wt.% nHA composite surface compared to pure SR. Furthermore, in the nanocomposite, cell spreading, morphology and density were distinctly different from that of pure SR. Pre-osteoblasts grown on SR-nHA were well spread, flat, large in size with a rough cell surface, and appeared as a group. In contrast, these features were less pronounced in SR (e.g. smooth cell surface, not well spread). Interestingly, an immunofluorescence study illustrated distinct fibronectin expression level, and stronger vinculin focal adhesion contacts associated with abundant actin stress fibers in pre-osteoblasts grown on the nanocomposite compared to SR, implying enhanced cell-substrate interaction. This finding was consistent with the total protein content and SDS-PAGE analysis. The study leads us to believe that further increase in nHA content in the SR matrix beyond 5wt.% will encourage even greater cellular response. The integration of cellular and molecular biology with materials science and engineering described herein provides a direction for the development of a new generation of nanostructured materials.
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Affiliation(s)
- W W Thein-Han
- Biomaterials and Biomedical Engineering Research Laboratory, Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504, USA
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30
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Zhang YM, Wang SL, Lei ZY, Fan DL. Mechanical and biological evaluations of beta-tricalcium phosphate/silicone rubber composite as a novel soft-tissue implant. Aesthetic Plast Surg 2009; 33:760-9. [PMID: 19452200 DOI: 10.1007/s00266-009-9363-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 04/14/2009] [Indexed: 11/29/2022]
Abstract
BACKGROUND Although silicone rubber (SR) implants are most commonly used and effective for soft-tissue augmentation, they still have been implicated in many adverse reactions. To overcome this problem, a novel composite beta-tricalcium phosphate/silicone rubber (beta-TCP/SR) was prepared by adding beta-TCP into a SR matrix. This study was to evaluate its application potential by investigating the mechanical properties and biocompatibility of beta-TCP/SR. METHODS Mechanical properties, including Shore A hardness and tensile strength, were evaluated with 3-mm-thick samples and a universal testing machine. Cytocompatibility tests were conducted in vitro using 0.2-mm-thick beta-TCP/SR samples by seeding fibroblasts onto different samples. Soft-tissue response to beta-TCP/SR and pull-out measurements were investigated 4 weeks and 24 weeks after implantation. RESULTS The main mechanical properties were all significantly changed after mixing beta-TCP into the SR matrix, except for tearing strength. The cytocompatibility test showed enhanced adhesion and proliferation of fibroblasts onto beta-TCP/SR. Fibrous tissue ingrowth after resorption of beta-TCP was observed by in vivo histologic analysis. The peri-implant capsules in the beta-TCP/SR group were thinner than in the SR group 24 weeks after implantation. In a 24-week test, the maximum force required to pull out the beta-TCP/SR sheet was about six times greater than that needed for SR. CONCLUSION Although some mechanical properties were significantly changed, the results of the cytocompatibility test and in vivo animal study still suggest that beta-TCP/SR may be more suitable as a soft-tissue implant than SR and has the potential to be used in plastic surgery.
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Affiliation(s)
- Yi-ming Zhang
- Department of Plastic and Cosmetic Surgery, Xinqiao Hospital, Third Military Medical University, Xinqiao Road, Sha Ping Ba District, Chongqing, 400037, China
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31
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Kleinstreuer C, Li Z, Basciano CA, Seelecke S, Farber MA. Computational mechanics of Nitinol stent grafts. J Biomech 2008; 41:2370-8. [PMID: 18644312 DOI: 10.1016/j.jbiomech.2008.05.032] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 05/23/2008] [Accepted: 05/28/2008] [Indexed: 10/21/2022]
Abstract
A finite element analysis of tubular, diamond-shaped stent grafts under representative cyclic loading conditions for abdominal aortic aneurysm (AAA) repair is presented. Commercial software was employed to study the mechanical behavior and fatigue performance of different materials found in commercially available stent-graft systems. Specifically, the effects of crimping, deployment, and cyclic pressure loading on stent-graft fatigue life, radial force, and wall compliances were simulated and analyzed for two types of realistic but different Nitinol materials (NITI-1 and NITI-2) and grafts (expanded polytetrafluoroethylene-ePTFE and polyethylene therephthalate-PET). The results show that NITI-1 stent has a better crimping performance than NITI-2. Under representative cyclic pressure loading, both NITI-1 and NITI-2 sealing stents are located in the safe zone of the fatigue-life diagram; however, the fatigue resistance of an NITI-1 stent is better than that of an NITI-2 stent. It was found that the two types of sealing stents do not damage a healthy neck artery. In the aneurysm section, the NITI-1&ePTFE, NITI-1&PET, and NITI-2&PET combinations were free of fatigue fracture when subjected to conditions of radial stress between 50 and 150mmHg. In contrast, the safety factor for the NITI-2&ePFTE combination was only 0.67, which is not acceptable for proper AAA stent-graft design. In summary, a Nitinol stent with PET graft may greatly improve fatigue life, while its compliance is much lower than the NITI-ePTFE combination.
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Affiliation(s)
- C Kleinstreuer
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910, USA.
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Korzhikov V, Roeker S, Vlakh E, Kasper C, Tennikova T. Synthesis of Multifunctional Polyvinylsaccharide Containing Controllable Amounts of Biospecific Ligands. Bioconjug Chem 2008; 19:617-25. [DOI: 10.1021/bc700383w] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- V. Korzhikov
- Institute of Macromolecular Compounds, Russian Academy of Science, Bolshoy pr. 31, 199004, St. Petersburg, Russia, and Institut für Technische Chemie der Universität Hannover, Callinstr. 3, 30167 Hannover, Germany
| | - S. Roeker
- Institute of Macromolecular Compounds, Russian Academy of Science, Bolshoy pr. 31, 199004, St. Petersburg, Russia, and Institut für Technische Chemie der Universität Hannover, Callinstr. 3, 30167 Hannover, Germany
| | - E. Vlakh
- Institute of Macromolecular Compounds, Russian Academy of Science, Bolshoy pr. 31, 199004, St. Petersburg, Russia, and Institut für Technische Chemie der Universität Hannover, Callinstr. 3, 30167 Hannover, Germany
| | - C. Kasper
- Institute of Macromolecular Compounds, Russian Academy of Science, Bolshoy pr. 31, 199004, St. Petersburg, Russia, and Institut für Technische Chemie der Universität Hannover, Callinstr. 3, 30167 Hannover, Germany
| | - T. Tennikova
- Institute of Macromolecular Compounds, Russian Academy of Science, Bolshoy pr. 31, 199004, St. Petersburg, Russia, and Institut für Technische Chemie der Universität Hannover, Callinstr. 3, 30167 Hannover, Germany
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Small-diameter biodegradable scaffolds for functional vascular tissue engineering in the mouse model. Biomaterials 2007; 29:1454-63. [PMID: 18164056 DOI: 10.1016/j.biomaterials.2007.11.041] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 11/24/2007] [Indexed: 10/22/2022]
Abstract
The development of neotissue in tissue engineered vascular grafts remains poorly understood. Advances in mouse genetic models have been highly informative in the study of vascular biology, but have been inaccessible to vascular tissue engineers due to technical limitations on the use of mouse recipients. To this end, we have developed a method for constructing sub-1mm internal diameter (ID) biodegradable scaffolds utilizing a dual cylinder chamber molding system and a hybrid polyester sealant scaled for use in a mouse model. Scaffolds constructed from either polyglycolic acid or poly-l-lactic acid nonwoven felts demonstrated sufficient porosity, biomechanical profile, and biocompatibility to function as vascular grafts. The scaffolds implanted as either inferior vena cava or aortic interposition grafts in SCID/bg mice demonstrated excellent patency without evidence of thromboembolic complications or aneurysm formation. A foreign body immune response was observed with marked macrophage infiltration and giant cell formation by post-operative week 3. Organized vascular neotissue, consisting of endothelialization, medial generation, and collagen deposition, was evident within the internal lumen of the scaffolds by post-operative week 6. These results present the ability to create sub-1mm ID biodegradable tubular scaffolds that are functional as vascular grafts, and provide an experimental approach for the study of vascular tissue engineering using mouse models.
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Barnes CP, Sell SA, Boland ED, Simpson DG, Bowlin GL. Nanofiber technology: designing the next generation of tissue engineering scaffolds. Adv Drug Deliv Rev 2007; 59:1413-33. [PMID: 17916396 DOI: 10.1016/j.addr.2007.04.022] [Citation(s) in RCA: 656] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Accepted: 04/16/2007] [Indexed: 11/25/2022]
Abstract
Tissue engineering is an interdisciplinary field that has attempted to utilize a variety of processing methods with synthetic and natural polymers to fabricate scaffolds for the regeneration of tissues and organs. The study of structure-function relationships in both normal and pathological tissues has been coupled with the development of biologically active substitutes or engineered materials. The fibrillar collagens, types I, II, and III, are the most abundant natural polymers in the body and are found throughout the interstitial spaces where they function to impart overall structural integrity and strength to tissues. The collagen structures, referred to as extracellular matrix (ECM), provide the cells with the appropriate biological environment for embryologic development, organogenesis, cell growth, and wound repair. In the native tissues, the structural ECM proteins range in diameter from 50 to 500 nm. In order to create scaffolds or ECM analogues, which are truly biomimicking at this scale, one must employ nanotechnology. Recent advances in nanotechnology have led to a variety of approaches for the development of engineered ECM analogues. To date, three processing techniques (self-assembly, phase separation, and electrospinning) have evolved to allow the fabrication of nanofibrous scaffolds. With these advances, the long-awaited and much anticipated construction of a truly "biomimicking" or "ideal" tissue engineered environment, or scaffold, for a variety of tissues is now highly feasible. This review will discuss the three primary technologies (with a focus on electrospinning) available to create tissue engineering scaffolds that are capable of mimicking native tissue, as well as explore the wide array of materials investigated for use in scaffolds.
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Hinds MT, Rowe RC, Ren Z, Teach J, Wu PC, Kirkpatrick SJ, Breneman KD, Gregory KW, Courtman DW. Development of a reinforced porcine elastin composite vascular scaffold. J Biomed Mater Res A 2007; 77:458-69. [PMID: 16453334 DOI: 10.1002/jbm.a.30571] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Elastin, a principal structural component of native arteries, has distinct biological and mechanical advantages when used as a biomaterial; however, its low ultimate tensile strength has limited its use as an arterial conduit. We have developed a scaffold, consisting of a purified elastin tubular conduit strengthened with fibrin bonded layers of acellular small intestinal submucosa (aSIS) for potential use as a small diameter vascular graft. The addition of aSIS increased the ultimate tensile strength of the elastin conduits nine-fold. Burst pressures for the elastin composite vascular scaffold (1,396 +/- 309 mmHg) were significantly higher than pure elastin conduits (162 +/- 36 mmHg) and comparable to native saphenous veins. The average suture pullout strength of the elastin composite vascular scaffolds was 14.612 +/- 3.677 N, significantly higher than the pure elastin conduit (0.402 +/- 0.098 N), but comparable to native porcine carotid arteries (13.994 +/- 4.344 N). Cyclic circumferential strain testing indicated that the composite scaffolds were capable of withstanding physiological loading conditions for at least 83 h. Implantation of the elastin composites as carotid interposition grafts in swine demonstrated its superiority to clinically acceptable ePTFE with significantly longer average patency times of 5.23 h compared to 4.15 h. We have developed a biologically based elastin scaffold with suitable mechanical properties and low thrombogenicity for in vivo implantation, and with the potential for cellular repopulation and host integration reestablishing an appropriate elastic artery.
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Affiliation(s)
- Monica T Hinds
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, 97006, USA.
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Aumsuwan N, Heinhorst S, Urban MW. Antibacterial Surfaces on Expanded Polytetrafluoroethylene; Penicillin Attachment. Biomacromolecules 2007; 8:713-8. [PMID: 17291097 DOI: 10.1021/bm061050k] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Expanded polytetrafluoroethylene (ePTFE) was chemically modified to retard the growth of Staphylococcus aureus bacteria. This was accomplished by microwave plasma reactions in the presence of maleic anhydride (MA) to create acid functional groups on ePTFE surfaces, followed by esterification reactions with 200 and 600 molecular weight linear polyethylene glycol (PEG). Such surfaces were utilized for further reactions with penicillin (PEN) through etherification reactions to create anti-microbial surfaces. These reactions resulted in surface morphological changes, and spectroscopic analysis using attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR) revealed the formation of ester linkages resulting from reactions between PEN and PEG functionalities. Antibacterial activities were evaluated by a series of experiments where PEN-modified ePTFE specimens were immersed in a liquid aureus culture, and the bacteria growth was quantified by measuring % absorbance of the suspension at 600 nm wavelength. The lowest absorbance was observed for the solution containing PEN-PEG-MA-ePTFE specimens, thus showing highly effective anti-bacterial activity toward gram-positive Staphylococcus aureus bacteria. To our best knowledge, this is the first study that shows PEN-ePTFE surface modifications that are effective against gram-positive aureus bacteria.
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Affiliation(s)
- Nattharika Aumsuwan
- School of Polymers and High Performance Materials, Shelby F. Thames Polymer Science Research Center, The University of Southern Mississippi, Hattiesburg, Mississippi 39406, USA
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Sell SA, McClure MJ, Barnes CP, Knapp DC, Walpoth BH, Simpson DG, Bowlin GL. Electrospun polydioxanone–elastin blends: potential for bioresorbable vascular grafts. Biomed Mater 2006; 1:72-80. [DOI: 10.1088/1748-6041/1/2/004] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Slifka AJ, Drexler ES, Wright JE, Shandas R. Bubble-test method for synthetic and bovine vascular material. J Biomech 2005; 39:1939-42. [PMID: 16085073 DOI: 10.1016/j.jbiomech.2005.05.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Accepted: 05/25/2005] [Indexed: 11/30/2022]
Abstract
A measurement system has been designed and constructed at NIST for the study of the mechanical properties of synthetic and bovine vascular materials. The measurement technique was validated on latex, where good agreement was found with the Neo-Hookean model. Measurements were also made on expanded polytetrafluoroethylene, which is commonly used for vascular grafts. The measurements of this material were carried out over a pressure range greater than would be seen in vivo. However, the strains were still small enough to effectively apply the Neo-Hookean model to these data.
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Affiliation(s)
- A J Slifka
- NIST, Materials Reliability Division, m/s 853, 325 Broadway, Boulder, CO 80305, USA.
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Jian-Wei X, Randolph MA, Peretti GM, Nazzal JA, Roses RE, Morse KR, Yaremchuk MJ. Producing a Flexible Tissue-Engineered Cartilage Framework Using Expanded Polytetrafluoroethylene Membrane as a Pseudoperichondrium. Plast Reconstr Surg 2005; 116:577-89. [PMID: 16079694 DOI: 10.1097/01.prs.0000172985.81897.dc] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Both native and engineered cartilage is brittle and fractures easily without perichondrium. The aim of this study was to understand the role of the perichondrium and try to enhance the flexible properties of tissue-engineered cartilage using expanded polytetrafluoroethylene (ePTFE) membrane as a pseudoperichondrium. METHODS The study was conducted in two phases. In phase I, native swine auricular cartilage of different thicknesses was studied by histologic evaluation and failure testing. Next, isolated perichondrium was bonded to native cartilage slices using fibrin glue or Dermabond and tested to failure. In phase II, swine auricular chondrocytes were suspended in fibrin glue. The chondrocyte-fibrin glue composites were then bound to expanded polytetrafluoroethylene membrane in two trilaminar configurations: In group EC-1, the membrane was in the center, whereas it was on the surfaces in group EC-2. Specimens were implanted into nude mice for 4 weeks, 8 weeks, 12 weeks, and 8 months and subjected to histologic evaluation and failure testing. RESULTS In phase I, the results demonstrated that perichondrium securely bonded to the cartilage plays an important role in maintaining the flexible nature of elastic cartilage. In phase II, failure testing revealed that specimens in group EC-1 (expanded polytetrafluoroethylene core) were fractured during bending and destroyed after torsion, whereas those in group EC-2 (cartilage core) returned to their original shape without fracturing even after rigorous torsion. Histologic analysis demonstrated that transplanted chondrocytes penetrated into the microporous structure of expanded polytetrafluoroethylene and created a bond to it. CONCLUSION It is possible to engineer flexible cartilage using expanded polytetrafluoroethylene as a pseudoperichondrium.
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Affiliation(s)
- Xu Jian-Wei
- Department of Plastic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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Abstract
The primary goal of engineering cartilage as a therapeutic approach is to restore the physiological conditions of an affected or defective tissue in the body. Cartilage tissue is distributed widely in the human body and possesses an organization related to the specific demand of a particular anatomical region. In selecting the proper material for engineering cartilage, the functional demands of the replacement tissue must be considered. In summary, there is a multitude of scaffolds, naturally occurring and synthetic, that are suitable for engineering cartilage. Investigators have shown that the characteristics of the neocartilage differ significantly depending upon which scaffold is used. There are also large differences when a single scaffold is tested in vitro as opposed to in vivo. Moreover, the addition of other materials internally or externally to the cartilage composite influences the physical and biomechanical properties of the newly formed tissue. The results achieved so far are extremely encouraging and motivate further investigative efforts in the field. The biochemical composition and, more importantly, the biomechanical properties of the native tissue still represent the ideal replacement tissue.
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Affiliation(s)
- Mark A Randolph
- Division of Plastic Surgery, Harvard Medical School, Massachusetts General Hospital, WAC 453, 15 Parkman Street, Boston, MA 02114, USA.
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Xu JW, Nazzal J, Peretti GM, Kirchhoff CH, Randolph MA, Yaremchuk MJ. Tissue-Engineered Cartilage Composite With Expanded Polytetrafluoroethylene Membrane. Ann Plast Surg 2001; 46:527-32. [PMID: 11352427 DOI: 10.1097/00000637-200105000-00012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The authors report a new approach using expanded polytetrafluoroethylene (ePTFE) membrane as pseudoperichondrium to support engineered cartilage. Swine auricular chondrocytes were isolated and mixed with fibrin glue to achieve a final concentration of 40 x 10(6) cells per milliliter. The fibrin glue-cell suspension was assembled with ePTFE and the constructs were implanted into the dorsal subcutaneous pockets of nude mice for 12 weeks. Two experimental groups were prepared in this study: (1) ePTFE placed in the central part of the specimen in group 1 and (2) ePTFE placed on the outside surfaces in group 2. All specimens were subjected to histological and gross mechanical evaluation. Histological results showed neocartilage formation in both groups. The integration between neocartilage and ePTFE forms a tight bond. Gross mechanical testing revealed that the flexibility of specimens in group 2 were similar to that of native cartilage with intact perichondrium, whereas the flexibility of specimens in group 1 were poor. From these results the authors conclude that it is possible to produce a tissue-engineered cartilage framework using ePTFE as a support material to simulate the perichondrium.
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Affiliation(s)
- J W Xu
- Department of Plastic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA
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