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Liu C, Campbell SB, Li J, Bannerman D, Pascual-Gil S, Kieda J, Wu Q, Herman PR, Radisic M. High Throughput Omnidirectional Printing of Tubular Microstructures from Elastomeric Polymers. Adv Healthc Mater 2022; 11:e2201346. [PMID: 36165232 PMCID: PMC9742311 DOI: 10.1002/adhm.202201346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 09/09/2022] [Indexed: 01/28/2023]
Abstract
Bioelastomers are extensively used in biomedical applications due to their desirable mechanical strength, tunable properties, and chemical versatility; however, three-dimensional (3D) printing bioelastomers into microscale structures has proven elusive. Herein, a high throughput omnidirectional printing approach via coaxial extrusion is described that fabricates perfusable elastomeric microtubes of unprecedently small inner diameter (350-550 µm) and wall thickness (40-60 µm). The versatility of this approach is shown through the printing of two different polymeric elastomers, followed by photocrosslinking and removal of the fugitive inner phase. Designed experiments are used to tune the microtube dimensions and stiffness to match that of native ex vivo rat vasculature. This approach affords the fabrication of multiple biomimetic shapes resembling cochlea and kidney glomerulus and affords facile, high-throughput generation of perfusable structures that can be seeded with endothelial cells for biomedical applications. Post-printing laser micromachining is performed to generate micro-sized holes (520 µm) in the tube wall to tune microstructure permeability. Importantly, for organ-on-a-chip applications, the described approach takes only 3.6 min to print microtubes (without microholes) over an entire 96-well plate device, in contrast to comparable hole-free structures that take between 1.5 and 6.5 days to fabricate using a manual 3D stamping approach.
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Affiliation(s)
- Chuan Liu
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Scott B. Campbell
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Jianzhao Li
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Dawn Bannerman
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Simon Pascual-Gil
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Jennifer Kieda
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Qinghua Wu
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Peter R. Herman
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Milica Radisic
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
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Valtanen RS, Yang YP, Gurtner GC, Maloney WJ, Lowenberg DW. Synthetic and Bone tissue engineering graft substitutes: What is the future? Injury 2021; 52 Suppl 2:S72-S77. [PMID: 32732118 DOI: 10.1016/j.injury.2020.07.040] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/05/2020] [Accepted: 07/18/2020] [Indexed: 02/02/2023]
Abstract
The management of large segmental bone defects caused by trauma or disease remains clinically challenging within orthopaedics. The major impediment to bone healing with current treatment options is insufficient vascularization and incorporation of graft material. Lack of rapid adequate vascularization leads to cellular necrosis within the inner regions of the implanted material and a failure of bone regeneration. Current treatment options for critical size bone defects include the continued "gold standard" autograft, allograft, synthetic bone graft substitutes, vascularized fibular graft, induced membrane technique, and distraction osteogenesis. Bone tissue engineering (BTE) remains an exciting prospect for the treatment of large segmental bone defects; however, current clinical integration of engineered scaffolds remains low. We believe that the barrier to clinical application of bone tissue engineering constructs lies in the lack of concomitant vascularization of these scaffolds. This mini-review outlines the progress made and the significant limitations remaining in successful clinical incorporation of engineered synthetic bone substitutes for segmental defects.
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Affiliation(s)
- Rosa S Valtanen
- Department of Orthopaedic Surgery, Stanford University School of Medicine, 450 Broadway St., Mailcode 6342, Redwood City, CA 94063 USA
| | - Yunzhi P Yang
- Department of Orthopaedic Surgery, Stanford University School of Medicine, 450 Broadway St., Mailcode 6342, Redwood City, CA 94063 USA
| | - Geoffrey C Gurtner
- Department of Plastic Surgery, Stanford University School of Medicine, Stanford, USA
| | - William J Maloney
- Department of Orthopaedic Surgery, Stanford University School of Medicine, 450 Broadway St., Mailcode 6342, Redwood City, CA 94063 USA
| | - David W Lowenberg
- Department of Orthopaedic Surgery, Stanford University School of Medicine, 450 Broadway St., Mailcode 6342, Redwood City, CA 94063 USA.
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Kuźmińska A, Kwarta D, Ciach T, Butruk-Raszeja BA. Cylindrical Polyurethane Scaffold Fabricated Using the Phase Inversion Method: Influence of Process Parameters on Scaffolds' Morphology and Mechanical Properties. MATERIALS (BASEL, SWITZERLAND) 2021; 14:2977. [PMID: 34072853 PMCID: PMC8198356 DOI: 10.3390/ma14112977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/23/2021] [Accepted: 05/27/2021] [Indexed: 12/15/2022]
Abstract
This work presents a method of obtaining cylindrical polymer structures with a given diameter (approx. 5 mm) using the phase inversion technique. As part of the work, the influence of process parameters (polymer hardness, polymer solution concentration, the composition of the non-solvent solution, process time) on the scaffolds' morphology was investigated. Additionally, the influence of the addition of porogen on the scaffold's mechanical properties was analyzed. It has been shown that the use of a 20% polymer solution of medium hardness (ChronoFlex C45D) and carrying out the process for 24 h in 0:100 water/ethanol leads to the achievement of repeatable structures with adequate flexibility. Among the three types of porogens tested (NaCl, hexane, polyvinyl alcohol), the most favorable results were obtained for 10% polyvinyl alcohol (PVA). The addition of PVA increases the range of pore diameters and the value of the mean pore diameter (9.6 ± 3.2 vs. 15.2 ± 6.4) while reducing the elasticity of the structure (Young modulus = 3.6 ± 1.5 MPa vs. 9.7 ± 4.3 MPa).
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Affiliation(s)
- Aleksandra Kuźmińska
- Biomedical Engineering Laboratory, Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, 00-645 Warsaw, Poland; (D.K.); (T.C.); (B.A.B.-R.)
| | - Dominika Kwarta
- Biomedical Engineering Laboratory, Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, 00-645 Warsaw, Poland; (D.K.); (T.C.); (B.A.B.-R.)
| | - Tomasz Ciach
- Biomedical Engineering Laboratory, Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, 00-645 Warsaw, Poland; (D.K.); (T.C.); (B.A.B.-R.)
- Centre for Advanced Materials and Technologies CEZAMAT, Warsaw University of Technology, Poleczki 19, 02-822 Warsaw, Poland
| | - Beata A. Butruk-Raszeja
- Biomedical Engineering Laboratory, Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, 00-645 Warsaw, Poland; (D.K.); (T.C.); (B.A.B.-R.)
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Li J, Gao Q, Chen Z, Yang X. Small diameter blood vessels with controllable micropore structure induced by centrifugal force for improved endothelialization. Eng Life Sci 2020; 20:181-185. [PMID: 32874181 PMCID: PMC7447902 DOI: 10.1002/elsc.201900123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 12/03/2019] [Accepted: 12/19/2019] [Indexed: 11/11/2022] Open
Abstract
The micropore structure is prerequisite for fast and durable endothelialization of artificial small diameter blood vessels (ASDBVs). Although some methods, such as salt leaching, coagulation, and electrospinning, have been developed to construct micropores for ASDBVs, the uncontrollability of the structure and the complicated procedures of the process are still the issues to be concerned about. In this study, a compact device based on the principle of centrifugal force is established and used to prepare polyurethane (PU) ASDBVs with micropore structures by blasting different porogens. It is found that the glass beads could construct micropores with regular round shape, uniform distribution, and controllable size (60-350 µm), which significantly improves the endothelialization of PU-based ASDBVs, especially when the pore size is about 60 µm. This method is easy-accessible and wide-applicable, which provides a new pathway for the research and development of ASDBVs.
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Affiliation(s)
- Jinge Li
- Polymer Composites Engineering LaboratoryChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchunJilinP. R. China
| | - Qinwei Gao
- State Key Laboratory of Polymer Physics and ChemistryChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchunJilinP. R. China
- School of Applied Chemistry and EngineeringUniversity of Science and Technology of ChinaHefeiAnhuiP. R. China
| | - Zhaobin Chen
- Polymer Composites Engineering LaboratoryChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchunJilinP. R. China
| | - Xiaoniu Yang
- Polymer Composites Engineering LaboratoryChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchunJilinP. R. China
- State Key Laboratory of Polymer Physics and ChemistryChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchunJilinP. R. China
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Bil M, Kijeńska-Gawrońska E, Głodkowska-Mrówka E, Manda-Handzlik A, Mrówka P. Design and in vitro evaluation of electrospun shape memory polyurethanes for self-fitting tissue engineering grafts and drug delivery systems. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 110:110675. [PMID: 32204102 DOI: 10.1016/j.msec.2020.110675] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 01/15/2020] [Accepted: 01/15/2020] [Indexed: 12/11/2022]
Abstract
Integration of multiple features including shape memory, biodegradation, and sustained drug delivery in a single material offers the opportunity to significantly improve the abilities of implantable devices for cardiovascular system regeneration. Two types of shape memory polyurethanes (SMPUs): PU-PLGA and PU-PLLA/PEG differing in soft segments composition that comprising blends of various biodegradable polyols, i.e. D,l-lactide-co-glycolide diol (o-PLGA), poly(e-caprolactone) diols (o-PCL) with various molecular weights, poly-l-lactide diol (o-PLLA), polyethylene glycol (o-PEG) were synthesized and further utilized to electrospun nanofibrous - rapamycin (Rap) delivery system. Structure characterization by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DCS) and hydrophilicity measurements were performed to gain more insights on the influence of the particular units of the softs segments on the transition temperature (Ttrans), shape recovery, degradation profile, and drug release kinetics. In vitro study in PBS solution revealed that incorporation of o-PLGA segments to SMPUs is favorable over o-PEG as increased shape memory performance was observed. Moreover, presence of PLGA in PU-PLGA gave more predictable degradation profile in comparison to PU-PLLA/PEG system. Human Cardiac Fibroblasts (HCF) viability tests in vitro confirmed that the amount of Rap released from evaluated PU-PLLA/PEG/Rap and PU-PLGA/Rap drug delivery systems was sufficient to inhibit cells growth on the surface of the tested materials.
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Affiliation(s)
- Monika Bil
- Materials Design Division, Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Woloska Street, 02-507 Warsaw, Poland.
| | - Ewa Kijeńska-Gawrońska
- Materials Design Division, Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Woloska Street, 02-507 Warsaw, Poland
| | - Eliza Głodkowska-Mrówka
- Department of Experimental Hematology, Department of Laboratory Medicine, Institute of Hematology and Transfusion Medicine, 5 Indiry Gandhi Str, 02-776 Warsaw, Poland
| | - Aneta Manda-Handzlik
- Department of Laboratory Diagnostics and Clinical Immunology of Developmental Age, Medical University of Warsaw, 63A Żwirki i Wigury Street, 02-091 Warsaw, Poland
| | - Piotr Mrówka
- Department of Biophysics and Human Physiology, Medical University of Warsaw, 5 Chalubinskiego Str., 02-004 Warsaw, Poland
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Li S, Wang K, Hu Q, Zhang C, Wang B. Direct-write and sacrifice-based techniques for vasculatures. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2019; 104:109936. [PMID: 31500055 DOI: 10.1016/j.msec.2019.109936] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 05/22/2019] [Accepted: 07/01/2019] [Indexed: 12/27/2022]
Abstract
Fabricating biomimetic vasculatures is considered one of the greatest challenges in tissue regeneration due to their complex structures across various length scales. Many strategies have been investigated on how to fabricate tissue-engineering vasculatures (TEVs), including vascular-like and vascularized structures that can replace their native counterparts. The advancement of additive manufacturing (AM) technologies has enabled a wide range of fabrication techniques that can directly-write TEVs with complex and delicate structures. Meanwhile, sacrifice-based techniques, which rely on the removal of encapsulated sacrificial templates to form desired cavity-like structures, have also been widely studied. This review will specifically focus on the two most promising methods in these recently developed technologies, which are the direct-write method and the sacrifice-based method. The performance, advantages, and shortcomings of each technique are analyzed and compared. In the discussion, we list current challenges in this field and present our vision of next-generation TEVs technologies. Perspectives on future research in this field are given at the end.
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Affiliation(s)
- Shuai Li
- Georgia Tech Manufacturing Institute, Georgia Institute of Technology, Atlanta, GA 30332, USA; Rapid Manufacturing Engineering Center, School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China
| | - Kan Wang
- Georgia Tech Manufacturing Institute, Georgia Institute of Technology, Atlanta, GA 30332, USA.
| | - Qingxi Hu
- Rapid Manufacturing Engineering Center, School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China; Shanghai Key Laboratory of Intelligent Manufacturing and Robotics, Shanghai University, Shanghai 200072, China; National Demonstration Center for Experimental Engineering Training Education, Shanghai University, Shanghai 200444, China.
| | - Chuck Zhang
- Georgia Tech Manufacturing Institute, Georgia Institute of Technology, Atlanta, GA 30332, USA; H. Milton Stewart School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Ben Wang
- Georgia Tech Manufacturing Institute, Georgia Institute of Technology, Atlanta, GA 30332, USA; H. Milton Stewart School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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7
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Elsayed Y, Lekakou C, Tomlins P. Modeling, simulations, and optimization of smooth muscle cell tissue engineering for the production of vascular grafts. Biotechnol Bioeng 2019; 116:1509-1522. [PMID: 30737955 DOI: 10.1002/bit.26955] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 02/01/2019] [Accepted: 02/06/2019] [Indexed: 12/20/2022]
Abstract
The paper presents a transient, continuum, two-phase model of the tissue engineering in fibrous scaffolds, including transport equations for the flowing culture medium, nutrient and cell concentration with transverse and in-plane diffusion and cell migration, a novel feature of local in-plane transport across a phenomenological pore and innovative layer-by-layer cell filling approach. The model is successfully validated for the smooth muscle cell tissue engineering of a vascular graft using crosslinked, electrospun gelatin fiber scaffolds for both static and dynamic cell culture, the latter in a dynamic bioreactor with a rotating shaft on which the tubular scaffold is attached. Parametric studies evaluate the impact of the scaffold microstructure, cell dynamics, oxygen transport, and static or dynamic conditions on the rate and extent of cell proliferation and depth of oxygen accessibility. An optimized scaffold of 75% dry porosity is proposed that can be tissue engineered into a viable and still fully oxygenated graft of the tunica media of the coronary artery within 2 days in the dynamic bioreactor. Such scaffold also matches the mechanical properties of the tunica media of the human coronary artery and the suture retention strength of a saphenous vein, often used as a coronary artery graft.
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Affiliation(s)
- Yahya Elsayed
- Department of Mechanical Engineering Sciences, Engineering Materials Centre, University of Surrey, Guildford, Surrey, UK.,Department of Mechanical Engineering Sciences, Centre of Biomedical Engineering, University of Surrey, Guildford, Surrey, UK
| | - Constantina Lekakou
- Department of Mechanical Engineering Sciences, Engineering Materials Centre, University of Surrey, Guildford, Surrey, UK
| | - Paul Tomlins
- National Physical Laboratory, Teddington, Middlesex, UK
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8
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Jie M, Mao S, Liu H, He Z, Li HF, Lin JM. Evaluation of drug combination for glioblastoma based on an intestine-liver metabolic model on microchip. Analyst 2018; 142:3629-3638. [PMID: 28853486 DOI: 10.1039/c7an00453b] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
An intestine-liver-glioblastoma biomimetic system was developed to evaluate the drug combination therapy for glioblastoma. A hollow fiber (HF) was embedded into the upper layer of the microfluidic chip for culturing Caco-2 cells to mimic drug delivery as an artificial intestine. HepG2 cells cultured in the bottom chamber of the chip acted as an artificial liver for metabolizing the drugs. The dual-drug combination to glioblastoma U251 cells was evaluated based on the intestine-liver metabolic model. The drugs, irinotecan (CPT-11), temozolomide (TMZ) and cyclophosphamide (CP), were used to dynamically stimulate the cells by continuous infusion into the intestine unit. After intestine absorption and liver metabolism, the prodrugs were transformed to active metabolites, which induced glioblastoma cells apoptosis. The anticancer activity of the CPT-11 and TMZ combination is significantly enhanced compared to that of the single drug treatments. Combination index (CI) values of the combination groups, CPT-11 and TMZ, CPT-11 and CP, and TMZ and CP, at half maximal inhibitory concentration were 0.137, 0.288, and 0.482, respectively. The results indicated that the CPT-11 and TMZ combination was superior to the CPT-11 and CP group as well as the TMZ and CP group towards the U251 cells. The metabolism mechanism of CPT-11 and TMZ was further studied by coupling with mass spectrometric analysis. The biomimetic model enables the performance of long-term cell co-culture, drug delivery, metabolism and real-time analysis of drug effects, promising systematic in vitro mimicking of physiological and pharmacological processes.
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Affiliation(s)
- Mingsha Jie
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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Stahl AM, Yang YP. Tunable Elastomers with an Antithrombotic Component for Cardiovascular Applications. Adv Healthc Mater 2018; 7:e1800222. [PMID: 29855176 PMCID: PMC6317886 DOI: 10.1002/adhm.201800222] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/26/2018] [Indexed: 12/27/2022]
Abstract
This study reports the development of a novel family of biodegradable polyurethanes for use as tissue engineered cardiovascular scaffolds or blood-contacting medical devices. Covalent incorporation of the antiplatelet agent dipyridamole into biodegradable polycaprolactone-based polyurethanes yields biocompatible materials with improved thromboresistance and tunable mechanical strength and elasticity. Altering the ratio of the dipyridamole to the diisocyanate linking unit and the polycaprolactone macromer enables control over both the drug content and the polymer cross-link density. Covalent cross-linking in the materials achieves significant elasticity and a tunable range of elastic moduli similar to that of native cardiovascular tissues. Interestingly, the cross-link density of the polyurethanes is inversely related to the elastic modulus, an effect attributed to decreasing crystallinity in the more cross-linked polymers. In vitro characterization shows that the antiplatelet agent is homogeneously distributed in the materials and is released slowly throughout the polymer degradation process. The drug-containing polyurethanes support endothelial cell and vascular smooth muscle cell proliferation, while demonstrating reduced levels of platelet adhesion and activation, supporting their candidacy as promising substrates for cardiovascular tissue engineering.
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Affiliation(s)
- Alexander M. Stahl
- Departments of Chemistry, Stanford University, Stanford, CA, 94305, USA
- Departments of Orthopaedic Surgery, Stanford University, Stanford, CA, 94305, USA
| | - Yunzhi Peter Yang
- Departments of Orthopaedic Surgery, Stanford University, Stanford, CA, 94305, USA
- Departments of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
- Departments of Bioengineering, Stanford University, Stanford, CA, 94305, USA
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Elomaa L, Yang YP. Additive Manufacturing of Vascular Grafts and Vascularized Tissue Constructs. TISSUE ENGINEERING. PART B, REVIEWS 2017; 23:436-450. [PMID: 27981886 PMCID: PMC5652978 DOI: 10.1089/ten.teb.2016.0348] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/28/2016] [Indexed: 12/13/2022]
Abstract
There is a great need for engineered vascular grafts among patients with cardiovascular diseases who are in need of bypass therapy and lack autologous healthy blood vessels. In addition, because of the severe worldwide shortage of organ donors, there is an increasing need for engineered vascularized tissue constructs as an alternative to organ transplants. Additive manufacturing (AM) offers great advantages and flexibility of fabrication of cell-laden, multimaterial, and anatomically shaped vascular grafts and vascularized tissue constructs. Various inkjet-, extrusion-, and photocrosslinking-based AM techniques have been applied to the fabrication of both self-standing vascular grafts and porous, vascularized tissue constructs. This review discusses the state-of-the-art research on the use of AM for vascular applications and the key criteria for biomaterials in the AM of both acellular and cellular constructs. We envision that new smart printing materials that can adapt to their environment and encourage rapid endothelialization and remodeling will be the key factor in the future for the successful AM of personalized and dynamic vascular tissue applications.
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Affiliation(s)
- Laura Elomaa
- Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, California
| | - Yunzhi Peter Yang
- Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, California
- Department of Materials Science and Engineering, Stanford University School of Engineering, Stanford, California
- Department of Bioengineering, Stanford University School of Engineering, Stanford, California
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11
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Grena B, Alayrac JB, Levy E, Stolyarov AM, Joannopoulos JD, Fink Y. Thermally-drawn fibers with spatially-selective porous domains. Nat Commun 2017; 8:364. [PMID: 28848237 PMCID: PMC5573721 DOI: 10.1038/s41467-017-00375-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 06/25/2017] [Indexed: 01/26/2023] Open
Abstract
The control of mass transport using porous fibers is ubiquitous, with applications ranging from filtration to catalysis. Yet, to date, porous fibers have been made of single materials in simple geometries, with limited function. Here we report the fabrication and characterization of thermally drawn multimaterial fibers encompassing internal porous domains alongside non-porous insulating and conductive materials, in highly controlled device geometries. Our approach utilizes phase separation of a polymer solution during the preform-to-fiber drawing process, generating porosity as the fiber is drawn. Engineering the preform structure grants control over the geometry and materials architecture of the final porous fibers. Electrical conductivity of the selectrolyte-filled porous domains is substantiated through ionic conductivity measurements using electrodes thermally drawn in the cross-section. Pore size tunability between 500 nm–10 µm is established by regulating the phase separation kinetics. We further demonstrate capillary breakup of cylindrical porous structures porous microspheres within the fiber core. Porous polymer fibers show great potential for a range of applications, but their simple structures typically limit their functionality. Here, the authors combine a thermal drawing process with polymer solution phase separation to fabricate porous multimaterial fibers with complex internal architectures.
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Affiliation(s)
- Benjamin Grena
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Jean-Baptiste Alayrac
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Etgar Levy
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | | | - John D Joannopoulos
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Yoel Fink
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA. .,Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA. .,Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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12
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Liu M, Zhou Z, Chai Y, Zhang S, Wu X, Huang S, Su J, Jiang J. Synthesis of cell composite alginate microfibers by microfluidics with the application potential of small diameter vascular grafts. Biofabrication 2017; 9:025030. [PMID: 28485303 DOI: 10.1088/1758-5090/aa71da] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Fabrication of small diameter vascular grafts (SDVGs) with appropriate responses for clinical application is still challenging. In the present work, the production and characterization of solid alginate based microfibers as potential SDVG candidates through the method of microfluidics were considered original. A simple glass microfluidic device with a 'L-shape' cylindrical-flow channel in the microfluidic platform was developed. The gelation of microfibers occurred when the alginate solution and a CaCl2 solution were introduced as a core flow and as a sheath flow, respectively. The diameters of the microfibers could be controlled by varying the flow rates and the glass capillary tubes diameters at their tips. The generated microfibers had somewhat rough and porous surfaces, their suture retention strengths were comparable to the strength of other tissue engineered grafts. The encapsulated mesenchymal stem cells proliferated well in the microfibers, and showed a stable endothelialization under the angiogenesis effects of vascular endothelial growth factor and fibroblastic growth factor. The in vivo implant into the mice abdomens indicated that cell composite microfibers caused a mild host reaction. These encouraging results suggest great promise of the application of microfluidics as a future alternative in SDVGs engineering.
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Affiliation(s)
- Mingying Liu
- Key Laboratory for Biorheological Science and Technology of Ministry of Education; State and Local Joint Engineering Laboratory for Vascular Implants; Bioengineering College, Chongqing University, Chongqing, 400044, People's Republic of China
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13
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Li Y, Li X, Zhao R, Wang C, Qiu F, Sun B, Ji H, Qiu J, Wang C. Enhanced adhesion and proliferation of human umbilical vein endothelial cells on conductive PANI-PCL fiber scaffold by electrical stimulation. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2017; 72:106-112. [DOI: 10.1016/j.msec.2016.11.052] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 10/25/2016] [Accepted: 11/13/2016] [Indexed: 12/31/2022]
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14
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Bosio VE, Brown J, Rodriguez MJ, Kaplan DL. Biodegradable Porous Silk Microtubes for Tissue Vascularization. J Mater Chem B 2016; 5:1227-1235. [PMID: 28944059 DOI: 10.1039/c6tb02712a] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cardiovascular diseases are the leading cause of mortality around the globe, and microvasculature replacements to help stem these diseases are not available. Additionally, some vascular surgeries needing small diameter vascular grafts present different performance requirements. In this work silk fibroin scaffolds based on silk/polyethylene oxide blends were developed as microtubes for vasculature needs and for different tissue regeneration times, mechanical properties and structural designs. Systems with 13, 14 and 15% silk alone or blended with 1 or 2% of polyethylene oxide (PEO) were used to generate porous microtubes using gel-spinning. Microtubes with inner diameters (ID) of 150-300 μm and 100 μm wall thickness were fabricated. The systems were assessed for porosity, mechanical properties, enzymatic degradability, and in vitro vascular endothelial cell attachment and metabolic activity. After 14 days all tubes supported the proliferation of cells and cell attachment increased with porosity. The silk tubes with PEO had similar crystallinity but higher elastic modulus compared with the systems without PEO. The silk (13%)/PEO (1%) system showed the highest porosity (20 μm pore diameters on average), highest cell attachment and fastest degradation profile. There was a good correlation between these parameters with silk concentration and the presence of PEO. The results demonstrate the ability to generate versatile and tunable tubular biomaterials based on silk-PEO-blends with potential for microvascular grafts.
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Affiliation(s)
- V E Bosio
- Institute of Applied Biotechnology CINDEFI (CCT La Plata-CONICET, U.N.L.P.), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calle 47 y 115, 1900 La Plata, Argentina.,Department of Biomedical Engineering, Tufts University, Medford, MA02155, USA
| | - J Brown
- Department of Biomedical Engineering, Tufts University, Medford, MA02155, USA
| | - M J Rodriguez
- Department of Biomedical Engineering, Tufts University, Medford, MA02155, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA02155, USA
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15
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Boire TC, Balikov DA, Lee Y, Guth CM, Cheung-Flynn J, Sung HJ. Biomaterial-Based Approaches to Address Vein Graft and Hemodialysis Access Failures. Macromol Rapid Commun 2016; 37:1860-1880. [PMID: 27673474 PMCID: PMC5156561 DOI: 10.1002/marc.201600412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/15/2016] [Indexed: 12/19/2022]
Abstract
Veins used as grafts in heart bypass or as access points in hemodialysis exhibit high failure rates, thereby causing significant morbidity and mortality for patients. Interventional or revisional surgeries required to correct these failures have been met with limited success and exorbitant costs, particularly for the US Centers for Medicare & Medicaid Services. Vein stenosis or occlusion leading to failure is primarily the result of neointimal hyperplasia. Systemic therapies have achieved little long-term success, indicating the need for more localized, sustained, biomaterial-based solutions. Numerous studies have demonstrated the ability of external stents to reduce neointimal hyperplasia. However, successful results from animal models have failed to translate to the clinic thus far, and no external stent is currently approved for use in the US to prevent vein graft or hemodialysis access failures. This review discusses current progress in the field, design considerations, and future perspectives for biomaterial-based external stents. More comparative studies iteratively modulating biomaterial and biomaterial-drug approaches are critical in addressing mechanistic knowledge gaps associated with external stent application to the arteriovenous environment. Addressing these gaps will ultimately lead to more viable solutions that prevent vein graft and hemodialysis access failures.
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Affiliation(s)
- Timothy C Boire
- Department of Biomedical Engineering, Vanderbilt University, 37235, Nashville, TN, USA
| | - Daniel A Balikov
- Department of Biomedical Engineering, Vanderbilt University, 37235, Nashville, TN, USA
| | - Yunki Lee
- Department of Biomedical Engineering, Vanderbilt University, 37235, Nashville, TN, USA
| | - Christy M Guth
- Division of Vascular Surgery, Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, 37235, USA
| | - Joyce Cheung-Flynn
- Division of Vascular Surgery, Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, 37235, USA
| | - Hak-Joon Sung
- Department of Biomedical Engineering, Vanderbilt University, 37235, Nashville, TN, USA
- Severance Biomedical Science Institute, College of Medicine, Yonsei University, Seoul, 120-752, Republic of Korea
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16
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Mercado-Pagán ÁE, Stahl AM, Ramseier ML, Behn AW, Yang Y. Synthesis and characterization of polycaprolactone urethane hollow fiber membranes as small diameter vascular grafts. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 64:61-73. [PMID: 27127029 DOI: 10.1016/j.msec.2016.03.068] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/24/2016] [Accepted: 03/21/2016] [Indexed: 12/30/2022]
Abstract
The design of bioresorbable synthetic small diameter (<6mm) vascular grafts (SDVGs) capable of sustaining long-term patency and endothelialization is a daunting challenge in vascular tissue engineering. Here, we synthesized a family of biocompatible and biodegradable polycaprolactone (PCL) urethane macromers to fabricate hollow fiber membranes (HFMs) as SDVG candidates, and characterized their mechanical properties, degradability, hemocompatibility, and endothelial development. The HFMs had smooth surfaces and porous internal structures. Their tensile stiffness ranged from 0.09 to 0.11N/mm and their maximum tensile force from 0.86 to 1.03N, with minimum failure strains of approximately 130%. Permeability varied from 1 to 14×10(-6)cm/s, burst pressures from 1158 to 1468mmHg, and compliance from 0.52 to 1.48%/100mmHg. The suture retention forces ranged from 0.55 to 0.81N. HFMs had slow degradation profiles, with 15 to 30% degradation after 8weeks. Human endothelial cells proliferated well on the HFMs, creating stable cell layer coverage. Hemocompatibility studies demonstrated low hemolysis (<2%), platelet activation, and protein adsorption. There were no significant differences in the hemocompatibility of HFMs in the absence and presence of endothelial layers. These encouraging results suggest great promise of our newly developed materials and biodegradable elastomeric HFMs as SDVG candidates.
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Affiliation(s)
| | - Alexander M Stahl
- Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA; Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Michelle L Ramseier
- Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA; Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Anthony W Behn
- Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA
| | - Yunzhi Yang
- Department of Orthopedic Surgery, Stanford University, Stanford, CA, USA; Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA; Department of Bioengineering, Stanford University, Stanford, CA, USA.
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17
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Fabrication and characterisation of biomimetic, electrospun gelatin fibre scaffolds for tunica media-equivalent, tissue engineered vascular grafts. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2015; 61:473-83. [PMID: 26838874 DOI: 10.1016/j.msec.2015.12.081] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 12/02/2015] [Accepted: 12/28/2015] [Indexed: 11/20/2022]
Abstract
It is increasingly recognised that biomimetic, natural polymers mimicking the extracellular matrix (ECM) have low thrombogenicity and functional motifs that regulate cell-matrix interactions, with these factors being critical for tissue engineered vascular grafts especially grafts of small diameter. Gelatin constitutes a low cost substitute of soluble collagen but gelatin scaffolds so far have shown generally low strength and suture retention strength. In this study, we have devised the fabrication of novel, electrospun, multilayer, gelatin fibre scaffolds, with controlled fibre layer orientation, and optimised gelatin crosslinking to achieve not only compliance equivalent to that of coronary artery but also for the first time strength of the wet tubular acellular scaffold (swollen with absorbed water) same as that of the tunica media of coronary artery in both circumferential and axial directions. Most importantly, for the first time for natural scaffolds and in particular gelatin, high suture retention strength was achieved in the range of 1.8-1.94 N for wet acellular scaffolds, same or better than that for fresh saphenous vein. The study presents the investigations to relate the electrospinning process parameters to the microstructural parameters of the scaffold, which are further related to the mechanical performance data of wet, crosslinked, electrospun scaffolds in both circumferential and axial tubular directions. The scaffolds exhibited excellent performance in human smooth muscle cell (SMC) proliferation, with SMCs seeded on the top surface adhering, elongating and aligning along the local fibres, migrating through the scaffold thickness and populating a transverse distance of 186 μm and 240 μm 9 days post-seeding for scaffolds of initial dry porosity of 74 and 83%, respectively.
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18
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Elsayed Y, Lekakou C, Labeed F, Tomlins P. Smooth muscle tissue engineering in crosslinked electrospun gelatin scaffolds. J Biomed Mater Res A 2015; 104:313-21. [PMID: 26378902 DOI: 10.1002/jbm.a.35565] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/04/2015] [Accepted: 09/15/2015] [Indexed: 11/11/2022]
Abstract
Crosslinked, multi-layer electrospun gelatin fiber scaffolds with generally ±45 degree fiber orientation have been used to grow human umbilical vein smooth muscle cells (HUVSMCs) to create a vascular tunica media graft. Scaffolds of different fiber diameter (2-5 μm in wet state), pore size, and porosity (16-21% in wet state) were assessed in terms of cell adherence and viability, cell proliferation, and migration in both in-plane and transverse directions through the scaffold as a function of time under static cell culture conditions. HUVSMC cell viability reached between 80 and 92% for all scaffolds after 9 days in culture. HUVSMCs adhered, elongated, and orientated in the fiber direction, and migrated through a scaffold thickness of 200-235 μm 9 days post-seeding under static conditions. The best scaffold was then used to assess the tissue engineering of HUVSMCs under dynamic conditions for a rotating, cell seeded, tubular scaffold in the bioreactor containing the culture medium. Dynamic conditions almost doubled the rate of cell proliferation through the scaffold, forming full tissue throughout a scaffold of 250-300 μm thickness 6 days post-seeding.
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Affiliation(s)
- Yahya Elsayed
- Advanced Materials Group, University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom
| | - Constantina Lekakou
- Advanced Materials Group, University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom
| | - Fatima Labeed
- Centre of Biomedical Engineering, University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom
| | - Paul Tomlins
- National Physical Laboratory (NPL) Teddington, Middlesex, TW11 0LW, United Kingdom
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