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Zagiczek SN, Weiss-Tessbach M, Kussmann M, Moser D, Stoiber M, Moscato F, Schima H, Grasl C. Two-photon lithography for customized microstructured surfaces and their influence on wettability and bacterial load. 3D Print Med 2024; 10:12. [PMID: 38627256 PMCID: PMC11022422 DOI: 10.1186/s41205-024-00211-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 03/21/2024] [Indexed: 04/19/2024] Open
Abstract
BACKGROUND Device-related bacterial infections account for a large proportion of hospital-acquired infections. The ability of bacteria to form a biofilm as a protective shield usually makes treatment impossible without removal of the implant. Topographic surfaces have attracted considerable attention in studies seeking antibacterial properties without the need for additional antimicrobial substances. As there are still no valid rules for the design of antibacterial microstructured surfaces, a fast, reproducible production technique with good resolution is required to produce test surfaces and to examine their effectiveness with regard to their antibacterial properties. METHODS In this work various surfaces, flat and with microcylinders in different dimensions (flat, 1, 3 and 9 μm) with a surface area of 7 × 7 mm were fabricated with a nanoprinter using two-photon lithography and evaluated for their antibiofilm effect. The microstructured surfaces were cultured for 24 h with different strains of Pseudomonas aeruginosa and Staphylococcus aureus to study bacterial attachment to the patterned surfaces. In addition, surface wettability was measured by a static contact angle measurement. RESULTS Contact angles increased with cylinder size and thus hydrophobicity. Despite the difference in wettability, Staphylococcus aureus was not affected by the microstructures, while for Pseudomonas aeruginosa the bacterial load increased with the size of the cylinders, and compared to a flat surface, a reduction in bacteria was observed for one strain on the smallest cylinders. CONCLUSIONS Two-photon lithography allowed rapid and flexible production of microcylinders of different sizes, which affected surface wettability and bacterial load, however, depending on bacterial type and strain.
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Affiliation(s)
- Sophie Nilsson Zagiczek
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, AKH 4L, 1090, Vienna, Austria
| | - Matthias Weiss-Tessbach
- Department of Medicine I, Division of Infectious Diseases and Tropical Medicine, Medical University of Vienna, 1090, Vienna, Austria
| | - Manuel Kussmann
- Department of Medicine I, Division of Infectious Diseases and Tropical Medicine, Medical University of Vienna, 1090, Vienna, Austria
| | - Doris Moser
- Department of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, 1090, Vienna, Austria
| | - Martin Stoiber
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, AKH 4L, 1090, Vienna, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, 1090, Vienna, Austria
| | - Francesco Moscato
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, AKH 4L, 1090, Vienna, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, 1090, Vienna, Austria
- Austrian Cluster for Tissue Regeneration, 1090, Vienna, Vienna, Austria
| | - Heinrich Schima
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, AKH 4L, 1090, Vienna, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, 1090, Vienna, Austria
- Department for Cardiac Surgery, Medical University of Vienna, 1090, Vienna, Austria
| | - Christian Grasl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, AKH 4L, 1090, Vienna, Austria.
- Ludwig Boltzmann Institute for Cardiovascular Research, 1090, Vienna, Austria.
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2
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Rohringer S, Grasl C, Ehrmann K, Hager P, Hahn C, Specht SJ, Walter I, Schneider KH, Zopf LM, Baudis S, Liska R, Schima H, Podesser BK, Bergmeister H. Biodegradable, Self-Reinforcing Vascular Grafts for In Situ Tissue Engineering Approaches. Adv Healthc Mater 2023; 12:e2300520. [PMID: 37173073 DOI: 10.1002/adhm.202300520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/21/2023] [Indexed: 05/15/2023]
Abstract
Clinically available small-diameter synthetic vascular grafts (SDVGs) have unsatisfactory patency rates due to impaired graft healing. Therefore, autologous implants are still the gold standard for small vessel replacement. Bioresorbable SDVGs may be an alternative, but many polymers have inadequate biomechanical properties that lead to graft failure. To overcome these limitations, a new biodegradable SDVG is developed to ensure safe use until adequate new tissue is formed. SDVGs are electrospun using a polymer blend composed of thermoplastic polyurethane (TPU) and a new self-reinforcing TP(U-urea) (TPUU). Biocompatibility is tested in vitro by cell seeding and hemocompatibility tests. In vivo performance is evaluated in rats over a period for up to six months. Autologous rat aortic implants serve as a control group. Scanning electron microscopy, micro-computed tomography (µCT), histology, and gene expression analyses are applied. TPU/TPUU grafts show significant improvement of biomechanical properties after water incubation and exhibit excellent cyto- and hemocompatibility. All grafts remain patent, and biomechanical properties are sufficient despite wall thinning. No inflammation, aneurysms, intimal hyperplasia, or thrombus formation are observed. Evaluation of graft healing shows similar gene expression profiles of TPU/TPUU and autologous conduits. These new biodegradable, self-reinforcing SDVGs may be promising candidates for clinical use in the future.
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Affiliation(s)
- Sabrina Rohringer
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Austrian Cluster for Tissue Regeneration, Donaueschingenstraße 13, Vienna, 1200, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
| | - Christian Grasl
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
| | - Katharina Ehrmann
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Austrian Cluster for Tissue Regeneration, Donaueschingenstraße 13, Vienna, 1200, Austria
- Institute of Applied Synthetic Chemistry, Technical University of Vienna, Getreidemarkt 9/163, Vienna, 1060, Austria
| | - Pia Hager
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
| | - Clemens Hahn
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
| | - Sophie J Specht
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
| | - Ingrid Walter
- Department of Pathobiology, University of Veterinary Medicine, Veterinaerplatz 1, Vienna, 1210, Austria
| | - Karl H Schneider
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Austrian Cluster for Tissue Regeneration, Donaueschingenstraße 13, Vienna, 1200, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
| | - Lydia M Zopf
- Austrian Cluster for Tissue Regeneration, Donaueschingenstraße 13, Vienna, 1200, Austria
- Ludwig Boltzmann Institute for Traumatology, Donaueschingenstraße 13, Vienna, 1200, Austria
| | - Stefan Baudis
- Austrian Cluster for Tissue Regeneration, Donaueschingenstraße 13, Vienna, 1200, Austria
- Institute of Applied Synthetic Chemistry, Technical University of Vienna, Getreidemarkt 9/163, Vienna, 1060, Austria
| | - Robert Liska
- Austrian Cluster for Tissue Regeneration, Donaueschingenstraße 13, Vienna, 1200, Austria
- Institute of Applied Synthetic Chemistry, Technical University of Vienna, Getreidemarkt 9/163, Vienna, 1060, Austria
| | - Heinrich Schima
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
| | - Bruno K Podesser
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Austrian Cluster for Tissue Regeneration, Donaueschingenstraße 13, Vienna, 1200, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
| | - Helga Bergmeister
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, Vienna, 1090, Austria
- Austrian Cluster for Tissue Regeneration, Donaueschingenstraße 13, Vienna, 1200, Austria
- Ludwig Boltzmann Institute for Cardiovascular Research, Waehringer Gürtel 18-20, Vienna, 1090, Austria
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3
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Enayati M, Schneider KH, Almeria C, Grasl C, Kaun C, Messner B, Rohringer S, Walter I, Wojta J, Budinsky L, Walpoth BH, Schima H, Kager G, Hallström S, Podesser BK, Bergmeister H. S-nitroso human serum albumin as a nitric oxide donor in drug-eluting vascular grafts: Biofunctionality and preclinical evaluation. Acta Biomater 2021; 134:276-288. [PMID: 34329787 DOI: 10.1016/j.actbio.2021.07.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/22/2021] [Accepted: 07/22/2021] [Indexed: 11/28/2022]
Abstract
Currently available synthetic small diameter vascular grafts reveal low patency rates due to thrombosis and intimal hyperplasia. Biofunctionalized grafts releasing nitric oxide (NO) in situ may overcome these limitations. In this study, a drug-eluting vascular graft was designed by blending polycaprolactone (PCL) with S-nitroso-human-serum-albumin (S-NO-HSA), a nitric oxide donor with prolonged half-life. PCL-S-NO-HSA grafts and patches were fabricated via electrospinning. The fabrication process was optimized. Patches were characterized in vitro for their morphology, drug release, biomechanics, inflammatory effects, cell proliferation, and expression of adhesion molecules. The selected optimized formulation (8%PCL-S-NO-HSA) had superior mechanical/morphological properties with high protein content revealing extended NO release (for 28 days). 8%PCL-S-NO-HSA patches significantly promoted endothelial cell proliferation while limiting smooth muscle cell proliferation. Expression of adhesion molecules (ICAM-1, VCAM-1) and pro-inflammatory macrophage/cytokine markers (CD80, IL-1α, TNF-α) was significantly reduced. 8%PCL-S-NO-HSA patches had superior immunomodulatory properties by up-regulating anti-inflammatory cytokines (IL-10) and M2 macrophage marker (CD163) at final time points. Grafts were further evaluated in a small rodent model as aortic implants up to 12 weeks. Grafts were assessed by magnetic resonance imaging angiography (MRI) in vivo and after retrieval by histology. All grafts remained 100 % patent with no signs of thrombosis or calcification. 8%PCL-S-NO-HSA vascular grafts supported rapid endothelialization, whereas smooth muscle cell proliferation was hampered in earlier phases. This study indicates that 8%PCL-S-NO-HSA grafts effectively support long-term in situ release of bioactive NO. The beneficial effects observed can be promising features for long-term success of small diameter vascular grafts. STATEMENT OF SIGNIFICANCE: Despite extensive research in the field of small diameter vascular graft replacement, there is still no appropriate substitute to autografts yet. Various limitations are associated with currently available synthetic vascular grafts such as thrombogenicity and intimal hyperplasia. Therefore, developing new generations of such conduits has become a major focus of research. One of the most significant signaling molecules that are involved in homeostasis of the vascular system is nitric oxide. The new designed nitric-oxide eluting vascular grafts described in this study induce rapid surface endothelialization and late migration of SMCs into the graft wall. These beneficial effects have potential to improve current limitations of small diameter vascular grafts.
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Affiliation(s)
- Marjan Enayati
- Center for Biomedical Research, Medical University Vienna, Austria; Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Karl H Schneider
- Center for Biomedical Research, Medical University Vienna, Austria; Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Ciarra Almeria
- Center for Biomedical Research, Medical University Vienna, Austria
| | - Christian Grasl
- Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Austria
| | - Christoph Kaun
- Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria
| | - Barbara Messner
- Cardiac Surgery Research Laboratory, Department of Cardiac Surgery, Medical University Vienna, Austria
| | - Sabrina Rohringer
- Center for Biomedical Research, Medical University Vienna, Austria; Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria
| | - Ingrid Walter
- Department of Pathobiology, University of Veterinary Medicine, Vienna, Austria
| | - Johann Wojta
- Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria
| | - Lubos Budinsky
- Preclinical Imaging Laboratory, Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Faculty of Chemical and Food Technology, Central Laboratories, Slovak University of Technology, Bratislava, Slovakia
| | - Beat H Walpoth
- Emeritus, Cardiovascular Surgery and Research, University Hospital & University of Geneva, Geneva, Switzerland
| | - Heinrich Schima
- Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Austria
| | - Gerd Kager
- Division of Physiological Chemistry, Otto Loewi Research Center, Medical University of Graz, Graz, Austria
| | - Seth Hallström
- Division of Physiological Chemistry, Otto Loewi Research Center, Medical University of Graz, Graz, Austria
| | - Bruno K Podesser
- Center for Biomedical Research, Medical University Vienna, Austria; Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Helga Bergmeister
- Center for Biomedical Research, Medical University Vienna, Austria; Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria.
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4
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Pereira AT, Schneider KH, Henriques PC, Grasl C, Melo SF, Fernandes IP, Kiss H, Martins MCL, Bergmeister H, Gonçalves IC. Graphene Oxide Coating Improves the Mechanical and Biological Properties of Decellularized Umbilical Cord Arteries. ACS Appl Mater Interfaces 2021; 13:32662-32672. [PMID: 34240610 DOI: 10.1021/acsami.1c04028] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The lack of small-diameter vascular grafts (inner diameter <5 mm) to substitute autologous grafts in arterial bypass surgeries has a massive impact on the prognosis and progression of cardiovascular diseases, the leading cause of death globally. Decellularized arteries from different sources have been proposed as an alternative, but their poor mechanical performance and high collagen exposure, which promotes platelet and bacteria adhesion, limit their successful application. In this study, these limitations were surpassed for decellularized umbilical cord arteries through the coating of their lumen with graphene oxide (GO). Placental and umbilical cord arteries were decellularized and perfused with a suspension of GO (C/O ratio 2:1) with ∼1.5 μm lateral size. A homogeneous GO coating that completely covered the collagen fibers was obtained for both arteries, with improvement of mechanical properties being achieved for umbilical cord decellularized arteries. GO coating increased the maximum force in 27%, the burst pressure in 29%, the strain in 25%, and the compliance in 10%, compared to umbilical cord decellularized arteries. The achieved theoretical burst pressure (1960 mmHg) and compliance (13.9%/100 mmHg) are similar to the human saphenous vein and mammary artery, respectively, which are used nowadays as the gold standard in coronary and peripheral artery bypass surgeries. Furthermore, and very importantly, coatings with GO did not compromise the endothelial cell adhesion but decreased platelet and bacteria adhesion to decellularized arteries, which will impact on the prevention of thrombosis and infection, until full re-endothetialization is achieved. Overall, our results reveal that GO coating has an effective role in the improvement of decellularized umbilical cord artery performance, which is a huge step toward their application as a small-diameter vascular graft.
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Affiliation(s)
- Andreia T Pereira
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto, 4200-135 Porto, Portugal
- Center for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Karl H Schneider
- Center for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
- Ludwig Boltzmann Institute of Cardiovascular Research, 1090 Vienna, Austria
| | - Patrícia C Henriques
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto, 4200-135 Porto, Portugal
| | - Christian Grasl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria
| | - Sofia F Melo
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto, 4200-135 Porto, Portugal
| | - Inês P Fernandes
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto, 4200-135 Porto, Portugal
| | - Herbert Kiss
- Department of Obstetrics and Gynecology, Division of Obstetrics and Feto-Maternal Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - M Cristina L Martins
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto, 4200-135 Porto, Portugal
| | - Helga Bergmeister
- Center for Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
- Ludwig Boltzmann Institute of Cardiovascular Research, 1090 Vienna, Austria
| | - Inês C Gonçalves
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto, 4200-135 Porto, Portugal
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal
- FEUP-Faculdade de Engenharia da Universidade do Porto, 4200-465 Porto, Portugal
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5
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Schneider KH, Rohringer S, Kapeller B, Grasl C, Kiss H, Heber S, Walter I, Teuschl AH, Podesser BK, Bergmeister H. Riboflavin-mediated photooxidation to improve the characteristics of decellularized human arterial small diameter vascular grafts. Acta Biomater 2020; 116:246-258. [PMID: 32871281 DOI: 10.1016/j.actbio.2020.08.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/27/2020] [Accepted: 08/25/2020] [Indexed: 02/06/2023]
Abstract
Vascular grafts with a diameter of less than 6 mm are made from a variety of materials and techniques to provide alternatives to autologous vascular grafts. Decellularized materials have been proposed as a possible approach to create extracellular matrix (ECM) vascular prostheses as they are naturally derived and inherently support various cell functions. However, these desirable graft characteristics may be limited by alterations of the ECM during the decellularization process leading to decreased biomechanical properties and hemocompatibility. In this study, arteries from the human placenta chorion were decellularized using two distinct detergents (Triton X-100 or SDS), which differently affect ECM ultrastructure. To overcome biomechanical strength loss and collagen fiber exposure after decellularization, riboflavin-mediated UV (RUV) crosslinking was used to uniformly crosslink the collagenous ECM of the grafts. Graft characteristics and biocompatibility with and without RUV crosslinking were studied in vitro and in vivo. RUV-crosslinked ECM grafts showed significantly improved mechanical strength and smoothening of the luminal graft surfaces. Cell seeding using human endothelial cells revealed no cytotoxic effects of the RUV treatment. Short-term aortic implants in rats showed cell migration and differentiation of host cells. Functional graft remodeling was evident in all grafts. Thus, RUV crosslinking is a preferable tool to improve graft characteristics of decellularized matrix conduits.
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6
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Enayati M, Puchhammer S, Iturri J, Grasl C, Kaun C, Baudis S, Walter I, Schima H, Liska R, Wojta J, Toca-Herrera JL, Podesser BK, Bergmeister H. Assessment of a long-term in vitro model to characterize the mechanical behavior and macrophage-mediated degradation of a novel, degradable, electrospun poly-urethane vascular graft. J Mech Behav Biomed Mater 2020; 112:104077. [PMID: 32942230 DOI: 10.1016/j.jmbbm.2020.104077] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/13/2020] [Accepted: 08/23/2020] [Indexed: 10/23/2022]
Abstract
An assessment tool to evaluate the degradation of biodegradable materials in a more physiological environment is still needed. Macrophages are critical players in host response, remodeling and degradation. In this study, a cell culture model using monocyte-derived primary macrophages was established to study the degradation, macro-/micro-mechanical behavior and inflammatory behavior of a new designed, biodegradable thermoplastic polyurethane (TPU) scaffold, over an extended period of time in vitro. For in vivo study, the scaffolds were implanted subcutaneously in a rat model for up to 36 weeks. TPU scaffolds were fabricated via the electrospinning method. This technique provided a fibrous scaffold with an average fiber diameter of 1.39 ± 0.76 μm and an average pore size of 7.5 ± 1.1 μm. The results showed that TPU scaffolds supported the attachment and migration of macrophages throughout the three-dimensional matrix. Scaffold degradation could be detected in localized areas, emphasizing the role of adherent macrophages in scaffold degradation. Weight loss, molecular weight and biomechanical strength reduction were evident in the presence of the primary macrophage cells. TPU favored the switch from initial pro-inflammatory response of macrophages to an anti-inflammatory response over time both in vitro and in vivo. Expression of MMP-2 and MMP-9 (the key enzymes in tissue remodeling based on ECM modifications) was also evident in vitro and in vivo. This study showed that the primary monocyte-derived cell culture model represents a promising tool to characterize the degradation, mechanical behavior as well as biocompatibility of the scaffolds during an extended period of observation.
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Affiliation(s)
- Marjan Enayati
- Center for Biomedical Research, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria
| | - Sarah Puchhammer
- Center for Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Jagoba Iturri
- Institute for Biophysics, Department of Nanobiotechnology, BOKU University for Natural Resources and Life Sciences, Vienna, Austria
| | - Christian Grasl
- Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
| | - Christoph Kaun
- Division of Internal Medicine II, Medical University Vienna, Austria
| | - Stefan Baudis
- Institute of Applied Synthetic Chemistry, Technische Universität Wien, Vienna, Austria
| | - Ingrid Walter
- Department of Pathobiology, Veterinary University, Vienna, Austria
| | - Heinrich Schima
- Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
| | - Robert Liska
- Institute of Applied Synthetic Chemistry, Technische Universität Wien, Vienna, Austria
| | - Johann Wojta
- Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria; Division of Internal Medicine II, Medical University Vienna, Austria
| | - José Luis Toca-Herrera
- Institute for Biophysics, Department of Nanobiotechnology, BOKU University for Natural Resources and Life Sciences, Vienna, Austria
| | - Bruno K Podesser
- Center for Biomedical Research, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria
| | - Helga Bergmeister
- Center for Biomedical Research, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute for Cardiovascular Research, Vienna, Austria.
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7
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Stoiber M, Grasl C, Frieberger K, Moscato F, Bergmeister H, Schima H. Impact of the testing protocol on the mechanical characterization of small diameter electrospun vascular grafts. J Mech Behav Biomed Mater 2020; 104:103652. [DOI: 10.1016/j.jmbbm.2020.103652] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/09/2020] [Accepted: 01/21/2020] [Indexed: 01/01/2023]
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8
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Ehrmann K, Potzmann P, Dworak C, Bergmeister H, Eilenberg M, Grasl C, Koch T, Schima H, Liska R, Baudis S. Hard Block Degradable Polycarbonate Urethanes: Promising Biomaterials for Electrospun Vascular Prostheses. Biomacromolecules 2020; 21:376-387. [PMID: 31718163 DOI: 10.1021/acs.biomac.9b01255] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We report biodegradable thermoplastic polyurethanes for soft tissue engineering applications, where frequently used carboxylic acid ester degradation motifs were substituted with carbonate moieties to achieve superior degradation properties. While the use of carbonates in soft blocks has been reported, their use in hard blocks of thermoplastic polyurethanes is unprecedented. Soft blocks consist of poly(hexamethylene carbonate), and hard blocks combine hexamethylene diisocyanate with the newly synthesized cleavable carbonate chain extender bis(3-hydroxypropylene)carbonate (BHPC), mimicking the motif of poly(trimethylene carbonate) with highly regarded degradation properties. Simultaneously, the mechanical benefits of segmented polyurethanes are exploited. A lower hard block concentration in BHPC-based polymers was more suitable for vascular grafts. Nonacidic degradation products and hard block dependent degradation rates were found. Implantation of BHPC-based electrospun degradable vascular prostheses in a small animal model revealed high patency rates and no signs of aneurysm formations. Specific vascular graft remodeling and only minimal signs of inflammatory reactions were observed.
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Affiliation(s)
- Katharina Ehrmann
- Institute of Applied Synthetic Chemistry, Division of Macromolecular Chemistry , TU Wien , Getreidemarkt 9/163 MC , 1060 Vienna , Austria.,Division of Biomedical Research , Medical University of Vienna , Währinger Gürtel 18-20 , 1090 Vienna , Austria.,Austrian Cluster for Tissue Regeneration , 1200 Vienna , Austria
| | - Paul Potzmann
- Institute of Applied Synthetic Chemistry, Division of Macromolecular Chemistry , TU Wien , Getreidemarkt 9/163 MC , 1060 Vienna , Austria.,Austrian Cluster for Tissue Regeneration , 1200 Vienna , Austria
| | - Claudia Dworak
- Institute of Applied Synthetic Chemistry, Division of Macromolecular Chemistry , TU Wien , Getreidemarkt 9/163 MC , 1060 Vienna , Austria.,Austrian Cluster for Tissue Regeneration , 1200 Vienna , Austria
| | - Helga Bergmeister
- Division of Biomedical Research , Medical University of Vienna , Währinger Gürtel 18-20 , 1090 Vienna , Austria.,Ludwig Boltzmann Institute for Cardiovascular Research , Währinger Gürtel 18-20 , 1090 Vienna , Austria.,Austrian Cluster for Tissue Regeneration , 1200 Vienna , Austria
| | - Magdalena Eilenberg
- Division of Biomedical Research , Medical University of Vienna , Währinger Gürtel 18-20 , 1090 Vienna , Austria.,Department of Surgery , Medical University of Vienna , Währinger Gürtel 18-20 , 1090 Vienna , Austria
| | - Christian Grasl
- Ludwig Boltzmann Institute for Cardiovascular Research , Währinger Gürtel 18-20 , 1090 Vienna , Austria.,Center for Medical Physics and Biomedical Engineering , Medical University of Vienna , Währinger Gürtel 18-20 , 1090 Vienna , Austria
| | - Thomas Koch
- Institute of Materials Science and Technology , TU Wien , Getreidemarkt 9/308 , 1060 Vienna , Austria
| | - Heinrich Schima
- Ludwig Boltzmann Institute for Cardiovascular Research , Währinger Gürtel 18-20 , 1090 Vienna , Austria.,Center for Medical Physics and Biomedical Engineering , Medical University of Vienna , Währinger Gürtel 18-20 , 1090 Vienna , Austria
| | - Robert Liska
- Institute of Applied Synthetic Chemistry, Division of Macromolecular Chemistry , TU Wien , Getreidemarkt 9/163 MC , 1060 Vienna , Austria.,Austrian Cluster for Tissue Regeneration , 1200 Vienna , Austria
| | - Stefan Baudis
- Institute of Applied Synthetic Chemistry, Division of Macromolecular Chemistry , TU Wien , Getreidemarkt 9/163 MC , 1060 Vienna , Austria.,Austrian Cluster for Tissue Regeneration , 1200 Vienna , Austria
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9
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Eilenberg M, Enayati M, Ehebruster D, Grasl C, Walter I, Messner B, Baudis S, Potzmann P, Kaun C, Podesser BK, Wojta J, Bergmeister H. Long Term Evaluation of Nanofibrous, Bioabsorbable Polycarbonate Urethane Grafts for Small Diameter Vessel Replacement in Rodents. Eur J Vasc Endovasc Surg 2019; 59:643-652. [PMID: 31874809 DOI: 10.1016/j.ejvs.2019.11.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/14/2019] [Accepted: 11/04/2019] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Biodegradable materials for in situ vascular tissue engineering could meet the increasing clinical demand for sufficient synthetic small diameter vascular substitutes in aortocoronary bypass and peripheral vascular surgery. The aim of this study was to design a new degradable thermoplastic polycarbonate urethane (dPCU) with improved biocompatibility and optimal biomechanical properties. Electrospun conduits made from dPCU were evaluated in short and long term follow up and compared with expanded polytetrafluoroethylene (ePTFE) controls. METHODS Both conduits were investigated prior to implantation to assess their biocompatibility and inflammatory potential via real time polymerase chain reaction using a macrophage culture. dPCU grafts (n = 28) and ePTFE controls (n = 28) were then implanted into the infrarenal abdominal aorta of Sprague-Dawley rats. After seven days, one, six, and 12 months, grafts were analysed by histology and immunohistochemistry (IHC) and assessed biomechanically. RESULTS Anti-inflammatory signalling was upregulated in dPCU conduits and increased significantly over time in vitro. dPCU and ePTFE grafts offered excellent long and short term patency rates (92.9% in both groups at 12 months) in the rat model without dilatation or aneurysm formation. In comparison to ePTFE, dPCU grafts showed transmural ingrowth of vascular specific cells resulting in a structured neovessel formation around the graft. The graft material was slowly reduced, while the compliance of the neovessel increased over time. CONCLUSION The newly designed dPCU grafts have the potential to be safely applied for in situ vascular tissue engineering applications. The degradable substitutes showed good in vivo performance and revealed desirable characteristics such as biomechanical stability, non-thrombogenicity, and minimal inflammatory response after long term implantation.
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Affiliation(s)
- Magdalena Eilenberg
- Department of Surgery, Medical University of Vienna, Vienna, Austria; Centre for Biomedical Research, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Medical University of Vienna, Vienna, Austria
| | - Marjan Enayati
- Centre for Biomedical Research, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Medical University of Vienna, Vienna, Austria
| | - Daniel Ehebruster
- Centre for Biomedical Research, Medical University of Vienna, Vienna, Austria
| | - Christian Grasl
- Ludwig Boltzmann Cluster for Cardiovascular Research, Medical University of Vienna, Vienna, Austria; Centre of Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Ingrid Walter
- Department of Pathobiology, Veterinary University, Vienna, Austria
| | - Barbara Messner
- Surgical Research Laboratories-Cardiac Surgery, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - Stefan Baudis
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Paul Potzmann
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Christoph Kaun
- Ludwig Boltzmann Cluster for Cardiovascular Research, Medical University of Vienna, Vienna, Austria; Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria
| | - Bruno K Podesser
- Centre for Biomedical Research, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Medical University of Vienna, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Johann Wojta
- Ludwig Boltzmann Cluster for Cardiovascular Research, Medical University of Vienna, Vienna, Austria; Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria
| | - Helga Bergmeister
- Centre for Biomedical Research, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Medical University of Vienna, Vienna, Austria.
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10
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Stoiber M, Aigner P, Grasl C, Röhrich M, Moscato F, Schima H. Dynamic measurement of centering forces on transvalvular cannulas. Artif Organs 2019; 44:E150-E160. [PMID: 31693191 PMCID: PMC7154544 DOI: 10.1111/aor.13597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 10/29/2019] [Accepted: 10/29/2019] [Indexed: 01/04/2023]
Abstract
In heart failure therapy, minimally invasive devices (transcatheter valves, catheter‐based cannulas or pumps) are increasingly used. The interaction with the valve is of special importance as valve damage, backflow, and thrombus formation are known complications. Therefore, the aim of this in vitro study was to characterize the forces acting on different sized transvalvular cannulas at various transvalvular pressures for four different valves. In a pulsatile setup radial and tangential forces on transvalvular cannulas were measured for bioprosthetic, artificial pericardial tissue, fresh, and fixated porcine valves. The cannula position was varied from a central position to the wall in 10° rotational steps for the whole circular range and the use of different cannula diameters (4, 6, and 8 mm) and transvalvular pressures (40‐100 mmHg). Centering forces of four different aortic valve types were identified and the three leaflets were visible in the force distribution. At the mid of the cusps and at the largest deflection the forces were highest (up to 0.8 N) and lowest in the commissures (up to 0.2 N). Whereas a minor influence of the cannula diameter was found, the transvalvular pressure linearly increased the forces but did not alter the force patterns. Centering forces that act on transvalvular cannulas were identified in an in vitro setup for several valves and valve types. Lowest centering forces were found in the commissures and highest forces were found directly at the cusps. At low pressures, low centering forces and an increased cannula movement can be expected.
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Affiliation(s)
- Martin Stoiber
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Ludwig-Boltzmann Institute for Cardiovascular Research, Vienna, Austria
| | - Philipp Aigner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Ludwig-Boltzmann Institute for Cardiovascular Research, Vienna, Austria
| | - Christian Grasl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Ludwig-Boltzmann Institute for Cardiovascular Research, Vienna, Austria
| | - Michael Röhrich
- Department of Anesthesia, Critical Care and Pain Therapy, Medical University of Vienna, Vienna, Austria
| | - Francesco Moscato
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Ludwig-Boltzmann Institute for Cardiovascular Research, Vienna, Austria
| | - Heinrich Schima
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.,Ludwig-Boltzmann Institute for Cardiovascular Research, Vienna, Austria.,Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria
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11
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Schneider KH, Enayati M, Grasl C, Walter I, Budinsky L, Zebic G, Kaun C, Wagner A, Kratochwill K, Redl H, Teuschl AH, Podesser BK, Bergmeister H. Acellular vascular matrix grafts from human placenta chorion: Impact of ECM preservation on graft characteristics, protein composition and in vivo performance. Biomaterials 2018; 177:14-26. [PMID: 29885585 DOI: 10.1016/j.biomaterials.2018.05.045] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 05/18/2018] [Accepted: 05/26/2018] [Indexed: 02/06/2023]
Abstract
Small diameter vascular grafts from human placenta, decellularized with either Triton X-100 (Triton) or SDS and crosslinked with heparin were constructed and characterized. Graft biochemical properties, residual DNA, and protein composition were evaluated to compare the effect of the two detergents on graft matrix composition and structural alterations. Biocompatibility was tested in vitro by culturing the grafts with primary human macrophages and in vivo by subcutaneous implantation of graft conduits (n = 7 per group) into the flanks of nude rats. Subsequently, graft performance was evaluated using an aortic implantation model in Sprague Dawley rats (one month, n = 14). In situ graft imaging was performed using MRI angiography. Retrieved specimens were analyzed by electromyography, scanning electron microscopy, histology and immunohistochemistry to evaluate cell migration and the degree of functional tissue remodeling. Both decellularization methods resulted in grafts of excellent biocompatibility in vitro and in vivo, with low immunogenic potential. Proteomic data revealed removal of cytoplasmic proteins with relative enrichment of ECM proteins in decelluarized specimens of both groups. Noteworthy, LC-Mass Spectrometry analysis revealed that 16 proteins were exclusively preserved in Triton decellularized specimens in comparison to SDS-treated specimens. Aortic grafts showed high patency rates, no signs of thrombus formation, aneurysms or rupture. Conduits of both groups revealed tissue-specific cell migration indicative of functional remodeling. This study strongly suggests that decellularized allogenic grafts from the human placenta have the potential to be used as vascular replacement materials. Both detergents produced grafts with low residual immunogenicity and appropriate mechanical properties. Observed differences in graft characteristics due to preservation method had no impact on successful in vivo performance in the rodent model.
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Affiliation(s)
- Karl H Schneider
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria; Center for Biomedical Research Medical University of Vienna, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Marjan Enayati
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria; Center for Biomedical Research Medical University of Vienna, Vienna, Austria
| | - Christian Grasl
- Center for Biomedical Research Medical University of Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
| | - Ingrid Walter
- Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Lubos Budinsky
- Preclinical Imaging Laboratory, Division of Molecular and Gender Imaging, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Gabriel Zebic
- Center for Biomedical Research Medical University of Vienna, Vienna, Austria
| | - Christoph Kaun
- Division of Internal Medicine II, Medical University of Vienna, Vienna, Austria
| | - Anja Wagner
- Department of Pediatric and Adolescent Medicine, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Molecular Stress Research in Peritoneal Dialysis, Vienna, Austria
| | - Klaus Kratochwill
- Department of Pediatric and Adolescent Medicine, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Molecular Stress Research in Peritoneal Dialysis, Vienna, Austria
| | - Heinz Redl
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in AUVA Trauma Center, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Andreas H Teuschl
- Department of Biochemical Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria; City of Vienna Competence Team Siganltransduction, Vienna, Austria
| | - Bruno K Podesser
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria; Center for Biomedical Research Medical University of Vienna, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria
| | - Helga Bergmeister
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria; Center for Biomedical Research Medical University of Vienna, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Vienna, Austria.
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12
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Grasl C, Stoiber MH, Bergmeister H, Schima H. P577A versatile electrospinning technique to manufacture scaffolds with adjustable fiber networks. Cardiovasc Res 2018. [DOI: 10.1093/cvr/cvy060.429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- C Grasl
- Medical University of Vienna, Center for Medical Physics & Biomedical Engineering, Vienna, Austria
| | - M H Stoiber
- Medical University of Vienna, Center for Medical Physics & Biomedical Engineering, Vienna, Austria
| | - H Bergmeister
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
| | - H Schima
- Medical University of Vienna, Center for Medical Physics & Biomedical Engineering, Vienna, Austria
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13
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Stoiber MH, Grasl C, Bergmeister H, Schima H. P576Dynamic hoop tensile tests of electrospun small diameter vascular grafts. Cardiovasc Res 2018. [DOI: 10.1093/cvr/cvy060.428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- M H Stoiber
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
| | - C Grasl
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
| | - H Bergmeister
- Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
| | - H Schima
- Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
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14
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Arras MML, Jana R, Mühlstädt M, Maenz S, Andrews J, Su Z, Grasl C, Jandt KD. In Situ Formation of Nanohybrid Shish-Kebabs during Electrospinning for the Creation of Hierarchical Shish-Kebab Structures. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00153] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Matthias M. L. Arras
- Chair
of Materials Science, Otto Schott Institute of Materials Research,
Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Richard Jana
- Chair
of Materials Science, Otto Schott Institute of Materials Research,
Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Mike Mühlstädt
- Chair
of Materials Science, Otto Schott Institute of Materials Research,
Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Stefan Maenz
- Chair
of Materials Science, Otto Schott Institute of Materials Research,
Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Joseph Andrews
- Chair
of Materials Science, Otto Schott Institute of Materials Research,
Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Zhiqiang Su
- State
Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Christian Grasl
- Center
for Medical Physics and Biomedical Engineering, Medical University of Vienna, AKH, Ebene 4L, Währinger Gürtel 18-20, 1090 Vienna, Austria
- Ludwig
Boltzmann
Cluster for Cardiovascular Research, AKH, Ebene 1Q, Währinger Gürtel 18-20, 1090 Vienna, Austria
| | - Klaus D. Jandt
- Chair
of Materials Science, Otto Schott Institute of Materials Research,
Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
- Jena
Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany
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15
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Fröhlich SM, Eilenberg M, Svirkova A, Grasl C, Liska R, Bergmeister H, Marchetti-Deschmann M. Mass spectrometric imaging of in vivo protein and lipid adsorption on biodegradable vascular replacement systems. Analyst 2016. [PMID: 26198453 DOI: 10.1039/c5an00921a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cardiovascular diseases present amongst the highest mortality risks in Western civilization and are frequently caused by arteriosclerotic vessel failure. Coronary artery and peripheral vessel reconstruction necessitates the use of small diameter systems that are mechanically stress-resistant and biocompatible. Expanded polytetrafluorethylene (ePTFE) is amongst the materials used most frequently for non-degradable and bio-degradable vessel reconstruction procedures, with thermoplastic polyurethanes (TPU) representing a promising substitute. The present study describes and compares the biological adsorption and diffusion occurring with both materials following implantation in rat models. Gel electrophoresis and thin-layer chromatography, combined with mass spectrometry and mass spectrometry imaging, were utilized to identify the adsorbed lipids and proteins. The results were compared with the analytes present in native aorta tissue. It was revealed that both polymers were severely affected by biological adsorption after 10 min in vivo. Proteins associated with cell growth and migration were identified, especially on the luminal graft surface, while lipids were found to be located on both the luminal and abluminal surfaces. Lipid adsorption and cholesterol diffusion were found to be correlated with the polymer modifications identified on degradable thermoplastic urethane graft samples, with the latter revealing extensive cholesterol adsorption. The present study demonstrates an interaction between biological matter and both graft materials, and provides insights into polymer changes, in particular, those observed with thermoplastic urethanes already after 10 min in vivo exposure. ePTFE demonstrated minor polymer modifications, whereas several different polymer signals were observed for TPU, all were co-localized with biological signals.
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Affiliation(s)
- Sophie M Fröhlich
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna, Austria.
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16
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Schuh CMAP, Morton TJ, Banerjee A, Grasl C, Schima H, Schmidhammer R, Redl H, Ruenzler D. Activated Schwann Cell-Like Cells on Aligned Fibrin-Poly(Lactic-Co-Glycolic Acid) Structures: A Novel Construct for Application in Peripheral Nerve Regeneration. Cells Tissues Organs 2015; 200:287-99. [PMID: 26372904 DOI: 10.1159/000437091] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2015] [Indexed: 11/19/2022] Open
Abstract
Tissue engineering approaches in nerve regeneration search for ways to support gold standard therapy (autologous nerve grafts) and to improve results by bridging nerve defects with different kinds of conduits. In this study, we describe electrospinning of aligned fibrin-poly(lactic-co-glycolic acid) (PLGA) fibers in an attempt to create a biomimicking tissue-like material seeded with Schwann cell-like cells (SCLs) in vitro for potential use as an in vivo scaffold. Rat adipose-derived stem cells (rASCs) were differentiated into SCLs and evaluated with flow cytometry concerning their differentiation and activation status [S100b, P75, myelin-associated glycoprotein (MAG), and protein 0 (P0)]. After receiving the proliferation stimulus forskolin, SCLs expressed S100b and P75; comparable to native, activated Schwann cells, while cultured without forskolin, cells switched to a promyelinating phenotype and expressed S100b, MAG, and P0. Human fibrinogen and thrombin, blended with PLGA, were electrospun and the alignment and homogeneity of the fibers were proven by scanning electron microscopy. Electrospun scaffolds were seeded with SCLs and the formation of Büngner-like structures in SCLs was evaluated with phalloidin/propidium iodide staining. Carrier fibrin gels containing rASCs acted as a self-shaping matrix to form a tubular structure. In this study, we could show that rASCs can be differentiated into activated, proliferating SCLs and that these cells react to minimal changes in stimulus, switching to a promyelinating phenotype. Aligned electrospun fibrin-PLGA fibers promoted the formation of Büngner-like structures in SCLs, which also rolled the fibrin-PLGA matrix into a tubular scaffold. These in vitro findings favor further in vivo testing.
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Affiliation(s)
- Christina M A P Schuh
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Vienna, Austria
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17
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Bergmeister H, Seyidova N, Schreiber C, Strobl M, Grasl C, Walter I, Messner B, Baudis S, Fröhlich S, Marchetti-Deschmann M, Griesser M, di Franco M, Krssak M, Liska R, Schima H. Biodegradable, thermoplastic polyurethane grafts for small diameter vascular replacements. Acta Biomater 2015; 11:104-13. [PMID: 25218664 DOI: 10.1016/j.actbio.2014.09.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 08/01/2014] [Accepted: 09/03/2014] [Indexed: 11/19/2022]
Abstract
Biodegradable vascular grafts with sufficient in vivo performance would be more advantageous than permanent non-degradable prostheses. These constructs would be continuously replaced by host tissue, leading to an endogenous functional implant which would adapt to the need of the patient and exhibit only limited risk of microbiological graft contamination. Adequate biomechanical strength and a wall structure which promotes rapid host remodeling are prerequisites for biodegradable approaches. Current approaches often reveal limited tensile strength and therefore require thicker or reinforced graft walls. In this study we investigated the in vitro and in vivo biocompatibility of thin host-vessel-matched grafts (n=34) formed from hard-block biodegradable thermoplastic polyurethane (TPU). Expanded polytetrafluoroethylene (ePTFE) conduits (n=34) served as control grafts. Grafts were analyzed by various techniques after retrieval at different time points (1 week; 1, 6, 12 months). TPU grafts showed significantly increased endothelial cell proliferation in vitro (P<0.001). Population by host cells increased significantly in the TPU conduits within 1 month of implantation (P=0.01). After long-term implantation, TPU implants showed 100% patency (ePTFE: 93%) with no signs of aneurysmal dilatation. Substantial remodeling of the degradable grafts was observed but varied between subjects. Intimal hyperplasia was limited to ePTFE conduits (29%). Thin-walled TPU grafts offer a new and desirable form of biodegradable vascular implant. Degradable grafts showed equivalent long-term performance characteristics compared to the clinically used, non-degradable material with improvements in intimal hyperplasia and ingrowth of host cells.
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Affiliation(s)
- Helga Bergmeister
- Division of Biomedical Research, Medical University of Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria.
| | - Nargiz Seyidova
- Division of Biomedical Research, Medical University of Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
| | - Catharina Schreiber
- Division of Biomedical Research, Medical University of Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
| | - Magdalena Strobl
- Division of Biomedical Research, Medical University of Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
| | - Christian Grasl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
| | - Ingrid Walter
- Department of Pathobiology, University of Veterinary Medicine, Vienna, Austria
| | - Barbara Messner
- Surgical Research Laboratories - Cardiac Surgery, Department of Surgery, Medical University of Vienna, Austria
| | - Stefan Baudis
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria
| | - Sophie Fröhlich
- Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna, Austria
| | | | - Markus Griesser
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria
| | - Matt di Franco
- Computational Image Analysis and Radiology Lab, Department of Radiology, Medical University of Vienna, Austria
| | - Martin Krssak
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Medical University of Vienna, Austria; Centre of Excellence, High Field MR, Department of Radiology, Medical University of Vienna, Austria
| | - Robert Liska
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria
| | - Heinrich Schima
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria; Ludwig Boltzmann Cluster for Cardiovascular Research, Vienna, Austria
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18
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19
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Seyidova N, Grasl C, Stoiber M, Schreiber C, Walter I, Seidler K, Ligond SC, Baudis S, Liska R, Bernhard D, Schima H, Bergmeister H. Biocompatibility evaluation of bioresorbable vascular substitutes. Cardiovasc Pathol 2013. [DOI: 10.1016/j.carpath.2013.01.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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20
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Bergmeister H, Schreiber C, Grasl C, Walter I, Plasenzotti R, Stoiber M, Bernhard D, Schima H. Healing characteristics of electrospun polyurethane grafts with various porosities. Acta Biomater 2013; 9:6032-40. [PMID: 23237988 DOI: 10.1016/j.actbio.2012.12.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 11/12/2012] [Accepted: 12/05/2012] [Indexed: 01/22/2023]
Abstract
Pore size and porosity control the rate and depth of cellular migration in electrospun vascular fabrics and thus have a strong impact on long-term graft success. In this study we investigated the effect of graft porosity on cell migration in vitro and in vivo. Polyurethane (PU) grafts were fabricated by electrospinning as fine-mesh, low-porosity grafts (void fraction (VF) 53%) and coarse-mesh, high-porosity grafts (VF 80%). The fabricated grafts were evaluated in vitro for endothelial cell attachment and proliferation. Prostheses were investigated in a rat model for either 7 days, 1, 3 or 6 months (n=7 per time point) and analyzed after retrieval by biomechanical analysis and various histological techniques. Cell migration was calculated by computer-assisted morphometry. In vitro, fine-pore mesh favored early cell attachment. In vivo, coarse mesh grafts revealed significantly higher cell populations at all time points in all areas of the conduit wall. Biomechanical tests indicated sufficient compliance, tensile and suture retention strength before and after implantation. Increased porosity improves host cell ingrowth and survival in electrospun conduits. These conduits show successful natural host vessel reconstitution without limitation of biomechanical properties.
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Affiliation(s)
- Helga Bergmeister
- Division of Biomedical Research, Medical University Vienna, Vienna, Austria.
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21
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Grasl C, Arras M, Stoiber M, Bergmeister H, Schima H. Steering of an electrospinning jet by dynamic manipulation of the electric field. BIOMED ENG-BIOMED TE 2013; 58 Suppl 1:/j/bmte.2013.58.issue-s1-C/bmt-2013-4091/bmt-2013-4091.xml. [DOI: 10.1515/bmt-2013-4091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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22
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Arras MML, Grasl C, Bergmeister H, Schima H. Electrospinning of aligned fibers with adjustable orientation using auxiliary electrodes. Sci Technol Adv Mater 2012; 13:035008. [PMID: 27877496 PMCID: PMC5090285 DOI: 10.1088/1468-6996/13/3/035008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 05/21/2012] [Indexed: 05/19/2023]
Abstract
A conventional electrospinning setup was upgraded by two turnable plate-like auxiliary high-voltage electrodes that allowed aligned fiber deposition in adjustable directions. Fiber morphology was analyzed by scanning electron microscopy and attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR). The auxiliary electric field constrained the jet bending instability and the fiber deposition became controllable. At target speeds of 0.9 m s-1 90% of the fibers had aligned within 2°, whereas the angular spread was 70° without the use of auxiliary electrodes. It was even possible to orient fibers perpendicular to the rotational direction of the target. The fiber diameter became smaller and its distribution narrower, while according to the FTIR-ATR measurement the molecular orientation of the polymer was unaltered. This study comprehensively documents the feasibility of directed fiber deposition and offers an easy upgrade to existing electrospinning setups.
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Affiliation(s)
- Matthias M L Arras
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria
- Institute for Material Science and Technology, Friedrich Schiller University, 07743 Jena, Germany
| | - Christian Grasl
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria
- Ludwig Boltzmann Cluster for Cardiovascular Research, 1090 Vienna, Austria
| | - Helga Bergmeister
- Ludwig Boltzmann Cluster for Cardiovascular Research, 1090 Vienna, Austria
- Division of Biomedical Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Heinrich Schima
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Vienna, Austria
- Ludwig Boltzmann Cluster for Cardiovascular Research, 1090 Vienna, Austria
- Department of Cardiac Surgery, Medical University of Vienna, 1090 Vienna, Austria
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Baudis S, Ligon SC, Seidler K, Weigel G, Grasl C, Bergmeister H, Schima H, Liska R. Hard-block degradable thermoplastic urethane-elastomers for electrospun vascular prostheses. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/pola.25887] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Bergmeister H, Grasl C, Walter I, Plasenzotti R, Stoiber M, Schreiber C, Losert U, Weigel G, Schima H. Electrospun small-diameter polyurethane vascular grafts: ingrowth and differentiation of vascular-specific host cells. Artif Organs 2011; 36:54-61. [PMID: 21848935 DOI: 10.1111/j.1525-1594.2011.01297.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
No small-diameter synthetic graft has yet shown comparable performance to autologous vessels. Synthetic conduits fail due to their inherent surface thrombogenicity and the development of intimal hyperplasia. In addressing these shortcomings, electrospinning offers an interesting alternative to other nanostructured, cardiovascular substitutes because of the close match of electrospun materials to the biomechanical and structural properties of native vessels. In this study, we investigated the in vivo behavior of electrospun, small-diameter conduits in a rat model. Vascular grafts composed of polyurethane were fabricated by electrospinning. Prostheses were implanted into the abdominal aorta in 40 rats for either 7 days, 4 weeks, 3 months, or 6 months. Retrieved specimens were evaluated by histology, immunohistochemical staining, confocal laser scanning microscopy, and scanning electron microscopy. At all time points, we found no evidence of foreign body reaction or graft degradation. The overall patency rate of the intravascular implants was 95%. Within 7 days, grafts revealed ingrowth of host cells. CD34+ cells increased significantly from 7 days up to 6 months of implantation (P < 0.05). Myofibroblasts and myocytes showed increasing cell numbers up to 3 months (P < 0.05). Ki67 staining indicated unaltered cell proliferation during the whole follow-up period. Besides biomechanical benefits, electrospun polyurethane grafts exhibit excellent biocompatibility in vivo. Cell immigration and differentiation seems to be promoted by the nanostructured artificial matrix.
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Affiliation(s)
- Helga Bergmeister
- Division of Biomedical Research, Medical University of Vienna, AKH, Waehringer Guertel 18-20, 1090 Wien, Austria.
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Grasl C, Bergmeister H, Stoiber M, Schima H, Weigel G. Electrospun polyurethane vascular grafts: in vitro mechanical behavior and endothelial adhesion molecule expression. J Biomed Mater Res A 2010; 93:716-23. [PMID: 19609874 DOI: 10.1002/jbm.a.32584] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Engineered small diameter vascular grafts must closely match mechanical characteristics of native vessels and exhibit stimulus-responsive bioactivity. In this study, mechanical homogeneity of electrospun small diameter polyurethane grafts as well as spontaneous attachment, proliferation, and adhesion molecule expression of endothelial cells (EC) in their presence was studied in vitro. Axial and circumferential tensile strengths were measured and found to be twofold higher in the circumferential direction. EC attachment was easily achieved without precoating the fiber matrix. Stimulation of EC with interleukin-1beta (IL-1beta) led to a statistically significant upregulation of the adhesion molecules E-Selectin, ICAM-1, and VCAM-1. Quantification of adhesion molecule expression by means of energy-dispersive X-ray microanalysis revealed no differences in the stimulatory responses of EC cultured on electrospun polyurethane when compared with cells grown on tissue culture-treated cover slips. Summarizing, highly uniform small diameter polyurethane grafts were fabricated and shown to allow spontaneous EC attachment. The synthetic graft surface neither impaired the endothelial response toward IL-1beta stimulation nor did it adversely affect the regulation of expression of endothelial adhesion molecules.
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Affiliation(s)
- Christian Grasl
- Center for Biomedical Engineering and Physics, Medical University of Vienna, Vienna, Austria
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26
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Stoiber M, Grasl C, Pirker S, Raderer F, Schistek R, Huber L, Gittler P, Schima H. A Passive Magnetically and Hydrodynamically Suspended Rotary Blood Pump. Artif Organs 2009; 33:250-7. [DOI: 10.1111/j.1525-1594.2009.00715.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Seebacher G, Grasl C, Stoiber M, Rieder E, Kasimir MT, Dunkler D, Simon P, Weigel G, Schima H. Biomechanical properties of decellularized porcine pulmonary valve conduits. Artif Organs 2008; 32:28-35. [PMID: 18181800 DOI: 10.1111/j.1525-1594.2007.00452.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tissue-engineered heart valves constructed from a xenogeneic or allogeneic decellularized matrix might overcome the disadvantages of current heart valve substitutes. One major necessity besides effective decellularization is to preserve the biomechanical properties of the valve. Native and decellularized porcine pulmonary heart valve conduits (PPVCs) (with [n = 10] or without [n = 10] cryopreservation) were compared to cryopreserved human pulmonary valve conduits (n = 7). Samples of the conduit were measured for wall thickness and underwent tensile tests. Elongation measurement was performed with a video extensometer. Decellularized PPVC showed a higher failure force both in longitudinal (+73%; P < 0.01) and transverse (+66%; P < 0.001) direction compared to human homografts. Failure force of the tissue after cryopreservation was still higher in the porcine group (longitudinal: +106%, P < 0.01; transverse: +58%, P < 0.001). In comparison to human homografts, both decellularized and decellularized cryopreserved porcine conduits showed a higher extensibility in longitudinal (decellularized: +61%, P < 0.001; decellularized + cryopreserved: +51%, P < 0.01) and transverse (decellularized: +126%, P < 0.001; decellularized + cryopreserved: +118%, P < 0.001) direction. Again, cryopreservation did not influence the biomechanical properties of the decellularized porcine matrix.
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Affiliation(s)
- Gernot Seebacher
- Department of Cardiothoracic Surgery, Medical University of Vienna, Vienna, Austria
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Stoiber M, Grasl C, Pirker S, Huber L, Gittler P, Schima H. Experimental Validation of Numerical Simulations: A Comparison of Computational Fluid Dynamics and the Oil Film Method. Int J Artif Organs 2007; 30:363-8. [PMID: 17520575 DOI: 10.1177/039139880703000413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background Today Computational Fluid Dynamics (CFD) is used for simulating flow in many applications. The quality of the results, however, depends on various factors, like grid quality, boundary conditions and the computational model of the fluid. For this reason, it is important to validate the performed computation with experimental results. In this work, a comparison of numerical simulation with the oil film method was performed for two cardiovascular applications. Methods The investigations were conducted at various geometries, such as a bended cannula tubing, an impeller of a magnetically levitated rotary blood pump and tips of inflow cannulas. The oil film for the experimental validation was composed of black oil color and varnish. In the numerical simulation, color abrasion was displayed with a special post-processing tool by means of wall-attached pathlines. Results With the proper choice of numerical parameters, the computer simulations and the oil film method demonstrated good correlation. Improper generation of the simulation grid did lead to divergent results between the numerical simulation and the experiment. For the pump impeller as well as for the inflow cannulas, the calculation and the experiment showed similar flow patterns with backflow and stall zones. Conclusion The oil film method represents a fast and simple approach to help validate numerical simulations of fluid flow. The experimentally generated near wall flow patterns can be easily compared with the solution of the CFD analysis.
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Affiliation(s)
- M Stoiber
- Center for Biomedical Engineering and Physics, Medical University of Vienna, Vienna - Austria.
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Dobrowsky W, Naudé J, Widder J, Dobrowsky E, Millesi W, Pavelka R, Grasl C, Reichel M. Continuous hyperfractionated accelerated radiotherapy with/without mitomycin C in head and neck cancer. Int J Radiat Oncol Biol Phys 1998; 42:803-6. [PMID: 9845100 DOI: 10.1016/s0360-3016(98)00321-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate the effect of mitomycin C to an accelerated hyperfractionated radiation therapy. The aim was to test a very short schedule with/without mitomycin C (MMC) with conventional fractionation in histologically verified squamous cell carcinoma of the head and neck region. METHODS AND MATERIALS From October 1990 to December 1996, 188 patients entered the trial. Tumors originated in the oral cavity in 54, oropharynx in 82, larynx in 20, and hypopharynx in 32 cases, respectively. Patients' stages were predominantly T3 and T4 (158/188, 84%) and most patients had lymph node metastases (144/188, 77%) at diagnosis. Only 22 patients were female, 166 were male, the median age of patients was 57 years (range 34 to 76 years). Patients were randomized to one of the following three treatment options: conventional fractionation (CF) consisting of 70 Gy in 35 fractions over 7 weeks (65 patients) or continuous hyperfractionated accelerated radiation therapy (V-CHART; 62 patients) or continuous hyperfractionated accelerated radiation therapy with 20 mg/sqm MMC on day 5 (V-CHART + MMC; 61 patients). By the accelerated regimens, the total dose of 55.3 Gy was delivered within 17 consecutive days, by 33 fractions. On day 1, a single dose of 2.5 Gy was given, from day 2 to 17 a dose of 1.65 Gy was delivered twice: the interfraction interval was 6 hours or more. RESULTS Mucositis was very intense after accelerated therapy, most patients experiencing a grade III/IV reaction. The mucosal reaction did not differ whether MMC was administered or not. Patients treated by accelerated fractionation experienced a confluent mucosal reaction 12-14 days following start of therapy and recovered (no reaction) within 6 weeks. The skin reaction was not considered different in the three treatment groups. Those patients treated with additional chemotherapy experienced a grade III/IV hematologic toxicity in 12/61 patients. Initial complete response (CR) was recorded in 43% following CF, 58% after V-CHART, and 67% after V-CHART + MMC, respectively (p < 0.05). Actuarial survival (Kaplan-Meier) was significantly improved in the combined treated patients. Local tumor control was 28%, 32%, and 56% following CF, V-CHART, and V-CHART + MMC, respectively (p < 0.05). CONCLUSION We conclude that our continuous hyperfractionated accelerated radiation therapy regimen is equal to conventional fractionation, suggesting that by shortening the overall treatment time from 7 weeks to 17 days a reduction in dose from 70 Gy to 55.3 Gy is possible, with maintenance of local tumor control rates. The administration of MMC to the accelerated regimen is tolerable and improves the outcome for patients significantly.
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Affiliation(s)
- W Dobrowsky
- Department of Radiotherapy and Radiobiology, University of Vienna, Allgemeines Krankenhaus der Stadt Wien, Austria
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