1
|
Yeomans J, Sandu L, Sastry A. Pipeline Flex embolisation device with Shield Technology for the treatment of patients with intracranial aneurysms: periprocedural and 6 month outcomes. Neuroradiol J 2020; 33:471-478. [PMID: 33092461 DOI: 10.1177/1971400920966749] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND AND PURPOSE The Pipeline Flex embolisation device with Shield Technology (Pipeline Shield) is a novel flow diverter which reduces intra-vessel thrombogenicity. This study summarises periprocedural outcomes and 6-month follow-up results following its introduction in a tertiary interventional neuroradiology centre. MATERIALS AND METHODS This prospective, single-arm study assessed 32 aneurysms treated over a 21-month time period from the time of procedure to 6 months post-procedure. Data collected included patient demographics, aneurysm features and intraprocedural and 6-month post-procedural complications. RESULTS The mean age of the cohort was 58.8 ± Standard Deviation 8.5 years. Twenty-eight aneurysms were treated electively and four acutely. The elective cases received dual antiplatelet therapy post-procedure. The acute cases received single antiplatelet therapy post-procedure. Of the target aneurysms, 16/32 (50%) were small (<10 mm), 13/32 (41%) were large (10-25 mm) and 3/32 (9%) were giant (≥25 mm). There was no mortality in the series. There were two periprocedural complications (2/32, 6.2%): a stroke and a dissection. There were no post-procedural complications. At 6 months post-procedure, satisfactory occlusion (defined as Raymond-Roy 1 or 2) was achieved in 90.6% and 93.8% by way of magnetic resonance angiography and digital subtraction angiography assessment, respectively. There was no implant migration, no significant intraluminal hyperplasia or in-stent stenosis and no cases of aneurysm recurrence. CONCLUSION The Pipeline Shield has an excellent 6- month safety profile with an acceptable rate of intraprocedural complications, no post-procedure complications and no mortality in this case series of 32 acute and elective cases.
Collapse
|
2
|
Badv M, Bayat F, Weitz JI, Didar TF. Single and multi-functional coating strategies for enhancing the biocompatibility and tissue integration of blood-contacting medical implants. Biomaterials 2020; 258:120291. [PMID: 32798745 DOI: 10.1016/j.biomaterials.2020.120291] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/27/2020] [Accepted: 08/01/2020] [Indexed: 12/27/2022]
Abstract
Device-associated clot formation and poor tissue integration are ongoing problems with permanent and temporary implantable medical devices. These complications lead to increased rates of mortality and morbidity and impose a burden on healthcare systems. In this review, we outline the current approaches for developing single and multi-functional surface coating techniques that aim to circumvent the limitations associated with existing blood-contacting medical devices. We focus on surface coatings that possess dual hemocompatibility and biofunctionality features and discuss their advantages and shortcomings to providing a biocompatible and biodynamic interface between the medical implant and blood. Lastly, we outline the newly developed surface modification techniques that use lubricant-infused coatings and discuss their unique potential and limitations in mitigating medical device-associated complications.
Collapse
Affiliation(s)
- Maryam Badv
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada; Department of Mechanical Engineering, McMaster University, Hamilton, Ontario, Canada
| | - Fereshteh Bayat
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada
| | - Jeffrey I Weitz
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada; Thrombosis & Atherosclerosis Research Institute (TaARI), Hamilton, Ontario, Canada; Department of Medicine, McMaster University, Hamilton, Ontario, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Tohid F Didar
- School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada; Department of Mechanical Engineering, McMaster University, Hamilton, Ontario, Canada; Institute for Infectious Disease Research (IIDR), McMaster University, Hamilton, Ontario, Canada.
| |
Collapse
|
3
|
Sefton MV, Gorbet MB. Nonthrombogenic Treatments and Strategies. Biomater Sci 2020. [DOI: 10.1016/b978-0-12-816137-1.00035-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
4
|
Lenz-Habijan T, Bhogal P, Bannewitz C, Hannes R, Monstadt H, Simgen A, Mühl-Benninghaus R, Reith W, Henkes H. Prospective study to assess the tissue response to HPC-coated p48 flow diverter stents compared to uncoated devices in the rabbit carotid artery model. Eur Radiol Exp 2019; 3:47. [PMID: 31807964 PMCID: PMC6895370 DOI: 10.1186/s41747-019-0128-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 10/10/2019] [Indexed: 01/08/2023] Open
Abstract
Background Flow diverters (FDs) are widely used in the treatment of intracranial aneurysms, but the required medication increases the risk of haemorrhagic complications and limits their use in the acute setting. Surface modified FDs may limit the need for dual antiplatelet therapy (DAPT). Hydrophilic polymer coating (HPC) may reduce the need of medication. Methods This explorative study, approved by the local authorities and the local welfare committee, compared stent behaviour and overall tissue response between HPC-coated FDs and uncoated FDs, both implanted into the common carotid arteries of eight New Zealand white rabbits. Endothelialisation, inflammatory response, and performance during implantation were assessed. Angiographic follow-up was performed to observe the patency of the devices after implantation and after 30 days. Histological examinations were performed at 30 days to assess foreign body reaction and endothelialisation. Kruskal-Wallis and Wilcoxon tests were used to compare non-parametric variables. Results Angiography showed that both coated and uncoated FDs performed well during implantation. All devices remained patent during immediate follow-up and after 30 days. Histopathology showed no significant difference in inflammation within the vessel wall between the two cohorts (2.12 ± 0.75 vs. 1.96 ± 0.79, p = 0.7072). Complete endothelialisation of the stent struts was seen with very similar (0.04 ± 0.02 mm vs. 0.04 ± 0.03 mm, p = 0.892) neoendothelial thickness between the two cohorts after 30 days. Conclusion Taking into account the limitation in sample size, non-significant differences between the HPC-coated and uncoated FDs regarding implantation, foreign body response, and endothelialisation were found.
Collapse
Affiliation(s)
| | - Pervinder Bhogal
- Department of Interventional Neuroradiology, The Royal London Hospital, Whitechapel Road, London, E1 1BB, UK.
| | | | | | | | - Andreas Simgen
- Department of Neuroradiology, Saarland University, Homburg, Saar, Germany
| | | | - Wolfgang Reith
- Department of Neuroradiology, Saarland University, Homburg, Saar, Germany
| | - Hans Henkes
- Neuroradiological Clinic, Klinikum Stuttgart, Stuttgart, Germany.,Medical Faculty, University Duisburg-Essen, Essen, Germany
| |
Collapse
|
5
|
Abstract
The vasculature is a dynamic environment in which blood platelets constantly survey the endothelium for sites of vessel damage. The formation of a mechanically coherent hemostatic plug to prevent blood loss relies on a coordinated series of ligand-receptor interactions governing the recruitment, activation, and aggregation of platelets. The physical biology of each step is distinct in that the recruitment of platelets depends on the mechanosensing of the platelet receptor glycoprotein Ib for the adhesive protein von Willebrand factor, whereas platelet activation and aggregation are responsive to the mechanical forces sensed at adhesive junctions between platelets and at the platelet-matrix interface. Herein we take a biophysical perspective to discuss the current understanding of platelet mechanotransduction as well as the measurement techniques used to quantify the physical biology of platelets in the context of thrombus formation under flow.
Collapse
Affiliation(s)
- Caroline E Hansen
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Children's Healthcare of Atlanta/Emory University School of Medicine, Atlanta, Georgia 30332, USA; .,Wallace H. Coulter Department of Biomedical Engineering and Institute for Electronics and Nanotechnology, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, USA
| | - Yongzhi Qiu
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Children's Healthcare of Atlanta/Emory University School of Medicine, Atlanta, Georgia 30332, USA; .,Wallace H. Coulter Department of Biomedical Engineering and Institute for Electronics and Nanotechnology, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, USA
| | - Owen J T McCarty
- Department of Cell, Developmental, and Cancer Biology, Oregon Health & Science University, Portland, Oregon 97239, USA.,Division of Hematology and Medical Oncology and Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Wilbur A Lam
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Children's Healthcare of Atlanta/Emory University School of Medicine, Atlanta, Georgia 30332, USA; .,Wallace H. Coulter Department of Biomedical Engineering and Institute for Electronics and Nanotechnology, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, USA
| |
Collapse
|
6
|
Ishihara K. Revolutionary advances in 2‐methacryloyloxyethyl phosphorylcholine polymers as biomaterials. J Biomed Mater Res A 2019; 107:933-943. [DOI: 10.1002/jbm.a.36635] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 01/24/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Kazuhiko Ishihara
- Department of Materials Engineering The University of Tokyo 7‐3‐1 Hongo, Bunkyo‐ku, Tokyo 113‐8656 Japan
| |
Collapse
|
7
|
Martínez Moreno R, Bhogal P, Lenz-Habijan T, Bannewitz C, Siddiqui A, Lylyk P, Hannes R, Monstadt H, Henkes H. In vivo canine study of three different coatings applied to p64 flow-diverter stents: initial biocompatibility study. Eur Radiol Exp 2019; 3:3. [PMID: 30671686 PMCID: PMC6342750 DOI: 10.1186/s41747-018-0084-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 12/27/2018] [Indexed: 11/26/2022] Open
Abstract
Background Flow-diverter stents (FDSs) have revolutionised the treatment of intracranial aneurysms. However, associated dual antiplatelet treatment is mandatory. We investigated the biocompatibility of three proprietary antithrombogenic coatings applied to FDSs. Methods After Institutional Animal Care and Use Committee approval, four domestic juvenile female dogs (weight 19.9 ± 0.9 kg, mean ± standard deviation) were commenced on three different oral antiplatelet regimes: no medication (n = 1), acetylsalicylic acid (n = 2), and acetylsalicylic acid and clopidogrel (n = 1). Four p64 FDSs were randomly implanted into the subclavian, common carotid, and external carotid arteries of each dog, including both uncoated p64 stents and p64 stents coated with three different antithrombogenic hydrophilic coating (HPC). Angiography and histological examinations were performed. Wilcoxon/Kruskal-Wallis and ANOVA were used with p value < 0.05 considered as significant. Results Minimal inflammatory cell infiltration and no device-associated granulomatous cell inflammation were observed. No significant difference in adventitial inflammation (p = 0.522) or neointimal/medial inflammation (p = 0.384) between coated and uncoated stents as well as between the different stent groups regarding endothelial cell loss, surface fibrin/platelet deposition, medial smooth muscle cell loss, or adventitial fibrosis were found. Acute self-limiting thrombus formed on 6/16 implants (37.5%), and all of the thrombi were noted on devices implanted in the common or external carotid artery irrespective of the surface coating. Two of 12 p64 HPC-coated stents (16.7%) and 1/4 uncoated p64 stents (25%) showed severe or complete stenosis at delayed angiography. Conclusions In these preliminary in vivo experiments, HPC-coated p64 FDSs appeared to be biocompatible, without acute inflammation.
Collapse
Affiliation(s)
| | - Pervinder Bhogal
- Department of Interventional Neuroradiology, The Royal London Hospital, Whitechapel Road, London, E1 1BB, UK.
| | | | | | - Adnan Siddiqui
- Jacobs School of Medicine and Biomedical Science, University of Buffalo, Buffalo, NY, USA
| | - Pedro Lylyk
- Clinica Sagrada Familia, ENERI, Buenos Aires, Argentina
| | | | | | - Hans Henkes
- Neurozentrum, Klinikum Stuttgart, Stuttgart, Germany.,Medical Faculty, University Duisburg-Essen, Essen, Germany
| |
Collapse
|
8
|
Hydrophilic Stent Coating Inhibits Platelet Adhesion on Stent Surfaces: Initial Results In Vitro. Cardiovasc Intervent Radiol 2018; 41:1779-1785. [PMID: 30039502 PMCID: PMC6182755 DOI: 10.1007/s00270-018-2036-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 05/20/2018] [Indexed: 11/30/2022]
Abstract
Background Endovascular stents and flow diverter stents (FDS) have revolutionized the treatment of intradural aneurysms; however, the need for dual anti-platelet treatment (DAPT) limits their use and can cause additional issues. Therefore, there is a need to develop stent coatings that negate the need for DAPT. Methods Two different hydrophilic polymer coatings (HPC-I and HPC-II) were used to coat small nickel titanium plates to initially test the hydrophilic properties of these coatings when applied to nickel titanium. The plates were subsequently incubated with non-medicated whole blood from healthy volunteers for 10 min and stained with a CD61 immunofluorescent antibody that allows detection of adherent platelets. The coatings were applied to FDS wires and were again incubated with non-medicated whole blood from the same volunteers. Scanning electron microscopy was used to detect adherent platelets on the wire surface. Results The HPC-II coating (1.12 ± 0.4%) showed a significantly lower CD61 +ve cell count (p ≤ 0.001) compared to both uncoated NiTi plates (48.61 ± 7.3%) and those with the HPC-I coating (mean 40.19 ± 8.9%). Minimal adherent platelets were seen on the FDS nickel titanium wires coated with the HPC-II compared to uncoated FDS under electron microscopy. Conclusion There is a significant decrease in the number of adherent CD61 +ve platelets on nickel titanium surfaces coated with the HPC-II coating compared to uncoated surfaces. The coating can be successfully applied to the wires of flow diverters. The results of this study are promising with regard to the development of new anti-thrombogenic endovascular devices.
Collapse
|
9
|
Karrer L, Duwe J, Zisch AH, Khabiri E, Cikirikcioglu M, Napoli A, Goessl A, Schaffner T, Hess OM, Carrel T, Kalangos A, Hubbell JA, Walpoth BH. PPS-PEG Surface Coating to Reduce Thrombogenicity of Small Diameter ePTFE Vascular Grafts. Int J Artif Organs 2018; 28:993-1002. [PMID: 16288437 DOI: 10.1177/039139880502801006] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Aims Patency failure of small vascular synthetic grafts is still a major problem for coronary and peripheral revascularization. Thus, three new surface coatings of small synthetic grafts were tested in an acute pig model to evaluate their thrombogenicity (extracorporeal arterio-venous shunt) and in a chronic rat model to evaluate the tissue reaction they induced (subcutaneous implantation). Methods In five domestic pigs (25–30 kg) an extracorporeal femoro-femoral arterio-venous shunt model was used. The study protocol included first a non-heparinized perfusion sequence followed by graft perfusion after 10,000 UI iv heparin. Grafts were perfused for 3 and 9 minutes. The following coatings were tested on ePTFE grafts: poly-propylene sulphide (PPS) – poly-ethylene glycol (PEG) (wet and dry applications) as well as carbon. Two sets of control were used, one dry and one wet (vehicle only). After perfusion grafts were examined by scanning electron microscopy for semiquantitative assessment (score 0–3) of cellular and microthrombi deposition. To assess tissue compatibility, pieces of each material were implanted subcutaneously in 16 Wistar rats. At 2, 4, 8, 12 weeks four animals each were sacrificed for semi-quantitative (score 0–3) histologic evaluation of tissue reaction. Results In the pig model, cellular deposition and microthrombi formation increased over time. In non-heparinized animals, the coatings did not improve the surface characteristics, since they did not prevent microthrombi formation and cellular deposition. In heparinized animals, thrombogenicity was lowest in coated grafts, especially in PPS–PEG dry (P&0.05), and highest in controls. Cell deposition was lowest in PPS–PEG dry, but this difference was not statistically significant vs. controls. In the rat model, no significant differences of the tissue reaction could be shown between materials. Conclusion While all coatings failed to add any benefit for lowering tissue reaction, surface coating with PPS–PEG (dry application) reduced thrombogenicity significantly (in heparinized animals) and thus appears to be promising for improving graft patency of small synthetic vascular prostheses.
Collapse
Affiliation(s)
- L Karrer
- Department of Cardiovascular Surgery, University Hospital (HCUG), Geneva--Switzerland
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Graft Modification Strategies to Improve Patency of Prosthetic Arteriovenous Grafts for Hemodialysis. J Vasc Access 2016; 17 Suppl 1:S85-90. [DOI: 10.5301/jva.5000526] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2015] [Indexed: 11/20/2022] Open
Abstract
Prosthetic arteriovenous grafts (AVGs) are indicated for vascular access for long-term hemodialysis in patients in whom creation or maintenance of an arteriovenous fistula (AVF) has failed or is contraindicated. AVGs have an inferior long-term patency as compared to AVFs. To ameliorate patency rates of prosthetic AVGs, different strategies have emerged to improve graft materials. This review aims to describe current strategies and future perspectives on graft modification, by graft geometry, drug coatings and graft surface technology, to improve AVG patency.
Collapse
|
11
|
Transcatheter pulmonary valve replacement by hybrid approach using a novel polymeric prosthetic heart valve: proof of concept in sheep. PLoS One 2014; 9:e100065. [PMID: 24926892 PMCID: PMC4057289 DOI: 10.1371/journal.pone.0100065] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 05/21/2014] [Indexed: 11/26/2022] Open
Abstract
Background Since 2000, transcatheter pulmonary valve replacement has steadily advanced. However, the available prosthetic valves are restricted to bioprosthesis which have defects like poor durability. Polymeric heart valve is thought as a promising alternative to bioprosthesis. In this study, we introduced a novel polymeric transcatheter pulmonary valve and evaluated its feasibility and safety in sheep by a hybrid approach. Methods We designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflets were made of 0.1-mm expanded polytetrafluoroethylene (ePTFE) coated with phosphorylcholine. We chose glutaraldehyde-treated bovine pericardium valves as control. Pulmonary valve stents were implanted in situ by a hybrid transapical approach in 10 healthy sheep (8 for polymeric valve and 2 for bovine pericardium valve), weighing an average of 22.5±2.0 kg. Angiography and cardiac catheter examination were performed after implantation to assess immediate valvular functionality. After 4-week follow-up, angiography, echocardiography, computed tomography, and cardiac catheter examination were used to assess early valvular function. One randomly selected sheep with polymeric valve was euthanized and the explanted valved stent was analyzed macroscopically and microscopically. Findings Implantation was successful in 9 sheep. Angiography at implantation showed all 9 prosthetic valves demonstrated orthotopic position and normal functionality. All 9 sheep survived at 4-week follow-up. Four-week follow-up revealed no evidence of valve stent dislocation or deformation and normal valvular and cardiac functionality. The cardiac catheter examination showed the peak-peak transvalvular pressure gradient of the polymeric valves was 11.9±5.0 mmHg, while that of two bovine pericardium valves were 11 and 17 mmHg. Gross morphology demonstrated good opening and closure characteristics. No thrombus or calcification was seen macroscopically. Conclusions This design of the novel ePTFE transcatheter pulmonary valve is safe and effective to deploy in sheep by hybrid approach, and the early valvular functionality is good.
Collapse
|
12
|
Abstract
Autogenous vein is the conduit of choice in the surgical creation of bypasses of small-to-medium-caliber vessels in patients with peripheral occlusive arterial disease and will remain so for the near future. The success rate of bypasses using conduits of diameters greater than 6 mm has been excellent, whereas the majority of bypasses using smaller conduits fail within 5 years. In addition, due to a steep increase in rates of diabetes and decreasing cardiovascular mortality rates, increasing challenges are presented by this population. These facts have motivated much of the research in the cardiovascular arena over the past four decades, with improved techniques and new materials. Strategies to improve outcomes include the use of alternative materials including autologous, nonautologous and prosthetic grafts, utilizing different methods for their harvesting and preservation; tissue engineering, using either polymer- or biological-based scaffolds for cell seeding; endovascular methodologies; and gene therapy. This report presents an overview of the several options currently available in the management of patients with peripheral arterial occlusive disease, as well as the ongoing research directed towards the creation of an artificial engineered vessel, discussing experimental work in which endothelial cells have been seeded on different scaffolds and finally the potential application of gene therapy in the field of vascular reconstruction.
Collapse
Affiliation(s)
- Luis Leon
- Department of Surgery, Hines VA Hospital, IL 60141, USA.
| | | |
Collapse
|
13
|
Abstract
Since the introduction of synthetic vascular grafts in the 1960s, only two-stage endothelial cell seeding has demonstrated any significant improvement over conventional vascular grafts, and its benefits have yet to be demonstrated on a large scale. Tissue engineering is a rapidly expanding field with great potential, but efforts to construct tissue-engineered arterial grafts have, to date, yielded little clinical success. This review explores the latest approaches to the construction of a superior vascular graft, along with its potential for use in the clinic in the future.
Collapse
Affiliation(s)
- Chris D Daly
- University of Queensland, Centre for Research in Vascular Biology, 4072, QLD, Australia
| | | | | | | |
Collapse
|
14
|
|
15
|
Feghhi S, Sniadecki NJ. Mechanobiology of platelets: techniques to study the role of fluid flow and platelet retraction forces at the micro- and nano-scale. Int J Mol Sci 2011; 12:9009-30. [PMID: 22272117 PMCID: PMC3257114 DOI: 10.3390/ijms12129009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 11/24/2011] [Accepted: 11/28/2011] [Indexed: 12/29/2022] Open
Abstract
Coagulation involves a complex set of events that are important in maintaining hemostasis. Biochemical interactions are classically known to regulate the hemostatic process, but recent evidence has revealed that mechanical interactions between platelets and their surroundings can also play a substantial role. Investigations into platelet mechanobiology have been challenging however, due to the small dimensions of platelets and their glycoprotein receptors. Platelet researchers have recently turned to microfabricated devices to control these physical, nanometer-scale interactions with a higher degree of precision. These approaches have enabled exciting, new insights into the molecular and biomechanical factors that affect platelets in clot formation. In this review, we highlight the new tools used to understand platelet mechanobiology and the roles of adhesion, shear flow, and retraction forces in clot formation.
Collapse
Affiliation(s)
- Shirin Feghhi
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA 98195, USA; E-Mail:
| | - Nathan J. Sniadecki
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA 98195, USA; E-Mail:
- Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, WA 98105, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-206-685-6591; Fax: +1-206-685-8047
| |
Collapse
|
16
|
Liao D, Wang X, Lin PH, Yao Q, Chen C. Covalent linkage of heparin provides a stable anti-coagulation surface of decellularized porcine arteries. J Cell Mol Med 2010; 13:2736-2743. [PMID: 19040421 DOI: 10.1111/j.1582-4934.2008.00589.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Establishing thrombosis-resistant surface is crucial to develop tissue-engineered small diameter vascular grafts for arterial reconstructive procedures. The objective of this study was to evaluate the stability and anti-coagulation properties of heparin covalently linked to decellularized porcine carotid arteries. Cellular components of porcine carotid arteries were completely removed with chemical and physical means. Heparin was covalently linked to the decellularized vessels by a chemical reaction of the carboxyl end of amino acids with hydroxylamine sulphate salt and heparin-EDC. Bound heparin contents were measured by quantitative colorimetric assay of toluidine blue staining. The average content of heparin in treated vessels was 35.6 +/- 11.6 mg/cm(2) tissue, which represented 6.21 +/- 2.03 UPS heparin/cm(2) tissue. The stability of heparin linkage was tested by incubating the heparin-linked vessels either in PBS at 37 degrees C or in 70% alcohol at room temperature up to 21 days, showing no significant reduction of heparin content. Anti-coagulation property of bound heparin was determined with a clotting time assay using fresh dog blood. Standardized small pieces of non-heparin-bound vessels were clotted in fresh dog blood within 10 min., whereas all heparin-bound vessels did not form clot during 1-hr observation. In vivo platelet deposition of the vessel was determined with a baboon model of the femoral arteriovenous external shunt and (111)Indium labelling of platelets. There were 1.38 +/- 0.07 x 10(9) and 0.64 +/- 0.11 x 10(9) baboon platelets deposited on the control and heparin-linked vessels, respectively, at 60 min. These data demonstrate that covalent linkage of heparin provides an effective and stable anti-coagulation surface of decellularized porcine carotid arteries. This study may suggest a new strategy to develop tissue-engineered biological vascular grafts, which could be used for human coronary or low extremity artery bypasses.
Collapse
Affiliation(s)
- Dan Liao
- Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, and Michael E. DeBakey VA Medical Center, Houston, TX, USA
| | - Xinwen Wang
- Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, and Michael E. DeBakey VA Medical Center, Houston, TX, USA
| | - Peter H Lin
- Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, and Michael E. DeBakey VA Medical Center, Houston, TX, USA
| | - Qizhi Yao
- Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, and Michael E. DeBakey VA Medical Center, Houston, TX, USA
| | - Changyi Chen
- Molecular Surgeon Research Center, Division of Vascular Surgery and Endovascular Therapy, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, and Michael E. DeBakey VA Medical Center, Houston, TX, USA
| |
Collapse
|
17
|
Wang Q, McGoron AJ, Pinchuk L, Schoephoerster RT. A novel small animal model for biocompatibility assessment of polymeric materials for use in prosthetic heart valves. J Biomed Mater Res A 2010; 93:442-53. [PMID: 19569223 DOI: 10.1002/jbm.a.32562] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A composite polymeric material, poly(styrene-block-isobutylene-block-styrene) (SIBS) with an embedded reinforcement polyethylene terephthalate (PET) fabric, is undergoing investigation for potential use in a novel heart valve. The purpose of this study was to develop and implement a small animal model to assess the biocompatibility of composite samples in a cardiovascular tissue and blood-contacting environment. Composite samples were manufactured using dip coating and solvent casting with two coating thicknesses (25 and 50 microm). A novel rat abdominal aorta model was developed to test the dip-coated samples in a similar pulsatile flow condition to its intended use, and both dip-coated and solvent-cast samples were tested using a rat subcutaneous model. Tissue response, defined by degree of cellular infiltration and encapsulation, was minimized when a smooth coating of SIBS shielded the PET fabric from exposure to blood and tissue, and the degree of tissue response was directly correlated with the degree of surface roughness. Surface modification using phospholipid further reduces the tissue response. We have demonstrated the applicability of using a novel rat abdominal aorta model for biocompatibility assessment of polymeric materials that will be used in cardiovascular implants. For the purpose of this study, our results indicate that solvent casting with a 25-microm SIBS coating thickness will provide optimal biocompatibility for the SIBS valve.
Collapse
Affiliation(s)
- Qiang Wang
- Department of Biomedical Engineering, Florida International University, 10555 West Flagler Street, EC 2610, Miami, Florida 33174, USA
| | | | | | | |
Collapse
|
18
|
Wang S, Gupta AS, Sagnella S, Barendt PM, Kottke-Marchant K, Marchant RE. Biomimetic fluorocarbon surfactant polymers reduce platelet adhesion on PTFE/ePTFE surfaces. JOURNAL OF BIOMATERIALS SCIENCE. POLYMER EDITION 2009; 20:619-35. [PMID: 19323880 PMCID: PMC2852637 DOI: 10.1163/156856209x426439] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We describe a series of fluorocarbon surfactant polymers designed as surface-modifying agents for improving the thrombogenicity of ePTFE vascular graft materials by the reduction of platelet adhesion. The surfactant polymers consist of a poly(vinyl amine) backbone with pendent dextran and perfluoroundecanoyl branches. Surface modification is accomplished by a simple dip-coating process in which surfactant polymers undergo spontaneous surface-induced adsorption and assembly on PTFE/ePTFE surface. The adhesion stability of the surfactant polymer on PTFE was examined under dynamic shear conditions in PBS and human whole blood with a rotating disk system. Fluorocarbon surfactant polymer coatings with three different dextran to perfluorocarbon ratios (1:0.5, 1:1 and 1:2) were compared in the context of platelet adhesion on PTFE/ePTFE surface under dynamic flow conditions. Suppression of platelet adhesion was achieved for all three coated surfaces over the shear-stress range of 0-75 dyn/cm2 in platelet-rich plasma (PRP) or human whole blood. The effectiveness depended on the surfactant polymer composition such that platelet adhesion on coated surfaces decreased significantly with increasing fluorocarbon branch density at 0 dyn/cm2. Our results suggest that fluorocarbon surfactant polymers can effectively suppress platelet adhesion and demonstrate the potential application of the fluorocarbon surfactant polymers as non-thrombogenic coatings for ePTFE vascular grafts.
Collapse
Affiliation(s)
- Shuwu Wang
- NanoMimetics, Inc., 1768 E. 25th Street, Cleveland, OH 44114, USA.
| | | | | | | | | | | |
Collapse
|
19
|
Silvestri D, Cristallini C, Gagliardi M, Barbani N, D'Acunto M, Ciardelli G, Giusti P. Acrylic Copolymers as Candidates for Drug-Eluting Coating of Vascular Stents. J Biomater Appl 2008; 24:353-83. [DOI: 10.1177/0885328208095198] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of the present work is the synthesis and characterization of polymer materials showing good adhesion, drug loading, and delivery properties, for potential cardiovascular application. In particular, poly(methylmethacrylate-co-acrylic acid) copolymers are prepared in different compositions by a radical polymerization and investigated as potential materials to coat metallic stents and to carry out a local drug release. Films obtained by dissolving the copolymer in an appropriate organic solvent (also loaded with an anti-restenosis drug, such as tacrolimus) are investigated: physicochemical properties, adhesiveness to metallic stent material, and kinetics of drug release in physiological environment are studied.
Collapse
Affiliation(s)
- D. Silvestri
- Department of Chemical Engineering, Industrial Chemistry and Materials Science, University of Pisa, Italy, , Interdepartmental Centre for the study and evaluation of Biomaterials and Endo-prosthesis'Nicolino Marchetti' (C.I.B.E.), Pisa, Italy
| | - C. Cristallini
- CNR Institute for Composite and Biomedical Materials IMCB Pisa, c/o Department of Chemical Engineering, Italy
| | - M. Gagliardi
- Department of Chemical Engineering, Industrial Chemistry and Materials Science, University of Pisa, Italy
| | - N. Barbani
- Department of Chemical Engineering, Industrial Chemistry and Materials Science, University of Pisa, Italy
| | - M. D'Acunto
- Department of Chemical Engineering, Industrial Chemistry and Materials Science, University of Pisa, Italy
| | - G. Ciardelli
- Department of Mechanics, Politecnico in Turin, Italy
| | - P. Giusti
- Department of Chemical Engineering, Industrial Chemistry and Materials Science, University of Pisa, Italy, CNR Institute for Composite and Biomedical Materials IMCB Pisa, c/o Department of Chemical Engineering, Italy, Interdepartmental Centre for the study and evaluation of Biomaterials and Endo-prosthesis
| |
Collapse
|
20
|
Vallières K, Petitclerc E, Laroche G. Covalent grafting of fibronectin onto plasma-treated PTFE: influence of the conjugation strategy on fibronectin biological activity. Macromol Biosci 2007; 7:738-45. [PMID: 17457945 DOI: 10.1002/mabi.200600267] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Surface coating of synthetic materials is often considered to improve biomedical devices biocompatibility. In this study, we covalently bound fibronectin (FN) onto ammonia plasma-treated PTFE via two crosslinkers, namely glutaric anhydride (GA) and sulfosuccinimidyl-4-(p-maleimidophenyl)butyrate (sulfo-SMPB). With respect to clean PTFE, cell adhesion increased markedly on both FN grafted surfaces, although it was twice higher on PTFE-GA-FN than on PTFE-SMPB-FN. ELISA experiments performed with a polyclonal antibody revealed that the amount of FN is identical on both surfaces while monoclonal antibody specific to the RGD binding site clearly demonstrated a greater availability when FN is surface grafted through GA. These results provide evidence of a variation in protein conformation correlated with the surface conjugation strategy.
Collapse
Affiliation(s)
- Karine Vallières
- Unité de Biotechnologie et de Bioingénierie, Centre de recherche du CHUQ, Hôpital Saint-François d'Assise, 10 rue de l'Espinay, Québec, Canada, G1L 3L5
| | | | | |
Collapse
|
21
|
Roles of chymase in stenosis occurring after polytetrafluoroethylene graft implantations. Life Sci 2007; 81:1291-300. [DOI: 10.1016/j.lfs.2007.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 08/23/2007] [Accepted: 09/07/2007] [Indexed: 11/17/2022]
|
22
|
Jordan SW, Chaikof EL. Novel thromboresistant materials. J Vasc Surg 2007; 45 Suppl A:A104-15. [PMID: 17544031 DOI: 10.1016/j.jvs.2007.02.048] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 02/17/2007] [Indexed: 11/30/2022]
Abstract
The development of a clinically durable small-diameter vascular graft as well as permanently implantable biosensors and artificial organ systems that interface with blood, including the artificial heart, kidney, liver, and lung, remain limited by surface-induced thrombotic responses. Recent breakthroughs in materials science, along with a growing understanding of the molecular events that underlay thrombosis, has led to the design and clinical evaluation of a variety of biologically active coatings that inhibit components of the coagulation pathway and platelet responses by surface immobilization or controlled release of bioactive agents. This report reviews recent progress in generating synthetic thromboresistant surfaces that inhibit (1) protein and cell adsorption, (2) thrombin and fibrin formation, and (3) platelet activation and aggregation.
Collapse
|
23
|
Wilson JT, Cui W, Sun XL, Tucker-Burden C, Weber CJ, Chaikof EL. In vivo biocompatibility and stability of a substrate-supported polymerizable membrane-mimetic film. Biomaterials 2007; 28:609-17. [PMID: 17055571 DOI: 10.1016/j.biomaterials.2006.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Accepted: 09/03/2006] [Indexed: 12/20/2022]
Abstract
The cell membrane establishes an important paradigm for the molecular engineering of coatings for implantable devices because of its intrinsic biocompatibility and ability to act as a template for the assembly of diverse membrane-associated macromolecules. A stabilized membrane-mimetic film was assembled on alginate/Ca(2+) hydrogel microcapsules by in situ polymerization of an acrylate functionalized phospholipid. The phospholipid monomer was prepared as unilamellar vesicles and fused onto octadecyl chains that were components of an amphiphilic terpolymer anchored onto a polyelectrolyte multilayer (PEM) by electrostatic interactions. Microcapsules coated with a membrane-mimetic film were implanted into the peritoneal cavity of C57BL/6 mice, and the short-term biostability and biocompatibility of membrane-mimetic films assembled on two different alginate/poly(l-lysine) PEM cushions were compared. The nature of the underlying PEM support had a profound impact on the biocompatibility of the membrane-mimetic film, as the percentage of retrieved microcapsules completely overgrown with host cells shifted from 66+/-5.9% to less than 1% when modifications to the PEM were made. When assembled on the appropriate PEM support, biocompatibility of membrane-mimetic-coated microspheres was high wherein 87.5+/-5.7% of the implanted microspheres were retrieved 4 weeks after implantation and 92.6+/-6.4% of the retrieved capsules were free of cell adhesion or fibrotic overgrowth. Finally, 4 weeks after implantation, microspheres coated with a Texas red-labeled membrane-mimetic film were imaged with confocal microscopy and exhibited a uniform film around the periphery of the implant, indicating a high degree of film biostability. Hence, membrane-mimetic films provide a new route for generating robust, biocompatible, and biochemically heterogeneous coatings for implantable devices through molecular self-assembly.
Collapse
Affiliation(s)
- John T Wilson
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA 30332, USA
| | | | | | | | | | | |
Collapse
|
24
|
|
25
|
Chevallier P, Janvier R, Mantovani D, Laroche G. In vitro biological performances of phosphorylcholine-grafted ePTFE prostheses through RFGD plasma techniques. Macromol Biosci 2005; 5:829-39. [PMID: 16134089 DOI: 10.1002/mabi.200500088] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Arterial prostheses made of microporous Teflon (ePTFE) are currently used in vascular surgery as bypasses for small and medium vessels. However, several clinical complications, such as thrombosis, frequently occur in these prostheses when implanted in humans. In this work, an original strategy was developed to improve the hemocompatibility of ePTFE prostheses, based on glow-discharge surface modification followed by chemical grafting of phosphorylcholine, known for its hemocompatible properties. This procedure leads to a covalent attachment of the molecules, therefore preventing their removal by shear stress induced by blood flow at the implant wall. The improvement of the blood compatibility properties of the modified ePTFE arterial prostheses have been investigated by in vitro tests such as thromboelastography, neutrophil adsorption, platelet aggregation, and cell cultures. These in vitro tests put in evidence that thrombogenicity index, platelet aggregation, and neutrophil adhesion were decreased by the molecule grafted on the prostheses. Moreover, the cell growth on the surface of the PRC-grafted prostheses was greatly enhanced in comparison to the virgin prosthesis. Based on these results, it could be concluded that PRC grafting on ePTFE prostheses permit to improve in vitro hemocompatibility and biocompatibility in comparison with their virgin counterpart.
Collapse
Affiliation(s)
- Pascale Chevallier
- Unité de Biotechnologie et de Bioingénierie, Centre de Recherche de l'Hôpital Saint-François d'Assise, CHUQ, 10 rue de l'Espinay, Québec G1L 3L5, Canada
| | | | | | | |
Collapse
|
26
|
Hausleiter J, Kastrati A, Mehilli J, Schühlen H, Pache J, Dotzer F, Glatthor C, Siebert S, Dirschinger J, Schömig A. A randomized trial comparing phosphorylcholine-coated stenting with balloon angioplasty as well as abciximab with placebo for restenosis reduction in small coronary arteries. J Intern Med 2004; 256:388-97. [PMID: 15485474 DOI: 10.1111/j.1365-2796.2004.01398.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVE The objective of this randomized trial was to assess the antirestenotic effects of phosphorylcholine (PC)-coated stents as well as of abciximab in small coronary arteries when compared with percutaneous transluminal coronary angioplasty (PTCA) and placebo respectively. BACKGROUND Stent coating with PC has been shown to reduce protein absorption and platelet activation which may reduce the risk of restenosis. Furthermore, on the basis of nondedicated studies abciximab is believed to reduce the risk of restenosis after coronary interventions. METHODS A total of 502 patients with lesions situated in small coronary arteries (vessel diameter </=2.5 mm) were randomly assigned to be treated with either PC-coated stents (n = 253) or PTCA (n = 249) and with either abciximab (n = 251) or placebo (n = 251) with the use of a 2 x 2 factorial design. All patients were pretreated with 600 mg clopidogrel. The primary end-point was the incidence of angiographic restenosis (>/=50% diameter stenosis) at follow-up; death or myocardial infarction, and target vessel revascularization (TVR), were assessed as secondary end-points. RESULTS Angiographic restenosis did not differ between patients treated with PC-coated stents or with PTCA (39.0% vs. 34.2%; P = 0.30) and between patients receiving abciximab or placebo (39.3% vs. 34.3%; P = 0.29). Similarly, the need for TVR at 1-year follow-up did not differ between patients receiving PC-coated stents or PTCA (20.2% vs. 20.5%; P = 0.98) as well as between patients treated with abciximab or placebo (18.7% vs. 21.9%; P = 0.44). CONCLUSIONS PC-coated stents and abciximab failed to reduce the incidence of angiographic restenosis after percutaneous coronary intervention of small coronary arteries. These data strengthen the belief that future studies on prevention of restenosis in small coronary arteries should focus on drug-eluting stents.
Collapse
Affiliation(s)
- J Hausleiter
- Deutsches Herzzentrum München, Klinik an der TU München, Munich, Germany.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Lin PH, Chen C, Bush RL, Yao Q, Lumsden AB, Hanson SR. Small-caliber heparin-coated ePTFE grafts reduce platelet deposition and neointimal hyperplasia in a baboon model. J Vasc Surg 2004; 39:1322-8. [PMID: 15192575 DOI: 10.1016/j.jvs.2004.01.046] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Intimal hyperplasia and graft thrombosis are major causes of graft failure. Heparin prolongs graft patency and inhibits neointimal hyperplasia in animal models. The purpose of this study was to evaluate the effect of a heparin-coated expanded polytetrafluoroethylene (ePTFE) graft on platelet deposition and anastomotic neointimal hyperplasia after aortoiliac bypass grafting in a baboon model. METHODS Heparin-coated ePTFE grafts (4-mm diameter) were incorporated into exteriorized femoral arteriovenous shunts placed in five baboons. Platelet deposition was analyzed by measuring the accumulation of indium 111-labeled platelets on the grafts, with dynamic scintillation camera imaging. Eight adult male baboons (mean weight, 9.3 kg) underwent bilateral aortoiliac bypass grafting with ePTFE grafts (4-mm internal diameter). In each animal a heparin-coated ePTFE graft was placed in one aortoiliac artery, and an uncoated graft, which served as the control, was placed in the contralateral aortoiliac artery. All grafts were harvested at 4 weeks, and were analyzed quantitatively for neointimal hyperplasia at graft-vessel anastomoses. RESULTS Early platelet deposition on heparin-coated grafts after 1 to 4 hours of ex vivo circuitry was significantly reduced. All the harvested aortoiliac grafts were patent at 4 weeks. There was a significant reduction in neointimal area at both proximal (0.26 +/- 0.11 mm(2)) and distal (0.29 +/- 0.14 mm(2)) anastomoses in the heparin-coated grafts, compared with proximal (0.56 +/- 0.18 mm(2)) and distal (0.63 +/- 0.21 mm(2)) anastomoses in the untreated control grafts (P <.05). In addition, neointimal cell proliferation assayed with bromodeoxyuridine (BrdU) incorporation was reduced in the graft neointima (3.47% +/- 0.43%) in heparin-coated grafts compared with the graft neointima (6.21% +/- 0.59%) in untreated control grafts (P <.05). CONCLUSIONS Small-caliber heparin-coated ePTFE grafts significantly reduce platelet deposition and anastomotic neointimal hyperplasia and cell proliferation, without measurable side effects, in baboons. Surface coating with heparin in small-caliber ePTFE grafts is useful for improving prosthetic bypass graft patency. CLINICAL RELEVANCE An autologous vein graft is the ideal bypass conduit in peripheral arterial reconstruction; however, many patients who undergo bypass grafting do not have adequate or available autologous vein graft. As a result surgeons often must rely on prosthetic grafts as an alternative conduit in arterial bypass procedures. Clinical outcomes with prosthetic grafts in peripheral arterial reconstruction are generally inferior to those with autologous vein bypass grafts, in part because of anastomotic neointimal hyperplasia. This study evaluated the effect of small-caliber heparin-coated expandable polytetrafluoroethylene (ePTFE) grafts in aortoiliac reconstruction in a baboon model. The study found that heparin-coated ePTFE grafts resulted in less intimal hyperplasia and less platelet deposition after implantation, compared with noncoated control ePTFE grafts.
Collapse
MESH Headings
- Anastomosis, Surgical
- Animals
- Aorta, Abdominal/cytology
- Aorta, Abdominal/metabolism
- Aorta, Abdominal/surgery
- Blood Platelets/cytology
- Blood Platelets/drug effects
- Blood Platelets/metabolism
- Blood Vessel Prosthesis Implantation
- Cell Division/drug effects
- Coated Materials, Biocompatible/therapeutic use
- Disease Models, Animal
- Endothelial Cells/cytology
- Endothelial Cells/drug effects
- Endothelial Cells/metabolism
- Fibrinolytic Agents/therapeutic use
- Heparin/therapeutic use
- Hyperplasia/drug therapy
- Iliac Artery/cytology
- Iliac Artery/metabolism
- Iliac Artery/surgery
- Immunohistochemistry
- Male
- Models, Cardiovascular
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Papio
- Polytetrafluoroethylene/therapeutic use
- Tunica Intima/pathology
Collapse
Affiliation(s)
- Peter H Lin
- Division of Vascular Surgery & Endovascular Therapy, DeBakey Department of Surgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | | | | | | | | | | |
Collapse
|
28
|
Johnson MS, McLennan G, Lalka SG, Whitfield RM, Dreesen RG. The porcine hemodialysis access model. J Vasc Interv Radiol 2001; 12:969-77. [PMID: 11487678 DOI: 10.1016/s1051-0443(07)61578-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To create a porcine hemodialysis access model that reliably reproduces intimal hyperplasia (IH) of the outflow vein similar to that which causes access failure in human patients undergoing dialysis treatments. MATERIALS AND METHODS Surgical technique for creation of side-to-side iliac-artery-to-ipsilateral-iliac-vein (IAV) native fistulas and IAV conduits was optimized in three standard-bred pigs. Persistent patency of fistulas and conduits was demonstrated in two additional pigs allowed to survive for 1 week. IAV fistulas and contralateral 2-cm polytetrafluoroethylene IAV conduits were created in five additional pigs. Venous outflow from these fistulas and conduits was evaluated with venography and intravascular ultrasound (IVUS) immediately after creation (day 0) and at 2-week intervals for as long as 64 days. Animals were killed at 30 days (n = 1), 42 days (n = 2), or 64 days (n = 2), and the arteries, veins, and conduits were evaluated histologically. RESULTS IAV native fistulas remained patent until the animals' death and conduits remained patent for at least 14 days in four of five pigs; both the fistula and conduit likely occluded before 16-day follow-up in the fifth pig. At 42-64 days, venography demonstrated maximum fistula outflow vein diameter stenoses of 53%-76% and maximum conduit outflow vein stenoses of 44%-84%, and IVUS demonstrated maximum area stenoses of 64%-86% and 43%-82%, respectively. Three of five conduits occluded, one before 16-day follow-up, one between 14 and 28 days, and the other after 42 days. Histologic sections demonstrated IH predominantly affecting the veins at the anastomoses and central (cephalad) to the anastomoses in all pigs. CONCLUSION This porcine model reproduces IH in the fistula or conduit outflow vein with measurable stenosis. Such a model might allow relevant preclinical evaluation of interventional devices and techniques intended to reduce the effects of IH in human patients undergoing dialysis treatments.
Collapse
Affiliation(s)
- M S Johnson
- Department of Radiology, Indiana University School of Medicine, University Hospital 0279, 550 N. University Blvd., Indianapolis, IN 46202-5253, USA.
| | | | | | | | | |
Collapse
|
29
|
Abstract
PURPOSE Intimal hyperplasia at the venous anastomosis of dialysis access grafts causes early failure, although increased flow inhibits intimal hyperplasia in arterial grafts and after vessel injury. We designed a sheep model to study this process. METHODS Polytetrafluoroethylene (PTFE) grafts were placed in the necks of sheep from the carotid artery to the external jugular vein. Grafts were harvested after perfusion fixation at 4, 8, and 12 weeks and submitted for histologic and immunohistochemical examination, including morphometry of neointimal lesions. RESULTS The venous anastomoses developed thick neointima within the PTFE graft by 4 weeks. Lesions at the venous end were significantly thicker than those at the arterial end by 8 weeks (1.2 +/- 0.1 vs 0.38 +/- 0.05 mm, P <.02) and had greater cross-sectional area at both 4 (0.32 +/- 0.21 vs 3.6 +/- 0.8 mm(2), n = 7, P <.02) and 8 weeks (9.8 +/- 1.9 vs 1.1 +/- 0.7 mm(2), n = 7, P <.02). Only one of the four grafts (25%) in the 12-week group remained patent. Lesions were composed of smooth muscle cells, matrix, and thrombus of various ages. Cellular proliferation was prominent in neointima adjacent to thrombus and in granulation tissue surrounding the graft. Organizing thrombus contributed significantly to luminal narrowing. CONCLUSION The sheep model of dialysis access reliably produces venous stenosis within 4 weeks. Lesions develop in the absence of uremia, graft puncture, or dialysis, suggesting that these factors are not necessary for graft failure. The continued presence of thrombus and high rates of cellular proliferation suggest ongoing injury is an important cause of lesion formation. This model allows study of the cellular mechanisms of dialysis failure.
Collapse
Affiliation(s)
- T R Kohler
- Department of Surgery, University of Washington, the VA Puget Sound Health Care System, Seattle 98108, USA
| | | |
Collapse
|
30
|
Borovetz HS, Burke JF, Chang TMS, Colas A, Cranin AN, Curtis J, Gemmell CH, Griffith BP, Hallab NJ, Heller J, Hoffman AS, Jacobs JJ, Ideker R, Katz JL, Kennedy J, Lemons JE, Malchesky PS, Morgan JR, Padera RE, Patel AS, Reffojo MF, Roby MS, Rohr TE, Schoen FJ, Sefton MV, Sheridan RT, Smith DC, Spelman FA, Tarcha PJ, Tomapkins RG, Venugopalan R, Wagner WR, Yager P, Yarmush ML. Application of Materials in Medicine, Biology, and Artificial Organs. Biomater Sci 1996. [DOI: 10.1016/b978-012582460-6/50010-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|