Bruce P Murphy

Bruce P Murphy
Trinity College Dublin | TCD · Centre for Bioengineering

About

46
Publications
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1,039
Citations
Introduction

Publications

Publications (46)
Article
Background Animal-derived pericardium is the key material that enables the successful clinical use of bioprosthetic heart valves. Recently, transcatheter heart valves have placed more emphasis on the enhancement of this tissue, especially in terms of producing a uniform, thin, durable tissue. In this study, we provide a new method to achieve thinne...
Article
Aim: Cell repopulation of tissue-engineered vascular grafts (TEVGs) from decellularized arterial scaffolds is limited by dense concentric tunica media layers which impede cells migrating radially between the layers. We aimed to develop and validate a new microneedle device to modify decellularized carotid arteries with radial microchannels to enhan...
Article
The limited regenerative capacity of the heart after a myocardial infarct results in remodeling processes that can progress to congestive heart failure (CHF). Several strategies including mechanical stabilization of the weakened myocardium and regenerative approaches (specifically stem cell technologies)have evolved which aim to prevent CHF. Howeve...
Article
As treatments for myocardial infarction (MI) continue to improve, the population of people suffering from heart failure (HF) is rising significantly. Novel treatment strategies aimed at achieving long-term functional stabilisation and improvement in heart function post MI include the delivery of biomaterial hydrogels and myocardial matrix-based the...
Article
Full-text available
Injectable hydrogels that aim to mechanically stabilise the weakened left ventricle wall to restore cardiac function or to deliver stem cells in cardiac regenerative therapy have shown promising data. However, the clinical translation of hydrogel-based therapies has been limited due to difficulties injecting them through catheters. We have engineer...
Article
Injectable hydrogels that aim to mechanically stabilise the weakened left ventricle wall to restore cardiac function or to deliver stem cells in cardiac regenerative therapy have shown promising data. However, the clinical translation of hydrogel-based therapies has been limited due to difficulties injecting them through catheters. We have engineer...
Article
Full-text available
The clinical translation of regenerative therapy for the diseased heart, whether in the form of cells, macromolecules or small molecules, is hampered by several factors: the poor retention and short biological half-life of the therapeutic agent, the adverse side effects from systemic delivery, and difficulties with the administration of multiple do...
Article
Full-text available
Venous grafts have been used to bypass stenotic arteries for many decades. However, this “gold standard” treatment is far from optimal, with long-term vein graft patency rates reported to be as low as 50% at >15 years. These results could be a result of the structural and functional differences of veins compared to arteries. In this study we develo...
Article
The development of nanomedicines for the treatment of cancer focuses on the local targeted delivery of chemotherapeutic drugs to enhance drug efficacy and reduce adverse effects. The nanomedicines which are currently approved for clinical use are mainly successful in terms of improved bioavailability and tolerability but do not necessarily increase...
Article
Full-text available
Localized delivery of stem cells is potentially a promising therapeutic strategy for regenerating damaged myocardium. Many studies focus on limiting the biologic component of cell loss, but few address the contribution of mechanical factors. This study investigates optimal parameters for retaining the largest volume of cell loaded hydrogels post in...
Article
Full-text available
Heart failure is a significant clinical issue. It is the cause of enormous healthcare costs worldwide and results in significant morbidity and mortality. Cardiac regenerative therapy has progressed considerably from clinical and preclinical studies delivering simple suspensions of cells, macromolecule, and small molecules to more advanced delivery...
Article
In cases of severely diseased mitral valves (MV), the required treatment is often valve replacement. Bioprosthetic and stentless replacement valves are usually either fully or partially composed of animal derived tissue treated with a decellularization process, a cross-linking process, or both. In this study, we analysed the effects of these treatm...
Article
Mitral valve prolapse is often caused by either elongated or ruptured chordae tendineae (CT). In many cases, rupture is spontaneous, meaning there is no underlying cause. We hypothesised that spontaneous rupture may be due to mechanical fatigue. To investigate this hypothesis, we tested porcine marginal CT: in uniaxial tension, and in fatigue at a...
Article
Decellularized arterial scaffolds have achieved success in advancing towards clinical use for small diameter vascular graft applications. Issues remain with effectively cell seeding these scaffolds, which may result in slow remodeling in vivo and reduced patency rates. This study aims to efficiently bulk load decellularized arterial scaffolds with...
Article
The aim of this study was to determine the effect that a thermal renal denervation cycle has on the mechanical properties of the arterial wall. Porcine arterial tissue specimens were tested in three groups: native tissue, decellularized tissue, decellularized with collagen digestion (e.g. elastin only). One arterial specimen was used as an unheated...
Article
The goal of this study was to promote rapid repopulation of the medial layer of decellularized tissues for use as vascular grafts. We utilized a combined approach of biochemical and mechanical stimuli to enhance repopulation of decellularized porcine arterial tissue. Chitosan β-glycerophosphate loaded with hepatocyte growth factor (HGF) was injecte...
Article
The mitral valve annulus is a complex and irregular component of the mitral valve apparatus, serving both a structural and sphincteric role. We have sought to determine the mechanical properties of the mitral valve annulus segmentally. Twenty porcine hearts were dissected to isolate the annulus. The annulus was segmented into four sections: anterio...
Conference Paper
Full-text available
Decellularized arterial tissue has shown promising use as a scaffold for vascular tissue replacement; similar structural and functional characteristics to the native tissue are maintained and these scaffolds are non-thrombogenic, non immunogenic with the ability to remodel and grow in vivo[1]. However, there still remains a number of limiting facto...
Conference Paper
Mitral valve (MV) disease is the most prevalent form of heart valve disease among the US population [1]. MV disease can affect any one of the four components of the mitral valve: chordae tendinae, valve leaflets, papillary muscles or the supporting annulus. In one example of MV disease the annulus can become dilated, and this can subsequently lead...
Article
Objective: The standard approach for endovascular treatment of the renal artery is access via the common femoral artery. However, approximately one in eight patients have a renal artery take-off angle that is less than 50°. In these patients approaching via a femoral access site can be technically challenging. The goal of this study was to design...
Article
Decellularized arterial scaffolds have achieved success in advancing towards clinical use as vascular grafts. However, concerns remain regarding long term preservation and sterilisation of these scaffolds. Freeze-drying offers a means of overcoming these concerns. In this study, we investigated the effects of various freeze-drying protocols on dece...
Article
Atherosclerosis is a disease that causes obstructions to develop within the arterial system; these obstructions can result in an acute vascular event such as a heart attack or stroke, and potentially death. In the majority of cases a standard angioplasty balloon is sufficient to dilate the site of an obstruction; however difficult obstructions, suc...
Article
This study investigates the feasibility of utilising a grit blasting process to coat three nitinol substrates (a planer 2D surface, a circular wire and a cardiovascular stent geometry) with a hydroxyapatite coating. Surface characteristics of the coating on the three substrates were determined and additionally the durability of the coating post fat...
Article
Several challenges persist when attempting to utilize decellularized tissue as a scaffold for vascular tissue engineering. Namely: poor cell infiltration/migration, excessive culture times associated with repopulating the scaffolds, and the achievement of a quiescent medial layer. In an attempt to create an optimum vascular scaffold, we customized...
Article
Tissue engineering small diameter vascular grafts requires excessive culture times to produce an appropriate extracellular matrix (ECM). The use of decellularised exogenous tissue as a scaffold has the potential to overcome this limitation due to the preformed ideal ECM architecture that remains after decellularisation. While this scaffold reduces...
Article
Previous mechano-transduction studies have investigated the endothelial cell (EC) morphological response to mechanical stimuli; generally consisting of a wall shear stress (WSS) and a cyclic tensile hoop strain (THS). More recent studies have investigated the EC biochemical response (intercellular adhesion molecule, ICAM-1, and vascular cellular ad...
Article
Over the past 25 years, many laboratory based bioreactors have been used to study the cellular response to hemodynamic forces. The vast majority of these studies have focused on the effect of a single isolated hemodynamic force, generally consisting of a wall shear stress (WSS) or a tensile hoop strain (THS). However, investigating the cellular res...
Article
Full-text available
The aim of this study was to compare the interfragmentary compression generated across a simulated femoral fracture model by a conventional 4.5 mm AO/ASIF cortical lag screw with a differentially pitched cortical compression screw. A 45-degree osteotomy was made in a whole bone composite femoral shaft, this was internally fixed with either a conven...
Article
Full-text available
To date many bioreactor experiments have investigated the cellular response to isolated in vitro forces. However, in vivo, wall shear stress WSS and tensile hoop strain THS coexist. This article describes the techniques used to build and validate a novel vascular tissue bioreactor, which is capable of applying simultaneous wall shear stress and ten...
Article
Full-text available
Vascular stents are used to restore blood flow in stenotic arteries, and at present the implantation of a stent is the preferred revascularisation method for treating coronary artery disease, as the introduction of drug eluting stents (DESs) has lead to a significant improvement in the clinical outcome of coronary stenting. However the mechanical l...
Article
Full-text available
The goal of this study entails the development of computational models of in vitro procedures in order to obtain an enhanced understanding of the mecha-nisms underlying the response of adherent cells to mechanical stimuli. The well established phenomenon of cell alignment under conditions of cyclic substrate stretching is considered. Cell-substrate...
Article
Experimental testing carried out on various adherent cell types cultured on deformable substrates reveals specific patterns of cell reorientation in response to cyclic stretching of the substrate. In Wang et al. (2001. Specificity of endothelial cell reorientation in response to cyclic mechanical stretching. J. Biomech. 34, 1563), a number of subst...
Article
Atherosclerosis is a chief cause of heart attack, stroke and death in Western society. It is a disease of the large arteries characterised by the presence of atherosclerotic lesions, often observable as fatty streaks within the first decade of life. A number of factors influence the development and progression of atherosclerosis; however, hemodynam...
Article
Acrylic bone cement is used to fixate hip replacement implants into the bone. Creep and fatigue failure of the cement promote failure of the implant. For the purpose of implant testing, we derived a finite element algorithm that simulates creep and damage accumulation in acrylic bone cement. The simulation combines a Maxwell creep model, with a 3-D...
Article
Cardiovascular stents are metal scaffolds that are used in the treatment of atherosclerosis. These devices are typically composed of very thin struts (< or = 100 microm thickness, for coronary applications). At this size-scale the question arises as to the suitability of using bulk material properties in stent design. This paper investigates the us...
Article
Bone cement is subjected to multi-axial cyclic loading when used to fixate orthopedic prostheses for joint arthroplasty. In this study, tubular specimens of poly(methylmethacrylate) (PMMA) bone cement are subjected to internal pressure and cyclic axial loading to ascertain the influence of multi-axial loading on fatigue life. As expected, it was fo...
Article
Coronary stents are used to re-establish the vascular lumen and flow conditions within the coronary arteries; the typical thickness of a stent strut is 100 microm, and average grain sizes of approximately 25 microm exist in stainless steel stents. The purpose of this study is to investigate the effect of strut size on the stress strain behavior of...
Article
The long-term survival of cemented hip replacements depends on the ability of the cemented fixation to resist fatigue damage. Damage has been assumed to accumulate linearly (Miner's law) even though it is unlikely to be the case in such a porous brittle material. This study addresses the nonlinear stress-dependent nature of fatigue damage accumulat...
Article
When used for the fixation of orthopaedic implants poly(methyl methacrylate) bone cement is prepared during surgery, and polymerises in situ. The technique for preparation of the bone cement involves mixing the liquid monomer and powder: two common mixing methods are hand mixing and vacuum mixing. Previous studies have shown that porosity depends o...
Article
Damage accumulation in the cement mantle used to fixate bone prosthesis is one failure scenario for joint reconstruction. It can be described as the phenomenon of numerous microcracks initiating and propagating within the material. Microcracks grow in the cement mantle causing it to gradually lose its mechanical integrity, leading to loosening of t...

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Projects

Project (1)
Archived project
The development of a delivery catheter to facilitate the injection/polymerisation of a cell-seeded hydrogel to the wall of the heart using minimally invasive femoral access techniques.