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Subject = Bioengineering;
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Displaying Results 26 - 50 of 69 on page 2 of 3
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Defining the impaction frequency and threshold force required for femoral impaction grafting in revision hip arthroplasty. A human cadaveric mechanical study.
(2011)
O'REILLY, PETER; KELLY, DANIEL
Defining the impaction frequency and threshold force required for femoral impaction grafting in revision hip arthroplasty. A human cadaveric mechanical study.
(2011)
O'REILLY, PETER; KELLY, DANIEL
Abstract:
BACKGROUND AND PURPOSE: The two most common complications of femoral impaction bone grafting are femoral fracture and massive implant subsidence. We investigated fracture forces and implant subsidence rates in embalmed human femurs undergoing impaction grafting. The study consisted of two arms, the first examining the force at which femoral fracture occurs in the embalmed human femur, and the second examining whether significant graft implant/subsidence occurs following impaction at a set force at two different impaction frequencies. METHODS: Using a standardized impaction grafting technique with modifications, an initial group of 17 femurs underwent complete destructive impaction testing, allowing sequentially increased, controlled impaction forces to be applied until femoral fracture occurred. A second group of 8 femurs underwent impaction bone grafting at constant force, at an impaction frequency of 1 Hz or 10 Hz. An Exeter stem was cemented into the neomedullary canals. These co...
http://hdl.handle.net/2262/60181
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Developing bacteriocins of lactic acid bacteria into next generation biopreservatives
(2018)
Field, Des; Ross, R. Paul; Hill, Colin
Developing bacteriocins of lactic acid bacteria into next generation biopreservatives
(2018)
Field, Des; Ross, R. Paul; Hill, Colin
Abstract:
Bacteriocins are ribosomally synthesized peptides produced by bacteria which can kill other bacteria. Those produced by lactic acid bacteria (LAB) are of great interest as they are often employed in food processing and food fermentations as natural biopreservatives. In this review, we discuss the implementation of bioengineering to enhance the antimicrobial activity, antibacterial spectrum and physico-chemical properties of LAB bacteriocins. Additionally, we discuss the potential applications of bacteriocin derivatives for use as promising food preservatives alone or in combination with other naturally derived antimicrobials as a form of hurdle technology and the regulatory status of strains engineered through food-grade approaches.
http://hdl.handle.net/10468/5545
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Development of a gait training device for children with cerebral palsy
(2010)
BENNETT, GARETH; O'DONNELL, GARRET EDWARD; SIMMS, CIARAN KNUT
Development of a gait training device for children with cerebral palsy
(2010)
BENNETT, GARETH; O'DONNELL, GARRET EDWARD; SIMMS, CIARAN KNUT
Abstract:
Children with Cerebral Palsy (CP) can generally not walk unaided, but do have some weight bearing ability. Therefore walking aids are often more appropriate than wheelchairs, see figure 1. These devices facilitate mobility and also provide vital mechanical stimulation of the lower limbs [1]. However, existing designs show little evidence of being optimized for ergonomics and biomechanical function, let alone aesthetics. A current collaboration between Moorings Mediquip (Northern Ireland) and Trinity College Dublin funded by an Intertrade Ireland Fusion grant is concerned with developing a new gait trainer for children with CP which has improved functionality and aesthetic features compared to existing products.
http://hdl.handle.net/2262/39638
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Digital image correlation and finite element modelling as a method to determine mechanical properties of human soft tissue in vivo.
(2009)
SIMMS, CIARAN; MOERMAN, KEVIN MATTHEUS
Digital image correlation and finite element modelling as a method to determine mechanical properties of human soft tissue in vivo.
(2009)
SIMMS, CIARAN; MOERMAN, KEVIN MATTHEUS
Abstract:
The mechanical properties of human soft tissue are crucial for impact biomechanics, rehabilitation engineering and surgical simulation. Validation of these constitutive models using human data remains challenging and often requires the use of non-invasive imaging and inverse finite element (FE) analysis. Post processing data from imaging methods such as tagged magnetic resonance imaging (MRI) can be challenging. Digital Image Correlation (DIC) however is a relatively straightforward imaging method and thus the goal of this study was to assess the use of DIC in combination with FE modelling to determine the bulk material properties of human soft tissue. Indentation experiments were performed on a silicone gel soft tissue phantom. A two camera DIC setup was then used to record the 3D surface deformation. The experiment was then simulated using a FE model. The gel was modelled as Neo-Hookean hyperelastic and the material parameters were determined by minimising the error between the ex...
http://hdl.handle.net/2262/41171
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Dynamic patterns of mechanical stimulation co-localise with growth and cell proliferation during morphogenesis in the avian embryonic knee joint
(2011)
PRENDERGAST, PATRICK; RODDY, KAREN ANN; MURPHY, PAULA
Dynamic patterns of mechanical stimulation co-localise with growth and cell proliferation during morphogenesis in the avian embryonic knee joint
(2011)
PRENDERGAST, PATRICK; RODDY, KAREN ANN; MURPHY, PAULA
Abstract:
Muscle contractions begin in early embryonic life, generating forces that regulate the correct formation of the skeleton. In this paper we test the hypothesis that the biophysical stimulation generated by muscle forces may be a causative factor for the changes in shape of the knee joint as it grows. We do this by predicting the spatial and temporal patterns of biophysical stimuli, where cell proliferation and rudiment shape changes occur within the emerging tissues of the joint over time. We used optical projection tomography (OPT) to create anatomically accurate finite element models of the embryonic knee at three time points (stages) of development. OPT was also used to locate muscle attachment sites and AFM was used to determine material properties. An association was found between the emergence of joint shape, cell proliferation and the pattern of biophysical stimuli generated by embryonic muscle contractions. Elevated rates of growth and cell proliferation in the medial condyle...
http://hdl.handle.net/2262/48881
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Electrical impedance tomography with exploitation of symmetry
(2018)
McDermott, Barry; Porter, Emily; Jones, Marggie; McGinley, Brian; O'Halloran, Martin
Electrical impedance tomography with exploitation of symmetry
(2018)
McDermott, Barry; Porter, Emily; Jones, Marggie; McGinley, Brian; O'Halloran, Martin
Abstract:
Electrical Impedance Tomography (EIT) is an imaging technique involving an electrode array positioned around the area of interest. Alternating current is injected, and voltage measured, between electrode pairs in a prescribed pattern to produce a measurement set. This set is then processed to generate an image of the area. EIT has several potential biomedical applications including thoracic and neural imaging. Different EIT variants exist with most success being in the production of time difference images. Generation of absolute images (i.e., images generated from a single measurement time) is challenging due to the sensitivity of EIT to errors such as those of electrode placement. This challenge makes imaging of static or very slowly changing scenes, such as those featuring a tumour or an established haemorrhage, very difficult with EIT. In this work, the natural symmetry of an anatomy, such as the sagittal symmetry in the human head, is used to create a difference image without a ...
http://hdl.handle.net/10379/7517
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Enabling End-to-End Secure Connectivity for Low-Power IoT Devices with UAVs
(2020)
Rajakaruna, Archana; Manzoor, Ahsan; Porambage, Pawani; Liyanage, Madhusanka
Enabling End-to-End Secure Connectivity for Low-Power IoT Devices with UAVs
(2020)
Rajakaruna, Archana; Manzoor, Ahsan; Porambage, Pawani; Liyanage, Madhusanka
Abstract:
The 2019 IEEE Wireless and Networking Conference Workshops, Marrakech, Morocco, 15-18 April 2019
The proliferation of the Internet of Things (IoT) technologies have strengthen the self-monitoring and autonomous characteristics of the sensor networks deployed in numerous application areas. The recent developments of the edge computing paradigms have also enabled on-site processing and managing the capabilities of sensor networks. In this paper, we introduce a system model that enables end-to-end secure connectivity between low-power IoT devices and UAVs, that helps to manage the data processing tasks of heterogeneous wireless sensor networks. The performance of proposed solution is analyzed by using simulation results. Moreover, in order to demonstrate the practical usability of the proposed solution, the prototype implementation is presented using commercial off-the-shelf devices.
European Commission
Business Finland
Academy of Finland
http://hdl.handle.net/10197/11693
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Engineering of large cartilaginous constructs through the use of microchanneled hydrogels and rotational culture
(2009)
Kelly, Daniel; Buckley, Conor
Engineering of large cartilaginous constructs through the use of microchanneled hydrogels and rotational culture
(2009)
Kelly, Daniel; Buckley, Conor
Abstract:
The development of functional engineered cartilaginous tissues of sufficient size that can be used clinically to treat large defects remains a major and significant challenge. This study investigated if the introduction of microchannels into chondrocyte-seeded agarose hydrogels would result in the formation of a superior and more homogenous cartilaginous tissue due to enhanced nutrient transport. Microchannel construct cylinders were fabricated via a moulding process utilising a pillared structure to create the required architecture. Constructs were subjected to either constant rotation in a rotational bioreactor system or free swelling conditions. After 28 days of free swelling culture the presence of microchannels did not enhance GAG accumulation within the core of the construct compared to solid constructs (0.317 ? 0.002 % w/w vs. 0.401 ? 0.020 % w/w). However under dynamically rotating conditions, GAG accumulation in the cores (1.165 ? 0.132 % w/w) of microchannel constructs wer...
http://hdl.handle.net/2262/41118
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Estimation of 3D shape in the Patellofemoral Joint using Statistical Shape Models and 2D Data
(2010)
O'Kane, Colm
Estimation of 3D shape in the Patellofemoral Joint using Statistical Shape Models and 2D Data
(2010)
O'Kane, Colm
Abstract:
Disorders of the patellofemoral joint (PFJ) including PF osteoarthritis and PF pain disorder have been estimated to represent 25% of all patients presenting for knee joint treatment. The diagnosis and treatment of these disorders is curtailed by lack of understanding of the mechanical operation of the joint. A crucial aspect to be considered in understanding contact patterns and kinematics of the PFJ is the alignment of the patella in the trochlear groove. Investigation of patellar alignment necessitates accurate knowledge of the 3D articular surfaces of both patella and femur, along with underlying bone geometry. These 3D data are generally obtained for bones and cartilage plates through reconstruction of images from computed tomography (CT) and/or magnetic resonance imaging (MRI) respectively. This research proposes to develop a parametric model to enable the accurate estimation of the patient-specific 3D shape of a patella and distal femur from several 2D images. There are severa...
https://arrow.dit.ie/biodevcon/1
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Estimation of dispersive properties of encapsulation tissue surrounding deep brain stimulation electrodes in the rat
(2020)
Sridhar, Karthik; Evers, Judith; Botelho, Diego Pereira; Lowery, Madeleine M.
Estimation of dispersive properties of encapsulation tissue surrounding deep brain stimulation electrodes in the rat
(2020)
Sridhar, Karthik; Evers, Judith; Botelho, Diego Pereira; Lowery, Madeleine M.
Abstract:
The 41st International Engineering in Medicine and Biology Conference (EMBC 2019), Berlin, Germany, 23-27 July 2019
The aim of this study was to estimate the electrical properties of the encapsulation tissue surrounding chronically implanted electrodes for deep brain stimulation in the rat. The impedance spectrum of a concentric bipolar microelectrode implanted in the rat brain was measured immediately following surgery and after 8 weeks of implantation. The experimental impedance data were used in combination with a finite element model of the rat brain using a parametric sweep method to estimate the electrical properties of the tissue surrounding the electrode in acute and chronic conditions. In the acute case, the conductivity and relative permittivity of the peri-electrode space were frequency independent with an estimated conductivity of 0.38 S/m and relative permittivity of 123. The electrical properties of the encapsulation tissue in the chronic condition were fitted to a...
http://hdl.handle.net/10197/11281
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Expansion in the presence of FGF-2 enhances the functional development of cartilaginous tissues engineered using infrapatellar fat pad derived MSCs
(2012)
Kelly, Daniel; Buckley, Conor
Expansion in the presence of FGF-2 enhances the functional development of cartilaginous tissues engineered using infrapatellar fat pad derived MSCs
(2012)
Kelly, Daniel; Buckley, Conor
Abstract:
MSCs from non-cartilaginous knee joint tissues such as the infrapatellar fat pad (IFP) and synovium possess significant chondrogenic potential and provide a readily available and clinically feasible source of chondroprogenitor cells. Fibroblast growth factor-2 (FGF-2) has been shown to be a potent mitotic stimulator during ex vivo expansion of MSCs, as well as regulating their subsequent differentiation potential. The objective of this study was to investigate the longer term effects of FGF-2 expansion on the functional development of cartilaginous tissues engineered using MSCs derived from the IFP. IFP MSCs were isolated and expanded to passage 2 in a standard media formulation with or without FGF-2 (5ng/ml) supplementation. Expanded cells were encapsulated in agarose hydrogels, maintained in chondrogenic media for 42 days and analysed to determine their mechanical properties and biochemical composition. Culture media, collected at each feed, was also analysed for biochemical const...
http://hdl.handle.net/2262/64053
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Imaging arterial fibres using diffusion tensor imaging - feasibility study & preliminary results
(2010)
SIMMS, CIARAN; LALLY, CAITRIONA
Imaging arterial fibres using diffusion tensor imaging - feasibility study & preliminary results
(2010)
SIMMS, CIARAN; LALLY, CAITRIONA
Abstract:
MR diffusion tensor imaging (DTI) was used to analyze the fibrous structure of aortic tissue. A fresh porcine aorta was imaged at 7T using a spin echo sequence with the following parameters: matrix 128 ? 128 pixel; slice thickness 0.5 mm; interslice spacing 0.1 mm; number of slices 16; echo time 20.3 s; field of view 28mm ? 28 mm. Eigenvectors from the diffusion tensor images were calculated for the central image slice and the averaged tensors and the eigenvector corresponding to the largest eigenvalue showed two distinct angles corresponding to near 0? and 180? to the transverse plane of the aorta. Fibre tractography within the aortic volume imaged confirmed that fibre angles were oriented helically with lead angles of 15?2.5? and 175?2.5?. The findings correspond to current histological and microscopy data on the fibrous structure of aortic tissue, and therefore the eigenvectormaps and fibre tractography appear to reflect the alignment of the fibers in the aorta. In view of curren...
http://hdl.handle.net/2262/40227
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Imaging Arterial Fibres Using Diffusion Tensor Imaging Feasibility Study and Preliminary Results
(2010)
SIMMS, CIARAN; LALLY, CAITRIONA; KERSKENS, CHRISTIAN
Imaging Arterial Fibres Using Diffusion Tensor Imaging Feasibility Study and Preliminary Results
(2010)
SIMMS, CIARAN; LALLY, CAITRIONA; KERSKENS, CHRISTIAN
Abstract:
MR diffusion tensor imaging (DTI) was used to analyze the fibrous structure of aortic tissue. A fresh porcine aorta was imaged at 7T using a spin echo sequence with the following parameters: matrix 128 x 128 pixel; slice thickness 0.5 mm; interslice spacing 0.1 mm; number of slices 16; echo time 20.3 s; field of view 28 mm x 28 mm. Eigenvectors from the diffusion tensor images were calculated for the central image slice and the averaged tensors and the eigenvector corresponding to the largest eigenvalue showed two distinct angles corresponding to near 0 degrees and 180 degrees to the transverse plane of the aorta. Fibre tractography within the aortic volume imaged confirmed that fibre angles were oriented helically with lead angles of 15 +/- 2.5 degrees and 175 +/- 2.5 degrees. The findings correspond to current histological and microscopy data on the fibrous structure of aortic tissue, and therefore the eigenvector maps and fibre tractography appear to reflect the alignment of the ...
http://hdl.handle.net/2262/40219
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Impact of measurement noise, experimental design, and estimation methods on Modular Response Analysis based network reconstruction
(2019)
Thomaseth, Caterina; Fey, Dirk; Santra, Tapesh; Rukhlenko, Oleksii S.; Radde, Nicole E....
Impact of measurement noise, experimental design, and estimation methods on Modular Response Analysis based network reconstruction
(2019)
Thomaseth, Caterina; Fey, Dirk; Santra, Tapesh; Rukhlenko, Oleksii S.; Radde, Nicole E.; Kholodenko, Boris N.
Abstract:
Modular Response Analysis (MRA) is a method to reconstruct signalling networks from steady-state perturbation data which has frequently been used in different settings. Since these data are usually noisy due to multi-step measurement procedures and biological variability, it is important to investigate the effect of this noise onto network reconstruction. Here we present a systematic study to investigate propagation of noise from concentration measurements to network structures. Therefore, we design an in silico study of the MAPK and the p53 signalling pathways with realistic noise settings. We make use of statistical concepts and measures to evaluate accuracy and precision of individual inferred interactions and resulting network structures. Our results allow to derive clear recommendations to optimize the performance of MRA based network reconstruction: First, large perturbations are favorable in terms of accuracy even for models with non-linear steady-state response curves. Secon...
http://hdl.handle.net/10197/11037
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In vivo dynamics of the internal fibrous structure in smooth adhesive pads of insects
(2012)
DIRKS, JAN-HENNING
In vivo dynamics of the internal fibrous structure in smooth adhesive pads of insects
(2012)
DIRKS, JAN-HENNING
Abstract:
Many insects with smooth adhesive pads can rapidly enlarge their contact area by centripetal pulls on the legs, allowing them to cope with sudden mechanical perturbations such as gusts of wind or raindrops. The short time scale of this reaction excludes any neuromuscular control; it is thus more likely to be caused by mechanical properties of the pad?s specialised cuticle. This soft cuticle contains numerous branched fibrils oriented almost perpendicularly to the surface. Assuming a fixed volume of the water-filled cuticle, we hypothesized that pulls could decrease the fibril angle, thereby helping the contact area to expand laterally and longitudinally. Three-dimensional fluorescence microscopy on the cuticle of smooth stick insect pads confirmed that pulls significantly decreased the fibril angle. The fibril angle variation appeared insufficient to explain the observed increase in contact area. Direct strain measurements in the contact zone demonstrate that pulls not only expand ...
http://hdl.handle.net/2262/63761
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In-vivo generation of bone via endochondral ossification by in-vitro chondrogenic priming of adult human and rat mesenchymal stem cells
(2011)
O'BRIEN, FERGAL
In-vivo generation of bone via endochondral ossification by in-vitro chondrogenic priming of adult human and rat mesenchymal stem cells
(2011)
O'BRIEN, FERGAL
Abstract:
Background: Bone grafts are required to repair large bone defects after tumour resection or large trauma. The availability of patients?U? own bone tissue that can be used for these procedures is limited. Thus far bone tissue engineering has not lead to an implant which could be used as alternative in bone replacement surgery. This is mainly due to problems of vascularisation of the implanted tissues leading to core necrosis and implant failure. Recently it was discovered that embryonic stem cells can form bone via the endochondral pathway, thereby turning in-vitro created cartilage into bone in-vivo. In this study we investigated the potential of human adult mesenchymal stem cells to form bone via the endochondral pathway. Methods: MSCs were cultured for 28 days in chondrogenic, osteogenic or control medium prior to implantation. To further optimise this process we induced mineralisation in the chondrogenic constructs before implantation by changing to osteogen...
http://hdl.handle.net/2262/50749
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Integrating non-viral gene therapy and 3D bioprinting for bone, cartilage and osteochondral tissue engineering
(2018)
GONZALEZ FERNANDEZ, TOMAS
Integrating non-viral gene therapy and 3D bioprinting for bone, cartilage and osteochondral tissue engineering
(2018)
GONZALEZ FERNANDEZ, TOMAS
Abstract:
The repair of osteochondral defects, affecting both the articular cartilage and the underlying subchondral bone, is key for the effective recovery of joint homeostasis and the prevention of further cartilage degeneration and the onset of osteoarthritis (OA). Although important advances have been made in the field of tissue engineering to regenerate these injuries, the traditional approaches based on the formation of homogenous tissues fail to recapitulate the spatial complexity of the osteochondral unit. The objective of this thesis was to engineer a multiphasic tissue suitable for osteochondral defect regeneration by combining 3D bioprinting and non-viral gene delivery to spatially regulate the differentiation of mesenchymal stem cells (MSCs). Realising this objective first required (1) optimisation of the non-viral gene delivery vector, (2) the identification of suitable therapeutic gene combinations to direct MSC differentiation and (3) the development of printable biomaterials,...
http://hdl.handle.net/2262/82502
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Links with Canada Benefit DIT Prosthesis Research
(2010)
O'Kane, Colm
Links with Canada Benefit DIT Prosthesis Research
(2010)
O'Kane, Colm
Abstract:
Colm O’Kane is a lecturer in the School of Manufacturing and Design Engineering and a member of the DIT Biomedical Device and Assistive Technology Research Group. He is currently engaged in PhD research in the field of knee prosthesis development, focused on developing optimised strategies for partial and total joint replacements used in treatment of osteoarthritis of the knee joint. This article is an account of a research scholarship sponsored by the CHC Helicopter Corporation and awarded by the Ireland Canada University Foundation (ICUF). This foundation awards annual scholarships for research visits between Ireland and Canada with the aspiration of fostering links between the two countries’ research communities.
https://arrow.dit.ie/biodevart/1
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Local and regional mechanical characterisation of a collagen-glycosaminoglycan scaffold using high-resolution finite element analysis.
(2010)
O'BRIEN, FERGAL
Local and regional mechanical characterisation of a collagen-glycosaminoglycan scaffold using high-resolution finite element analysis.
(2010)
O'BRIEN, FERGAL
Abstract:
Artificial tissue growth requires cells to proliferate and differentiate within the host scaffold. As cell function is governed by mechano-sensitive selection, tissue type is influenced by the microscopic forces exposed to the cells, which is a product of macroscopically straining the scaffold. Accordingly, the microscopic strain environment within a CG scaffold is offered here. Using ?CT to characterise CG scaffold architecture, two high-resolution 3D FE models were used to predict the deformation mechanics. While also providing an analysis of region-specific features, such as relative density, pore diameters and microstructural elastic stability, the deformation patterns afforded strains to be inferred for seeded cells. The results indicate a regional dependence, in terms of architectural and mechanical properties. Specifically, the peripheral regions demonstrated the lowest volume fraction, the highest stress concentrations and the greatest potential for elastic instability. Conv...
http://hdl.handle.net/2262/40218
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Low oxygen tension is a more potent promoter of chondrogenic
(2010)
KELLY, DANIEL; BUCKLEY, CONOR
Low oxygen tension is a more potent promoter of chondrogenic
(2010)
KELLY, DANIEL; BUCKLEY, CONOR
Abstract:
During fracture healing and microfracture treatment of cartilage defects mesenchymal stem cells (MSCs) infiltrate the wound site, proliferate extensively and differentiate along a cartilaginous or an osteogenic lineage in response to local environmental cues. MSCs may be able to directly sense their mechanical environment or alternatively, the mechanical environment could act indirectly to regulate MSC differentiation by inhibiting angiogenesis and diminishing the supply of oxygen and other regulatory factors. Dynamic compression has been shown to regulate chondrogenesis of MSCs. In addition, previous studies have shown that a low oxygen environment promotes in vitro chondrogenesis of MSCs. The hypothesis of this study is that a low oxygen environment is a more potent promoter of chondrogenic differentiation of MSCs embedded in agarose hydrogels compared to dynamic compression. In MSC-seeded constructs supplemented with TGF-?3, GAG and collagen accumulation was higher in low oxygen ...
http://hdl.handle.net/2262/41079
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Mechanical characterisation of a customised decellularized scaffold for vascular tissue engineering
(2012)
MURPHY, BRUCE; DUFFY, GARRY; SHERIDAN, WILLIAM STEPHEN
Mechanical characterisation of a customised decellularized scaffold for vascular tissue engineering
(2012)
MURPHY, BRUCE; DUFFY, GARRY; SHERIDAN, WILLIAM STEPHEN
Abstract:
Several challenges persist when attempting to utilise 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 customised the properties of decellularized porcine carotid arteries by: (i) creating cavities within the medial layer to allow direct injection of cells, and (ii) controlling the amount of collagen digestion to increase the porosity. Histological examination of our customised scaffold revealed a highly porous tissue structure containing consistent medial cavities running longitudinally through the porous scaffold wall. Mechanical testing of the customised scaffold showed that our minimal localised disruption to the ECM does not have a detrimental effect on the bulk mechanical response of the tissue. The results demonstrate that an increased stiffness...
http://hdl.handle.net/2262/62425
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Mechanical Influences on Morphogenesis of the Knee Joint Revealed through Morphological, Molecular and Computational Analysis of Immobilised Embryos.
(2011)
PRENDERGAST, PATRICK; MURPHY, PAULA; RODDY, KAREN ANN
Mechanical Influences on Morphogenesis of the Knee Joint Revealed through Morphological, Molecular and Computational Analysis of Immobilised Embryos.
(2011)
PRENDERGAST, PATRICK; MURPHY, PAULA; RODDY, KAREN ANN
Abstract:
Very little is known about the regulation of morphogenesis in synovial joints. Mechanical forces generated from muscle contractions are required for normal development of several aspects of normal skeletogenesis. Here we show that biophysical stimuli generated by muscle contractions impact multiple events during chick knee joint morphogenesis influencing differential growth of the skeletal rudiment epiphyses and patterning of the emerging tissues in the joint interzone. Immobilisation of chick embryos was achieved through treatment with the neuromuscular blocking agent Decamethonium Bromide. The effects on development of the knee joint were examined using a combination of computational modelling to predict alterations in biophysical stimuli, detailed morphometric analysis of 3D digital representations, cell proliferation assays and in situ hybridisation to examine the expression of a selected panel of genes known to regulate joint development. This work revealed the precise changes ...
http://hdl.handle.net/2262/53205
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Mechano-regulation of mesenchymal stem cell differentiation and collagen organisation during skeletal tissue repair
(2009)
KELLY, DANIEL; NAGEL, THOMAS
Mechano-regulation of mesenchymal stem cell differentiation and collagen organisation during skeletal tissue repair
(2009)
KELLY, DANIEL; NAGEL, THOMAS
Abstract:
A number of mechano-regulation theories have been proposed that relate the differentiation pathway of mesenchymal stem cells (MSCs) to their local biomechanical environment. During spontaneous repair processes in skeletal tissues, the organisation of the extracellular matrix is a key determinant of its mechanical fitness. In this paper, we extend the mechano-regulation theory proposed by Prendergast et al. (J Biomech 30(6):539?548, 1997) to include the role of the mechanical environment on the collagen architecture in regenerating soft tissues. A large strain anisotropic poroelastic material model is used in a simulation of tissue differentiation in a fracture subject to cyclic bending (Cullinane et al. in J Orthop Res 20(3):579?586, 2002). The model predicts non-union with cartilage and fibrous tissue formation in the defect. Predicted collagen fibre angles, as determined by the principal decomposition of strain- and stress-type tensors, are similar to the architecture seen in nati...
http://hdl.handle.net/2262/41228
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Mesenchymal stem cell fate is regulated by the composition and mechanical properties of Collagen Glycosaminoglycan scaffolds
(2012)
O'BRIEN, FERGAL
Mesenchymal stem cell fate is regulated by the composition and mechanical properties of Collagen Glycosaminoglycan scaffolds
(2012)
O'BRIEN, FERGAL
Abstract:
In stem cell biology, focus has recently turned to the influence of the intrinsic properties of the extracellular matrix (ECM), such as structural, composition and elasticity, on stem cell differentiation. Utilising collagen-glycosaminoglycan (CG) scaffolds as an analogue of the ECM, this study set out to determine the effect of scaffold stiffness and composition on naive mesenchymal stem cell (MSC) differentiation in the absence of differentiation supplements. Dehydrothermal (DHT) and 1-ethyl-3-3-dimethyl aminopropyl carbodiimide (EDAC) crosslinking treatments were used to produce three homogenous CG scaffolds with the same composition but different stiffness values: 0.5, 1 and 1.5 kPa. In addition, the effect of scaffold composition on MSC differentiation was investigated by utilising two glycosaminoglycan (GAG) types: chondroitin sulphate (CS) and hyaluronic acid (HyA). Results demonstrated that scaffolds with the lowest stiffness (0.5 kPa) facilitated a significant up-regulation...
http://hdl.handle.net/2262/64034
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Oxygen tension differentially regulates the functional properties of cartilaginous tissues engineered from infrapatellar fat pad derived MSCs and articular chondrocytes.
(2010)
Kelly, Daniel; Buckley, Conor
Oxygen tension differentially regulates the functional properties of cartilaginous tissues engineered from infrapatellar fat pad derived MSCs and articular chondrocytes.
(2010)
Kelly, Daniel; Buckley, Conor
Abstract:
Background For current tissue engineering or regenerative medicine strategies, chondrocyte (CC)- or mesenchymal stem cell (MSC)-seeded constructs are typically cultured in normoxic conditions (20% oxygen). However, within the knee joint capsule a lower oxygen tension exists. Objective The objective of this study was to investigate how CCs and infrapatellar fad pad derived MSCs will respond to a low oxygen (5%) environment in 3D agarose culture. Our hypothesis was that culture in a low oxygen environment (5%) will enhance the functional properties of cartilaginous tissues engineered using both cell sources. Experimental design Cell-encapsulated agarose hydrogel constructs (seeded with CCs or infrapatellar fat pad (IFP) derived MSCs) were prepared and cultured in a chemically defined serum-free medium in the presence (CCs and MSCs) or absence (CCs only) of transforming growth factor-beta3 (TGF-?3) in normoxic (20%) or low oxygen (5%) conditions for 42 days. Constructs were assessed ...
http://hdl.handle.net/2262/41081
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