Rebecca is interested in cell physiology, particularly in understanding mechanisms of tissue breakdown during disease. Her PhD focussed on cartilage biology; investigating chondrocyte membrane proteins and their function in both healthy and osteoarthritic tissue. She has studied the effects of inflammation on joint tissues, and how inflammation can cause changes in protein expression and lead to changes in cell signalling and function. Using electrophysiological techniques, she has probed cellular function and developed a keen interest in the cell channelome, and its influence on the cellular electrome and membrane potential.
Recently, her experience with membrane proteins and cell physiology has led her to investigate the interactions of cells with different materials, in collaboration with the Faculty of Engineering and Physical Sciences. She is testing different scaffolds, their effect on cellular phenotype and evaluating their use as in vitro models for drug discovery.
Rebecca graduated in Bioveterinary Sciences from the University of Liverpool in 2007 and started her PhD in the same year in the School of Veterinary Science at the University of Liverpool. The main focus of Rebecca's PhD was investigating the role of ion channels and the resting membrane potential in healthy chondrocytes. This included modelling cell behaviour to determine the function of these membrane proteins in healthy cells and relating this to the osteoarthritic disease state. Rebecca's postdoctoral work continued in the Institute of Ageing and Chronic Disease at the University of Liverpool, investigating the effect of a number of pharmacological agents on cell function and ion channel expression, using electrophysiology. Rebecca joined the EU Framework 7 funded DBoard consortium in December 2012 as a postdoctoral research associate, investigating the effect of inflammatory conditions on chondrocyte function. In September 2014, Rebecca joined the University of Surrey as a Lecturer in Physiology.
- Module Lead for Cardiovascular, Respiratory and Musculoskeletal systems
- Cells and Genes in Context
- Cardiovascular, Respiratory and Musculoskeletal systems
- Integument and Alimentary systems
- Urological and Reproductive systems
- Organs of special senses and endocrine systems
University roles and responsibilities
- Outcomes Assessment, School of Veterinary Medicine
Postgraduate research supervision
Rebecca supervises a number of PhD students. She has collaborative projects with colleagues in both the School of Biosciences (Faculty of Health and Medical Sciences), the Department of Mechanical Engineering Sciences and the Department of Physics (Faculty of Engineering and Physical Sciences).
Courses I teach on
Diseases such as osteoarthritis (OA) are commonly characterized at the molecular scale by gene expression and subsequent protein production; likewise, the effects of pharmaceutical interventions are typically characterized by the effects of molecular interactions. However, these phenomena are usually preceded by numerous precursor steps, many of which involve significant ion influx or efflux. As a consequence, rapid assessment of cell electrophysiology could play a significant role in unravelling the mechanisms underlying drug interactions and progression of diseases, such as OA. In this study, we used dielectrophoresis (DEP), a technique that allows rapid, label-free determination of the dielectric parameters to assess the role of potassium ions on the dielectric characteristics of chondrocytes, and to investigate the electrophysiological differences between healthy chondrocytes and those from an in vitro arthritic disease model. Our results showed that DEP was able to detect a significant decrease in membrane conductance (6191 ± 738 vs. 8571 ± 1010 S/m2), membrane capacitance (10.3 ± 1.47 vs. 14.5 ± 0.01 mF/m2), and whole cell capacitance (5.4 ± 0.7 vs. 7.5 ± 0.3 pF) following inhibition of potassium channels using 10 mM tetraethyl ammonium, compared to untreated healthy chondrocytes. Moreover, cells from the OA model had a different response to DEP force in comparison to healthy cells; this was seen in terms of both a decreased membrane conductivity (782 S/m2 vs. 1139 S/m2) and a higher whole cell capacitance (9.58 ± 3.4 vs. 3.7 ± 1.3 pF). The results show that DEP offers a high throughput method, capable of detecting changes in membrane electrophysiological properties and differences between disease states.
Osteoarthritis (OA), a degenerative joint condition, is currently difficult to detect early enough for any of the current treatment options to be completely successful. Early diagnosis of this disease could increase the numbers of patients who are able to slow its progression. There are now several diseases where membrane protein biomarkers are used for early diagnosis. The numbers of proteins in the membrane is vast and so it is a rich source of potential biomarkers for OA but we need more knowledge of these before they can be considered practical biomarkers. How are they best measured and are they selective to OA or even certain types of OA? The first step in this process is to identify membrane proteins that change in OA. Here, we summarize several ion channels and receptors that change in OA models and/or OA patients, and may thus be considered candidates as novel membrane biomarkers of OA.
The effective growth of chondrocytes and the formation of cartilage is demonstrated on scaffolds of aligned carbon nanotubes; as two dimensional sheets and on three dimensional textiles. Raman spectroscopy is used to confirm the presence of chondroitin sulfate, which is critical in light of the unreliability of traditional dye based assays for carbon nanomaterial substrates. The textile exhibits a very high affinity for chondrocyte growth and could present a route to implantable, flexible cartilage scaffolds with tuneable mechanical properties.
Chondrocytes are the resident cells of articular cartilage and are responsible for synthesizing a range of collagenous and non-collagenous extracellular matrix macromolecules. Whilst chondrocytes exist at low densities in the tissue (1-10% of the total tissue volume in mature cartilage) they are extremely active cells and are capable of responding to a range of mechanical and biochemical stimuli. These responses are necessary for the maintenance of viable cartilage and may be compromised in inflammatory diseases such as arthritis. Although chondrocytes are non-excitable cells their plasma membrane contains a rich complement of ion channels. This diverse channelome appears to be as complex as one might expect to find in excitable cells although, in the case of chondrocytes, their functions are far less well understood. The ion channels so far identified in chondrocytes include potassium channels (K(ATP), BK, K(v), and SK), sodium channels (epithelial sodium channels, voltage activated sodium channels), transient receptor potential calcium or non-selective cation channels and chloride channels. In this review we describe this emerging channelome and discuss the possible functions of a range of chondrocyte ion channels.
Articular cartilage is a thin layer of hyaline cartilage that covers the surface of the bones of diarthrodial joints. It is an avascular, alymphatic and aneural tissue, with a smooth opalescent appearance. Cartilage is a highly organised and specialised tissue allowing free articulation, painless movement and transmission of force through the skeleton. Compared to other tissues, articular cartilage has a low rate of metabolic activity (Pearle et al. 2005 ). The tissue is maintained by a single specialised cell, the chondrocyte (Buckwalter et al. 1999 ), and is comprised of a highly organised matrix with a large extracellular matrix (ECM) to cell volume ratio. The basic structure is composed of a 3D collagen scaffold and aggregating proteoglycans (Jeffery et al. 1991 ). The arrangement, direction and location of these collagen fibrils vary, along with the cell density, matrix composition and overall thickness throughout the tissue, providing different mechanical properties across the joint. The composition of the ECM reflects its mechanical properties such as tensile strength (mainly collagens type II, IX, and XI) and compressive stiffness (such as proteoglycans and aggrecan). Small proteoglycans, including decorin, biglycan and fibromodulin, bind to other matrix macromolecules and thereby help to stabilise the matrix (Buckwalter and Mankin 1998a ). Additionally, collagen type VI and non- collagenous proteins, such as anchorin CII, tenascin and fi bronectin, are important mediators of cell–matrix interactions (Poole et al. 2001 ). The ECM acts as a signal transducer for the chondrocytes, creating mechanical, electrical and physicochemical signals that help to direct the synthetic and degradative activity of chondrocytes (Buckwalter and Mankin 1998a ). Articular cartilage is divided into four zones: the superficial (tangential), transitional, radial and calcifi ed (Eyre 2002 ). The physical and biochemical differences between the zones are important to allow the cartilage to resist both extrinsic and intrinsic forces due to mechanical stress and swelling in the proteoglycan- rich areas (Knudson and Knudson 2001 ). Cartilage tissue contains a large proportion of water (65–80 % by wet weight). Chondrocytes comprise approximately 5–10 % of the tissue total volume and collagens form 10–30 %, whilst proteoglycans and other molecules consist of 5–10 % of the tissue wet weight (Eyre 2002 ; Archer et al. 2003a ; Bhosale and Richardson 2008 ; Hunziker et al. 2007 ).
Understanding the rules of life is one of the most important scientific endeavours and has revolutionised both biology and biotechnology. Remarkable advances in observation techniques allow us to investigate a broad range of complex and dynamic biological processes in which living systems could exploit quantum behaviour to enhance and regulate biological functions. Recent evidence suggests that these non-trivial quantum mechanical effects may play a crucial role in maintaining the non-equilibrium state of biomolecular systems. Quantum biology is the study of such quantum aspects of living systems. In this review, we summarise the latest progress in quantum biology, including the areas of enzyme-catalysed reactions, photosynthesis, spin-dependent reactions, DNA, fluorescent proteins, and ion channels. Many of these results are expected to be fundamental building blocks towards understanding the rules of life.
Chondrogenic progenitor cells (CPCs) may be used as an alternative source of cells with potentially superior chondrogenic potential compared to mesenchymal stem cells (MSCs), and could be exploited for future regenerative therapies targeting articular cartilage in degenerative diseases such as osteoarthritis (OA). In this study, we hypothesised that CPCs derived from OA cartilage may be characterised by a distinct channelome. First, a global transcriptomic analysis using Affymetrix microarrays was performed. We studied the profiles of those ion channels and transporter families that may be relevant to chondroprogenitor cell physiology. Following validation of the microarray data with quantitative reverse transcription-polymerase chain reaction, we examined the role of calcium-dependent potassium channels in CPCs and observed functional large-conductance calcium-activated potassium (BK) channels involved in the maintenance of the chondroprogenitor phenotype. In line with our very recent results, we found that the KCNMA1 gene was upregulated in CPCs and observed currents that could be attributed to the BK channel. The BK channel inhibitor paxilline significantly inhibited proliferation, increased the expression of the osteogenic transcription factor RUNX2, enhanced the migration parameters, and completely abolished spontaneous Ca events in CPCs. Through characterisation of their channelome we demonstrate that CPCs are a distinct cell population but are highly similar to MSCs in many respects. This study adds key mechanistic data to the in-depth characterisation of CPCs and their phenotype in the context of cartilage regeneration.
We live in a world with an ever-increasing ageing population. Studying healthy ageing and reducing the socioeconomic impact of age-related diseases is a key research priority for the industrialised and developing countries, along with a better mechanistic understanding of the physiology and pathophysiology of ageing that occurs in a number of age-related musculoskeletal disorders. Arthritis and musculoskeletal disorders constitute a major cause of disability and morbidity globally and result in enormous costs for our health and social-care systems. By gaining a better understanding of healthy musculoskeletal ageing and the risk factors associated with premature ageing and senescence, we can provide better care and develop new and better-targeted therapies for common musculoskeletal disorders. This review is the outcome of a two-day multidisciplinary, international workshop sponsored by the Institute of Advanced Studies entitled “Musculoskeletal Health in the 21st Century” and held at the University of Surrey from 30th June-1st July 2015. The aim of this narrative review is to summarise current knowledge of musculoskeletal health, ageing and disease and highlight strategies for prevention and reducing the impact of common musculoskeletal diseases.
Objective To determine the frequency of provision and main providers (veterinary surgeons, nurses or trainees) of manual ventilation in UK veterinary practices. Furthermore, to determine the variation in peak inspiratory (inflation) pressure (PIP), applied to a lung model during manual ventilation, by three different groups of operators (inexperienced, experienced and specialist), before and after training. Study Design Questionnaire survey. Development of a lung model simulator with real-time biometric (manometry) feedback capability and its testing as a training tool on operators with a range of experiences. Methods Postal questionnaires were sent to 100 randomly selected veterinary practices. The lung model simulator was manually ventilated, in a staged process over three weeks, with and without real-time biometric feedback (PIP display), by three groups of volunteer operators: inexperienced, experienced and specialist. Results The questionnaires determined that veterinary nurses were responsible for providing the majority of manual ventilation in veterinary practices, mainly drawing on theoretical knowledge rather than any specific training. Thoracic surgery and apnoea were the main reasons for provision of manual ventilation. Specialists performed well when manually ventilating the lung model, regardless of feedback-training. Both inexperienced and experienced operators showed significant improvement in technique when using the feedback training tool: variation in PIP decreased significantly until subjects provided manual ventilation at peak inspiratory pressures within the defined optimum range. Preferences for different forms of feedback (graphical, numerical or scale display), revealed that the operators’ choice was not always the method which gave least variation in PIP. Conclusions and Clinical Relevance This study highlighted a need for training in manual ventilation at an early stage in veterinary and veterinary nursing careers and demonstrated how feedback is important in the process of experiential learning. A manometer device which can provide immediate feedback during training, or indeed in a real clinical setting, should improve patient safety.
Sigma-1 receptors are ligand-regulated chaperone proteins, involved in several cellular mechanisms. The aim of this systematic review was to examine the effects that the sigma-1 receptor has on the cardiovascular system. The interaction targets and proposed mechanisms of action of sigma-1 receptors were explored, with the aim of determining if the sigma-1 receptor is a potential pharmacological target for cardiac pathologies. This systematic review was conducted according to the PRISMA guidelines and these were used to critically appraise eligible studies. Pubmed and Scopus were systematically searched for articles investigating sigma-1 receptors in the cardiovascular system. Papers identified by the search terms were then subject to analysis against pre-determined inclusion criteria. 23 manuscripts met the inclusion criteria and were included in this review. The experimental platforms, experimental techniques utilised and the results of the studies were summarised. The sigma-1 receptor is found to be implicated in cardioprotection, via various mechanisms including stimulating the Akt-eNOS pathway, and reduction of Ca2+ leakage into the cytosol via modulating certain calcium channels. Sigma-1 receptors are also found to modulate other cardiac ion channels including different subtypes of potassium and sodium channels and have been shown to modulate intracardiac neuron excitability. The sigma-1 receptor is a potential therapeutic target for treatment of cardiac pathologies, particularly cardiac hypertrophy. We therefore suggest investigating the cardioprotective mechanisms of sigma-1 receptor function, alongside proposed potential ligands that can stimulate these functions.
BACKGROUND AND PURPOSE: Chondrocytes exist within cartilage and serve to maintain the extracellular matrix. It has been postulated that osteoarthritic (OA) chondrocytes lose the ability to regulate their volume, affecting extracellular matrix production. In previous studies, we identified expression of epithelial sodium channels (ENaC) in human chondrocytes, but their function remained unknown. Although ENaC typically has Na(+) transport roles, it is also involved in the cell volume regulation of rat hepatocytes. ENaC is a member of the degenerin (Deg) family, and ENaC/Deg-like channels have a low conductance and high sensitivity to benzamil. In this study, we investigated whether canine chondrocytes express functional ENaC/Deg-like ion channels and, if so, what their function may be. EXPERIMENTAL APPROACH: Canine chondrocytes were harvested from dogs killed for unassociated welfare reasons. We used immunohistochemistry and patch-clamp electrophysiology to investigate ENaC expression and video microscopy to analyse the effects of pharmacological inhibition of ENaC/Deg on cell volume regulation. KEY RESULTS: Immunofluorescence showed that canine chondrocytes expressed ENaC protein. Single-channel recordings demonstrated expression of a benzamil-sensitive Na(+) conductance (9 pS), and whole-cell experiments show this to be approximately 1.5 nS per cell with high selectivity for Na(+) . Benzamil hyperpolarized chondrocytes by approximately 8 mV with a pD2 8.4. Chondrocyte regulatory volume decrease (RVI) was inhibited by benzamil (pD2 7.5) but persisted when extracellular Na(+) ions were replaced by Li(+) . CONCLUSION AND IMPLICATIONS: Our data suggest that benzamil inhibits RVI by reducing the influx of Na(+) ions through ENaC/Deg-like ion channels and present ENaC/Deg as a possible target for pharmacological modulation of chondrocyte volume.