Aligned cellular and acellular collagen guidance substrates for peripheral nerve repair

There is a clinical demand to shorten the delay of reinnervation and improve functional recovery after peripheral nerve injury. A peripheral nerve repair device with the ability to direct and promote axon growth across a lesion would be a promising alternative to nerve autograft repair, the current gold standard treatment. The growth of axons across a lesion is most effective when supported by columns of aligned Schwann cells, as found in an autograft. Here we report the development of a robust aligned cellular collagen biomaterial that supports and directs neuronal growth. We also investigate the potential of these aligned cells to precondition the collagen biomaterial, before they are freeze-killed, leaving an acellular guidance matrix

Fabrication of an endoneurium using engineered neural tissue within a peripheral nerve repair conduit

Peripheral nerve injury as a result of trauma affects approximately 1 million people in Europe and America annually. The current clinical gold standard treatment for repairing long gaps is the nerve autograft, in which only ~50% of cases result in satisfactory functional recovery. Tissue-engineered cellular bridging devices for peripheral nerve repair could provide an attractive alternative to autografts. Sheets of engineered neural tissue (EngNT), which is formed from columns of Schwann cells within a 3D aligned collagen matrix, can promote directed neurite outgrowth in vitro. These sheets of EngNT can be arranged to form the ‘endoneurium’ of a peripheral nerve repair device. Two different arrangements, rod-based and sheet-based designs, were tested within a clinically approved tube, NeuraWrap™, in a 5mm gap in the rat sciatic nerve. Cross sections were stained to detect neurofilament after 4 weeks in vivo and revealed where the axons were growing in relation to the EngNT structures (this was divided into three zones for the analysis). The axon density was significantly greater in zone 1 than in zone 3 in the devices (P2 (mean ± SEM), compared to the sheet-based arrangement (B) (2920 ± 587 axons/mm2). The rod-based arrangement was more stable; there were no observed changes to its structure or orientation as a result of surgical handling or limb movement post-implantation. The designs are modular and can be adapted for the repair of bigger nerves by, for example, having multiple rod structures in the core of outer tubes or sheath wraps. Aligned cellular EngNT rods can form the basis of a functional conduit for peripheral nerve repair

A 3D <i>in vitro</i> model reveals differences in the astrocyte response elicited by potential stem cell therapies for CNS injury.

Aim: This study aimed to develop a 3D culture model to test the extent to which transplanted stem cells modulate astrocyte reactivity, where exacerbated glial cell activation could be detrimental to CNS repair success. Materials & methods: The reactivity of rat astrocytes to bone marrow mesenchymal stem cells, neural crest stem cells (NCSCs) and differentiated adipose-derived stem cells was assessed after 5 days. Schwann cells were used as a positive control. Results: NCSCs and differentiated Schwann cell-like adipose-derived stem cells did not increase astrocyte reactivity. Highly reactive responses to bone marrow mesenchymal stem cells and Schwann cells were equivalent. Conclusion: This approach can screen therapeutic cells prior to in vivo testing, allowing cells likely to trigger a substantial astrocyte response to be identified at an early stage. NCSCs and differentiated Schwann cell-like adipose-derived stem cells may be useful in treating CNS damage without increasing astrogliosis

Gold nanocarriers for transport of oligonucleotides across brain endothelial cells

Treatment of diseases that affect the CNS by gene therapy requires delivery of oligonucleotides to target cells within the brain. As the blood brain barrier prevents movement of large biomolecules, current approaches involve direct injection of the oligonucleotides, which is invasive and may have only a localised effect. The aim of this study was to investigate the potential of 2 nm galactose-coated gold nanoparticles (NP-Gal) as a delivery system of oligonucleotides across brain endothelium. DNA oligonucleotides of different types were attached to NP-Gal by the place exchange reaction and were characterised by EMSA (electrophoretic mobility shift assay). Several nanoparticle formulations were created, with single- or double-stranded (20nt or 40nt) DNA oligonucleotides, or with different amounts of DNA attached to the carriers. These nanocarriers were applied to transwell cultures of human brain endothelium in vitro (hCMEC/D3 cell-line) or to a 3D-hydrogel model of the blood-brain barrier including astrocytes. Transfer rates were measured by quantitative electron microscopy for the nanoparticles and qPCR for DNA. Despite the increase in nanoparticle size caused by attachment of oligonucleotides to the NP-Gal carrier, the rates of endocytosis and transcytosis of nanoparticles were both considerably increased when they carried an oligonucleotide cargo. Carriers with 40nt dsDNA were most efficient, accumulating in vesicles, in the cytosol and beneath the basal membrane of the endothelium. The oligonucleotide cargo remained attached to the nanocarriers during transcytosis and the transport rate across the endothelial cells was increased at least 50fold compared with free DNA. The nanoparticles entered the extracellular matrix and were taken up by the astrocytes in biologically functional amounts. Attachment of DNA confers a strong negative charge to the nanoparticles which may explain the enhanced binding to the endothelium and transcytosis by both vesicular transport and the transmembrane/cytosol pathway. These gold nanoparticles have the potential to transport therapeutic amounts of nucleic acids into the CNS

Fuelling an immune response: an ultrastructural study of immune-stimulated lymph nodes

A growing body of evidence suggests that adipocytes, and the triacylglycerol fatty acids within them, play an important role in supporting the inflammatory immune response. Inflammatory cytokines produced by an activated lymph node cause the release of fatty acids from neighbouring adipocytes, and the fatty acids are taken up into lymph node lymphoid cells, where they can be used as precursors for eicosanoid and plasma membrane synthesis, or as a fuel source. The mechanism of transport of fatty acids from adipocytes across the lymph node capsule and into lymphoid cells remains to be elucidated. Here we present evidence from light and electron microscopy that small fat-filled cells are found within the lymph node, and that 24 hours after an immune challenge they are associated with dendritic cells. The small adipocytes express S100 protein and insulin receptor, characteristics of mature adipocytes. Our observations suggest a mechanism for delivering triacylglycerol fatty acids directly to their site of use in supplying components for an immune response

Cerebrospinal fluid dynamics modulation by diet and cytokines in rats.

Background Idiopathic intracranial hypertension (IIH) is a neurological disorder characterised by raised cerebrospinal fluid (CSF) pressure in the absence of any intracranial pathology. IIH mainly affects women with obesity between the ages of 15 and 45. Two possible mechanisms that could explain the increased CSF pressure in IIH are excessive CSF production by the choroid plexus (CP) epithelium or impaired CSF drainage from the brain. However, the molecular mechanisms controlling these mechanisms in IIH remain to be determined. Methods In vivo ventriculo-cisternal perfusion (VCP) and variable rate infusion (VRI) techniques were used to assess changes in rates of CSF secretion and resistance to CSF drainage in female and male Wistar rats fed either a control (C) or high-fat (HF) diet (under anaesthesia with 20 μl/100 g medetomidine, 50 μl/100 g ketamine i.p). In addition, CSF secretion and drainage were assessed in female rats following treatment with inflammatory mediators known to be elevated in the CSF of IIH patients: C-C motif chemokine ligand 2 (CCL2), interleukin (IL)-17 (IL-17), IL-6, IL-1β, tumour necrosis factor-α (TNF-α), as well as glucocorticoid hydrocortisone (HC). Results Female rats fed the HF diet had greater CSF secretion compared to those on control diet (3.18 ± 0.12 μl/min HF, 1.49 ± 0.15 μl/min control). Increased CSF secretion was seen in both groups following HC treatment (by 132% in controls and 114% in HF) but only in control rats following TNF-α treatment (137% increase). The resistance to CSF drainage was not different between control and HF fed female rats (6.13 ± 0.44 mmH O min/μl controls, and 7.09 ± 0.26 mmH O min/μl HF). and when treated with CCL2, both groups displayed an increase in resistance to CSF drainage of 141% (controls) and 139% (HF) indicating lower levels of CSF drainage. Conclusions Weight loss and therapies targeting HC, TNF-α and CCL2, whether separately or in combination, may be beneficial to modulate rates of CSF secretion and/or resistance to CSF drainage pathways, both factors likely contributing to the raised intracranial pressure (ICP) observed in female IIH patients with obesity.</p

Building a supportive learning and teaching culture for science academics

The introduction of the Bradley voucher system has resulted in many universities focussing on specific strategies to enhance student engagement and retention. This is particularly the case with undergraduate science programs where interest is already lower than other disciplines (Norton, A., 2012). In one strategy, our SaMnet team has been working to facilitate an active culture with all teaching staff (both continuing and sessional) involved in the learning journey of this particular student cohort. In the hard, pure world of science academia (Becher & Trowler, 2001) the pressures to produce high levels of quality scientific research actively compete with academic priorities towards issues around teaching and learning and student experience. Identifying and overcoming potential barriers to success (Buckley & Du Toit, 2010) and ensuring key elements of community of practice (CoP) development are addressed (Kimble, Hildreth, & Bourdon, 2008) are critical to the success of this strategy. Our SaMnet team has been guided by the knowledge and resources of both the SaMnet team leaders and our own dynamic group capabilities. We have been strategically identifying and developing information to support the implementation of a Second Year Student Experience CoP within a research-focussed science school. These include the “What’s In It For Me?” matrix to help facilitate this process

UK hazards from a large Icelandic effusive eruption. Effusive Eruption Modelling Project final report

In response to the recent introduction of large, long-lasting gas-rich volcanic eruptions to the UK National Risk Register (risk H55) a modelling project has been conducted to improve our understanding of potential hazards to the UK from such an eruption on Iceland. A precautionary “reasonable worst case” eruption scenario based on the 1783-1784 CE Laki eruption has been determined using the results of an expert elicitation of scientists. This scenario has been simulated 80 times using two different atmospheric chemistry and transport models (NAME and EMEP4UK) over 10 years of meteorology (2003-2012). The results provide information on the range of concentrations of sulphur dioxide (SO2), sulphate aerosol (SO4) and some halogen species that might be experienced in the UK during such an eruption and the likelihood of key thresholds being exceeded and the duration of their exceedance. Data for the surface and for a range of key flight altitudes have been produced. These are evaluated against the threshold bandings of the UK’s Air Quality Index (AQI). The impact on UK ecosystems has also been considered. The data are intended to be used by UK Government Departments for further research into the impacts on the aviation, health, environmental and agricultural sectors. The results show that the prevailing meteorological conditions are the key influence on which parts of the North Atlantic and European region are affected at any time. The results demonstrate that the UK is unlikely to be affected by week after week of significantly elevated concentrations; rather there will a number of short (hours to days) pollution episodes where concentrations at the surface would be elevated bove Moderate and High air quality index levels. This pattern reflects the generally changeable nature of the weather in the UK. At the surface, consecutive exceedance durations are longer for SO4 than SO2, and can be particularly lengthy (1-2 weeks) in the Low air quality index levels, which may be of relevance to health impact assessments. The indications of potential peak concentrations and their corresponding AQI exceedance probabilities within this report serve to inform national, high-level generic risk planning. For more specific response planning, a much larger modelling study with multiple eruption scenarios and a greater number of meteorological realisations would be needed

Australian students transitioning through the “lost year” of higher education

The Issue Student transitions through university have previously focussed on the move into first year (retention and success strategies) from high school or out of university into the workforce (with career readiness and employability). However, second year transitions have only recently begun to attract attention as an area where students may experience hurdles which impact on their progression and overall degree experience and success. Evidence from Australian universities to date has shown similarities between Australian and International second year science cohorts in their thriving behaviours and their risk of academic slump (Loughlin et al, 2013; Gregory & McDonnell, 2012) Previous success strategies have looked at initial transition into second year (McBurnie et al, 2012, Harrison, 2007) or an embedded support strategy (Quinlavan, 2010). However, a more holistic approach to second year transition using multiple interventions is more likely to demonstrate long-term impact on student transition and success. There is also a need to gather more evidence of the “sophomore slump” within Australian institutions and to work collaboratively to achieve this. Approach Currently at Griffith University in the School of Biomolecular & Physical Sciences multiple aspects of engagement scheme has been implemented across all year levels. However, in second year, identifying and reflecting on individual student cohort challenges and providing support as appropriate is being trialled. Elements of both curricular and co-curricular in activities are incorporated, staff awareness is being developed and the entire process is being overseen by a second year student co-ordinator. At James Cook University initial interest has been cultivated with early adoption of identification of second year challenges specifically in the Faculties of Health and Arts/Education. At Deakin University a successful re-introduction activity for second year students has been hosted for several years and uptake of the Thriving Quotient survey will occur in 2013. At University of South Australia early interest in second year student transitions has developed from first year activities with initial evaluations being conducted. Development of a cross-institutional OLT submission for 2014 that looks at both gathering more evidence of slump using a triangulated data approach and then investigating and evaluating activities that will potentially reduce the impact slump may have on persistence and progression