Increased GFAP immunoreactivity by astrocytes in response to contact with dorsal root ganglia cells in a 3D culture model

Failure of repair mechanisms in the injured CNS is widely attributed to the inhibitory environment of the lesion site, most notably the formation of the glial scar which forms a physical and physiological barrier to axon regeneration. We developed an in vitro 3D cell culture model to investigate the response of astrocytes to cells found at the inhibitory interfaces formed following damage to the spinal cord. CellTrackerTM labelled dissociated DRGs were seeded onto astrocyte-populated collagen gels and maintained in culture for 5 days. Astrocytes near the DRG interface showed marked GFAP up-regulation and adopted a reactive morphology which was observed up to 1mm away. Intensity of GFAP fluorescence at this interface was 3 fold higher than that seen away from the interface or in controls (astrocyte only gels). Furthermore, the presence of DRG conditioned medium was not capable alone of eliciting this response. In conclusion this model may provide a useful tool for understanding reactive astrogliosis in response to cells found at inhibitory interfaces following spinal cord or dorsal root injury. The contact between astrocytes and satellite cells may be enough to induce astrocyte reactivity and formation of the gliotic scar, or this contact may induce the secretion of a soluble factor which is not released from DRG cultures under physiological conditions

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

Think Different: Applying the Old Macintosh Mantra to the Computability of the SUSY Auxiliary Field Problem

Starting with valise supermultiplets obtained from 0-branes plus field redefinitions, valise adinkra networks, and the "Garden Algebra," we discuss an architecture for algorithms that (starting from on-shell theories and, through a well-defined computation procedure), search for off-shell completions. We show in one dimension how to directly attack the notorious "off-shell auxiliary field" problem of supersymmetry with algorithms in the adinkra network-world formulation.Comment: 28 pages, 1 figur

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

Sir John and Lady Rita Cornforth: a distinguished chemical partnership

This review describes the life of Sir John Cornforth AC CBE FRS, who was awarded the Nobel Prize for Chemistry in 1975. It covers his early life in Australia, his work in Oxford, the National Institute for Medical Research, the Milstead Laboratory of Chemical Enzymology and the University of Sussex, together with the contributions made by his wife, Lady Rita Cornforth

Study of damage characteristics in composite structures from simulated lightning strikes

This work investigated experimentally the direct effects of simulated lightning strikes in carbon/epoxy and E-glass/epoxy laminates. The direct effects were represented by Joule heating and kinetic shock waves. The experimental set-up was designed to maximize these direct effects by employing a solid electrode, pointed vertically to the surface of the specimens with a small electrode gap. The damage mechanisms were found to be in the form of resin sublimation, delamination and fibre tufting. The damage characteristics depended on type of composite materials, lightning current and action integral. In the carbon/epoxy laminates, resin sublimation and degradation were dominant at relatively low currents and with the further increase in current fibre tufting appeared due to kinetic shock waves. Penetration into the laminates was found to be limited to the only top two plies in the extreme case. The damage characteristics of the E-glass/epoxy laminates with a tiny hole were dominated by extensive delamination due entirely to shock waves with little sign of Joule heating. Analytical work will be desired to aid establishment of relationships between the damage characteristics and the lightning strike parameters via lightning channel radius and raised temperatures

Engineered neural tissue with aligned, differentiated adipose-derived stem cells promotes peripheral nerve regeneration across a critical sized defect in rat sciatic nerve.

Adipose-derived stem cells were isolated from rats and differentiated to a Schwann cell-like phenotype in vitro. The differentiated cells (dADSCs) underwent self-alignment in a tethered type-1 collagen gel, followed by stabilisation to generate engineered neural tissue (EngNT-dADSC). The pro-regenerative phenotype of dADSCs was enhanced by this process, and the columns of aligned dADSCs in the aligned collagen matrix supported and guided neurite extension in vitro. EngNT-dADSC sheets were rolled to form peripheral nerve repair constructs that were implanted within NeuraWrap conduits to bridge a 15 mm gap in rat sciatic nerve. After 8 weeks regeneration was assessed using immunofluorescence imaging and transmission electron microscopy and compared to empty conduit and nerve graft controls. The proportion of axons detected in the distal stump was 3.5 fold greater in constructs containing EngNT-dADSC than empty tube controls. Our novel combination of technologies that can organise autologous therapeutic cells within an artificial tissue construct provides a promising new cellular biomaterial for peripheral nerve repair