Targeting patient recovery priorities in degenerative cervical myelopathy: design and rationale for the RECEDE-Myelopathy trial-study protocol.

INTRODUCTION: Degenerative cervical myelopathy (DCM) is a common and disabling condition of symptomatic cervical spinal cord compression secondary to degenerative changes in spinal structures leading to a mechanical stress injury of the spinal cord. RECEDE-Myelopathy aims to test the disease-modulating activity of the phosphodiesterase 3/phosphodiesterase 4 inhibitor Ibudilast as an adjuvant to surgical decompression in DCM. METHODS AND ANALYSIS: RECEDE-Myelopathy is a multicentre, double-blind, randomised, placebo-controlled trial. Participants will be randomised to receive either 60-100 mg Ibudilast or placebo starting within 10 weeks prior to surgery and continuing for 24 weeks after surgery for a maximum of 34 weeks. Adults with DCM, who have a modified Japanese Orthopaedic Association (mJOA) score 8-14 inclusive and are scheduled for their first decompressive surgery are eligible for inclusion. The coprimary endpoints are pain measured on a visual analogue scale and physical function measured by the mJOA score at 6 months after surgery. Clinical assessments will be undertaken preoperatively, postoperatively and 3, 6 and 12 months after surgery. We hypothesise that adjuvant therapy with Ibudilast leads to a meaningful and additional improvement in either pain or function, as compared with standard routine care. STUDY DESIGN: Clinical trial protocol V.2.2 October 2020. ETHICS AND DISSEMINATION: Ethical approval has been obtained from HRA-Wales.The results will be presented at an international and national scientific conferences and in a peer-reviewed journals. TRIAL REGISTRATION NUMBER: ISRCTN Number: ISRCTN16682024.

Understanding and modelling the economic impact of spinal cord injuries in the United Kingdom.

STUDY DESIGN: Economic modelling analysis. OBJECTIVES: To determine lifetime direct and indirect costs from initial hospitalisation of all expected new traumatic and non-traumatic spinal cord injuries (SCI) over 12 months. SETTING: United Kingdom (UK). METHODS: Incidence-based approach to assessing costs from a societal perspective, including immediate and ongoing health, rehabilitation and long-term care directly attributable to SCI, as well as aids and adaptations, unpaid informal care and participation in employment. The model accounts for differences in injury severity, gender, age at onset and life expectancy. RESULTS: Lifetime costs for an expected 1270 new cases of SCI per annum conservatively estimated as £1.43 billion (2016 prices). This equates to a mean £1.12 million (median £0.72 million) per SCI case, ranging from £0.47 million (median £0.40 million) for an AIS grade D injury to £1.87 million (median £1.95 million) for tetraplegia AIS A-C grade injuries. Seventy-one percent of lifetime costs potentially are paid by the public purse with remaining costs due to reduced employment and carer time. CONCLUSIONS: Despite the magnitude of costs, and being comparable with international estimates, this first analysis of SCI costs in the UK is likely to be conservative. Findings are particularly sensitive to the level and costs of long-term home and residential care. The analysis demonstrates how modelling can be used to highlight economic impacts of SCI rapidly to policymakers, illustrate how changes in future patterns of injury influence costs and help inform future economic evaluations of actions to prevent and/or reduce the impact of SCIs.

Large animal and primate models of spinal cord injury for the testing of novel therapies.

Large animal and primate models of spinal cord injury (SCI) are being increasingly utilized for the testing of novel therapies. While these represent intermediary animal species between rodents and humans and offer the opportunity to pose unique research questions prior to clinical trials, the role that such large animal and primate models should play in the translational pipeline is unclear. In this initiative we engaged members of the SCI research community in a questionnaire and round-table focus group discussion around the use of such models. Forty-one SCI researchers from academia, industry, and granting agencies were asked to complete a questionnaire about their opinion regarding the use of large animal and primate models in the context of testing novel therapeutics. The questions centered around how large animal and primate models of SCI would be best utilized in the spectrum of preclinical testing, and how much testing in rodent models was warranted before employing these models. Further questions were posed at a focus group meeting attended by the respondents. The group generally felt that large animal and primate models of SCI serve a potentially useful role in the translational pipeline for novel therapies, and that the rational use of these models would depend on the type of therapy and specific research question being addressed. While testing within these models should not be mandatory, the detection of beneficial effects using these models lends additional support for translating a therapy to humans. These models provides an opportunity to evaluate and refine surgical procedures prior to use in humans, and safety and bio-distribution in a spinal cord more similar in size and anatomy to that of humans. Our results reveal that while many feel that these models are valuable in the testing of novel therapies, important questions remain unanswered about how they should be used and how data derived from them should be interpreted.

Demonstrating efficacy in preclinical studies of cellular therapies for spinal cord injury - how much is enough?

Cellular therapies represent a novel treatment approach for spinal cord injury (SCI), with many different cellular substrates showing promise in preclinical animal models of SCI. Considerable interest therefore exists to translate such cellular interventions into human clinical trials. Balanced against the urgency for clinical translation is the desire to establish the robustness of a cellular therapy's efficacy in preclinical studies, thereby optimizing its chances of succeeding in human trials. Uncertainty exists, however, on the extent to which a therapy needs to demonstrate efficacy in the preclinical setting in order to justify the initiation of a lengthy, expensive, and potentially risky clinical trial. The purpose of this initiative was to seek perspectives on the level of evidence required in experimental studies of cellular therapies before proceeding with clinical trials of SCI. We conducted a survey of 27 SCI researchers actively involved in either preclinical and/or clinical research of cellular interventions for SCI, and then held a focus group meeting to facilitate more in-depth discussion around a number of translational issues. These included: the use of animal models, the use of injury models and mechanisms, the window for demonstrating efficacy, independent replication, defining "relevant, meaningful efficacy" in preclinical studies, and the expectation of therapeutic benefits for cellular interventions. Here we present the key findings from both the survey and focus group meeting in order to summarize and underscore the areas of consensus and disagreement amongst the sampled researchers. It is anticipated that the knowledge generated from this initiative will help to incite future scientific discussions and expert guidelines towards translation of a cell therapy for persons with SCI.

Tri-partite complex for axonal transport drug delivery achieves pharmacological effect.

BACKGROUND: Targeted delivery of pharmaceutical agents into selected populations of CNS (Central Nervous System) neurons is an extremely compelling goal. Currently, systemic methods are generally used for delivery of pain medications, anti-virals for treatment of dermatomal infections, anti-spasmodics, and neuroprotectants. Systemic side effects or undesirable effects on parts of the CNS that are not involved in the pathology limit efficacy and limit clinical utility for many classes of pharmaceuticals. Axonal transport from the periphery offers a possible selective route, but there has been little progress towards design of agents that can accomplish targeted delivery via this intraneural route. To achieve this goal, we developed a tripartite molecular construction concept involving an axonal transport facilitator molecule, a polymer linker, and a large number of drug molecules conjugated to the linker, then sought to evaluate its neurobiology and pharmacological behavior. RESULTS: We developed chemical synthesis methodologies for assembling these tripartite complexes using a variety of axonal transport facilitators including nerve growth factor, wheat germ agglutinin, and synthetic facilitators derived from phage display work. Loading of up to 100 drug molecules per complex was achieved. Conjugation methods were used that allowed the drugs to be released in active form inside the cell body after transport. Intramuscular and intradermal injection proved effective for introducing pharmacologically effective doses into selected populations of CNS neurons. Pharmacological efficacy with gabapentin in a paw withdrawal latency model revealed a ten fold increase in half life and a 300 fold decrease in necessary dose relative to systemic administration for gabapentin when the drug was delivered by axonal transport using the tripartite vehicle. CONCLUSION: Specific targeting of selected subpopulations of CNS neurons for drug delivery by axonal transport holds great promise. The data shown here provide a basic framework for the intraneural pharmacology of this tripartite complex. The pharmacologically efficacious drug delivery demonstrated here verify the fundamental feasibility of using axonal transport for targeted drug delivery.

Nitrate signalling to stomata and growing leaves: interactions with soil drying, ABA, and xylem sap pH in maize.

Increasing the nitrate (N) concentration in the rooting substrate above deficiency decreased stomatal conductance and leaf growth rate compared with sufficient N in maize seedlings (Zea mays L.) growing in drying substrate. Novel effects were detected when N in the non-deficient range was supplied directly to the xylem of detached shoots: concentrations above 2.0 mol m-3 KNO3 reduced transpiration, and concentrations above 12 mol m-3 KNO3 reduced leaf growth rate. Evidence is provided that the novel effects of N on transpiration and growth were mediated by pH-based ABA redistribution. ABA at 0.05 mol m-3, whilst ineffective alone, sensitized leaf growth to increases in KNO3 concentration (from 3.0 mol m-3), and the capacity of higher concentrations of ABA to reduce growth was enhanced by KNO3. Transpiration was sensitively reduced by KNO3, ABA, or buffers adjusted to pH 6.7-7.0 (compared with buffers adjusted to pH 5.0) alone. Nevertheless, a synergistic effect of KNO3 and either ABA or buffers adjusted to pH 6.7-7.0 was observed. Buffers of pH 5.6 supplied to detached shoots alleviated the depression of transpiration caused by 12 mol m-3 KNO3. Buffers adjusted to pH 6.7 increased the sensitivity of growth to KNO3. Xylem sap extracted from intact seedlings growing in drying soil exhibited an initial increase in N concentration, followed by a decrease at progressively lower soil water potentials. The importance for novel N signalling above deficiency is discussed with reference to the generality of fluctuations in soil and xylem N concentration within this range.

Alternation of wet and dry sides during partial rootzone drying irrigation alters root-to-shoot signalling of abscisic acid.

Partial rootzone drying (PRD) is an irrigation technique where water is distributed unevenly to the root system such that part is irrigated while the remainder is allowed to dry the soil. Tomato (Lycopersicon esculentum Mill.) plants were grown with their roots in two soil columns to compare the physiological consequences of alternation of wet and dry columns during PRD irrigation (alternate PRD, PRD-A) with retention of the same wet and dry columns (fixed PRD, PRD-F). When PRD plants received 50% less water than well-watered (WW) plants, xylem ABA concentration ([X-ABA]) increased and stomatal conductance decreased relative to WW plants. Although both sets of PRD plants received the same amount of water, [X-ABA] of PRD-A plants increased up to 2-fold above that of PRD-F plants, which further decreased stomatal conductance. Differences in [X-ABA] were detected within an hour of alternation, but did not persist beyond the photoperiod of alternation. [X-ABA] increased linearly as whole-pot soil water content (θpot) and leaf water potential (Ψleaf) declined, but the difference in [X-ABA] between the two sets of PRD plants was not due to differences in either θpot or Ψleaf. In PRD-F plants, the unwatered part of the root system contributes proportionally less to the transpiration stream as the soil progressively dries (Yao et al. 2001, Plant, Cell & Environment 24, 227-235). In PRD-A plants, we hypothesise that re-watering the dry part of the root system allows these roots to contribute proportionally more to total sap flux, thus liberating a pulse of ABA to the transpiration stream as the root ABA pool accumulated during soil drying is depleted. Since the enhancement of [X-ABA] caused by PRD-A increased as θpot and Ψleaf declined, an optimal frequency of alternation to maximise the cumulative physiological effects of this ABA pulse must consider possible negative impacts of leaf water deficit as soil water status declines.

Long-distance signals regulating stomatal conductance and leaf growth in tomato (Lycopersicon esculentum) plants subjected to partial root-zone drying.

Tomato (Lycopersicon esculentum Mill. cv. Ailsa Craig) plants were grown with roots split between two soil columns. After plant establishment, water was applied daily to one (partial root-zone drying-PRD) or both (well-watered control-WW) columns. Water was withheld from the other column in the PRD treatment, to expose some roots to drying soil. Soil and plant water status were monitored daily and throughout diurnal courses. Over 8 d, there were no treatment differences in leaf water potential (psileaf) even though soil moisture content of the upper 6 cm (theta) of the dry column in the PRD treatment decreased by up to 70%. Stomatal conductance (gs) of PRD plants decreased (relative to WW plants) when of the dry column decreased by 45%. Such closure coincided with increased xylem sap pH and did not require increased xylem sap abscisic acid (ABA) concentration ([X-ABA]). Detached leaflet ethylene evolution of PRD plants increased when of the dry column decreased by 55%, concurrent with decreased leaf elongation. The physiological significance of enhanced ethylene evolution of PRD plants was examined using a transgenic tomato (ACO1AS) with low stress-induced ethylene production. In response to PRD, ACO1AS and wild-type plants showed similar xylem sap pH, [X-ABA] and gs, but ACO1AS plants showed neither enhanced ethylene evolution nor significant reductions in leaf elongation. Combined use of genetic technologies to reduce ethylene production and agronomic technologies to sustain water status (such as PRD) may sustain plant growth under conditions where yield would otherwise be significantly reduced.

Biomass allocation in tomato (Lycopersicon esculentum) plants grown under partial rootzone drying: enhancement of root growth.

Tomato (Lycopersicon esculentum Mill.) plants were grown in either a glasshouse (GH) or a controlled environment cabinet (CEC) to assess the effects of partial rootzone drying (PRD) on biomass allocation. Control and PRD plants received the same amounts of water. In control plants, water was equally distributed between two compartments of a split-root system. In PRD plants, only one compartment was watered while the other was allowed to dry. At the end of each drying cycle, wet and dry compartments were alternated. In the GH, total biomass did not differ between PRD and control plants after four cycles of PRD, but PRD increased root biomass by 55% as resources were partitioned away from shoot organs. In the CEC, leaf water potential did not differ between treatments at the end of either of two cycles of PRD, but stomatal conductance of PRD plants was 20% less at the end of the first cycle than at the beginning. After two cycles of PRD in the CEC, biomass did not differ between PRD and control plants, but PRD increased root biomass by 19% over the control plants. The promotion of root biomass in PRD plants was associated with the alternation of wet and dry compartments, with increased root biomass occurring in the re-watered compartment after previous exposure to soil drying. Promotion of root biomass in field-grown PRD plants may allow the root system to access resources (water and nutrients) that would otherwise be unavailable to control plants. This may contribute to the ability of PRD plants to maintain similar leaf water potentials to conventionally irrigated plants, even when smaller irrigation volumes are supplied.

Non-hydraulic regulation of fruit growth in tomato plants (Lycopersicon esculentum cv. Solairo) growing in drying soil.

Tomato (Lycopersicon esculentum cv. Solairo) fruit growth, fruit mesocarp and leaf epidermal cell turgor, and fruit and leaf sub-epidermal apoplastic pH were monitored as plants were allowed to dry the soil in which they were rooted. Soil drying regimes involved splitting the root system of plants between two halves of a single pot separated by a solid impervious membrane to form a split-root system. Plants were then allowed to dry the soil in both halves of the pot (a soil-drying (SD) treatment) or water was supplied to one-half of the pot (a partial root-drying (PRD) treatment), allowing only one-half of the root system to dry the soil. A well-watered control treatment watered the soil on both halves of the pot. The rate of fruit growth was highly correlated with the soil water content of both sides of the SD treatment and the dry side of the PRD treatment. Soil drying caused a significant restriction in fruit growth rate, which was independent of any changes in the turgor of expanding fruit mesocarp cells in the PRD treatment. By supplying water to half of the root system, the turgors of mesocarp cells were maintained at values above those recorded in well-watered controls. The turgor of leaf epidermal cells exhibited a similar response. The pH of the sub-epidermal apoplastic compartment in leaves and fruit increased with soil drying. The dynamics of this increase in leaves and fruit were identical, suggesting free transport of this signal from shoot to fruit. Fruit growth rate and sub-epidermal pH within the fruit showed a strong correlation. The similarity of fruit growth response in the SD and PRD treatment, suggests that tomato plants respond to a discrete measure of soil water status and do not integrate measures to determine total soil water availability. The results of this study are not consistent with Lockhartian models of growth regulation in expanding fruit of a higher plant. A non-hydraulic, chemical-based signalling control of fruit growth in plants growing in drying soil is proposed.