Translation in Stroke Research Laboratory
The Translational Research in Stroke laboratory is part of the Priority Research Centre for Brain and Mental Health. We have a current strong focus in stroke neuroprotection, imaging and basic pathophysiology. We have active collaborations with several members of our own school, other schools within the University, with the clinical stroke research team based at the John Hunter Hospital (of which Dr Spratt is a member).
- Short duration hypothermia to prevent subsequent intracranial pressure rise
- Increasing perfusion to the ischaemic brain via leptomeningial collaterals
- Testing stroke sonothrombolysis using an improved experimental model of thromboembolic stroke
- The China-Australia Therapeutic Hypothermia in Stroke (CATHS) research program
- Improving patient selection for acute stroke therapies- an experimental model of CT brain perfusion after stroke
- CT imaging of cerebrospinal fluid (CSF) in rats
- Functional characterisation of a new regulatory for CAMKII at synapsis in vivo
- The use of enriched environment post stroke: translation from bench to bedside
Elevation of intracranial pressure (ICP) resulting in further neurological injury is a significant problem in stroke, and other forms of brain injury. Current therapies are often inadequate to control elevated ICP. Therapeutic hypothermia is the only non-perfusion neuroprotective therapy with proven benefit in human brain ischaemia (post cardiac arrest), and also lowers ICP. Clinical studies in a range of conditions have all used 12-24 hours or longer of hypothermia, and often encounter problems of rebound elevation of ICP during rewarming. However, recent experimental data from our laboratory demonstrated a dramatic benefit of 2.5 hours of mild-moderate hypothermia (32.5 0C) on ICP 24 hours later, with no evidence of rebound ICP elevation. This project provides a unique opportunity to advance fundamental knowledge regarding regulation of intracranial pressure in neurological disease, and has the potential to revolutionise, simplify and extend the application of therapeutic hypothermia to treat a wider range of neurological diseases.
The major cerebral arteries are linked by small bypass channels over the surface of the brain (termed leptomenigeal collaterals). Patients with adequate collateral blood supply during stroke have smaller strokes and a higher rate of reperfusion with tPA leading to improved outcome. Despite convincing evidence of the benefit of good collaterals on stroke outcome there has been minimal investigation into interventions that improve collateral status. This experimental study will utilise our laboratories middle cerebral artery thread occlusion model combined with cerebral blood flow measurements to trial new therapeutics that enhance collateral flow and correlate this with perfusion of the ischaemic brain.
Stroke is a leading cause of morbidity and mortality worldwide. Although there have been major advances in the treatment of acute stroke, the most effective treatment when administered - dissolving blood clots with tissue plasminogen activator (tPA) - only dissolves half of the major clot blockages it targets. The use of enhancers for dissolving clot is now being explored and preliminary evidence suggests that standard ultrasound used to image the brain may significantly increase the effectiveness of tPA. This experimental study will use our laboratory's unique ability to measure brain blood flow in experimental stroke and test combinations of tPA and ultrasound for their potential impact on stroke recovery.
By the analysis of stroke patients and an animal model of stroke, this project will use proteomics to (i) identify novel biomarkers for the prognosis of hypothermia and re-warming response in stroke, and (ii) identify proteins involved in the molecular response to hypothermia and re-warming after a stroke. This collaborative research effort involving both clinical and basic science researchers in Newcastle, Australia, and Harbin, China, will lead to the development of a clinically useful diagnostic for hypothermia outcome, as well as improve our understanding of the underlying mechanism of hypothermia-induced neuroprotection, leading to potential novel therapeutic targets.
5. Improving patient selection for acute stroke therapies- an experimental model of CT brain perfusion after stroke
Computed tomography perfusion (CTP) imaging is a relatively novel technique with huge potential to improve diagnosis and treatment in acute stroke patients worldwide. It uses widely available CT scanners, with imaging of tissue perfusion immediately following a bolus injection of an X-Ray visible dye into the veins (bolus tracking method). Recent major advances in scanner speed and coverage and perfusion imaging software have enabled development of this method. However, there are many unanswered questions regarding the tissue correlates of imaging findings, which can only be answered in animal models. Our pilot studies have determined that our rat stroke model is suitable for CTP imaging (McLeod et al. 2011). Our aim is to correlate CTP imaging findings with the degree of subsequent tissue injury, assessed with histological methods. Findings from our future studies have the potential to improve the diagnosis and treatment of stroke patients and enable the development of targeted drug therapies to salvage threatened brain tissue, leading to improved patient health outcomes. Proof of principle of 'penumbral selection' of an enriched population of thrombolysis responders comes from the recent clinical trial of tenecteplase from our affiliated clinical research group (Parsons et al. 2012).
Raised intracranial pressure (ICP) is a serious complication of ischaemic stroke, known to occur in both rats and humans. Recent studies in our laboratory have shown that ICP increases following mild-moderate stroke in an animal model. Increase in intracranial volume will cause an increase in pressure within the cranial compartment resulting from increased volume of one of the intracranial components (brain/oedema, blood or CSF). Cerebrospinal fluid (CSF) aqueduct volume and flow were investigated using a novel contrast-enhanced CT scanning method to quantify changes in CSF production following ischaemic stroke and determine whether this is a possible contributor to the observed ICP elevation.
CaMKII is an important regulatory molecule in the brain, where it plays an essential role in certain forms of learning and memory and in the appropriate development and maturation of neural pathways. It also undergoes specific changes in animal models of brain ischaemia (local deficiency in blood supply) and epilepsy. Recent evidence has shown that in nerve cells, the regulation and role of CaMKII is more complicated than previously thought, and that it differs in brain regions that exhibit differing sensitivities to stroke. This project investigates the roles of a new control mechanism in regulating the function of CaMKII in nerve cells. This will provide a more complete understanding of how CaMKII influences brain function and allow assessment of whether CaMKII regulation might be a suitable target for drugs aimed at protecting against the damaging effects of brain injury following stroke or heart attack.
Stroke is the leading cause of adult disability in Australia. What are clearly needed are better stroke recovery therapies to aid in rehabilitation after stroke. Increased activity is the basis of all proven recovery therapies, but most are therapist-driven and prohibitively expensive. Environmental enrichment (EE) consists of modifying the environment by provision of facilities and equipment to stimulate physical, social and cognitive activity. It shows great promise as a low-cost means to increase activity outside therapy times. Indeed, there is strong experimental data showing better functional recovery, coupled with clear evidence of neurobiological effects (Janssen et al. 2010). Interestingly, the different components used in EE (physical, social and cognitive) appear to result in some quite distinct neurobiological effects. However, essential gaps in our knowledge of EE remain and addressing these gaps will be essential to optimise EE for stroke patients.
|Dr Neil Spratt||Senior Lecturer, Senior Staff Specialist Neurology|
|Prof. Mike Calford||PVC Research|
|Dr Damian McLeod||Postdoctoral Researcher|
|Mrs Debbie-Gai Pepperall||Research Assistant|
|Ms Sarah McCann||Research Assistant|
|Ms Amelia Tomkins||PhD Student|
|Ms Lucy Murtha||PhD Student|
|Mr Daniel Beard||PhD Student|
|Ms Rebecca Hood||Honours Student|
|Ms Ariana Arulampalam||Honours Student|
|Ms Julia Bourke||Honours Student|
Affiliated Researchers, University of Newcastle:
|Mrs Heidi Janssen||Clinical PhD Student|
|Prof. Chris Levi||Neurologist HNELHD, School of Medicine & PH|
|Ms Di Marsden||Clinical PhD Student|
|A/Prof. Mark Parsons||Neurologist HNELHD, School of Medicine & PH|
|Prof. Michael Nilsson||HMRI Director|
|Prof. John Rostas||Medical Biochemistry|
|Dr Rohan Walker||Brain Repair and Rehabilitation|
|Prof Robin Callister||Human Physiology Laboratory|
|Dr Mark Baker||Proteomics, School of Life Sciences|
|Dr Nikki Verrils||Medical Biochemistry|
|Dr Kathryn Skelding||Medical Biochemistry|
|Mrs Janine Johnston||Brain and Mental Health|
|A/Prof. David Howells||Florey Neuroscience Institute|
|Prof. Manfred Kapps||Justus Liebig University, Giessen, Germany|
|Prof. Max Nedelmann||Justus Liebig University, Giessen, Germany|
Murtha, L., McLeod, D., Spratt, N. Epidural Intracranial Pressure Measurement in Rats using Fibre-optic Pressure Transducer. J. Vis. Exp., e3689, DOI: 10.3791/3689 (2012).
Janssen H, Bernhardt J, Collier JM, Sena ES, McElduff P, Attia J, Pollack M, Howells DW, Nilsson M, Calford MB, Spratt NJ. (2010) An Enriched Environment Improves Sensorimotor Function Post-Ischemic Stroke. Journal of Neurorehabilitation and Neural Repair 24:802-13
McLeod DD, Parsons MW, Levi CR, Beautement S, Buxton D, Roworth B, Spratt NJ. (2011) Establishing a rodent stroke perfusion CT model. International Journal of Stroke 6(4):284-289
Parsons, M., Spratt, N., Bivard, A., Campbell, B., Chung, K., Miteff, F., O'Brien, B., Bladin, C., McElduff, P., Allen, C., Bateman, G., Donnan, G., Davis, S., Levi, C., (2012). A Randomized Trial of Tenecteplase versus Alteplase for Acute Ischemic Stroke. New England Journal of Medicine. 366: 1099-1107.
Janssen, H., Speare, S., Spratt, N.J., Sena, E.S., Ada, L., Hannan, A.J., McElduff, P., Bernhardt, J., 2012. Exploring the efficacy of contraint in animal models of stroke: meta-analysis and systematic review of the current evidence. Neurorehabil Neural Repair. (Accepted for publication 4 Apr 2012).