Are Underlying Assumptions of Current Animal Models of Human Stroke Correct: from STAIRs to High Hurdles?

Procedural and Methodological Quality in Preclinical Stroke Research-A Cohort Analysis of the Rat MCAO Model Comparing Periods Before and After the Publication of STAIR/ARRIVE

The translation of preclinical stroke research into successful human clinical trials remains a challenging task. The first Stroke Therapy Academic Industry Roundtable (STAIR) recommendations for preclinical research and several other guidelines were published to address these challenges. Most guidelines recommend the use of physiological monitoring to detect the occurrence of undesired pathologies such as subarachnoid hemorrhage and to limit the variability of the infarct volume and–therefore-homogenize the experimental result for complete reporting particularly with respect to transparency and methodological rigor. From the years 2009 and 2019, 100 published articles each using a rat stroke model were analyzed to quantify parameters related to anesthesia, physiological monitoring, stroke model type, ischemia verification, and overall study quality over time. No significant difference in the frequency of cerebral blood flow (CBF) measurements over time (28/34% for 2009/2019) was found. Notably, significantly fewer studies reported temperature, blood pressure, and blood gas monitoring data in 2019 compared to 2009. On the other hand, an increase in general study quality parameters (e.g., randomization, reporting of approval) was seen. In conclusion, the frequency of periinterventional monitoring has decreased over time. Some general methodological quality aspects, however, partially have increased. CBF measurement–the gold standard for ischemia verification-was applied rarely. Despite the growing recognition of current guidelines such as STAIR and ARRIVE (both widely approved in 2019) reporting, methods and procedures mostly do not follow these guidelines. These deficits may contribute to the translational failure of preclinical stroke research in search for neuroprotective therapies.

Are researchers moving away from animal models as a result of poor clinical translation in the field of stroke? An analysis of opinion papers

Objectives

Despite decades of research using animals to develop pharmaceutical treatments for patients who have had a stroke, few therapeutic options exist. The vast majority of interventions successful in preclinical animal studies have turned out to have no efficacy in humans or to be harmful to humans. In view of this, we explore whether there is evidence of a move away from animal models in this field.

Methods

We used an innovative methodology, the analysis of opinion papers. Although we took a systematic approach to literature searching and data extraction, this is not a systematic review because the study involves the synthesis of opinions, not research evidence. Data were extracted from retrieved papers in chronological order and analysed qualitatively and descriptively.

Results

Eighty eligible papers, published between 1979 and 2018, were identified. Most authors were from academic departments of neurology, neuroscience or stroke research. Authors agreed that translational stroke research was in crisis. They held diverse views about the causes of this crisis, most of which did not fundamentally challenge the use of animal models. Some, however, attributed the translational crisis to animal–human species differences and one to a lack of human in vitro models. Most of the proposed solutions involved fine-tuning animal models, but authors disagreed about whether such modifications would improve translation. A minority suggested using human in vitro methods alongside animal models. One proposed focusing only on human in vitro methods.

Conclusion

Despite recognising that animal models have been unsuccessful in the field of stroke, most researchers exhibited a strong resistance to relinquishing them. Nevertheless, there is an emerging challenge to the use of animal models, in the form of human-focused in vitro approaches. For the sake of stroke patients there is an urgent need to revitalise translational stroke research and explore the evidence for these new approaches.

CNB-001, a pleiotropic drug is efficacious in embolized agyrencephalic New Zealand white rabbits and ischemic gyrencephalic cynomolgus monkeys

Ischemic stroke is an acute neurodegenerative disease that is extremely devastating to patients, their families and society. Stroke is inadequately treated even with endovascular procedures and reperfusion therapy. Using an extensive translational screening process, we have developed a pleiotropic cytoprotective agent with the potential to positively impact a large population of brain ischemia patients and revolutionize the process used for the development of new drugs to treat complex brain disorders. In this unique translational study article, we document that the novel curcumin-based compound, CNB-001, when administered as a single intravenous dose, has significant efficacy to attenuate clinically relevant behavioral deficits following ischemic events in agyrencephalic rabbits when administered 1 h post-embolization and reduces infarct growth in gyrencephalic non-human primates, when administered 5 min after initiation of middle cerebral artery occlusion. CNB-001 is safe and does not increase morbidity or mortality in either research species. Mechanistically, CNB-001 inhibits human 5- and 15-lipoxygenase in vitro, and can attenuate ischemia-induced inflammatory markers, and oxidative stress markers, while potentially promoting synaptic plasticity mediated by enhanced brain-derived neurotrophic factor (BDNF).

Is age a key factor contributing to the disparity between success of neuroprotective strategies in young animals and limited success in elderly stroke patients? Focus on protein homeostasis

Neuroprotection strategies to improve stroke outcome have been successful in the laboratory but not in clinical stroke trials, and thus have come under scrutiny by the medical community. Experimental stroke investigators are therefore under increased pressure to resolve this problem. Acute ischemic stroke represents a severe form of metabolic stress that activates many pathological processes and thereby impairs cellular functions. Traditionally, neuroprotection strategies were designed to improve stroke outcome by interfering with pathological processes triggered by ischemia. However, stroke outcome is also dependent on the brain's capacity to restore cellular functions impaired by ischemia, and this capacity declines with age. It is, therefore, conceivable that this age-dependent decline in the brain's self-healing capacity contributes to the disparity between the success of neuroprotective strategies in young animals, and limited success in elderly stroke patients. Here, prosurvival pathways that restore protein homeostasis impaired by ischemic stress should be considered, because their capacity decreases with increasing age, and maintenance of proteome fidelity is pivotal for cell survival. Boosting such prosurvival pathways pharmacologically to restore protein homeostasis and, thereby, cellular functions impaired by ischemic stress is expected to counterbalance the compromised self-healing capacity of aged brains and thereby help to improve stroke outcome.

Evolution of ischemic damage and behavioural deficit over 6 months after MCAo in the rat: Selecting the optimal outcomes and statistical power for multi-centre preclinical trials

Key disparities between the timing and methods of assessment in animal stroke studies and clinical trial may be part of the reason for the failure to translate promising findings. This study investigates the development of ischemic damage after thread occlusion MCAo in the rat, using histological and behavioural outcomes. Using the adhesive removal test we investigate the longevity of behavioural deficit after ischemic stroke in rats, and examine the practicality of using such measures as the primary outcome for future studies. Ischemic stroke was induced in 132 Spontaneously Hypertensive Rats which were assessed for behavioural and histological deficits at 1, 3, 7, 14, 21, 28 days, 12 and 24 weeks (n>11 per timepoint). The basic behavioural score confirmed induction of stroke, with deficits specific to stroke animals. Within 7 days, these deficits resolved in 50% of animals. The adhesive removal test revealed contralateral neglect for up to 6 months following stroke. Sample size calculations to facilitate the use of this test as the primary experimental outcome resulted in cohort sizes much larger than are the norm for experimental studies. Histological damage progressed from a necrotic infarct to a hypercellular area that cleared to leave a fluid filled cavity. Whilst absolute volume of damage changed over time, when corrected for changes in hemispheric volume, an equivalent area of damage was lost at all timepoints. Using behavioural measures at chronic timepoints presents significant challenges to the basic science community in terms of the large number of animals required and the practicalities associated with this. Multicentre preclinical randomised controlled trials as advocated by the MultiPART consortium may be the only practical way to deal with this issue.

Impact of Stroke Therapy Academic Industry Roundtable (STAIR) Guidelines on Peri-Anesthesia Care for Rat Models of Stroke: A Meta-Analysis Comparing the Years 2005 and 2015

Numerous studies using rats in stroke models have failed to translate into successful clinical trials in humans. The Stroke Therapy Academic Industry Roundtable (STAIR) has produced guidelines on the rodent stroke model for preclinical trials in order to promote the successful translation of animal to human studies. These guidelines also underline the importance of anaesthetic and monitoring techniques. The aim of this literature review is to document whether anaesthesia protocols (i.e., choice of agents, mode of ventilation, physiological support and monitoring) have been amended since the publication of the STAIR guidelines in 2009. A number of articles describing the use of a stroke model in adult rats from the years 2005 and 2015 were randomly selected from the PubMed database and analysed for the following parameters: country where the study was performed, strain of rats used, technique of stroke induction, anaesthetic agent for induction and maintenance, mode of intubation and ventilation, monitoring techniques, control of body temperature, vascular accesses, and administration of intravenous fluids and analgesics. For each parameter (stroke, induction, maintenance, monitoring), exact chi-square tests were used to determine whether or not proportions were significantly different across year and p values were corrected for multiple comparisons. An exact p-test was used for each parameter to compare the frequency distribution of each value followed by a Bonferroni test. The level of significant set at < 0.05. Results show that there were very few differences in the anaesthetic and monitoring techniques used between 2005 and 2015. In 2015, significantly more studies were performed in China and significantly fewer studies used isoflurane and nitrous oxide. The most striking finding is that the vast majority of all the studies from both 2005 and 2015 did not report the use of ventilation; measurement of blood gases, end-tidal carbon dioxide concentration, or blood pressure; or administration of intravenous fluids or analgesics. The review of articles published in 2015 showed that the STAIR guidelines appear to have had no effect on the anaesthetic and monitoring techniques in rats undergoing experimental stroke induction, despite the publication of said guidelines in 2009.

The role of sleep in recovery following ischemic stroke: A review of human and animal data

Despite advancements in understanding the pathophysiology of stroke and the state of the art in acute management of afflicted patients as well as in subsequent neurorehabilitation training, stroke remains the most common neurological cause of long-term disability in adulthood. To enhance stroke patients' independence and well-being it is necessary, therefore, to consider and develop new therapeutic strategies and approaches. We postulate that sleep might play a pivotal role in neurorehabilitation following stroke. Over the last two decades compelling evidence for a major function of sleep in neuroplasticity and neural network reorganization underlying learning and memory has evolved. Training and learning of new motor skills and knowledge can modulate the characteristics of subsequent sleep, which additionally can improve memory performance. While healthy sleep appears to support neuroplasticity resulting in improved learning and memory, disturbed sleep following stroke in animals and humans can impair stroke outcome. In addition, sleep disorders such as sleep disordered breathing, insomnia, and restless legs syndrome are frequent in stroke patients and associated with worse recovery outcomes. Studies investigating the evolution of post-stroke sleep changes suggest that these changes might also reflect neural network reorganization underlying functional recovery. Experimental and clinical studies provide evidence that pharmacological sleep promotion in rodents and treatment of sleep disorders in humans improves functional outcome following stroke. Taken together, there is accumulating evidence that sleep represents a "plasticity state" in the process of recovery following ischemic stroke. However, to test the key role of sleep and sleep disorders for stroke recovery and to better understand the underlying molecular mechanisms, experimental research and large-scale prospective studies in humans are necessary. The effects of hospital conditions, such as adjusting light conditions according to the patients' sleep-wake rhythms, or sleep promoting drugs and non-invasive brain stimulation to promote neuronal plasticity and recovery following stroke requires further investigation.

The High Cost of Stroke and Stroke Cytoprotection Research

Acute ischemic stroke is inadequately treated in the USA and worldwide due to a lengthy history of neuroprotective drug failures in clinical trials. The majority of victims must endure life-long disabilities that not only affect their livelihood, but also have an enormous societal economic impact. The rapid development of a neuroprotective or cytoprotective compound would allow future stroke victims to receive a treatment to reduce disabilities and further promote recovery of function. This opinion article reviews in detail the enormous costs associated with developing a small molecule to treat stroke, as well as providing a timely overview of the cell-death time-course and relationship to the ischemic cascade. Distinct temporal patterns of cell-death of neurovascular unit components provide opportunities to intervene and optimize new cytoprotective strategies. However, adequate research funding is mandatory to allow stroke researchers to develop and test their novel therapeutic approach to treat stroke victims.

Critical early thrombolytic and endovascular reperfusion therapy for acute ischemic stroke victims: a call for adjunct neuroprotection

Today, there is an enormous amount of excitement in the field of stroke victim care due to the recent success of MR. CLEAN, SWIFT PRIME, ESCAPE, EXTEND-IA, and REVASCAT endovascular trials. Successful intravenous (IV) recombinant tissue plasminogen activator (rt-PA) clinical trials [i.e., National Institute of Neurological Disorders and Stroke (NINDS) rt-PA trial, Third European Cooperative Acute Stroke Study (ECASSIII), and Third International Stroke study (IST-3)] also need to be emphasized. In the recent endovascular and thrombolytic trials, there is statistically significant improvement using both the National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin Score (mRS) scale, but neither approach promotes complete recovery in patients enrolled within any particular NIHSS or mRS score tier. Absolute improvement (mRS 0-2 at 90 days) with endovascular therapy is 13.5-31 %, whereas thrombolytics alone also significantly improve patient functional independence, but to a lesser degree (NINDS rt-PA trial 13 %). This article has 3 main goals: (1) first to emphasize the utility and cost-effectiveness of rt-PA to treat stroke; (2) second to review the recent endovascular trials with respect to efficacy, safety, and cost-effectiveness as a stroke treatment; and (3) to further consider and evaluate strategies to develop novel neuroprotective drugs. A thesis will be put forth so that future stroke trials and therapy development can optimally promote recovery so that stroke victims can return to "normal" life.

Translational intracerebral hemorrhage: a need for transparent descriptions of fresh tissue sampling and preclinical model quality

For years, strategies have been proposed to improve translational success in stroke research by improving the quality of animal studies. However, articles that report preclinical intracerebral hemorrhage (ICH) studies continue to lack adequate qualitative and quantitative descriptions of fresh brain tissue collection. They also tend to lack transparency about animal model quality. We conducted a systematic review of 82 ICH research articles to determine the level of detail reported for brain tissue collection. We found that only 24 (29 %) reported the volume, weight, or thickness of tissue collected and a specific description of the anatomical location. Thus, up to 71 % of preclinical ICH research articles did not properly define how fresh specimens were collected for biochemical measurements. Such omissions may impede reproducibility of results between laboratories. Although existing criteria have improved the quality of preclinical stroke studies, ICH researchers need to identify specific guidelines and strategies to avoid pitfalls, minimize bias, and increase reproducibility in this field.

A blinded, randomized study of L-arginine in small clot embolized rabbits

OBJECTIVE

Tissue plasminogen activator (tPA) is administered to acute ischemic stroke victims in a vehicle formulation containing high concentrations of L-arginine (3.5g/100mg vial), a well-known nitric oxide synthase (NOS) substrate and precursor to nitric oxide (NO), as well as an enhancer of cerebral blood flow.

METHODS

We studied the effects of tPA vehicle compared to tPA (3.3mg/kg) formulated in the same vehicle containing L-arginine, normal saline or normal saline containing L-arginine, on behavioral function following small clot embolic strokes in rabbits using clinical rating scores and quantal analysis curves as the primary end point. Treatments were administered intravenously (1ml/kg; 20% bolus/80% infused over 30min) starting 1h following the injection of small-sized blood clots into the brain vasculature and terminal behavior was measured 2days following embolization. Behavioral rating scores were used to calculate the effective stroke dose (P50 in mg) that produces neurological deficits in 50% of the rabbits.

RESULTS

In this study, tPA significantly (p=0.001) improved behavior compared to all other treatments including tPA vehicle, saline and saline-L-arginine, increasing the P50 by 141% over tPA vehicle. Saline-L-arginine was not significantly different from either saline or tPA vehicle (p>0.05).

CONCLUSION

This study demonstrates that the L-arginine component of the tPA vehicle does not contribute to the reproducible clinical improvement observed following tPA administration in rabbits. Moreover, the administration of L-arginine was not an effective method to promote behavioral recovery following embolic strokes in the stringent rabbit small clot stroke model, nor did L-arginine exacerbate behavioral deficits or intracerebral hemorrhage in embolized rabbits.

General anesthetics as a factor of effective neuroprotection in ischemic stroke models

Stroke is the second leading cause of death in the world. Unfortunately, only a few drugs have been proved in clinical trials. Drug development of the last decade has been focused substantially on a promising and heterogeneous group of neuroprotective drugs. Hundreds of compounds were suggested as new putative neuroprotectors, which effectiveness was confirmed in preclinical trials only. At the present time discrepancy between results of preclinical studies and clinical trials requires careful analysis. One of the least evaluated and probably the most noticeable reasons is general anesthesia - an obligatory component of an overwhelming majority of existing animal stroke models. The aim of the review is to describe known mechanisms of common general anesthetics influence on ionotropic and metabotropic plasma membrane receptors, and key signal pathways involved in neuronal hypoxic-ischemic injury and survival

Recommendations for preclinical research in hemorrhagic transformation

Hemorrhagic transformation (HT) is an important complication of ischemic stroke and is responsible for most of the mortality associated with acute reperfusion therapy. Although many important publications address the preclinical models of ischemic stroke, there are no current recommendations on the conduct of research aimed at understanding the mechanisms and consequences of HT. The purpose of this review is to present the various models used in HT research, the clinical correlates, and the experimental variables known to influence the quantitation of HT in preclinical investigation. Lastly, recommendations for the conduct of preclinical research in HT are provided.

A novel model of large vessel ischemic stroke in rabbits: microcatheter occlusion of the posterior cerebral artery

BACKGROUND AND PURPOSE

The rabbit small clot embolic model for large vessel occlusion (LVO) is well established, yet has limitations. Blind introduction of autologous thrombus often fails to completely occlude a target vessel and, when successful, the precise timing of occlusion and revascularization is difficult to control. Studies of cellular biology and neuroimaging of acute reversible cerebral ischemia (ie, penumbral tissue) would benefit from a rabbit model in which LVO can be reliably induced, easily confirmed, and in which the time of occlusion and revascularization can be precisely controlled.

METHODS

Transfemoral 1.5 F microcatheterization of the posterior cerebral artery (PCA) was performed in anesthetized rabbits (n=7) using fluoroscopic guidance. LVO with the wedged microcatheter was maintained for 30-210 min followed by reperfusion. Diffusion-weighted and T2 fluid-attenuated inversion recovery (FLAIR) MRI was performed 3 h after catheter removal on a 3 T scanner. Post-mortem histopathologic analysis of brain tissue was performed using triphenyltetrazolium chloride (TTC).

RESULTS

Placing of the 1.5 F microcatheter tip in the PCA was successful in all seven animals. Infarct size on matched diffusion-weighted and TTC sections was strongly correlated (r(2)=0.86). Transient PCA occlusion of 30-60 min resulted in infarction of the ipsilateral hippocampus and thalamus, sparing the cortex, while more prolonged occlusion (180-210 min) resulted in cortical infarction as well.

CONCLUSIONS

Image-guided microcatheter induction of PCA occlusion in rabbits can consistently produce time-dependent infarction of cortical and subcortical structures that is reliably detected by diffusion-weighted MRI, and thus may be a useful model for therapeutic studies in acute ischemic stroke.

A rat's whiskers point the way toward a novel stimulus-dependent, protective stroke therapy

Stroke is the fourth leading cause of death in the United States and the leading cause of long-term disability. Ischemic stroke, due to an interruption in blood supply, is particularly prevalent; 87% of all strokes are ischemic. Unfortunately, current options for acute treatment are extremely limited and there is a great need for new treatment strategies. This review will discuss evidence that mild sensory stimulation can completely protect the jeopardized brain from an impending stroke in a rodent model. When delivered within the first 2 hours following ischemic onset, this stimulation results in complete protection, including a full reestablishment of cortical function, sensorimotor capabilities, and blood flow. Identical stimulation, however, initiated 3 hours following ischemic onset, results in an increase in damage compared with untreated animals. The protective effect is not specific to a single sensory modality, anesthesia, or age, and increasing evoked cortical activity by increasing stimulation accelerates recovery. Taken together, these findings demonstrate that cortical activity is a critical factor for protection and suggest a new, exciting potential avenue for the development of acute stroke treatment strategies that may produce a noninvasive, drug-free, equipment-free, and side effect-free means of protecting from ischemic stroke.

Drug-like property profiling of novel neuroprotective compounds to treat acute ischemic stroke: guidelines to develop pleiotropic molecules

The development of novel neuroprotective compounds to treat acute ischemic stroke (AIS) has been problematic and quite complicated, since many candidates that have been tested clinically lacked significant pleiotropic activity, were unable to effectively cross the blood brain barrier (BBB), had poor bioavailability or were toxic. Moreover, the compounds did not confer significant neuroprotection or clinical efficacy measured using standard behavioral endpoints, when studied in clinical trials in a heterogeneous population of stroke patients. To circumvent some of the drug development problems describe above, we have used a rational funnel approach to identify and develop promising candidates. Using a step-wise approach, we have identified a series of compounds based upon two different neuroprotection assays. We have then taken the candidates and determined their "drug-like" properties. This guidelines article details in vitro screening assays used to show pleiotropic activity of a series of novel compounds; including enhanced neuroprotective activity compared to the parent compound fisetin. Moreover, for preliminary drug de-risking or risk reduction during development, we used compound assessment in the CeeTox assay, ADME toxicity using the AMES test for genotoxicity and interaction with Cytochrome P450 using CYP450 inhibition analysis against a spectrum of CYP450 enzymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) as a measure of drug interaction. Moreover, the compounds have been studied using a transfected Madin Darby canine kidney (MDCK) cell assay to assess blood brain barrier penetration (BBB). Using this series of assays, we have identified 4 novel molecules to be developed as an AIS treatment.

RIGOR guidelines: escalating STAIR and STEPS for effective translational research

Stroke continues to be a serious and significant health problem in the USA and worldwide. This article will emphasize the need for good laboratory practices, transparent scientific reporting, and the use of translational research models representative of the disease state to develop effective treatments. This will allow for the testing and development of new innovative strategies so that efficacious therapies can be developed to treat ischemic and hemorrhagic stroke. This article recommends guidelines for effective translational research, most importantly, the need for study blinding, study group randomization, power analysis, accurate statistical analysis, and a conflict of interest statement. Additional guidelines to ensure reproducibility of results and confirmation of efficacy in multiple species are discussed.

Synergistic Effect of AJW200, a von Willebrand Factor Neutralizing Antibody with Low Dose (0.9 mg/mg) Thrombolytic Therapy Following Embolic Stroke in Rabbits

The von Willebrand factor (vWF) is an acute stroke response protein involved in platelet aggregation, adhesion, inflammation, and thrombus formation, responses that occur following an ischemic stroke. We hypothesize that administration of an anti-vWF antibody (anti-vWF-Ab) may be used as adjunctive therapy with tissue plasminogen activator (tPA) to promote behavioral improvement following an embolic stroke. In this proof-of-concept study, which used a blinded and randomized design, we studied delayed treatment with the anti-vWF-Ab, AJW200 (0.30 mg/kg), alone or in combination with a rabbit low-dose of tPA (0.9 mg/kg) using the rabbit small clot embolic stroke model (RSCEM) with behavioral function as the primary clinically relevant endpoint. To evaluate the quantitative relationship between clot burden in brain and clinical scores, so that an effective stroke dose (P50) could be calculated, logistic sigmoidal quantal analysis curves were constructed. A beneficial treatment significantly increases P50 compared to control. The effect of antibody administration, either alone or with low dose tPA was compared to a "positive control", a standard rabbit optimized dose of tPA (3.3 mg/kg), as a measure of the maximum improvement potential in the RSCEM. The anti-vWF-Ab, AJW200, or control IgG were administered IV 1 hour following embolization, and behavior was measured 48 hours later. AJW200 plus low-dose tPA significantly increased the P50 value by 74% (p<0.05, t=2.612) and 81% (p<0.05, t=2.519) compared to low dose tPA or IgG, respectively, but not the AJW200 group (p>0.05). AJW200 increased the P50 value by 28%, (p>0.05) compared to the control IgG-treated group. Standard dose tPA increased the P50 value by 154% (p<0.05). Statistically, the combination response for AJW200 plus low-dose tPA was not significantly different from standard dose tPA (p=0.26). This study shows that the concomitant administration of the anti-vWF-Ab AJW200 with low dose tPA is synergistic and results in significantly improved behavioral function following embolic stroke. We postulate that neutralization of vWF may suppress or attenuate one or more aspects of the acute phase stroke cascade response including suppression of inflammatory response and reduced leukocyte adhesion.

Successfully Climbing the "STAIRs": Surmounting Failed Translation of Experimental Ischemic Stroke Treatments

The Stroke Therapy Academic Industry Roundtable (STAIR) provided initial (in 1999) and updated (in 2009) recommendations with the goal of improving preclinical stroke therapy assessment and to increase the translational potential of experimental stroke treatments. It is important for preclinical stroke researchers to frequently consider and revisit these concepts, especially since promising experimental stroke treatments continue to fail in human clinical trials. Therefore, this paper will focus on considerations for several key aspects of preclinical stroke studies including the selection and execution of the animal stroke model, drug/experimental treatment administration, and outcome measures to improve experimental validity and translation potential. Specific points of interest discussed include the incorporation of human comorbid conditions and drugs, the benefits of defining a proposed mechanism of action, replication of results using multiple methods, using clinically relevant routes of administration and treatment time windows, and performing and reporting good experimental methods to reduce bias such as, as suggested by the updated STAIR recommendations, sample size calculations, randomization, allocation concealment, blinding, and appropriate inclusion/exclusion criteria. It is our hope that reviewing and revisiting these considerations will benefit researchers in their investigations of stroke therapies and increase the likelihood of translational success in the battle against stroke.

Mild sensory stimulation protects the aged rodent from cortical ischemic stroke after permanent middle cerebral artery occlusion

BACKGROUND

Accumulated research has shown that the older adult brain is significantly more vulnerable to stroke than the young adult brain. Although recent evidence in young adult rats demonstrates that single-whisker stimulation can result in complete protection from ischemic damage after permanent middle cerebral artery occlusion (pMCAO), it remains unclear whether the same treatment would be effective in older animals.

METHODS AND RESULTS

Aged rats (21 to 24 months of age) underwent pMCAO and subsequently were divided into "treated" and "untreated" groups. Treated aged rats received intermittent single-whisker stimulation during a 120-minute period immediately after pMCAO, whereas untreated aged rats did not. These animals were assessed using a battery of behavioral tests 1 week before and 1 week after pMCAO, after which their brains were stained for infarct. An additional treated aged group and a treated young adult group also were imaged with functional imaging. Results demonstrated that the recovery of treated aged animals was indistinguishable from that of the treated young adult animals. Treated aged rats had fully intact sensorimotor behavior and no infarct, whereas untreated aged rats were impaired and sustained cortical infarct.

CONCLUSIONS

Taken together, our results confirm that single-whisker stimulation is protective in an aged rodent pMCAO model, despite age-associated stroke vulnerability. These findings further suggest potential for translation to the more clinically relevant older adult human population. (J Am Heart Assoc. 2012;1:e001255 doi: 10.1161/JAHA.112.001255.).

Transcranial near-infrared laser therapy applied to promote clinical recovery in acute and chronic neurodegenerative diseases

One of the most promising methods to treat neurodegeneration is noninvasive transcranial near-infrared laser therapy (NILT), which appears to promote acute neuroprotection by stimulating mitochondrial function, thereby increasing cellular energy production. NILT may also promote chronic neuronal function restoration via trophic factor-mediated plasticity changes or possibly neurogenesis. Clearly, NILT is a treatment that confers neuroprotection or neurorestoration using pleiotropic mechanisms. The most advanced application of NILT is for acute ischemic stroke based upon extensive preclinical and clinical studies. In laboratory settings, NILT is also being developed to treat traumatic brain injury, Alzheimer's disease and Parkinson's disease. There is some intriguing data in the literature that suggests that NILT may be a method to promote clinical improvement in neurodegenerative diseases where there is a common mechanistic component, mitochondrial dysfunction and energy impairment. This article will analyze and review data supporting the continued development of NILT to treat neurodegenerative diseases.

Scientific Rigor Recommendations for Optimizing the Clinical Applicability of Translational Research

The approval of new therapies to treat neurodegenerative disease conditions by the Food and Drug administration (FDA) has been hindered by many failed clinical trials, which were based upon "significant" efficacy in preclinical or translational studies. Additional problems during drug development related to significant adverse events and unforeseen toxicity have also hampered drug development. Recent reviews of preclinical data suggests that many studies have over-estimated efficacy due to poor or inadequate study design, exclusion of important data (negative or neutral) and lack of study randomization and blinding. This article describes in detail a set of recommendations to improve the quality of science being conducted in laboratories worldwide, with the goal of documenting in the peer-reviewed literature, including Journal of Neurology and Neurophysiology, the scientific basis for the continued development of specific strategies to treat neurodegenerative diseases such as Stroke, Alzheimer's disease, Huntington's disease, Parkinson's disease, Spinal cord injury, and Amyotrophic lateral sclerosis. The minimum recommendations for effective translational research include the need for model justification, study group randomization and blinding, power analysis calculations, appropriate statistical analysis of all data sets, and a conflict of interest statement by investigators. It will also be beneficial to demonstrate reproducible efficacy in multiple species and in studies done by independent laboratories.

Molecular markers and mechanisms of stroke: RNA studies of blood in animals and humans

Whole genome expression microarrays can be used to study gene expression in blood, which comes in part from leukocytes, immature platelets, and red blood cells. Since these cells are important in the pathogenesis of stroke, RNA provides an index of these cellular responses to stroke. Our studies in rats have shown specific gene expression changes 24  hours after ischemic stroke, hemorrhage, status epilepticus, hypoxia, hypoglycemia, global ischemia, and following brief focal ischemia that simulated transient ischemic attacks in humans. Human studies show gene expression changes following ischemic stroke. These gene profiles predict a second cohort with >90% sensitivity and specificity. Gene profiles for ischemic stroke caused by large-vessel atherosclerosis and cardioembolism have been described that predict a second cohort with >85% sensitivity and specificity. Atherosclerotic genes were associated with clotting, platelets, and monocytes, and cardioembolic genes were associated with inflammation, infection, and neutrophils. These gene profiles predicted the cause of stroke in 58% of cryptogenic patients. These studies will provide diagnostic, prognostic, and therapeutic markers, and will advance our understanding of stroke in humans. New techniques to measure all coding and noncoding RNAs along with alternatively spliced transcripts will markedly advance molecular studies of human stroke.