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The term "neuroprotection" is often misused, overused, or misunderstood. A reasonable definition of neuroprotection refers to the preservation of "neuronal structure and/or function." Although our knowledge about the cellular and molecular mechanisms of neurodegeneration has expanded, experimental systems and animal models that mimic the process or allow translation into clinical success remain limited. This editorial discusses reasons for this gap and strategies to close it. Experimental models can only mirror certain aspects of disease mechanisms in humans. Therefore, findings in these models need to be linked with patient data to improve real-life relevance. Successful neuroprotection depends on finding the right "window of opportunity" which varies from very short (stroke) to very long (Alzheimer's disease), necessitating the need to focus on strategies for very early disease recognition. This need challenges the strategies to be chosen, trial approaches and methodologies, and the allocation of resources. Additionally, outcome measures are often not well suited to assess neuroprotection. To this end, surrogate measures, including biomarkers, are useful endpoints to demonstrate evidence of target directed therapeutic utility. Finally, studies have shown that neuroprotection is not likely to succeed when targeting only one pathway. These obstacles have reduced the level of enthusiasm for neuroprotection in certain disease areas (e.g., stroke). Academia, industry, regulatory authorities, funding agencies and patient organizations have to cooperate to a greater extent in order to overcome these impediments and to encourage nonclassical concepts. These concepts will be interdisciplinary in order to achieve meaningful disease modification.

Background Hematopoietic growth factors have been suggested to induce neuroprotective and regenerative effects in various animal models of cerebral injury. However, the pathways involved remain widely unexplored. Aims This study aimed to investigate effects of local and systemic administration of granulocyte colony-stimulating factor on brain damage, functional recovery, and cerebral neurogenesis in an intracerebral haemorrhage whole blood injection model in rats. Methods Eight-week-old male Wistar rats ( n = 100) underwent induction of striatal intracerebral haemorrhage by autologous whole blood injection or sham procedure and were randomly assigned to either (a) systemic treatment with granulocyte colony-stimulating factor (60 μg/kg) for five-days; (b) single intracerebral injection of granulocyte colony-stimulating factor (60 μg/kg) into the cavity; or (c) application of vehicle for five-days. Bromodeoxyuridine-labelling and immunohistochemistry were used to analyze proliferation and survival of newly born cells in the sub-ventricular zone and the hippocampal dentate gyrus. Moreover, functional deficits and lesion volume were assessed until day 42 after intracerebral haemorrhage. Results Differences in lesion size or hemispheric atrophy between granulocyte colony-stimulating factor-treated and control groups did not reach statistical significance. Neither systemic, nor local granulocyte colony-stimulating factor administration induced neurogenesis within the dentate gyrus or the sub-ventricular zone. The survival of newborn cells in these regions was prevented by intracerebral granulocyte colony-stimulating factor application. A subtle benefit in functional recovery at day 14 after intracerebral haemorrhage induction was observed after granulocyte colony-stimulating factor treatment. Conclusion There was a lack of neuroprotective or neuroregenerative effects of granulocyte colony-stimulating factor in the present rodent model of intracerebral haemorrhage. Conflicting results from functional outcome assessment require further research. [ABSTRACT FROM AUTHOR]

The European Hypothermia Stroke Research Workshop was held in January 2010, in response to the alarming prospects of a significant increase of stroke expected in the coming years globally. Considering that a minority of patients (around 10%) are currently eligible for thrombolytic treatment, there is a need for an efficacious, cost-effective novel therapy that can be implemented broadly within European health care systems. Accordingly, the primary objective of the workshop was the definition of a research agenda aiming to assess the therapeutic benefits of hypothermia in patients with acute ischaemic stroke. The meeting was organised by the European Stroke Research Network for Hypothermia (EuroHyp) and attended by the representatives of World Stroke Organisation, European Stroke Organisation, Stroke Alliance for Europe, Society for Cryobiology and other organisations - specifically the European Space Agency, and small- and medium-sized enterprises based in EU member states. The participants adopted the 'Hypothermia for Stroke - Call to Action 2010', a declaration specifying the priorities for hypothermia research in acute ischaemic stroke. The research programme outlined - a clinical study programme designed to identify and validate therapeutic cooling as a novel treatment providing benefit to a large number of stroke patients - contains a well-integrated series of Phase II studies aiming to refine the intervention (depth, duration, and mode of cooling; antishivering strategy; patient selection) and a pivotal Phase III clinical trial. The proposed integrated Phase II and III clinical study programme would test the effectiveness of this optimised intervention, and would allow the development of evidence-based Clinical Practice Guidelines describing the optimal use of therapeutic hypothermia as a treatment strategy for stroke. [ABSTRACT FROM AUTHOR]

Abstract: Acetylsalicylic acid (ASA; Aspirin) has a neuroprotective potential by its anti-excitotoxic and anti-inflammatory effects. A temporary middle cerebral artery occlusion (tMCAO) model was used in 80 Wistar rats to evaluate whether a high dose of Aspirin (40 mg/kg) applied with different initiation time points after stroke onset (30 min, 3 h, 6 h, 12 h, 20 rats for each time group) and followed by repeated administration (1, 2 and 3 days) is neuroprotective. Neurological score and brain infarct volume were analyzed and indicated that postischemic therapy initiation at 30 min and as late as 6 h led to better neurological recovery (6 h, p =0.0046) and significant smaller infarct size (6 h, 57±9 mm3, n =10, p =0.0043) compared to the saline control group (110±13 mm3, n =10). Thus, there may be a relatively wide time window for acute stroke therapy with high dose Aspirin. [Copyright &y& Elsevier]

Abstract: Cerebral ischemia provokes an inflammatory cascade, which is assumed to secondarily worsen ischemic tissue damage. Linking adaptive and innate immunity dendritic cells (DCs) are key regulators of the immune system. The hematopoietic factor G-CSF is able to modulate DC-mediated immune processes. Although G-CSF is under investigation for the treatment of stroke, only limited information exists about its effects on stroke-induced inflammation. Therefore, we investigated the impact of G-CSF on cerebral DC migration and maturation as well as on the mediated immune response in an experimental stroke model in rats by means of transient middle cerebral artery occlusion (tMCAO). Immunohistochemistry and quantitative PCR were performed of the ischemic brain and flow cytometrical analysis of peripheral blood. G-CSF led to a reduction of the infarct size and an improved neurological outcome. Immunohistochemistry confirmed a reduced migration of DCs and mature antigen-presenting cells after G-CSF treatment. Compared to the untreated tMCAO group, G-CSF led to an inhibited DC activation and maturation. This was shown by a significantly decreased cerebral transcription of TLR2 and the DC maturation markers, CD83 and CD86, as well as by an inhibition of stroke-induced increase in immunocompetent DCs (OX62+OX6+) in peripheral blood. Cerebral expression of the proinflammatory cytokine TNF-α was reduced, indicating an attenuation of cerebral inflammation. Our data suggest an induction of DC migration and maturation under ischemic conditions and identify DCs as a potential target to modulate postischemic cerebral inflammation. Suppression of both enhanced DC migration and maturation might contribute to the neuroprotective action of G-CSF in experimental stroke. [Copyright &y& Elsevier]

Abstract: The endocannabinoids anandamide (AEA) and palmitoylethanolamide (PEA) act as endogenous protective factors of the brain, using different pathways of neuroprotection against neuronal damage. Although several in vivo and in vitro studies confirmed the neuroprotective efficacy of endocannabinoids, no experimental settings compare and explore the neuroprotective potential of AEA and PEA in an acute stroke model. In this study, we investigated the neuroprotective potential by infarct measurement after high (30 mg/kg body weight) and low dosage administration (10 mg/kg body weight) of the endocannabinoid PEA in 49 male Wistar rats. In additions we studied infarct volumes of 22 male Wistar rats receiving the endocannabinoid AEA with a dosage of 10 mg/kg body weight or placebo. The neurological outcome was assessed 24 h after ischemia. Endocannabinoids were given intraperitoneally 30 min after initiation of transient middle cerebral artery occlusion (tMCAO). Infarct volume was calculated on the basis of 2.3.5-triphenyltetrazolium chloride staining. In the PEA high-dose group a significant total infarct reduction of 35% compared to the control group could be observed. AEA-treated rats presented a total infarct reducing effect of 26% compared to controls. Neurological scores, evaluated 24 h after tMCAO and physiological parameters, obtained 45 and 90 min after onset of ischemia showed no significant differences among the groups. As shown here, the endocannabinoids AEA and PEA achieved a significant neuroprotective effect by reducing size of infarcted tissue after tMCAO. Both endocannabinoids may have the potential to treat acute stroke and exert neuroprotection through a variety of mechanisms. [Copyright &y& Elsevier]

Abstract: Pleiotropic mechanisms beyond their cholesterol lowering effect of 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors or statins such as pravastatin are known. We used a temporary middle cerebral artery occlusion (tMCAO) model in 114 Wistar rats to assess i) whether repeated injections of various doses of pravastatin (0.1, 0.5, 1 and 2 mg/kg) at 30 min, 6 h, 1, 2, 3, and 4 days after stroke onset are neuroprotective, ii) whether attenuation of striatal glutamate and interleukin-6 (IL-6) release is part of the neuroprotective mechanism, and iii) how local cerebral blood flow (CBF) is influenced by pravastatin both in the acute and late stage of ischemia. Animals were sacrificed 5 days after MCAO, infarct size was analyzed with 2,3,5-triphenyltetrazolium chloride (TTC) staining. As compared to saline (139±14 mm3, n =11), higher doses of pravastatin beyond 0.1 mg/kg significantly reduced infarct size with the greatest effect obtained with 1 mg/kg (60±14 mm3, n =11, P =0.0004). Using cerebral microdialyis in this dose group, we demonstrated that striatal glutamate increase in the ischemic hemisphere was attenuated by pravastatin compared to placebo. Likewise, IL-6 release was diminished at 2 h, but not at 6 h after tMCAO. Improvement of local CBF by pravastatin was observed at day 5, but not at 5 h after tMCAO, thus representing a more long term effect of pravastatin. In conclusion, a relatively high dose of pravastatin administered repetitively after stroke onset improved neurological outcome through various cholesterol-independent mechanisms. [Copyright &y& Elsevier]

Abstract: Background and purpose: The timing and mechanisms of protection by hyperbaric oxygen (HBO) in cerebral ischemia have only been partially elucidated. We monitored the early in vivo effects of HBO after 2 h transient focal ischemia using repetitive MRI. Methods: Wistar rats underwent filament occlusion of the middle cerebral artery (MCAO). 40 min after MCAO, rats were placed in a HBO chamber and breathed either 100% O2 at 3.0 atmospheres absolute (ata; n = 24) or at 1.0 ata (control; n = 24) for 1 h. Diffusion, perfusion and T2-weighted MR-images were obtained after 15 min and 3, 6 and 24 h of reperfusion. In 6 axial MR slices, volume of abnormal diffusion and T2w signals were measured in the ischemic hemisphere. Furthermore, hemispheric mean apparent diffusion coefficient- (ADC) and T2 values were calculated for statistical analysis. Results: HBO significantly reduced volume of abnormal DWI signal beginning immediately after reperfusion (control: 92 ± 28 mm3; HBO: 64 ± 17) and lesion size on T2w (control: 375 ± 91 mm3; HBO: 225 ± 39) after 24 h. Correspondingly, mean ADC levels were lower and T2 values higher in the ischemic hemisphere in the control group. HBO reduced histological infarct size at 24 h. Conclusion: High-dose intraischemic HBO therapy has an immediate protective on the brain which is superior to normobaric oxygen. [Copyright &y& Elsevier]

Acetylsalicylic acid (ASA) is neuroprotective through various pharmacological action sites. We used a temporary middle cerebral artery occlusion (tMCAO) model in 56 Wistar rats to assess whether repeated ASA injections at 30 min, 6 h, 1, 2, 3, and 4 days after stroke onset are neuroprotective. Animals were sacrificed 5 days after MCAO; infarct size was analyzed with 2,3,5-triphenyltetrazolium chloride staining. As compared to saline (164±13 mm3, n=14), only repeated injections of 40 mg/kg ASA (79±18 mm3, n=14, P=0.0029), but not of 20 mg/kg ASA (129±19 mm3, n=15), reduced infarct volume significantly. No significant change was noted with 40 mg/kg ASA injected only once at 30 min after MCAO (117±16 mm3, n=13). [Copyright &y& Elsevier]