Corrigendum to: PEGylated Albumin-Based Drug Carriers for the Treatment of Experimental Stroke

Sildenafil provides restorative therapeutic benefits in the treatment of experimental stroke. The majority of experimental studies on treatment of stroke have been performed in young animals; however, stroke is primarily a disease of the aged. Thus, using MRI, we evaluated the effects of sildenafil treatment of embolic stroke in aged animals. Aged male Wistar rats (18 months) were subjected to embolic stroke and treated daily with saline (n=10) or with sildenafil (n=10) initiated at 24 hours and subsequently for 7 days after onset of ischemia. MRI measurements were performed at 24 hours and weekly to 6 weeks after embolization. MRI and histological measurements demonstrated that sildenafil treatment of aged rats significantly enhanced angiogenesis and axonal remodeling after stroke compared to saline-treated aged rats. Local cerebral blood flow in the angiogenic area was elevated and expansion of the ipsilateral ventricle and, consequently, brain atrophy was significantly reduced in the sildenafil-treated rats. Treatment of embolic stroke in aged rats with sildenafil significantly augments angiogenesis and axonal remodeling, which increased local blood flow and reduced expansion of the ipsilateral ventricle 6 weeks after stroke compared to control aged rats. MRI can be used to investigate brain repair after stroke in aged rats.

See related article, pages 1751–1758. Since the ischemic penumbra was discovered and since a therapeutic window for acute ischemic stroke has been postulated, stroke experts are looking for safe and effective drugs to treat as many acute ischemic stroke patients as possible. Maturation of ischemic damage is a complex process, triggered by hypoperfusion at critical levels and spontaneously evolving toward cell death. It is a self-perpetuating process in which some critical steps (such as ion pumps failure and iNOS production) maintain and enhance the process.1 Reperfusion may reverse the ischemic cascade but, at the same time, induces a further damage. The risk/benefit ratio of reperfusion depends on the amount of penumbral salvageable tissue, that is “individual” and only partially predictable.2,3 Spontaneous reperfusion may occur, and symptoms may reverse, partially or totally, but the percentages of spontaneous reperfusion so far reported account for approximately the 24% of all stroke cases.4 A review of published articles about cerebral angiography in stroke reported that the percentage of spontaneous reperfusion …

The dose-effectiveness of intranasal VEGF in treatment of experimental stroke

Combination treatment of experimental stroke with Niaspan and Simvastatin, reduces axonal damage and improves functional outcome

Transient global cerebral ischemia (TGI) was induced in awake rats using the "four-vessel" occlusion model of Pulsinelli and Brierley. Blood pressure, arterial blood gases, cerebral blood flow, and cardiac output were measured during the acute (up to 2 hours) and chronic (2 to 72 hours) postischemic time periods. Coincident with the onset of TGI, cardiac output and caudate blood flow were depressed. The former returned to baseline within 30 minutes after the conclusion of TGI, and the latter progressed to hyperemia at 12 hours (81.8 +/- 4.9 vs 68.6 +/- 3.9 ml/min/100 gm tissue (mean +/- standard error of the mean] and oligemia at 72 hours (45.5 +/- 4.8 ml/min/100 gm tissue) post-TGI in the untreated control rats. Arterial blood gases and blood pressure were unchanged. Naloxone (1mg/kg) given at the time of TGI or as late as 60 minutes post-TGI and every 2 hours thereafter for 24 hours or bilateral cervical vagotomy prevented the depression in cardiac output and blocked the hyperemic-oligemic cerebral blood flow pattern that was predictive of stroke in this rat model. Changes in cardiac output after TGI in this model appear to be mediated by parasympathetic pathways to the heart from the brain stem. Opiate receptor blockade probably blocks endogenous opioid peptide stimulation of these brain-stem circulatory centers, which results in inhibition of parasympathetic activity and improvement in cardiac output. The usefulness of naloxone in the treatment of experimental stroke may be a function of its ability to improve cerebral perfusion in pressure-passive cerebrovascular territories. Variations in cardiac output during experimental stroke may explain the dissimilar responses to naloxone treatment reported by other investigators of experimental stroke.

Background: Herpes simplex virus (HSV) is prevalent in today’s world population, and there is evidence of potential HSV reactivation in patients with immune deficiency induced by acute stroke. However, the data on the use of antivirals in the setting of stroke are scarce. The aim of this study was to evaluate the reactivation of HSV-1 in patients with stroke, using several methods, and to assess the efficacy of acyclovir in the treatment of experimental stroke. In the employed methodology, PCR and dot-ELISA were used to detect the occurrence of HSV-1 in patients with acute stroke. White mice were infected with HSV-1 and experimental stroke was simulated. The infected mice with stroke were subdivided into two groups: one of them received no treatment, while the other one was treated with acyclovir. The level of HSV-1 reactivation was determined by the methods used in human patients. The brain tissue of experimental animals was also subjected to morphological and morphometrical study. The results of such work reveal that, by the applied serological method, HSV-1 was found in all patients with stroke. Herein, the increased level of HSV-1 was seen in the brain tissue and blood in 100% of the experimental infected animals. However, the use of acyclovir suppressed reproduction of HSV-1. Hence, it can be concluded that clinical and laboratory studies have demonstrated the different sensitivity of Dot-Elisa and PCR, with the former being more sensitive. Moreover, the use of acyclovir in the experiment inhibited viral reproduction and further development of viral infection. Still, chemic lesions in the brain persisted.

Inflammation following ischaemic stroke attracts high priority in current research, particularly using human-like models and long-term observation periods considering translational aspects. The present study aimed on the spatio-temporal course of macrophage-like cell accumulation after experimental thromboembolic stroke and addressed microglial and astroglial reactions in the ischaemic border zone. Further, effects of tissue plasminogen activator (tPA) as currently best treatment for stroke and the potentially neuroprotective co-administration of hyperbaric oxygen (HBO) were investigated. Rats underwent middle cerebral artery occlusion and were assigned to control, tPA or tPA+HBO. Twenty-four hours, 7, 14 and 28 days were determined as observation time points. The accumulation of macrophage-like cells was semiquantitatively assessed by CD68 staining in the ischaemic area and ischaemic border zone, and linked to the clinical course. CD11b, ionized calcium binding adaptor molecule 1 (Iba), glial fibrillary acidic protein (GFAP) and Neuronal Nuclei (NeuN) were applied to reveal delayed glial and neuronal alterations. In all groups, the accumulation of macrophage-like cells increased distinctly from 24 hours to 7 days post ischaemia. tPA+HBO tended to decrease macrophage-like cell accumulation at day 14 and 28. Overall, a trend towards an association of increased accumulation and pronounced reduction of the neurological deficit was found. Concerning delayed inflammatory reactions, an activation of microglia and astrocytes with co-occurring neuronal loss was observed on day 28. Thereby, astrogliosis was found circularly in contrast to microglial activation directly in the ischaemic area. This study supports previous data on long-lasting inflammatory processes following experimental stroke, and additionally provides region-specific details on glial reactions. The tendency towards a decreasing macrophage-like cell accumulation after tPA+HBO needs to be discussed critically since neuroprotective properties were recently ascribed to long-term inflammatory processes.

Inflammation following ischaemic stroke attracts high priority in current research, particularly using human-like models and long-term observation periods considering translational aspects. The present study aimed on the spatio-temporal course of macrophage-like cell accumulation after experimental thromboembolic stroke and addressed microglial and astroglial reactions in the ischaemic border zone. Further, effects of tissue plasminogen activator (tPA) as currently best treatment for stroke and the potentially neuroprotective co-administration of hyperbaric oxygen (HBO) were investigated. Rats underwent middle cerebral artery occlusion and were assigned to control, tPA or tPA+HBO. Twenty-four hours, 7, 14 and 28 days were determined as observation time points. The accumulation of macrophage-like cells was semiquantitatively assessed by CD68 staining in the ischaemic area and ischaemic border zone, and linked to the clinical course. CD11b, ionized calcium binding adaptor molecule 1 (Iba), glial fibrillary acidic protein (GFAP) and Neuronal Nuclei (NeuN) were applied to reveal delayed glial and neuronal alterations. In all groups, the accumulation of macrophage-like cells increased distinctly from 24 hours to 7 days post ischaemia. tPA+HBO tended to decrease macrophage-like cell accumulation at day 14 and 28. Overall, a trend towards an association of increased accumulation and pronounced reduction of the neurological deficit was found. Concerning delayed inflammatory reactions, an activation of microglia and astrocytes with co-occurring neuronal loss was observed on day 28. Thereby, astrogliosis was found circularly in contrast to microglial activation directly in the ischaemic area. This study supports previous data on long-lasting inflammatory processes following experimental stroke, and additionally provides region-specific details on glial reactions. The tendency towards a decreasing macrophage-like cell accumulation after tPA+HBO needs to be discussed critically since neuroprotective properties were recently ascribed to long-term inflammatory processes.

CDP-choline has shown neuroprotective effects in cerebral ischemia. In humans, although a recent trial International Citicoline Trial on Acute Stroke (ICTUS) has shown that global recovery is similar in CDP-choline and placebo groups, CDP-choline was shown to be more beneficial in some patients, such as those with moderate stroke severity and not treated with t-PA. Several mechanisms have been proposed to explain the beneficial actions of CDP-choline. We have now studied the participation of Sirtuin1 (SIRT1) in the neuroprotective actions of CDP-choline. Fischer rats and Sirt1⁻/⁻ mice were subjected to permanent focal ischemia. CDP-choline (0.2 or 2 g/kg), sirtinol (a SIRT1 inhibitor; 10 mg/kg), and resveratrol (a SIRT1 activator; 2.5 mg/kg) were administered intraperitoneally. Brains were removed 24 and 48 h after ischemia for western blot analysis and infarct volume determination. Treatment with CDP-choline increased SIRT1 protein levels in brain concomitantly to neuroprotection. Treatment with sirtinol blocked the reduction in infarct volume caused by CDP-choline, whereas resveratrol elicited a strong synergistic neuroprotective effect with CDP-choline. CDP-choline failed to reduce infarct volume in Sirt1⁻/⁻ mice. Our present results demonstrate a robust effect of CDP-choline like SIRT1 activator by up-regulating its expression. Our findings suggest that therapeutic strategies to activate SIRT1 may be useful in the treatment of stroke. Sirtuin 1 (SIRT1) is implicated in a wide range of cellular functions. Regarding stroke, there is no direct evidence. We have demonstrated that citicoline increases SIRT1 protein levels in brain concomitantly to neuroprotection. Citicoline fails to reduce infarct volume in Sirt1⁻/⁻ mice. Our findings suggest that therapeutic strategies acting on SIRT1 may be useful in the treatment of stroke.

Background: Granulocyte-colony stimulating factor (G-CSF) shows promise as a treatment for stroke. This systematic review assesses G-CSF in experimental ischaemic stroke. Methods: Relevant studies were identified with searches of Medline, Embase and PubMed. Data were extracted on stroke lesion size, neurological outcome and quality, and analysed using Cochrane Review Manager using random effects models; results are expressed as standardised mean difference (SMD) and odds ratio (OR). Results: Data were included from 19 publications incorporating 666 animals. G-CSF reduced lesion size significantly in transient (SMD − 1.63, p < 0.00001) but not permanent (SMD − 1.56, p = 0.11) focal models of ischaemia. Lesion size was reduced at all doses and with treatment commenced within 4 h of transient ischaemia. Neurological deficit (SMD − 1.37, p = 0.0004) and limb placement (SMD − 1.88, p = 0.003) improved with G-CSF; however, locomotor activity (≥ 4 weeks post-ischaemia) was not (SMD 0.76, p = 0.35). Death (OR 0.27, p < 0.0001) was reduced with G-CSF. Median study quality was 4 (range 0–7/8); Egger's test suggested significant publication bias ( p < 0.001). Conclusions: G-CSF significantly reduced lesion size in transient but not permanent models of ischaemic stroke. Motor impairment and death were also reduced. Further studies assessing dose response, administration time, length of ischaemia and long-term functional recovery are needed.

Hypothermia is robustly protective in pre-clinical models of both global and focal ischemia, as well as in patients after cardiac arrest. Although the mechanism for hypothermic neuroprotection remains unknown, reducing metabolic drive may play a role. Capitalizing on the beneficial effects of hypothermia while avoiding detrimental effects such as infection will be the key to moving this therapy forward as a treatment for stroke. AMPK is a master energy sensor that monitors levels of key energy metabolites. AMPK is activated via phosphorylation (pAMPK) when cellular energy levels are low, such as that seen during ischemia. AMPK activation appears to be detrimental in experimental stroke, likely via exacerbating ischemia-induced metabolic failure. We tested the hypothesis that hypothermia reduces AMPK activation. First, it was found that hypothermia reduced infarct after middle cerebral artery occlusion. Second, induced hypothermia reduced brain pAMPK in both sham control and stroke mice. Third, hypothermic neuroprotection was ameliorated after administration of compound C, an AMPK inhibitor. Finally, deletion of one of the catalytic isoforms of AMPK completely reversed the effect of hypothermia on stroke outcome after both acute and chronic survival. These effects were mediated by a reduction in AMPK activation rather than a reduction in LKB1, an upstream AMPK kinase. In summary, these studies provide evidence that hypothermia exerts its protective effect in part by inhibiting AMPK activation in experimental focal stroke. This suggests that AMPK represents a potentially important biological target for stroke treatment.

Lubeluzole attenuates K +-evoked extracellular accumulation of taurine in the striatum of healthy rats and rats with hepatic failure

Clinical stroke induces inflammatory processes leading to cerebral and splenic injury and profound peripheral immunosuppression. IL-10 expression is elevated during major CNS diseases and limits inflammation in the brain. Recent evidence demonstrated that transfer of IL-10(+) B-cells reduced infarct volume in male C57BL/6J (wild-type, WT) recipient mice when given 24h prior to or 4h after middle cerebral artery occlusion (MCAO). The purpose of this study was to determine if passively transferred IL-10(+) B-cells can exert therapeutic and immunoregulatory effects when injected 24h after MCAO induction in B-cell-sufficient male WT mice. The results demonstrated that IL-10(+) B-cell treated mice had significantly reduced infarct volumes in the ipsilateral cortex and hemisphere and improved neurological deficits vs. Vehicle-treated control mice after 60min occlusion and 96h of reperfusion. The MCAO-protected B-cell recipient mice had less splenic atrophy and reduced numbers of activated, inflammatory T-cells, decreased infiltration of T-cells and a less inflammatory milieu in the ischemic hemispheres compared with Vehicle-treated control mice. These immunoregulatory changes occurred in concert with the predominant appearance of IL-10-secreting CD8(+)CD122(+) Treg cells in both the spleen and the MCAO-affected brain hemisphere. This study for the first time demonstrates a major neuroprotective role for IL-10(+) B-cells in treating MCAO in male WT mice at a time point well beyond the ~4h tPA treatment window, leading to the generation of a dominant IL-10(+)CD8(+)CD122(+) Treg population associated with spleen preservation and reduced CNS inflammation.

The effects are reported of acute and long-term continuous administration of three opiate antagonists--naloxone, naltrexone, and diprenorphine--on neurological function, survival, and infarct size in a feline model of acute focal cerebral ischemia. All three drugs produced statistically significant improvement in motor function following acute administration without concomitant changes in level of consciousness; saline had no effect. Naloxone and naltrexone significantly prolonged survival (p less than 0.01); diprenorphine did not. Infarct size was not altered by any treatment administered. These findings confirm previous work suggesting that, with the appropriate methodology, treatment with opiate antagonists partially reverses neurological deficits. They also show that opiate antagonists prolong survival in certain conditions of acute and subacute focal cerebral ischemia without altering the area of infarcted tissue.

Clinical stroke induces inflammatory processes leading to cerebral and splenic injury and profound peripheral immunosuppression. IL-10 expression is elevated during major CNS diseases and limits inflammation in the brain. Recent evidence demonstrated that absence of B-cells led to larger infarct volumes and CNS damage after middle cerebral artery occlusion (MCAO) that could be prevented by transfer of IL-10(+) B-cells. The purpose of this study was to determine if the beneficial immunoregulatory effects on MCAO of the IL-10(+) B-cell subpopulation also extends to B-cell-sufficient mice that would better represent stroke subjects. CNS inflammation and infarct volumes were evaluated in male C57BL/6J (WT) mice that received either RPMI or IL-10(+) B-cells and underwent 60 min of middle cerebral artery occlusion (MCAO) followed by 96 h of reperfusion. Transfer of IL-10(+) B-cells markedly reduced infarct volume in WT recipient mice when given 24 h prior to or 4 h after MCAO. B-cell protected (24 h pre-MCAO) mice had increased regulatory subpopulations in the periphery, reduced numbers of activated, inflammatory T-cells, decreased infiltration of T-cells and a less inflammatory milieu in the ischemic hemispheres of the IL-10(+) B-cell-treated group. Moreover, transfer of IL-10(+) B-cells 24 h before MCAO led to a significant preservation of regulatory immune subsets in the IL-10(+) B-cell protected group presumably indicating their role in immunomodulatory mechanisms, post-stroke. Our studies are the first to demonstrate a major immunoregulatory role for IL-10(+) regulatory B-cells in preventing and treating MCAO in WT mice and also implicating their potential role in attenuating complications due to post-stroke immunosuppression.