Strong attenuation of ischemic and postischemic brain edema in rats by a novel free radical scavenger

Clinical evaluation of liver injury in patients with acute ischemic brain stroke treated with edaravone

AIM

  To elucidate the etiologic factors and features of liver injury in patients with acute ischemic brain stroke who were treated with edaravone and reported by their attending physicians to have developed serious liver injury.

METHODS

  The present study investigated 123 patients with a verified episode of liver injury among 132 patients with serious liver injury that had been reported attributable to edaravone.

RESULTS

  Ischemic and/or congestive liver (70.7%) were most predominant among the etiologic factors for liver injury, and edaravone-related liver injury accounted for 20.3% (25 patients). Evident liver injury (defined in the text) was found in 104 among 123 evaluated patients; 54 patients (51.9%) of the former subset showed severe liver injury (defined increases in serum aspartate and/or alanine aminotransferase levels of ≥1000 IU/L and/or serum total bilirubin levels of ≥5 mg/dL). Among 104 patients with evident liver injury, 65 showed recovery. Furthermore, 53 patients (51.0%) were complicated by renal disorders; all of these patients had ischemic and/or congestive liver, or severe infections.

CONCLUSIONS

  Edaravone was considered to be etiologic for liver injury in approximately 20% of evaluated patients. When a patient treated with edaravone developed liver injury therefore an investigation not only on edaravone but also on other potential etiologic factors (e.g. ischemic liver, congestive liver, and infection) and the quick implementation of appropriate treatments, especially for infections, revealed possible reductions in the incidences of severe liver injury and of complications by renal disorders.

Edaravone alleviates delayed neuronal death and long-dated cognitive dysfunction of hippocampus after transient focal ischemia in Wistar rat brains

Edaravone is currently being used in acute ischemic stroke both in clinical and experimental research as a potent antioxidant. Here we explore the effects of edaravone on delayed neuronal death (DND) and long-dated cognitive dysfunction of hippocampus after cerebral ischemia-reperfusion (IR) injury and explain the underlying mechanisms and pathways. Our findings suggested that edaravone not only significantly alleviated delayed neuronal death and cognitive dysfunction of hippocampus after cerebral focal ischemia, but also markedly decreased malondialdehyde (MDA) levels. In addition, edaravone increased superoxide dismutase (SOD) levels and reduced the levels of inflammatory cytokines such as IL-1β and TNF-α expression; edaravone, also suppressed glial fibrillary acidic protein (GFAP) proliferation at days 3, 7 and 30 after reperfusion. Overall, the consensus emerging from this body of data indicated that edaravone exerts a later neuroprotective effect to hippocampus through its ability to inhibit inflammation, suppression of astrocyte activation and scavenging free radicals in stroke events.

Effects of edaravone, a free radical scavenger, on serum levels of inflammatory biomarkers in acute brain infarction

The potent free radical scavenger edavarone is widely used in Japan to treat acute ischemic stroke within 24 hours after onset. Recent experimental studies have shown that edavarone alleviates blood-brain barrier disruption in conjunction with suppression of the inflammatory reaction in acute brain ischemia. We investigated the effects of edaravone on circulating inflammatory biomarkers in patients with ischemic stroke. Patients with acute ischemic stroke admitted 12-36 hours after onset of symptoms were prospectively enrolled. Intravenous edaravone at 60 mg/day for 14 days was administered to patients admitted 12-24 hours after symptom onset (edaravone group; n = 29). Patients admitted 24-36 hours after onset served as controls (control group; n = 34). Venous blood samples were obtained on admission and at 48 hours, 7 days, and 14 days after symptom onset. Serum concentrations of high-sensitivity C-reactive protein, interleukin (IL)-6, IL-10, IL-18, tumor necrosis factor α, matrix metalloproteinase (MMP)-2, and MMP-9 were measured. General linear models were used to compare changes in concentrations of these biomarkers over time between the groups. In the control group, the mean MMP-9 concentration increased gradually from 3.857 ± 1.880 ng/mL to 4.538 ± 1.966 ng/mL over the 14-day period (P = .027, one-way repeated-measures analysis of variance [ANOVA]), but the edavarone group demonstrated no such increase (P = .564). A significant group-time interaction was demonstrated only for MMP-9 (P = .029, two-way repeated-measures ANOVA), and no significant differences in other biomarkers were seen between groups. Our data indicate that edaravone suppresses serum MMP-9 level in patients with acute ischemic stroke. Further studies with a larger sample size are needed to explore the relationship between circulating MMP-9 level and the protective effect of edaravone.

Edaravone, a free radical scavenger, promotes engraftment of intraportally transplanted islet cells

OBJECTIVES

Pancreatic islet transplantation requires multiple transplants to achieve insulin independence. Only one third of the islet mass is stably engrafted; one of the causes of which is ascribed to oxidative stress. We confirmed the hypothesis that administration of edaravone, a free radical scavenger, in the early posttransplantation period promotes islet cell engraftment.

METHODS

Islet isograft from a single donor was intraportally transplanted into streptozotocin-diabetic F344 rats, and intravenous edaravone (3 mg/kg) was administered immediately and 24 hours after the transplantation. Plasma glucose concentrations were monitored for 28 days. Serum insulin levels were obtained on the second week. Morphologic studies were performed on insulin-immunostained and TUNEL-stained sections of the recipient liver.

RESULTS

In the edaravone-treated group, hyperglycemia was ameliorated, and 50% of rats achieved normoglycemia (<200 mg/dL). All rats in the control group remained hyperglycemic (>400 mg/dL). Insulin secretion of the edaravone-treated group was superior to the controls. Morphologically, the number and size of the islet β cells of the edaravone-treated group were larger than those of the controls. The number of TUNEL-positive cells in each islet of the edaravone-treated group were fewer than those of the controls.

CONCLUSIONS

In streptozotocin-diabetic rats, edaravone administration in the early posttransplantation period promotes engraftment of intraportally transplanted islet cells.

Vascular protection and restorative therapy in ischemic stroke

Possible strategies for treating stroke include: 1) thrombolytic therapy with tissue plasminogen activator (tPA): restoring cerebral blood flow in the acute phase of ischemic stroke but sometimes causing hemorrhagic transformation (HT); 2) stem cell therapy: the repair of disrupted neuronal networks with newly born neurons in the chronic phase of ischemic stroke. Firstly, we estimated the vascular protective effect of a free radical scavenger, edaravone, in the tPA-treated rat model of middle cerebral artery occlusion. Edaravone prevented dramatically decreased the hemorrhagic transformation and improved the neurologic score and survival rate of tPA-treated rats. Secondly, we attempted to restore brain tissue using a novel biomaterial, polydimethysiloxane-tetraethoxysilane (PDMS-TEOS) hybrid with or without vascular endothelial growth factor (VEGF), and we could show that implantation of a PDMS-TEOS scaffold with VEGF might be effective for treating old brain infarction or trauma. In the future, we will combine these strategies to develop more effective therapies for treatment of strokes.

Activation of dopamine D4 receptors is protective against hypoxia/reoxygenation-induced cell death in HT22 cells

Several reports have shown that some dopamine receptor ligands modulate the ischemia-reperfusion injury in animal models; however, its underling mechanisms are still unclear. In this study, we sought to establish an in vitro experimental model of hypoxia/reoxygenation (H/R) using HT22 cells that originated from mouse hippocampal neurons and to examine protective the effect of dopamine-receptor ligands against H/R-induced cell injury. The treatment with hypoxia for 18 h followed by reoxygenation for 6 h induced the elevation of intracellular reactive oxygen species (ROS) and reduction of mitochondrial membrane potential; however, lactate dehydrogenase (LDH) release was not changed at this time point. LDH release was increased after reoxygenation for 18 h and longer, and this increase in LDH release was suppressed by dopamine receptor agonists such as apomorphine and apocodeine. The suppressive effects of these agonists were reversibly inhibited by L750667, a D(4)-receptor antagonist but not by D(2)- or D(3)-receptor antagonists. In addition, PD168077, a selective dopamine D(4)-receptor agonist, also protected against H/R-induced cell death. These results suggest that H/R causes oxidative stress-induced cell death and that the activation of dopamine D(4) receptors protects against H/R-induced cell death in HT22 cells.

Pharmacokinetic interaction between puerarin and edaravone, and effect of borneol on the brain distribution kinetics of puerarin in rats

Objectives

The aim was to investigate the pharmacokinetic interaction between puerarin and edaravone, and the effect of borneol on the brain distribution kinetics of puerarin in rats.

Methods

A reversed-phase high performance liquid chromatography method was developed and validated for the simultaneous determination of puerarin and edaravone in rat plasma. The detection method was successfully applied to compare the pharmacokinetic interaction and brain distribution kinetics of puerarin and edaravone using in-situ microdialysis sampling in rats after intravenous administration and co-administration with a single dose.

Key findings

The method gave good linearity and no endogenous material interfered with the two target compounds and internal standard peaks. The limit of detection of puerarin and edaravone was 0.03 and 0.05 μg/ml, respectively. The average recovery of the two compounds from rat plasma was &gt;94%. The precision of the test was determined to be within 10%. The combination of puerarin and edaravone reduced drug elimination rates, gave a wider distribution, and the disposition of both drugs in rats was optimized. The distribution of puerarin in brain tissues was significantly increased and its elimination was noticeably slower with borneol pretreatment.

Conclusions

The results provide important information for the improved combined use of puerarin and edaravone with borneol pretreatment in clinical practice.

Cyclophosphamide promotes cell survival via activation of intracellular signaling in cultured cortical neurons

Cyclophosphamide (CP) has been used as an antitumour agent or immunosuppressant clinically, though the potential biological role of CP in the central nervous system (CNS) has not been clarified. In the present study, we found that pretreatment with CP prevented neuronal cell death caused by serum deprivation in cultured cortical neurons. Interestingly, CP stimulated activation of PI3K (phosphatidylinositol 3 kinase) and MAPK/ERK (mitogen-activated protein kinase/extracellular signal-regulated kinase) pathways, which are known as survival-promoting intracellular signalings. Furthermore, CP increased the expression of Bcl2, an anti-apoptotic factor. In the presence of inhibitors for PI3K or MAPK/ERK pathways, the CP-dependent neuronal survival and Bcl-2 up-regulation were both abolished. Importantly, significant increase in BDNF (brain-derived neurotrophic factor) expression was induced by CP application, implying that BDNF up-regulation is involved in the CP effect. We propose that CP has a protective effect on CNS neurons via the activation of intracellular signalings, and up-regulation of Bcl2 and BDNF.

Neuroprotective effect of the free radical scavenger MCI-186 in patients with cerebral infarction: clinical evaluation using magnetic resonance imaging and spectroscopy

A newly developed free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186), holds promise for clinical application. We clinically evaluated the effect of MCI-186 on cerebral infarction by using magnetic resonance imaging (MRI) and proton MR spectroscopy (MRS). Six patients with large supratentorial infarction were evaluated with sequential MRI and proton MRS. These patients were also administered MCI-186 for 14 days after ischemic insult (MCI-186 group). The findings were compared with those for patients who had supratentorial infarctions equivalent in size to those in the MCI-186 group but who had received only conventional therapy. The course of change of the size of infarction was evaluated by MRI, and the metabolic changes following cerebral infarction were evaluated by proton MRS. As a result, there was no significant difference between the initial size of infarction in the conventionally treated group and that in the MCI-186 treated groups, nor did the groups show significant difference in the sequential changes depicted by MRI in the area of infarction, midline shift, or amount of edema. However, on MRS, the N-acetyl aspartate signal was significantly higher in the MCI-186 group than in the conventionally treated patients. In conclusion, MCI-186 has an effect of preservation of N-acetyl-aspartate, which is thought to be a neuronal marker, in cerebral infarction.

Edaravone, a free radical scavenger, protects components of the neurovascular unit against oxidative stress in vitro

The concept of the neurovascular unit suggests that to be successful, stroke therapies must protect all neuronal, glial and endothelial components in brain. In this study, we tested the efficacy of the free radical scavenger edaravone in three cellular models of oxidative stress. HT22 neuronal cells were subjected to oxidative stress using the standard glutamate-induced glutathione depletion model. Primary rat astrocytes were exposed to H(2)O(2). Oxidative stress was induced in human brain endothelial cells with sodium nitroprusside (SNP). Edaravone significantly reduced oxidative cell death in both HT22 neuronal cells and primary rat astrocytes in a dose-dependent manner. SNP did not kill brain endothelial cells but instead reduced their production of brain-derived neurotrophic factor (BDNF). Edaravone significantly ameliorated this response. These data suggest that free radical scavengers are effective in all cell types of the neurovascular unit, and should still be considered as a potential therapeutic approach for stroke.

Remarkable increase in 3-nitrotyrosine in the cerebrospinal fluid in patients with lacunar stroke

The goal of our study was whether free radicals contribute to the pathogenesis of the lacunar stroke to investigate the day after hospitalization, the concentrations of 3-nitrotyrosine and tyrosine in the cerebrospinal fluid (CSF) from living patients. The subjects included 20 living patients with lacunar stroke and 20 controls. The NIH stroke scale score was used to assess the severity of the stroke, including that the patients were mild cases. There was no expansion of the infarct lesion in the brain, as assessed by CT on the day following admission. The concentration of 3-nitrotyrosine was significantly higher in patients with lacunar stroke. In contrast, the concentration of tyrosine did not differ between the two groups. Furthermore, the 3-nitrotyrosine/tyrosine ratio was significantly higher in patients with lacunar stroke than in controls. Our results show that free radicals are produced in the CSF of lacunar stroke patients and that nitration of neuronal proteines is enhanced under this condition. These obsetvations suggest that lacunar stroke patients should be treated with edaravon, which is a free radical scavenger usually prescribed for cases of major strokes, as it will likely improve the prognosis of these patients.

Edaravone attenuates cerebral ischemic injury by suppressing aquaporin-4

Aquaporin-4 (AQP4) plays a role in the generation of post-ischemic edema. Pharmacological modulation of AQP4 function may thus provide a novel therapeutic strategy for the treatment of stroke, tumor-associated edema, epilepsy, traumatic brain injury, and other disorders of the central nervous system (CNS) associated with altered brain water balance. Edaravone, a free radical scavenger, is used for the treatment of acute ischemic stroke (AIS) in Japan. In this study, edaravone significantly reduced the infarct area and improved the neurological deficit scores at 24h after reperfusion in a rat transient focal ischemia model. Furthermore, edaravone markedly reduced AQP4 immunoreactivity and protein levels in the cerebral infarct area. In light of observations that edaravone specifically inhibited AQP4 in a rat transient focal ischemia model, we propose that edaravone might reduce cerebral edema through the inhibition of AQP4 expression following cerebral infarction.

Gene and Stem Cell Therapy in Ischemic Stroke

Possible strategies for treating ischemic stroke include neuroprotection (preventing injured neurons from undergoing apoptosis in the acute phase of cerebral ischemia) and stem cell therapy (the repair of disrupted neuronal networks with newly born neurons in the chronic phase of cerebral ischemia). First, we estimated the neuroprotective effect of glial cell line-derived neurotrophic factor (GDNF) by administration of GFNF protein. GDNF protein showed a direct protective effect against ischemic brain damage. Pretreatment of animals with adenoviral vector containing GDNF gene (Ad-GDNF) 24 h before the subsequent transient middle cerebral artery occlusion (MCAO) effectively reduced infarcted volume. Secondly, we studied the neuroprotective effect of a calcium channel blocker, azelnidipine, or a by-product of heme degradation, biliverdin. Both azelnidipine and biliverdin had a neuroprotective effect in the ischemic brain through their antioxidative property. Lastly, we developed a restorative stroke therapy with a bioaffinitive scaffold, which is able to provide an appropriate platform for newly born neurons. In the future, we will combine these strategies to develop more effective therapies for treatment of strokes.

Selective blockade of mGlu5 metabotropic glutamate receptors is hepatoprotective against fulminant hepatic failure induced by lipopolysaccharide and D-galactosamine in mice

This study was designed to investigate the influence of 2-methyl-6-phenylethynyl pyridine hydrochloride (MPEP), an antagonist of metabotropic glutamate receptor subtype 5, in lipopolysaccharide (LPS) and d-galactosamine (D-GalN)-induced fulminant hepatic failure in mice. Mice were given an intraperitoneal injection of 50 microg kg(-1) LPS and 500 mg kg(-1) D-GalN. MPEP (1, 5 and 25 mg kg(-1)) was administered intraperitoneally 1 h before LPS/D-GalN injection. Twenty-four hours after administration of LPS/D-GalN, plasma was collected and used for biochemical assays. Mice were euthanized and histological analysis and toxicological parameters were carried out in the liver. MPEP, at all doses tested, protected against the increase in aspartate and alanine aminotransferase activities induced by LPS/D-GalN exposure. Ascorbic acid levels were not altered in all experimental groups. Glutathione S-transferase activity was increased by administration of LPS/D-GalN and MPEP did not modify the enzyme activity in mice. MPEP, at the doses of 5 and 25 mg kg(-1), was effective in protecting against the decrease in catalase activity caused by LPS/D-GalN administration in mice. The histological data showed that sections of liver from LPS/D-GalN-exposed mice presented extensive injuries. MPEP, at all doses tested, reduced the scores of liver damage and markedly ameliorated the degree of liver damage. The hepatoprotective effect of MPEP on fulminant hepatic failure induced by LPS and D-GalN in mice was demonstrated.

Effects of Pretreatment with a Xanthine Oxidase Inhibitor on Free Radical Levels during Carotid Endarterectomy

OBJECTIVE

Free radicals contribute to the tissue damage caused by ischaemia-reperfusion. The aim of the present study was to investigate whether preoperative antioxidant therapy (allopurinol) affects free radical levels in cerebral venous blood in connection with surgery for carotid artery stenosis.

MATERIALS AND METHODS

Twenty-five patients were randomised into the study. Thirteen were controls and 12 were pretreated with allopurinol the day before surgery. Before, during and after surgery, blood samples were drawn from the ipsilateral jugular vein. Radical levels were measured using the spin trap technique ex vivo using OXANOH as the spin trap. Multivariate statistics were used with Principal Component Analysis and Partial Least Square regression analysis.

RESULTS

Radical levels increased with diabetes, high leukocyte count, high creatinine and a high degree of contralateral stenosis. Radical levels decreased with high age, blood pressure, collateral circulation as well as operation for left-side carotid artery stenosis. After pretreatment with allopurinol, several of the relationships noted in the control group were eliminated, i.e. leukocyte count, side of operation, Betapred pretreatment and collateral circulation.

CONCLUSIONS

Radical levels can be determined in connection with surgery for carotid artery stenosis using an ex vivo spin trap method. With preoperative antioxidant therapy the relationships between enhanced radical levels and clinical data, as seen in control subjects, disappeared. This might indicate a beneficial effect of preoperative pretreatment with antioxidants.

Edaravone, a free radical scavenger, mitigates both gray and white matter damages after global cerebral ischemia in rats

Recent studies have shown that similar to cerebral gray matter (mainly composed of neuronal perikarya), white matter (composed of axons and glias) is vulnerable to ischemia. Edaravone, a free radical scavenger, has neuroprotective effects against focal cerebral ischemia even in humans. In this study, we investigated the time course and the severity of both gray and white matter damage following global cerebral ischemia by cardiac arrest, and examined whether edaravone protected the gray and the white matter. Male Sprague-Dawley rats were used. Global cerebral ischemia was induced by 5 min of cardiac arrest and resuscitation (CAR). Edaravone, 3 mg/kg, was administered intravenously either immediately or 60 min after CAR. The morphological damage was assessed by cresyl violet staining. The microtubule-associated protein 2 (a maker of neuronal perikarya and dendrites), the beta amyloid precursor protein (the accumulation of which is a maker of axonal damage), and the ionized calcium binding adaptor molecule 1 (a marker of microglia) were stained for immunohistochemical analysis. Significant neuronal perikaryal damage and marked microglial activation were observed in the hippocampal CA1 region with little axonal damage one week after CAR. Two weeks after CAR, the perikaryal damage and microglial activation were unchanged, but obvious axonal damage occurred. Administration of edaravone 60 min after CAR significantly mitigated the perikaryal damage, the axonal damage, and the microglial activation. Our results show that axonal damage develops slower than perikaryal damage and that edaravone can protect both gray and white matter after CAR in rats.

Accumulation of oxidative stress around the stroke-like lesions of MELAS patients

To investigate the relationship between oxidative stress and progressive spread of the stroke-like lesions in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) with 3243A>G mutation, we retrospectively analyzed the spread frequency in patients with and without treatment with the radical scavenger edaravone. Oxidative damage and defensive enzymes were histologically evaluated. Spread was significantly less frequent in the patients treated with edaravone. Although 8-hydroxy-2'-deoxyguanosine, a marker for oxidative damage of DNA, was obviously accumulated in peri-lesional surviving neurons, manganese superoxide dismutase and 8-oxoguanine glycosylase 1 were not up-regulated in those neurons. Increased oxidative stress and insufficient defense could be involved in the pathogenesis of the spreading lesions in MELAS.

Dissociation and protection of the neurovascular unit after thrombolysis and reperfusion in ischemic rat brain

In the ischemic brain, reperfusion with tissue plasminogen activator (tPA) sometimes causes catastrophic hemorrhagic transformation (HT); however, the mechanism remains elusive. Here, we show that the basement membrane, and not the endothelial cells, is vulnerable to ischemic/reperfusion injury with tPA treatment. We treated a spontaneously hypertensive rat model of middle cerebral artery occlusion (MCAO) with vehicle alone, tPA alone, or a free radical scavenger, edaravone, plus tPA. Light and electron microscopic analyses of each microvascular component revealed that the basement membrane disintegrated and became detached from the astrocyte endfeet in tPA-treated animals that showed HT. On the other hand, edaravone prevented the dissociation of the neurovascular unit, dramatically decreased the HT, and improved the neurologic score and survival rate of the tPA-treated rats. These results suggest that the basement membrane that underlies the endothelial cells is a key structure for maintaining the integrity of the neurovascular unit, and a free-radical scavenger can be a viable agent for inhibiting tPA-induced HT.

Hepatoprotective effect of 3-alkynyl selenophene on acute liver injury induced by D-galactosamine and lipopolysaccharide

The aim of this study was to investigate the hepatoprotective effect of 3-alkynyl selenophene (compound a), a selenophene compound, on acute liver injury induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS) in rats. The animals received compound a (25 and 50 mg/kg; per oral, p.o.) in the first day of treatment. In the second day, the rats received D-GalN (500 mg/kg; intraperitoneal, i.p.) and LPS (50 microg/kg; intraperitoneal, i.p.). Twenty-four hours after D-GalN/LPS administration animals were euthanized to the biochemical and histological analysis. Compound a (25 and 50 mg/kg; p.o.) protected against the increase in aspartate aminotransferase (AST) activity induced by D-GalN/LPS. Compound a at 50 mg/kg protected against the increase in alanine aminotransferase (ALT) activity induced by D-GalN/LPS. The inhibition of delta-aminolevulinic dehydratase (delta-ALA-D) activity and the decrease of ascorbic acid levels caused by D-GalN/LPS were protected by compound a (25 and 50 mg/kg). Glutathione S-transferase (GST) and catalase activities were not altered in all groups. The histological data showed that sections of liver from D-GalN/LPS-treated rats presented massive hemorrhage, the presence of inflammatory cells and necrosis. Compound a attenuated D-GalN/LPS-induced hepatic histopathological alterations. Based on the results, we demonstrated the hepatoprotective effect of compound a on acute liver injury induced by D-GalN/LPS.

Administration of free radical scavenger edaravone associated with higher frequency of hemorrhagic transformation in patients with cardiogenic embolism

Free radicals are known to activate coagulation and inhibit fibrinolysis. Edaravone, a free radical scavenger, protects vascular endothelial cells and neurons during acute brain ischemia in in vitro models. Hemorrhagic transformation and treatment outcomes were retrospectively examined in 76 patients with acute cardiogenic embolism treated with edaravone in addition to routine treatment within 24 hours of the onset of symptoms. Hemorrhagic transformation was categorized according to European Cooperative Acute Stroke Study-II. Patient characteristics were also evaluated, including evidence of hypertension, diabetes mellitus, hyperlipidemia, coronary heart disease, history of smoking, National Institutes of Health Stroke Scale on arrival, and modified Rankin scale at 3 months post-onset. Edaravone administration was one of the factors that contributed to increased frequency of hemorrhagic transformation, but had showed no significant relationship with the outcome. The present study showed that edaravone administration increased the frequency of hemorrhagic transformation with heparin in patients with cardiogenic embolism. Free radical scavenging may have promoted the coagulating conditions. Edaravone administration may allow reduction of the dose of heparin and tissue plasminogen activator in patients with acute ischemic stroke.

Efficacy of the free radical scavenger, edaravone, for motor palsy of acute lacunar infarction

OBJECTIVE

Free radicals are important in causing neural cell injury during cerebral infarction. Although there was a randomized, placebo-controlled, double-blind study at multiple centers in Japan showing the efficacy of the free radical scavenger, edaravone, in acute cerebral infarction, to date the clinical studies are few. This study investigated the effect of edaravone on the outcome of patients with acute lacunar infarction.

METHODS

We retrospectively evaluated 124 consecutive patients with first-ever acute lacunar infarctions who were admitted to our hospital within 24 hours after the onset between January 2004 and June 2007. Of these, 59 patients received both edaravone and conventional therapy (edaravone group), and the other 65 underwent conventional therapy only (non-edaravone group). There was no significant difference in patients' baseline characteristics in the two groups. The clinical outcome was assessed by the National Institutes of Health Stroke Scale (NIHSS).

RESULTS

The reduction of NIHSS scale during hospitalization (1.5+/-1.0 vs. 1.0+/-1.1; p = 0.007), especially that of the motor palsy scale (1.0+/-1.0 vs. 0.5+/-1.0; p = 0.006) was significantly larger, and the percentage of patients with a favorable outcome (NIHSS at discharge < or =1) (91.5% vs. 78.5%; p = 0.044) was significantly better in the edaravone group.

CONCLUSION

Edaravone improves the outcomes of patients with acute lacunar infarction, especially motor palsy, without regard to the conventional therapy performed concomitantly.

Role of secretory phospholipase a(2) in CNS inflammation: implications in traumatic spinal cord injury

Secretory phospholipases A(2) (sPLA(2)s) are a subfamily of lipolytic enzymes which hydrolyze the acyl bond at the sn-2 position of glycerophospholipids to produce free fatty acids and lysophospholipids. These products are precursors of bioactive eicosanoids and platelet-activating factor (PAF). The hydrolysis of membrane phospholipids by PLA(2) is a rate-limiting step for generation of eicosanoids and PAF. To date, more than 10 isozymes of sPLA(2) have been found in the mammalian central nervous system (CNS). Under physiological conditions, sPLA(2)s are involved in diverse cellular responses, including host defense, phospholipid digestion and metabolism. However, under pathological situations, increased sPLA(2) activity and excessive production of free fatty acids and their metabolites may lead to inflammation, loss of membrane integrity, oxidative stress, and subsequent tissue injury. Emerging evidence suggests that sPLA(2) plays a role in the secondary injury process after traumatic or ischemic injuries in the brain and spinal cord. Importantly, sPLA(2) may act as a convergence molecule that mediates multiple key mechanisms involved in the secondary injury since it can be induced by multiple toxic factors such as inflammatory cytokines, free radicals, and excitatory amino acids, and its activation and metabolites can exacerbate the secondary injury. Blocking sPLA(2) action may represent a novel and efficient strategy to block multiple injury pathways associated with the CNS secondary injury. This review outlines the current knowledge of sPLA(2) in the CNS with emphasis placed on the possible roles of sPLA(2) in mediating CNS injuries, particularly the traumatic and ischemic injuries in the brain and spinal cord.

[Neuroprotective therapy for ischemic stroke with free radical scavenger and gene-stem cell therapy]

A free radical scavenger Edaravone is the first clinical drug for neuroprotection in the world which has been used from 2001 in most ischemic stroke patients in Japan, and is especially useful in thrombolytic therapy with tissue plasminogen activator (tPA). Of great importance for regenerative therapy and gene therapy are the neural stem cells which are intrinsically activated or exogenously transplanted. Addition of NTFs greatly enhanced an intrinsic migration or invasion of stem cells into the scaffold, which could provide a future regenerative potential against ischemic brain damage at chronic stage.

The novel antioxidant edaravone: from bench to bedside

Over the last decade, important advances have been made to support the fact that reactive oxygen species (ROS) are generated and play a harmful role during the acute and late stages of cerebral ischemia. Several drugs, such as radical scavengers and antioxidants, have been evaluated in preclinical and clinical studies. Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one; Radicut, Mitsubishi Tanabe Pharma Corporation) is a novel antioxidant that is currently used in Japan for the treatment of patients in the acute stage of cerebral infarction. Edaravone scavenges ROS and inhibits proinflammatory responses after brain ischemia in animals and humans. In particular, postischemic inflammation, leading to brain edema and infarction due to neuronal damage and endothelial cell death, can be ameliorated by edaravone. In addition to these antistroke effects, edaravone has also been shown to prevent oxidative damage to various extracerebral organs. Therefore, in addition to its usefulness in the treatment of stroke, edaravone is expected to play an integral role in the treatment of many oxidative stress-related diseases.

Therapeutic strategy for ischemic stroke

Possible strategies for treating ischemic stroke include: (1) Neuroprotection: preventing damaged neurons from undergoing apoptosis in the acute phase of cerebral ischemia; (2) Stem cell therapy: the repair of broken neuronal networks with newly born neurons in the chronic phase of cerebral ischemia. Firstly, we studied the neuroprotective effect of a calcium channel blocker, azelnidipine, or a by-product of heme degradation, biliverdin, in the ischemic brain. These results revealed both azelnidipine and biliverdin had a neuroprotective effect in the ischemic brain through their anti-oxidative property. Secondly, we investigated the role of granulocyte colony-stimulating factor (G-CSF) by administering G-CSF to rats after cerebral ischemia and found G-CSF plays a critical role in neuroprotection. Lastly, we developed a restorative stroke therapy with a bio-affinitive scaffold, which is able to provide an appropriate environment for newly born neurons. In the future, we will combine these strategies to develop more effective therapies for treatment of strokes.

Edaravone protects against MPP+ -induced cytotoxicity in rat primary cultured astrocytes via inhibition of mitochondrial apoptotic pathway

Edaravone (Eda) is a potent scavenger of hydroxyl radicals and has been demonstrated to be beneficial for patients with acute ischemic stroke. This study was set out to investigate whether Eda protect against MPP(+)-induced cytotoxicity in rat primary cultured astrocytes. The results showed that pre-treatment with Eda inhibited astrocytic apoptosis and lactate dehydrogenase release induced by MPP(+) (200 microM). Further study revealed that Eda prevented GSH depletion, down-regulated mRNA expressions of NADPH oxidase membrane subunit gp91 and membrane-translocated subunit p47, and prevented the decreases of state 3 respiration respiration and respiratory control ratio induced by MPP(+), and thereby inhibited reactive oxygen species production evoked by MPP(+). Moreover, Eda could ameliorate mitochondrial respiratory function, restrain, and prevent mitochondrial membrane potential loss induced by MPP(+). Consequently, Eda inhibited releases of cytochrome c and apoptosis-inducing factor induced by MPP(+). Taken together, these findings reveal for the first time that Eda protects against MPP(+)-induced astrocytic apoptosis via decreasing intracellular reactive oxygen species level and subsequently inhibiting mitochondrial apoptotic pathway. The antiapoptosis effects of Eda on astrocytes may provide a new perspective on neuroprotective therapy.

Combination effects of normobaric hyperoxia and edaravone on focal cerebral ischemia-induced neuronal damage in mice

We evaluated the potential neuroprotective effects of combination treatment with normobaric hyperoxia (NBO) and edaravone, a potent scavenger of hydroxyl radicals, on acute brain injuries after stroke. Mice subjected to 2-h filamental middle cerebral artery occlusion were treated with NBO (95% O2, during the ischemia) alone, with edaravone (1.5 mg/kg, intravenously after the ischemia) alone, with both of these treatments (combination), or with vehicle. The histological and neurological score were assessed at 22-h after reperfusion. Infarct volume was significantly reduced in the combination group [36.3+/-6.7 mm3 (n=10) vs. vehicle: 65.5+/-5.9 mm3 (n=14) P<0.05], but not in the two monotherapy-groups [NBO: 50.5+/-5.8 mm3 (n=14) and edaravone: 56.7+/-5.8 mm3 (n=10)]. The combination therapy reduced TUNEL-positive cells in the ischemic boundary zone both in cortex [6.0+/-1.4 x 10(2)/mm2 (n=5) vs. vehicle: 18.9+/-2.4 x 10(2)/mm2 (n=5), P<0.01] and subcortex [11.6+/-1.5 x 10(2)/mm2 (n=5) vs. vehicle: 22.5+/-2.1 x 10(2)/mm2 (n=5), P<0.01]. NBO and combination groups exhibited significantly reduced neurological deficit scores at 22-h after reperfusion (vs. vehicle, P<0.05). Combination therapy with NBO plus edaravone prevented the neuronal damage after focal cerebral ischemia and reperfusion in mice, compared with monotherapy of NBO or edaravone.

Edaravone, a free radical scavenger, ameliorates experimental autoimmune encephalomyelitis

Reactive oxygen species (ROS) are implicated in the pathogenesis of multiple sclerosis (MS) and its murine model experimental autoimmune encephalomyelitis (EAE). The effect of edaravone, a free radical scavenger, on EAE was investigated in this study. Treatment with edaravone significantly ameliorated the clinical severity of EAE, and a reduced infiltration of lymphocytes was observed based on a histological analysis. The expression of inducible NO synthase (iNOS) in the spinal cords appeared to be reduced by the treatment with edaravone and this effect was confirmed in vitro. A reduction of both the cellular infiltration and the expression of iNOS may therefore underlie the mechanisms of the beneficial effect of edaravone on EAE.

Acute neurovascular unit protective action of pinocembrin against permanent cerebral ischemia in rats

Acute vascular- and neuroprotective effects of pinocembrin (1) were evaluated in a rat model of focal cerebral ischemia. Focal cerebral ischemia was induced by the middle cerebral artery occlusion (MCAO) for 24 h. 5,7-Dihydroxyflavanone (compound 1; at 3, 10, or 30 mg/kg), intravenously injected at 0, 8, and 16 h after MCAO, reduced the cerebral infarct volumes by 47, 39, and 37%, respectively, as visualized by 2,3,5-triphenyltetrazolium chloride staining (P < 0.01). Treatment with 1 also reduced brain swelling and improved behavioral deficits significantly (P < 0.01 and 0.05, respectively). To evaluate the effect of 1 on blood-brain barrier (BBB) disruption, mixture of Evans Blue (EB) and sodium fluorescein (NF) was intravenously injected immediately after MCAO. Global NF/EB uptake and fluorescence imaging of local BBB disruption were measured. Treatment with compound 1 reduced the leakage of both dyes, manifesting a preventive action in BBB integrity. This is the first time to demonstrate that 1 has acute neurovascular protective action against permanent focal cerebral ischemia. The mechanism of neurovascular protective action of 1 is under investigation.

Supplementation with a synthetic polyphenol limits oxidative stress and enhances neuronal cell viability in response to hypoxia-re-oxygenation injury

Oxidative stress is associated with the pathology of acute and chronic neurodegenerative disease. Cultured human neuronal cells exposed to experimental hypoxia-re-oxygenation (H/R) injury responded with an increased production of reactive oxygen species (ROS) and a significant decrease in intracellular ATP. Expression of genes encoding for hypoxia-inducible factor 1-alpha (HIF1-alpha), inducible haemoxygenase-1 (HO-1), glucose transporter-1 (Glut-1), the oxygen-sensor neuroglobin (Nb) and Cu,Zn-superoxide dismutase (SOD1), catalase (CAT) and glutathione peroxidase-1 (Gpx-1) increased significantly in response to the insult. Enhanced expression of HO-1, SOD1 and CAT correlated with an increase in the corresponding protein activity. Despite the cellular response to bolster antioxidant capacity, apoptosis and necrosis increased following H/R injury. In contrast, ROS accumulation, the endogenous gene response and cell death was limited in neuronal cells pre-incubated with 50 or 100, but not 10 microM of the phenolic antioxidant 3,3',5,5'-tetra-t-butyl-biphenyl-4,4'-diol (BP) prior to H/R injury. These data indicate that the early endogenous gene response to H/R injury is unable to inhibit neuronal dysfunction and that increasing cellular antioxidant capacity with a synthetic polyphenol (>10 microM) is potentially neuro-protective.

Molecular mechanisms of apoptosis in cerebral ischemia: multiple neuroprotective opportunities

Cerebral ischemia/reperfusion (I/R) injury triggers multiple and distinct but overlapping cell signaling pathways, which may lead to cell survival or cell damage. There is overwhelming evidence to suggest that besides necrosis, apoptosis do contributes significantly to the cell death subsequent to I/R injury. Both extrinsic and intrinsic apoptotic pathways play a vital role, and upon initiation, these pathways recruit downstream apoptotic molecules to execute cell death. Caspases and Bcl-2 family members appear to be crucial in regulating multiple apoptotic cell death pathways initiated during I/R. Similarly, inhibitor of apoptosis family of proteins (IAPs), mitogen-activated protein kinases, and newly identified apoptogenic molecules, like second mitochondrial-activated factor/direct IAP-binding protein with low pI (Smac/Diablo), omi/high-temperature requirement serine protease A2 (Omi/HtrA2), X-linked mammalian inhibitor of apoptosis protein-associated factor 1, and apoptosis-inducing factor, have emerged as potent regulators of cellular apoptotic/antiapoptotic machinery. All instances of cell survival/death mechanisms triggered during I/R are multifaceted and interlinked, which ultimately decide the fate of brain cells. Moreover, apoptotic cross-talk between major subcellular organelles suggests that therapeutic strategies should be optimally directed at multiple targets/mechanisms for better therapeutic outcome. Based on the current knowledge, this review briefly focuses I/R injury-induced multiple mechanisms of apoptosis, involving key apoptotic regulators and their emerging roles in orchestrating cell death programme. In addition, we have also highlighted the role of autophagy in modulating cell survival/death during cerebral ischemia. Furthermore, an attempt has been made to provide an encouraging outlook on emerging therapeutic approaches for cerebral ischemia.

Clinical analysis of 207 patients who developed renal disorders during or after treatment with edaravone reported during post-marketing surveillance

BACKGROUND

The post-marketing surveillance of edaravone has reported serious adverse reactions, including renal and hepatic disorders. Renal disorders were the most frequently reported serious/important adverse reactions, which led to the evaluation of their causation by edaravone, their severity, and the recovery of renal function.

METHODS

A retrospective review was carried out of 207 Japanese patients with acute stroke who developed renal disorders on edaravone treatment.

RESULTS

No particular factor other than edaravone was found as a possible cause of the renal disorders in 17 patients (8.2%). In 91.8% of the patients evaluated, factors other than edaravone were associated with the development of renal disorders. Severe deterioration of systemic status (e.g., a severe infection or a decrease in blood pressure) was considered to be a highly probable cause of renal disorders that occurred before or during treatment with edaravone in 135 patients (65.2%). Fifty-nine patients (28.5%) underwent blood purification treatment (BPT). In the remaining 148 patients without BPT, the peak serum creatinine (SCr) level during follow-up was 3 mg/dl or more in 93 patients (44.9%) and less than 3 mg/dl in 55 patients (26.6%). The severity of renal disorders was moderate to severe in 73.3% of the 207 patients, and renal function recovered in 43%.

CONCLUSIONS

Appropriate treatment of deteriorated systemic status and the discontinuation of edaravone administration following the early discovery of renal disorders are recommended to reduce the development of severe renal disorders during edaravone treatment. The precise role(s) of edaravone in the pathogenesis of renal disorders should be evaluated in the future.

A case report of acute renal failure and fulminant hepatitis associated with edaravone administration in a cerebral infarction patient

A 60-year-old male with cerebral infarction was admitted to our hospital and treated with edaravone. On day 12 of hospitalization, he suddenly lost consciousness and went into shock. Based on the laboratory findings, acute renal failure (ARF), fulminant hepatitis, and disseminated intravascular coagulation (DIC) were diagnosed. We immediately initiated continuous hemodiafiltration for three days and performed three sessions of plasma exchange. Following this, a gradual improvement was observed in the patient's general condition and laboratory values. On day 17 of hospitalization, intermittent hemodialysis (HD) was initiated. On day 20 of hospitalization, his renal function started to improve with an increase in urine volume. HD was successfully discontinued on the same day. Although the drug lymphocyte stimulation test for edaravone was negative, edaravone-induced fulminant hepatitis was suggested based on liver biopsy findings. We present a case of ARF, fulminant hepatitis, and DIC due to edaravone administration that was successfully treated with blood purification techniques. Since the use of edaravone treatment is expected to increase in the future, it is essential that clinicians consider the potential adverse effects of this treatment. It is suggested that blood purification is effective in inducing remission in patients with complications due to edaravone treatment.

Nitric oxide-induced apoptosis in cultured rat astrocytes: protection by edaravone, a radical scavenger

Nitric oxide induces apoptosis-like cell death in cultured astrocytes, but the exact mechanism is not known. This study further characterized the mechanism of nitric oxide-induced cytotoxicity, and examined the effect of edaravone, a radical scavenger, on cytotoxicity. Treatment of cultured rat astrocytes with sodium nitroprusside (SNP), a nitric oxide donor, for 72 h, decreased cell viability by causing apoptosis-like cell death. The injury was accompanied by increases in the production of reactive oxygen species and in the level of nuclear apoptosis-inducing factor, but not in caspase activity. SNP-induced cytotoxicity was blocked by the c-jun N-terminal protein kinase (JNK) inhibitor SP600125 (20 microM), the p38 mitogen-activated protein (MAP) kinase inhibitor SB203580 (20 microM), and the extracellular signal-regulating kinase (ERK) inhibitor U0126 (10 microM), and the nitric oxide donor stimulated the phosphorylation of p38 MAP kinase, JNK, and ERK. Edaravone (10 microM) protected astrocytes against SNP-induced cell injury and it inhibited SNP-induced phosphorylation of p38 MAP kinase, JNK, and ERK, and the production of reactive oxygen species. Edaravone also attenuated SNP-induced increase in nuclear apoptosis-inducing factor levels. These results suggest that MAP kinase pathways play a key role in nitric oxide-induced apoptosis and that edaravone protects against nitric oxide-induced cytotoxicity by inhibiting nitric oxide-induced MAP kinase activation in astrocytes.

Pulse radiolysis study on free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one)

The reactions between edaravone and various one-electron oxidants such as (*)OH, N(3)(*), Br(2)(-), and SO(4)(-), have been studied by pulse radiolysis techniques. The transient species produced by the reaction of edaravone with (*)OH radical shows an absorption band with lambda(max)=320 nm, while the oxidation by N(3)(*), Br(2)(-), SO(4)(-) and CCl(3)OO(*) results in an absorption band with lambda(max)=345 nm. Different from the previous reports, the main transient species by the reaction of edaravone with (*)OH radical in the absence of O(2) is attributed to OH-adducts. At neutral condition (pH 7), the rate constants of edaravone reacting with (*)OH, N(3)(*), SO(4)(-), CCl(3)OO(*), and e(aq)(-) are estimated to be 8.5x10(9), 5.8x10(9), 6x10(8), 5.0x10(8) and 2.4x10(9)dm(3)mol(-1)s(-1), respectively. From the pH dependence on the formation of electron adducts and on the rate constant of edaravone with hydrated electron, the pK(a) of edaravone is estimated to be 6.9+/-0.1.

Effects of MCI-186 upon neutrophil-derived active oxygens

Reactions of 3-methyl-1-phenyl-2-pyrazoline-5-one (MCI-186) with hypochlorous acid and superoxide were analysed by spectrophotometry and mass spectrometry. The results were applied to the neutrophil system to evaluate the scavenging activity of neutrophil-derived active oxygen species by MCI-186. MCI-186 reacted rapidly with hypochlorous acid (1 x 10(6) M(-1)s(-1)) to form a chlorinated intermediate, followed by a slow conversion to a new spectrum. MCI-186 consumed 3 moles of hypochlorous acid and did not react with superoxide. The newly synthesized fluorescence probes, 2-[6-(4'-amino)-phenoxy-3H-xanthen-3-on-9-yl]benzoic acid (APF) and 2-[6-(4'-hydroxy)phenoxy-3H-anthen-3-on-9-yl]benzoic acid (HPF) successfully detected neutrophil-derived active oxygens (Setsukinai K, Urano Y, Kakinuma K, Majima HJ, Nagano T. Development of novel fluorescence probes that can reliably detect reactive oxygen species and distinguish specific species. J Biol Chem 2003; 278: 3170-3175). The rate constants for the reaction of hypochlorous acid with MCI-186 and fluorescence probes was in the order of MCI-186 > APF > HPF. Fluorescence due to the oxidation of APF and HPF was observed with the stimulated neutrophils. The result that the intensity from APF oxidation was higher than that from HPF oxidation is compatible with reports that APF selectively reacts with hypochlorous acid. Fluorescence due to oxidation of both APF and HPF decreased when the reactions were carried out in the presence of a fluorescence probe and MCI-186 in a dose-dependent manner. These results indicate that MCI-186 effectively scavenges neutrophil-derived hypochlorous acid and other active oxygens.

Reduction of cerebral infarction in rats by biliverdin associated with amelioration of oxidative stress

Biliverdin (BV), one of the byproducts of heme catalysis through heme oxygenase (HO) system, is a scavenger of reactive oxygen species (ROS). We hypothesized that BV treatment could protect rat brain cells from oxidative injuries via its anti-oxidant efficacies. Cerebral infarction was induced by transient middle cerebral artery occlusion (tMCAO) for 90 min, followed by reperfusion. BV or vehicle was administered intraperitoneally immediately after reperfusion. The size of the cerebral infarction 2 days after tMCAO was evaluated by 2,3,5-triphenyltetrazolium chloride (TTC) stain. Superoxide generation 4 h after tMCAO was determined by detection of oxidized hydroethidine. In addition, the oxidative impairment of neurons were immunohistochemically assessed by stain for lipid peroxidation with 4-hydroxy-2-nonenal (4-HNE) and damaged DNA with 8-hydroxy-2'-deoxyguanosine (8-OHdG). BV treatment significantly reduced infarct volume of the cerebral cortices associated with less superoxide production and decreased oxidative injuries of brain cells. The present study demonstrated that treatment with BV ameliorated the oxidative injuries on neurons and decreased brain infarct size in rat tMCAO model.