G-CSF administration is neuroprotective following transient cerebral ischemia even in the absence of a functional NOS-2 gene

Development of a reactive oxygen species-sensitive nitric oxide synthase inhibitor for the treatment of ischemic stroke

Ischemic stroke is caused by a blockage of cerebral blood flow resulting in neuronal and glial hypoxia leading to inflammatory and reactive oxygen species (ROS)-mediated cell death. Nitric oxide (NO) formed by NO synthase (NOS) is known to be protective in ischemic stroke, however NOS has been shown to 'uncouple' under oxidative conditions to instead produce ROS. Nitrones are antioxidant molecules that are shown to trap ROS to then decompose and release NO. In this study, the nitrone 5 was designed such that its decomposition product is a NOS inhibitor, 6, effectively leading to NOS inhibition specifically at the site of ROS production. The ability of 5 to spin-trap radicals and decompose to 6 was observed using EPR and LC-MS/MS. The pro-drug concept was tested in vitro by measuring cell viability and 6 formation in SH-SY5Y cells subjected to oxygen glucose deprivation (OGD). 5 was found to be more efficacious and more potent than PBN, and was able to increase phospho-Akt while reducing nitrotyrosine and cleaved caspase-3 levels. 6 treatment, but not 5, was found to decrease NO production in LPS-stimulated microglia. Doppler flowmetry on anesthetized mice showed increased cerebral blood flow upon intravenous administration of 1mg/kg of 5, but a return to baseline upon administration of 10mg/kg, likely due to its dual nature of antioxidant/NO-donor and NOS-inhibition. Mice treated with 5 after permanent ischemia exhibited a >30% reduction in infarct volume, and higher formation of 6 in ischemic tissue resulting in region specific effects limited to the infarct area.

Intraventricular infusion of a low fraction of serum enhances neurogenesis and improves recovery in a rodent stroke model

Enhancing endogenous neurogenesis is a potential therapeutic strategy in stroke treatment. We have previously demonstrated that treatment with a fraction of serum with molecular weight of less than 100 kDa (100K) combined with bFGF promoted neurogenesis of cultured stem and progenitor cells (NSPCs). In this study, we further evaluated the efficacy of intraventricular administration of 100K with bFGF (100K/bFGF) in a rat model of transient middle cerebral artery occlusion (MCAO). Rats administered 100K/bFGF on post-stroke day 1 exhibited a higher number of Ki67 and Nestin immunoreactive cells at the subventricular zone (SVZ) area and in the infarcted brain, indicating promotion of NSPCs proliferation. The 100K/bFGF treatment also predominantly increased the number of MAP-2 immunoreactive cells rather than GFAP immunoreactive cells at the SVZ area and in the infarcted regions, implying that 100K/bFGF dominated NSPCs differentiating into neurons rather than astrocytes. Importantly, treatment with 100K/bFGF significantly improved the animals' motor coordination. These findings demonstrated that treatment with a low serum fraction and bFGF benefited ischemic stroke likely through promotion of the proliferation and neuronal differentiation of endogenous NSPCs.

Ferulic acid ameliorates nerve injury induced by cerebral ischemia in rats

This study was designed to investigate the protective effect of ferulic acid (FA) on nerve injury induced by cerebral ischemia. Focal cerebral ischemia was induced by occlusion of the right middle cerebral artery and reperfusion 90 min later in male Sprague-Dawley rats. Daily treatment of the rats with FA was initiated 30 min after the surgery, and was continued for 7 days. The efficacy of FA against nerve injury was assessed by neurological deficit scores as well as pathohistological observation. The expression levels in the brain and level in the peripheral blood of erythropoietin (EPO) and granulocyte colony-stimulating factor (G-CSF) were analyzed by immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), respectively. The results showed that FA attenuated nerve injury of the hippocampus, significantly ameliorated neurological deficits, and increased EPO but not G-CSF expression in the hippocampus and the peripheral blood of ischemic rats. The findings indicate that FA has certain protective effects on the nerve injury of cerebral ischemia, and suggest that promoting EPO in the brain and peripheral blood may be one of the neuroprotective mechanisms of FA.

Tissue-protective cytokines: structure and evolution

Cytokines are important mediators of host defense and immunity, and were first identified for their role in immunity to infections. It was then found that some of them are pathogenic mediators in inflammatory diseases and much of the emphasis is now on pro-inflammatory cytokines, also in consideration of the fact that TNF inhibitors became effective drugs in chronic inflammatory diseases. The recent studies on the tissue-protective activities of erythropoietin (EPO) led to the term "tissue-protective cytokine." We discuss here how tissue-protective actions might be common to other cytokines, particularly those of the 4-alpha helical structural superfamily.

Stem cell therapy for cerebral ischemia: from basic science to clinical applications

Recent stem cell technology provides a strong therapeutic potential not only for acute ischemic stroke but also for chronic progressive neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis with neuroregenerative neural cell replenishment and replacement. In addition to resident neural stem cell activation in the brain by neurotrophic factors, bone marrow stem cells (BMSCs) can be mobilized by granulocyte-colony stimulating factor for homing into the brain for both neurorepair and neuroregeneration in acute stroke and neurodegenerative diseases in both basic science and clinical settings. Exogenous stem cell transplantation is also emerging into a clinical scene from bench side experiments. Early clinical trials of intravenous transplantation of autologous BMSCs are showing safe and effective results in stroke patients. Further basic sciences of stem cell therapy on a neurovascular unit and neuroregeneration, and further clinical advancements on scaffold technology for supporting stem cells and stem cell tracking technology such as magnetic resonance imaging, single photon emission tomography or optical imaging with near-infrared could allow stem cell therapy to be applied in daily clinical applications in the near future.

Monocyte chemoattractant protein-1-deficiency impairs the expression of IL-6, IL-1β and G-CSF after transient focal ischemia in mice

Monocyte chemoattractant protein-1 (MCP-1), a chemokine secreted by neurons and astrocytes following stroke is known to aggravate ischemia-related damage. Previous studies revealed that MCP-1-deficient mice develop smaller infarcts and have an improved neurological outcome, whereas mice overexpressing MCP-1 show worsened brain damage and impaired neurological function. The aim of the present study was to elucidate the molecular background of the enhanced recovery in MCP-1-deficient mice after stroke. For this purpose, we (1) performed expression analyses on crucial post-stroke related inflammatory genes in MCP-1-deficient mice compared to wildtype controls, (2) analyzed a possible impact of MCP-1 on astrocyte activation (3) investigated the cellular origin of respective inflammatory cytokines and (4) analyzed the impact of MCP-1 secretion on the migration of both neutrophil granulocytes and T-cells. Here we report that MCP-1-deficiency leads to a shift towards a less inflammatory state following experimental occlusion of the middle cerebral artery including an impaired induction of interleukin-6, interleukin-1β and granulocyte-colony stimulating factor expression as well as a subsequent diminished influx of hematogenous cells. Additionally, MCP-1-deficient mice developed smaller infarcts 36 hours after experimental stroke. Investigations revealed no differences in transcription of tumor necrosis factor-α and astrogliosis 12 and 36 hours after onset of ischemia. These novel results help to understand post ischemic, inflammatory mechanisms and might give further arguments towards therapeutical interventions by modulation of MCP-1 expression in post stroke inflammation.