Fibronectin and neuroprotective effect of granulocyte colony-stimulating factor in focal cerebral ischemia

G-CSF improving combined whole brain radiotherapy and immunotherapy prognosis of non-small cell lung cancer brain metastases

OBJECTIVE

To evaluate the therapeutic advantage of G-CSF to whole brain radiotherapy (WBRT) in combination with immunotherapy as a first-line treatment for non-small cell lung cancer (NSCLC) brain metastases (BMs).

METHODS

In this retrospective study, 117 patients (37 in G-CSF group and 80 in no G-CSF group) who underwent first-line WBRT combined with immunotherapy were enrolled. Their survival, intracranial response, BM-related symptoms and toxicity were evaluated.

RESULTS

The overall survival (OS) of patients in G-CSF group was significantly improved compared to patients no G-CSF group (median time: 14.8 vs 10.2 months; HR: 0.61, 95 % CI: 0.38-0.97, p = 0.035). However, there were no significant differences in intracranial responses between the two groups (p > 0.05). The G-CSF group exhibited a significantly higher rate of relief from BM-related symptoms compared to the no G-CSF group (91.7 % vs 59.5 %, p = 0.037). Cox proportional hazards regression analyses indicated that after-treatment ALC > 0.9 × 10^9/L (HR 0.57, 95 % CI 0.32-0.99, p = 0.046) and Hb > 110 g/dL (HR 0.41, 95 % CI 0.24-0.71, p = 0.001) were significant potential factors associated with extended OS. The addition of G-CSF was well tolerated and effectively reduced the incidence of neutropenia (0 % vs 5.0 %, p = 0.17).

CONCLUSION

Integrating G-CSF with WBRT and immunotherapy as a first-line treatment for NSCLC-BMs has exhibited significant efficacy and favorable tolerability.

PDGFR-positive cell-mediated post-stroke remodeling of fibronectin and laminin 2 for tissue repair and functional recovery

Post-stroke intra-infarct repair promotes peri-infarct neural reorganization leading to functional recovery. Herein, we examined the remodeling of extracellular matrix proteins (ECM) that constitute the intact basal membrane after permanent middle cerebral artery occlusion (pMCAO) in mice. Among ECM, collagen type IV remained localized on small vessel walls surrounding CD31-positive endothelial cells within infarct areas. Fibronectin was gradually deposited from peri-infarct areas to the ischemic core, in parallel with the accumulation of PDGFRβ-positive cells. Cultured PDGFRβ-positive pericytes produced fibronectin, which was enhanced by the treatment with PDGF-BB. Intra-infarct deposition of fibronectin was significantly attenuated in pericyte-deficient Pdgfrb^+/-mice. Phagocytic activity of macrophages against myelin debris was significantly enhanced on fibronectin-coated dishes. In contrast, laminin α2, produced by GFAP- and aquaporin 4-positive astrocytes, accumulated strongly in the boundary of peri-infarct areas. Pericyte-conditioned medium increased the expression of laminin α2 in cultured astrocytes, partly through TGFβ1. Laminin α2 increased the differentiation of oligodendrocyte precursor cells into oligodendrocytes and the expression of myelin-associated proteins. Peri-infarct deposition of laminin α2 was significantly reduced in Pdgfrb^+/-mice, with attenuated oligodendrogenesis in peri-infarct areas. Collectively, intra-infarct PDGFRβ-positive cells may orchestrate post-stroke remodeling of key ECM that create optimal environments promoting clearance of myelin debris and peri-infarct oligodendrogenesis.

Pericytes for Therapeutic Approaches to Ischemic Stroke

Pericytes are perivascular multipotent cells located on capillaries. Although pericytes are discovered in the nineteenth century, recent studies have found that pericytes play an important role in maintaining the blood—brain barrier (BBB) and regulating the neurovascular system. In the neurovascular unit, pericytes perform their functions by coordinating the crosstalk between endothelial, glial, and neuronal cells. Dysfunction of pericytes can lead to a variety of diseases, including stroke and other neurological disorders. Recent studies have suggested that pericytes can serve as a therapeutic target in ischemic stroke. In this review, we first summarize the biology and functions of pericytes in the central nervous system. Then, we focus on the role of dysfunctional pericytes in the pathogenesis of ischemic stroke. Finally, we discuss new therapies for ischemic stroke based on targeting pericytes.

Neuroprotection through G-CSF: recent advances and future viewpoints

Granulocyte-colony stimulating factor (G-CSF), a member of the cytokine family of hematopoietic growth factors, is 19.6 kDa glycoprotein which is responsible for the proliferation, maturation, differentiation, and survival of neutrophilic granulocyte lineage. Apart from its proven clinical application to treat chemotherapy-associated neutropenia, recent pre-clinical studies have highlighted the neuroprotective roles of G-CSF i.e., mobilization of haemopoietic stem cells, anti-apoptotic, neuronal differentiation, angiogenesis and anti-inflammatory in animal models of neurological disorders. G-CSF is expressed by numerous cell types including neuronal, immune and endothelial cells. G-CSF is released in autocrine manner and binds to its receptor G-CSF-R which further activates numerous signaling transduction pathways including PI3K/AKT, JAK/STAT and MAP kinase, and thereby promote neuronal survival, proliferation, differentiation, mobilization of hematopoietic stem and progenitor cells. The expression of G-CSF receptors (G-CSF-R) in the different brain regions and their upregulation in response to neuronal insult indicates the autocrine protective signaling mechanism of G-CSF by inhibition of apoptosis, inflammation, and stimulation of neurogenesis. These observed neuroprotective effects of G-CSF makes it an attractive target to mitigate neurodegeneration associated with neurological disorders. The objective of the review is to highlight and summarize recent updates on G-CSF as a therapeutically versatile neuroprotective agent along with mechanisms of action as well as possible clinical applications in neurodegenerative disorders including AD, PD and HD.

The Protective and Reparative Role of Colony-Stimulating Factors in the Brain with Cerebral Ischemia/Reperfusion Injury

Stroke is a debilitating disease and has the ability to culminate in devastating clinical outcomes. Ischemic stroke followed by reperfusion entrains cerebral ischemia/reperfusion (I/R) injury, which is a complex pathological process and is associated with serious clinical manifestations. Therefore, the development of a robust and effective poststroke therapy is crucial. Granulocyte colony-stimulating factor (GCSF) and erythropoietin (EPO), originally discovered as hematopoietic growth factors, are versatile and have transcended beyond their traditional role of orchestrating the proliferation, differentiation, and survival of hematopoietic progenitors to one that fosters brain protection/neuroregeneration. The clinical indication regarding GCSF and EPO as an auspicious therapeutic strategy is conferred in a plethora of illnesses, including anemia and neutropenia. EPO and GCSF alleviate cerebral I/R injury through a multitude of mechanisms, involving antiapoptotic, anti-inflammatory, antioxidant, neurogenic, and angiogenic effects. Despite bolstering evidence from preclinical studies, the multiple brain protective modalities of GCSF and EPO failed to translate in clinical trials and thereby raises several questions. The present review comprehensively compiles and discusses key findings from in vitro, in vivo, and clinical data pertaining to the administration of EPO, GCSF, and other drugs, which alter levels of colony-stimulating factor (CSF) in the brain following cerebral I/R injury, and elaborates on the contributing factors, which led to the lost in translation of CSFs from bench to bedside. Any controversial findings are discussed to enable a clear overview of the role of EPO and GCSF as robust and effective candidates for poststroke therapy.

The Role of Basement Membranes in Cerebral Amyloid Angiopathy

Dementia is a neuropsychiatric syndrome characterized by cognitive decline in multiple domains, often leading to functional impairment in activities of daily living, disability, and death. The most common causes of age-related progressive dementia include Alzheimer's disease (AD) and vascular cognitive impairment (VCI), however, mixed disease pathologies commonly occur, as epitomized by a type of small vessel pathology called cerebral amyloid angiopathy (CAA). In CAA patients, the small vessels of the brain become hardened and vulnerable to rupture, leading to impaired neurovascular coupling, multiple microhemorrhage, microinfarction, neurological emergencies, and cognitive decline across multiple functional domains. While the pathogenesis of CAA is not well understood, it has long been thought to be initiated in thickened basement membrane (BM) segments, which contain abnormal protein deposits and amyloid-β (Aβ). Recent advances in our understanding of CAA pathogenesis link BM remodeling to functional impairment of perivascular transport pathways that are key to removing Aβ from the brain. Dysregulation of this process may drive CAA pathogenesis and provides an important link between vascular risk factors and disease phenotype. The present review summarizes how the structure and composition of the BM allows for perivascular transport pathways to operate in the healthy brain, and then outlines multiple mechanisms by which specific dementia risk factors may promote dysfunction of perivascular transport pathways and increase Aβ deposition during CAA pathogenesis. A better understanding of how BM remodeling alters perivascular transport could lead to novel diagnostic and therapeutic strategies for CAA patients.

Vascular and Neuronal Protection in the Developing Retina: Potential Therapeutic Targets for Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a common retinal disease in preterm babies. To prolong the lives of preterm babies, high oxygen is provided to mimic the oxygen level in the intrauterine environment for postnatal organ development. However, hyperoxia-hypoxia induced pathological events occur when babies return to room air, leading to ROP with neuronal degeneration and vascular abnormality that affects retinal functions. With advances in neonatal intensive care, it is no longer uncommon for increased survival of very-low-birth-weight preterm infants, which, therefore, increased the incidence of ROP. ROP is now a major cause of preventable childhood blindness worldwide. Current proven treatment for ROP is limited to invasive retinal ablation, inherently destructive to the retina. The lack of pharmacological treatment for ROP creates a great need for effective and safe therapies in these developing infants. Therefore, it is essential to identify potential therapeutic agents that may have positive ROP outcomes, especially in preserving retinal functions. This review gives an overview of various agents in their efficacy in reducing retinal damages in cell culture tests, animal experiments and clinical studies. New perspectives along the neuroprotective pathways in the developing retina are also reviewed.

Roles of Pericytes in Stroke Pathogenesis

Stroke is a cerebrovascular disorder that affects many people worldwide. In addition to the well-established functions of astrocytes and microglia in stroke pathogenesis, pericytes also play an important role in stroke progression and recovery. As perivascular multi-potent cells and an important component of the blood–brain barrier (BBB), pericytes have been shown to exert a large variety of functions, including serving as stem/progenitor cells and maintaining BBB integrity. Here in this review, we summarize the roles of pericytes in stroke pathogenesis, with a focus on their effects in cerebral blood flow, BBB integrity, angiogenesis, immune responses, scar formation and fibrosis.

The trophic effect of nerve growth factor in primary cultures of rat hippocampal neurons is associated to an anti-inflammatory and immunosuppressive transcriptional program

Nerve growth factor, the prototype of a family of neurotrophins, elicits differentiation and survival of peripheral and central neuronal cells. Although its neural mechanisms have been studied extensively, relatively little is known about the transcriptional regulation governing its effects. We have previously observed that in primary cultures of rat hippocampal neurons treatment with nerve growth factor for 72 hr increases neurite outgrowth and cell survival. To obtain a comprehensive view of the underlying transcriptional program, we performed whole-genome expression analysis by microarray technology. We identified 541 differentially expressed genes and characterized dysregulated pathways related to innate immunity: the complement system and neuro-inflammatory signaling. The exploitation of such genes and pathways may help interfering with the intracellular mechanisms involved in neuronal survival and guide novel therapeutic strategies for neurodegenerative diseases.

Granulocyte Colony-Stimulating Factor (G-CSF) for the Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a common medical condition with a poor prognosis for recovery and catastrophic effects on a patient's quality of life. Available treatments for SCI are limited, and the evidence suggesting their harmful side effects is more consistent than any suggestion of clinical benefit. Developing novel safe and effective therapeutic options for SCI is crucial. Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic cytokine with known multifaceted effects on the central nervous system. Herein, we review the accumulating preclinical evidence for the beneficial effects of G-CSF on functional and structural outcomes after SCI. Meanwhile we present and discuss multiple mechanisms for G-CSF's neuroprotective and neuroregenerative actions through the results of these studies. In addition, we present the available clinical evidence indicating the efficacy and safety of G-CSF administration for the treatment of acute and chronic traumatic SCI, compression myelopathy, and SCI-associated neuropathic pain. Our review indicates that although the quality of clinical evidence regarding the use of G-CSF in SCI is inadequate, the encouraging available preclinical and clinical data warrant its further clinical development, and bring new hope to the longstanding challenge that is treatment of SCI.

Combination of endogenous neural stem cell mobilization and lithium chloride treatment for hydrocephalus following intraventricular hemorrhage

As there are multiple factors causing hydrocephalus subsequent to intraventricular hemorrhage (IVH), it is difficult to achieve the best treatment effect using a single drug alone. In the present study, the protective effect of combination treatment with granulocyte-colony stimulating factor (G-CSF) and lithium chloride against hydrocephalus after IVH was investigated. A total of 130 adult male Sprague-Dawley rats were divided into five groups, including the IVH control, G-CSF treatment, lithium chloride treatment, combination treatment and sham surgery groups. An IVH rat model was established in order to examine the effect of combination treatment on hydrocephalus incidence. A TUNEL assay was performed to detect neuronal apoptosis in the five groups. In addition, the protein expression levels of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were detected by western blot analysis. The differentiation of nerve cells in the brain tissue obtained from the five rat groups was also determined with double immunofluorescence staining. The results demonstrated that administration of G-CSF or lithium chloride alone was able to only partly relieve the incidence of hydrocephalus after IVH. By contrast, combination treatment with G-CSF and lithium chloride significantly attenuated the development of hydrocephalus following IVH. TUNEL assay showed that neuronal apoptosis was significantly reduced by the combination treatment with G-CSF and lithium chloride. Furthermore, the expression of Bcl-2 was upregulated, whereas Bax expression was downregulated in the combination treatment group. The results also detected the highest expression of BrdU/GFAP, BrdU/NeuN and BrdU/PSA-NCAM in the combination treatment group. In conclusion, the combination of endogenous neural stem cell mobilization (using G-CSF) and lithium chloride treatment resulted in highly reduced incidence of hydrocephalus after IVH by inhibiting neuronal apoptosis.

Radix Ilicis Pubescentis total flavonoids combined with mobilization of bone marrow stem cells to protect against cerebral ischemia/reperfusion injury

Previous studies have shown that Radix Ilicis Pubescentis total flavonoids have a neuroprotective effect, but it remains unclear whether Radix Ilicis Pubescentis total flavonoids have a synergistic effect with the recombinant human granulocyte colony stimulating factor-mobilized bone marrow stem cell transplantation on cerebral ischemia/reperfusion injury. Rat ischemia models were administered 0.3, 0.15 and 0.075 g/kg Radix Ilicis Pubescentis total flavonoids from 3 days before modeling to 2 days after injury. Results showed that Radix Ilicis Pubescentis total flavonoids could reduce pathological injury in rats with cerebral ischemia/reperfusion injury. The number of Nissl bodies increased, Bax protein expression decreased, Bcl-2 protein expression increased and the number of CD34-positive cells increased. Therefore, Radix Ilicis Pubescentis total flavonoids can improve the bone marrow stem cell mobilization effect, enhance the anti-apoptotic ability of nerve cells, and have a neuroprotective effect on cerebral ischemia/reperfusion injury in rats.

PDGFR-β Plays a Key Role in the Ectopic Migration of Neuroblasts in Cerebral Stroke

The neuroprotective agents and induction of endogenous neurogenesis remain to be the urgent issues to be established for the care of cerebral stroke. Platelet-derived growth factor receptor beta (PDGFR-β) is mainly expressed in neural stem/progenitor cells (NSPCs), neurons and vascular pericytes of the brain; however, the role in pathological neurogenesis remains elusive. To this end, we examined the role of PDGFR-β in the migration and proliferation of NSPCs after stroke. A transient middle cerebral-arterial occlusion (MCAO) was introduced into the mice with conditional Pdgfrb-gene inactivation, including N-PRβ-KO mice where the Pdgfrb-gene was mostly inactivated in the brain except that in vascular pericytes, and E-PRβ-KO mice with tamoxifen-induced systemic Pdgfrb-gene inactivation. The migration of the DCX(+) neuroblasts from the subventricular zone toward the ischemic core was highly increased in N-PRβ-KO, but not in E-PRβ-KO as compared to Pdgfrb-gene preserving control mice. We showed that CXCL12, a potent chemoattractant for CXCR4-expressing NSPCs, was upregulated in the ischemic lesion of N-PRβ-KO mice. Furthermore, integrin α3 intrinsically expressed in NSPCs that critically mediates extracellular matrix-dependent migration, was upregulated in N-PRβ-KO after MCAO. NSPCs isolated from N-PRβ-KO rapidly migrated on the surface coated with collagen type IV or fibronectin that are abundant in vascular niche and ischemic core. PDGFR-β was suggested to be critically involved in pathological neurogenesis through the regulation of lesion-derived chemoattractant as well as intrinsic signal of NSPCs, and we believe that a coordinated regulation of these molecular events may be able to improve neurogenesis in injured brain for further functional recovery.

G-CSF attenuates neuroinflammation and stabilizes the blood-brain barrier via the PI3K/Akt/GSK-3β signaling pathway following neonatal hypoxia-ischemia in rats

OBJECTIVE

Neonatal hypoxia occurs in approximately 60% of premature births and is associated with a multitude of neurological disorders. While various treatments have been developed, translating them from bench to bedside has been limited. We previously showed G-CSF administration was neuroprotective in a neonatal hypoxia-ischemia rat pup model, leading us to hypothesize that G-CSF inactivation of GSK-3β via the PI3K/Akt pathway may attenuate neuroinflammation and stabilize the blood-brain barrier (BBB).

METHODS

P10 Sprague-Dawley rat pups were subjected to unilateral carotid artery ligation followed by hypoxia for 2.5h. We assessed inflammation by measuring expression levels of IKKβ, NF-κB, TNF-α, IL-1β, IL-10, and IL-12 as well as neutrophil infiltration. BBB stabilization was evaluated by measuring Evans blue extravasation, and Western blot analysis of Claudin-3, Claudin-5, ICAM-1, and VCAM-1.

MEASUREMENTS AND MAIN RESULTS

First, the time course study showed that p-β-catenin/β-catenin, IKKβ, and NF-κB expression levels peaked at 48h post-HI. The knockdown of GSK-3β with siRNA prevented the HI-induced increase of p-β-catenin/β-catenin, IKKβ, and NF-κB expression levels 48h after HI. G-CSF treatment reduced brain water content and neuroinflammation by downregulating IKKβ, NF-κB, TNF-α, IL-1β, and IL-12 and upregulating IL-10, thereby reducing neutrophil infiltration. Additionally, G-CSF stabilizes the BBB by downregulating VCAM-1 and ICAM-1, as well as upregulating Claudins 3 and 5 in endothelial cells. G-CSFR knockdown by siRNA and Akt inhibition by Wortmannin reversed G-CSF's neuroprotective effects.

CONCLUSIONS

We demonstrate G-CSF plays a pivotal role in attenuating neuroinflammation and BBB disruption following HI by inactivating GSK-3β through the PI3K/Akt pathway.

Involvement of platelet-derived growth factor receptor β in fibrosis through extracellular matrix protein production after ischemic stroke

Fibrosis is concomitant with repair processes following injuries in the central nervous system (CNS). Pericytes are considered as an origin of fibrosis-forming cells in the CNS. Here, we examined whether platelet-derived growth factor receptor β (PDGFRβ), a well-known indispensable molecule for migration, proliferation, and survival of pericytes, was involved in the production of extracellular matrix proteins, fibronectin and collagen type I, which is crucial for fibrosis after ischemic stroke. Immunohistochemistry demonstrated induction of PDGFRβ expression in vascular cells of peri-infarct areas at 3-7days in a mouse stroke model. The PDGFRβ-expressing cells extended from peri-infarct areas toward the ischemic core after day 7 while expressing fibronectin and collagen type I in the infarct areas. In contrast, desmin and α-smooth muscle actin, markers of pericytes, were only expressed in vascular cells. In PDGFRβ heterozygous knockout mice, the expression of fibronectin and collagen type I was attenuated at both mRNA and protein levels with an enlargement of the infarct volume after ischemic stroke compared with that in wild-type littermates. In cultured brain pericytes, the expression of PDGF-B, PDGFRβ, fibronectin, and collagen type I, but not desmin, was significantly increased by serum depletion (SD). The SD-induced upregulation of fibronectin and collagen type I was suppressed by SU11652, an inhibitor of PDGFRβ, while PDGF-B further increased the SD-induced upregulation. In conclusion, the expression level of PDGFRβ may be a crucial determinant of fibrosis after ischemic stroke. Moreover, PDGFRβ signaling participates in the production of fibronectin and collagen type I after ischemic stroke.

Neuroprotection of granulocyte colony-stimulating factor during the acute phase of transient forebrain ischemia in gerbils

The present study investigates the potential protective effects of granulocyte colony-stimulating factor (G-CSF) and underlying mechanisms in a gerbil model of global cerebral ischemia. We examined neuronal death, inflammatory reaction and neurogenesis in hippocampus 72 h after transient forebrain ischemia and investigated functional deficits. G-CSF was administered intraperitoneally 24 h before ischemia and then daily. Treatment with G-CSF at 25-50 μg/kg significantly reduced neuronal loss in the hippocampus CA1 area but not at 10 ug/kg. G-CSF at 50 μg/kg significantly decreased the level of TNF-α, the number of Iba1 (microglia marker) positive cells and reduced locomotor activity 72 h after transient forebrain ischemia. Furthermore, the number of DCX-positive cells in the hippocampal dentate gyrus increased in with G-CSF treatment. Our findings indicate that G-CSF reduces hippocampal neuronal cell death dose-dependently and attenuates sensorimotor deficits after transient forebrain ischemia. These neuroprotective effects of G-CSF may be linked to inhibition of inflammation and possibly increased neurogenesis in the hippocampus.

Systemic G-CSF attenuates cerebral inflammation and hypomyelination but does not reduce seizure burden in preterm sheep exposed to global hypoxia-ischemia

Hypoxic-ischemic encephalopathy (HIE) is common in preterm infants, but currently no curative therapy is available. Cell-based therapy has a great potential in the treatment of hypoxic-ischemic preterm brain injury. Granulocyte-colony stimulating factor (G-CSF) is known to mobilize endogenous hematopoietic stem cells (HSC) and promotes proliferation of endogenous neural stem cells. On these grounds, we hypothesized that systemic G-CSF would be neuroprotective in a large translational animal model of hypoxic-ischemic injury in the preterm brain. Global hypoxia-ischemia (HI) was induced by transient umbilical cord occlusion in instrumented preterm sheep. G-CSF treatment (100μg/kg intravenously, during five consecutive days) was started one day before the global HI insult to ascertain mobilization of endogenous stem cells within the acute phase after global HI. Mobilization of HSC and neutrophils was studied by flow cytometry. Brain sections were stained for microglia (IBA-1), myelin basic protein (MBP) and myeloperoxidase (MPO) to study microglial proliferation, white matter injury and neutrophil invasion respectively. Electrographic seizure activity was analyzed using amplitude-integrated electroencephalogram (aEEG). G-CSF effectively mobilized CD34-positive HSC in the preterm sheep. In addition, G-CSF caused marked mobilization of neutrophils, but did not influence enhanced invasion of neutrophils into the preterm brain after global HI. Microglial proliferation and hypomyelination following global HI were reduced as a result of G-CSF treatment. G-CSF did not cause a reduction of the electrographic seizure activity after global HI. In conclusion, G-CSF induced mobilization of endogenous stem cells which was associated with modulation of the cerebral inflammatory response and reduced white matter injury in an ovine model of preterm brain injury after global HI. G-CSF treatment did not improve neuronal function as shown by seizure analysis. Our study shows that G-CSF treatment has neuroprotective potential following hypoxic-ischemic injury in the preterm brain.

Granulocyte-colony stimulating factor in combination with stem cell factor confers greater neuroprotection after hypoxic-ischemic brain damage in the neonatal rats than a solitary treatment

Neonatal hypoxia-ischemia (HI) is a devastating condition resulting in neuronal cell death and often culminates in neurological deficits. Granulocyte-colony stimulating factor (G-CSF) has been shown to have neuroprotective activity via inhibition of apoptosis and inflammation in various stroke models. Stem cell factor (SCF) regulates hematopoietic stem cells in the bone marrow and has been reported to have neuroprotective properties in an experimental ischemic stroke model. In this study we aim to determine the protective effects of G-CSF in combination with SCF treatment after experimental HI. Seven-day old Sprague-Dawley rats were subjected to unilateral carotid artery ligation followed by 2.5 hours of hypoxia. Animals were randomly assigned to five groups: Sham (n=8), Vehicle (n=8), HI with G-CSF treatment (n=9), HI with SCF treatment (n=9) and HI with G-CSF+SCF treatment (coadministration group; n=10). G-CSF (50 µg/kg), SCF (50 µg/kg) and G-CSF+SCF (50 µg/kg) were administered intraperitoneally 1 hour post HI followed by daily injection for 4 consecutive days (five total injections). Animals were euthanized 14 days after HI for neurological testing. Additionally assessment of brain, heart, liver, spleen and kidney atrophy was performed. Both G-CSF and G-CSF+SCF treatments improved body growth and decreased brain atrophy at 14 days post HI. No significant differences were found in the peripheral organ weights between groups. Finally, the G-CSF+SCF coadministration group showed significant improvement in neurological function. Our data suggest that administration of G-CSF in combination with SCF not only prevented brain atrophy but also significantly improved neurological function.

Ischemic postconditioning diminishes matrix metalloproteinase 9 expression and attenuates loss of the extracellular matrix proteins in rats following middle cerebral artery occlusion and reperfusion

AIMS

Ischemic postconditioning (IPostC) has been proved to have neuroprotective effects for cerebral ischemia, but the underlying mechanism remains elusive. This study aimed at validating the neuroprotective effects of IPostC and investigating whether the neuroprotection of IPostC is associated with matrix metalloproteinase 9 (MMP9) and the extracellular matrix proteins, laminin and fibronectin, following cerebral ischemia/reperfusion in rats.

METHODS

The rats in middle cerebral artery occlusion (MCAO) group underwent MCAO and reperfusion, and the animals in MCAO + IPostC group were treated by occluding bilateral common carotid arteries for 10 seconds and then reperfusing for 10 seconds for five episodes at the beginning of MCAO. Apoptosis was detected with terminal deoxynucleotidyl transferase dUTP nick end labeling staining. The expression of MMP9, laminin, and fibronectin was measured with immunofluorescence and enzyme-linked immunosorbent assay.

RESULTS

IPostC reduced brain edema and infarct volume and improved the neurological function. Furthermore, IPostC decreased cell apoptosis compared with the MCAO group. Compared to the MCAO group, IPostC treatment reduced MMP9 expression. Moreover, the results showed that the expression of laminin and fibronectin significantly increased in the MCAO + IPostC group compared to the MCAO group.

CONCLUSION

These findings indicated that diminishment of MMP9 expression and the attenuation of degradation of laminin and fibronectin may be involved in the protective mechanisms of postconditioning against cerebral ischemia/reperfusion injury.

Endogenous granulocyte colony-stimulating factor: a biomarker in acute ischemic stroke

Granulocyte colony-stimulating factor (G-CSF) may protect ischemic brain injury either in animal or human. No studies have reported that endogenous G-CSF (enG-CSF) level is related to the severity of ischemic stroke. This study was designed to assess the severity of ischemic patients correlated with the alteration of enG-CSF on the 1st day after an ischemic event. Patient's plasma enG-CSF and scoring of National Institute of Health Stroke Scale were measured on the 1st day after ischemic stroke. The acute ischemic stroke could significantly induce enG-GCF secretion as compared with healthy control group (16.77 vs. 22.86 μg/L, p = 0.001). Elevated enG-CSF concentration was positively correlated with the severity of stroke patients on day 1 after the event (p = 0.006; Spearman correlation coefficient = 0.268). The enG-CSF is a good biomarker for prediction of severity of acute ischemic stroke.

Role of central nervous system periostin in cerebral ischemia

BACKGROUND AND PURPOSE

Although periostin, an extracellular matrix glycoprotein, plays pivotal roles in survival, migration, and regeneration in various cells, its expression and function in the brain are still unknown. Here, we investigated the expression and role of periostin in the ischemic brain.

METHODS

Expression of full-length periostin (periostin 1 [Pn1]) and its splicing variant lacking exon 17 (periostin 2 [Pn2]) was examined by real-time reverse transcription polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemical staining in male C57BL6/J mice. The actions of periostin were examined in adult primary neuronal culture and in a transient middle cerebral artery occlusion (tMCAo) model.

RESULTS

Expression of Pn2, but not of Pn1, mRNA was markedly changed after tMCAo. Pn2 mRNA was decreased in the ischemic core at 3 hours after ischemia. At 24 hours, Pn2 mRNA was significantly increased in both the peri-ischemic and ischemic regions. Periostin was mainly observed in neurons in normal brain. However, neuronal expression of periostin was decreased temporarily in the ischemic region, but increased in astrocytes and around endothelial cells at 24 hours after tMCAo. Of importance, intracerebroventricular injection of Pn2 resulted in a significant reduction in infarct volume at 24 hours after tMCAo associated with phosphorylation of Akt. Also, the Pn2-treated mice survived longer until 1 week after tMCAo. Pn2 significantly inhibited neuronal death under hypoxia and stimulated neurite outgrowth.

CONCLUSIONS

Here, we demonstrated that periostin was expressed in the brain, and exogenous Pn2 exhibited neuroprotective effects and accelerated neurite outgrowth. Additional studies on periostin may provide new insights into the treatment of ischemic stroke.

Growth factors in ischemic stroke

Data from pre-clinical and clinical studies provide evidence that colony-stimulating factors (CSFs) and other growth factors (GFs) can improve stroke outcome by reducing stroke damage through their anti-apoptotic and anti-inflammatory effects, and by promoting angiogenesis and neurogenesis. This review provides a critical and up-to-date literature review on CSF use in stroke. We searched for experimental and clinical studies on haemopoietic GFs such as granulocyte CSF, erythropoietin, granulocyte-macrophage colony-stimulating factor, stem cell factor (SCF), vascular endothelial GF, stromal cell-derived factor-1α and SCF in ischemic stroke. We also considered studies on insulin-like growth factor-1 and neurotrophins. Despite promising results from animal models, the lack of data in human beings hampers efficacy assessments of GFs on stroke outcome. We provide a comprehensive and critical view of the present knowledge about GFs and stroke, and an overview of ongoing and future prospects.

A potential for granulocyte-colony stimulating factor for use as a prophylactic agent for heatstroke in rats

Heatstroke is a form of excessive hyperthermia associated with a systemic inflammatory response that leads to multi-organ dysfunction in which central nervous system disorders predominate. Herein we determined to ascertain whether heat-induced multi-organ dysfunction in rats could be attenuated by granulocyte-colony stimulating factor (G-CSF) preconditioning. Anesthetized rats were divided into 2 major groups and given vehicle solution (isotonic saline, 0.3 ml, subcutaneously) or G-CSF (50-200 μg/kg body weight in 0.3 ml normal saline, subcutaneously) daily and consecutively for 5 days before the start of thermal experiments. They were exposed to an ambient temperature of 43°C for 68 min to induce heatstroke. G-CSF preconditioning significantly prolonged the survival time in heatstroke rats in a dose-related way (82-98 min vs 127-243 min). The non-preconditioning heatstroke animals showed hyperthermia, arterial hypotension, increased serum levels of systemic inflammatory response molecules, increased hypothalamic apoptotic cell numbers as well as neuronal damage scores, and increased serum levels of renal and hepatic dysfunction indicators. These heatstroke syndromes could be significantly reduced by G-CSF preconditioning. Thus our results revealed a potential for G-CSF used as a prophylactic agent for heatstroke in rats.

Regulatory factors of mesenchymal stem cell migration into injured tissues and their signal transduction mechanisms

Adult stem cells hold great promise for wound healing and tissue regeneration. Mesenchymal stem cells (MSCs), for example, have been shown to play a role in tissue repair. Research has shown that endogenous bone marrow MSCs or exogenously delivered MSCs migrate to the sites of injury and participate in the repair process. The precise mechanisms underlying migration of MSCs into the injured tissue are still not fully understood, although multiple signaling pathways and molecules were reported, including both chemoattractive factors and endogenous electric fields at wounds. This review will briefly summarize the regulatory facors and signaling transduction pathways involved in migration of MSCs. A better understanding of the molecular mechanisms involved in the migration of MSCs will help us to develop new stem cell-based therapeutic strategies in regenerative medicine.

Fasudil, a Rho kinase inhibitor, drives mobilization of adult neural stem cells after hypoxia/reoxygenation injury in mice

Rho kinase (ROCK) is important in fundamental processes of cell proliferation and survival. Blockade of ROCK promotes stem cell survival in vitro and axonal regeneration in vivo, exhibiting therapeutic potential such as spinal cord injuries and stroke. Here, we used the model of hypoxia/reoxygenation (H/R) injury to explore the possibility whether Fasudil, a ROCK inhibitor in clinical application for subarachnoid hemorrhage and stroke, mobilizes adult neural stem cells in vivo. Most interestingly, Fasudil triggers neurogenesis especially in the subventricular zone after H/R. The increase of Brdu+ cholinergic neurons was observed in striatum and forebrain cortex of Fasudil-treated mice after 30 days. Further observation demonstrates that both levels of granulocyte colony-stimulating factor (G-CSF) and astrocytes expressing G-CSF were elevated in mice treated with Fasudil, as compared to mice injected with saline. In vitro H/R model of cultured astrocytes, Fasudil promoted astrocytes to produce G-CSF in a dose-dependent manner. In addition, antibody neutralization and receptor blocking of the G-CSF pathway clearly demonstrate that Fasudil-induced neurogenesis was mediated partially through astrocyte-derived G-CSF. Our results indicate that Fasudil might represent a promising therapeutic perspective by mobilizating endogenous adult neural stem cells in the CNS.

Rho kinase inhibitor Fasudil induces neuroprotection and neurogenesis partially through astrocyte-derived G-CSF

Rho-kinases (ROCK) are serine/threonine kinases that play an important role in fundamental processes of cell migration, proliferation and survival. Blockade of ROCK promotes axonal regeneration and neuroprotection, thereby exhibiting therapeutic potentials for clinical application to spinal cord damage and stroke. Here we explored the mechanisms of Fasudil, a ROCK inhibitor, in neuroprotection and neurogenesis by using oxygen-glucose deprivation (OGD) as an in vitro ischemia model. Fasudil stimulates astrocytes to produce granulocyte colony-stimulating factor (G-CSF). Astrocyte-conditioned medium treated with Fasudil (ACM-F) contributes to the generation of neurospheres, and decreases neuron death. Neutralization of G-CSF in ACM-F and blocking of G-CSF receptor in neuronal cell cultures revealed that Fasudil-induced neuroprotection and/or neurogenesis are mediated partially through astrocyte-derived G-CSF. Our results indicate that ROCK inhibition by Fasudil, protecting neurons and mobilizating neural stem cells, might represent a useful therapeutic perspective for various neurological disorders characterized by neuron death.

Granulocyte-colony stimulating factor for stroke treatment: mechanisms of action and efficacy in preclinical studies

G-CSF is widely employed for the treatment of chemotherapy-induced neutropenia. Recently, neuroprotective effects of G-CSF in animal stroke models were discovered including infarct size reduction and enhancement of functional recovery. The underlying mechanisms of action of G-CSF in ischemia appear to be a direct anti-apoptotic activity in neurons and a neurogenesis inducing capacity. Additional effects may be based on the stimulation of new blood-vessel formation, the stimulation of immunocompetence and -modulation as well as on bone marrow mobilization. In addition to a discussion of these mechanisms, we will review the available preclinical studies and analyze their impact on the overall efficacy of G-CSF in experimental stroke.

Granulocyte-colony stimulating factor in experimental stroke and its effects on infarct size and functional outcome: A systematic review

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 (> or =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.

Both systemic and local application of granulocyte-colony stimulating factor (G-CSF) is neuroprotective after retinal ganglion cell axotomy

Background

The hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) plays a crucial role in controlling the number of neutrophil progenitor cells. Its function is mediated via the G-CSF receptor, which was recently found to be expressed also in the central nervous system. In addition, G-CSF provided neuroprotection in models of neuronal cell death. Here we used the retinal ganglion cell (RGC) axotomy model to compare effects of local and systemic application of neuroprotective molecules.

Results

We found that the G-CSF receptor is robustly expressed by RGCs in vivo and in vitro. We thus evaluated G-CSF as a neuroprotectant for RGCs and found a dose-dependent neuroprotective effect of G-CSF on axotomized RGCs when given subcutaneously. As stem stell mobilization had previously been discussed as a possible contributor to the neuroprotective effects of G-CSF, we compared the local treatment of RGCs by injection of G-CSF into the vitreous body with systemic delivery by subcutaneous application. Both routes of application reduced retinal ganglion cell death to a comparable extent. Moreover, G-CSF enhanced the survival of immunopurified RGCs in vitro.

Conclusion

We thus show that G-CSF neuroprotection is at least partially independent of potential systemic effects and provide further evidence that the clinically applicable G-CSF could become a treatment option for both neurodegenerative diseases and glaucoma.

Angiogenesis after cerebral ischemia

Though the vascular system of the adult brain is extremely stable under normal baseline conditions, endothelial cells start to proliferate in response to brain ischemia. The induction of angiogenesis, primarily in the ischemic boundary zone, enhances oxygen and nutrient supply to the affected tissue. Additionally, the generation of new blood vessels facilitates highly coupled neurorestorative processes including neurogenesis and synaptogenesis which in turn lead to improved functional recovery. To take advantage of angiogenesis as a therapeutic concept for stroke treatment, the knowledge of the precise molecular mechanisms is mandatory. Especially, since a couple of growth factors involved in post-ischemic angiogenesis may have detrimental adverse effects in the brain by increasing vascular permeability. This article summarizes the knowledge of molecular mechanisms of angiogenesis following cerebral ischemia. Finally, experimental pharmacological and cellular approaches to stimulate and enhance post-ischemic angiogenesis are discussed.

Methodological quality of animal studies of neuroprotective agents currently in phase II/III acute ischemic stroke trials

BACKGROUND AND PURPOSE

Numerous neuroprotective agents have proven effective in animal stroke studies, but every drug has failed to achieve its primary outcome when brought forward to clinical trials. We analyzed the quality and adequacy of animal studies supporting the efficacy of NXY-059 and other neuroprotective agents that are currently being investigated in phase II/III trials.

METHODS

We conducted a systematic search of all neuroprotective drugs in Phase II or III trials and collected data from animal studies of focal cerebral ischemia testing agents systemically administered within 24 hours of occlusion. The methodological rigor of each individual study was evaluated using 5 criteria derived from the STAIR guidelines. The adequacy of the preclinical "package" for each drug was then evaluated by combining the results of all studies for each drug to determine which of a further 5 STAIR criteria were met before moving forward from animal to human studies.

RESULTS

Our search yielded 13 agents of which 10 had published data in peer-reviewed journals. There is substantial within-drug variability in the quality of preclinical studies as well as substantial variation in the completeness of the collective preclinical literature for different drugs. There has been little or no improvement in the quality of animal studies since NXY-059, and current agents have not been subjected to a more complete preclinical evaluation.

CONCLUSIONS

There is significant heterogeneity in the quality of animal testing for neuroprotective agents in stroke. Drugs in the post-SAINT era have not been subjected to more thorough preclinical evaluation.

Cell biology and clinical promise of G-CSF: immunomodulation and neuroprotection

In the light of the enthusiasm to use of recombinant human granulocyte colony-stimulating factor (G-CSF) for immunomodulation and neuroprotection, it should be remembered that the current knowledge is based on a century of laborious research. G-CSF is a pleiotropic cytokine playing a major role as regulator of haematopoiesis. Although the precise mechanisms of G-CSF are not known, there is growing evidence supporting the notion that G-CSF also exerts profound immunoregulatory effect in adaptive immunity and has a neuroprotective role in both cerebral ischemia and neurodegeneration. Here, we describe the immunomodulation and the neuroprotection that can be achieved with G-CSF, and summarize possible mechanisms of G-CSF as a potential therapeutic agent in autoimmune diseases and neurological disorders. Our understanding of these novel sites of action of G-CSF has opened therapeutic avenues for the treatment of autoimmune diseases and neurological disorders, and has translated the beneficial effects of G-CSF from basic experiments to clinical patients.

Acute neurodegeneration and the inflammasome: central processor for danger signals and the inflammatory response?

Activation of the inflammatory response is a crucial event in the adverse outcome of cerebral ischemia, which is promoted by proinflammatory cytokines such as interleukin (IL)-1beta. Although caspase-1 is necessary for IL-1beta processing, the 'upstream' signaling pathways were, until recently, essentially unknown. Fortunately, the inflammasome, a multiprotein complex responsible for activating caspase-1 and caspase-5, has recently been characterized. The activation of the inflammasome can result in one of several consequences such as cytokine secretion, cell death, or the development of a stress-resistant state. The significance of the inflammasome for the initiation of the inflammatory response during systemic diseases has already been shown and members of the inflammasome complex were recently found to be induced in acute brain injury. However, the specific pathophysiologic role of the inflammasome in neurodegenerative disorders still remains to be clarified. The underlying theories (e.g., danger signal theory) along with the signaling pathways that link the inflammasome to acute neurodegeneration will be discussed here. Furthermore, the stimuli that potentially activate the inflammasome in cerebral ischemia will be specified, as well as their relation to well-known pathways activating the innate immune response (e.g., Toll-like receptor signaling) and the consequences that result from their activation (beneficial versus deleterious).

Meta-analysis of the efficacy of granulocyte-colony stimulating factor in animal models of focal cerebral ischemia

BACKGROUND AND PURPOSE

Recent reports have described the efficacy of the hematopoietic growth factor granulocyte-colony stimulating factor (G-CSF) in animal stroke models. Early clinical multicenter trials evaluating the effect of G-CSF in acute stroke and pilot clinical trials for the subacute phase are ongoing. To guide further development, a meta-analysis was performed to assess the effects of G-CSF on infarct size and sensorimotor deficits.

METHODS

Using electronic and manual searches of the literature, we identified studies describing the efficacy of G-CSF in animal models of focal cerebral ischemia. Two reviewers independently selected studies and extracted data on study quality, G-CSF doses, time of administration, and outcome measured as infarct volume and/or sensorimotor deficit. Data from all studies were pooled by meta-regression analyses.

RESULTS

Thirteen studies including 277 animals for infarct size calculation and 258 animals for assessment of sensorimotor deficit met the criteria for inclusion. Overall efficacy of G-CSF regarding infarct size reduction was 42%. Meta-regression analysis revealed a 0.8% (P<0.0001) decrease in infarct size per 1-mug/kg increase in G-CSF dose when applied within the first 6 hours and a 2.1% (P<0.0001) decrease when applied later than 6 hours after induction of ischemia with a significant (P=0.0004) greater infarct size reduction after delayed treatment. Sensorimotor deficits categorized into 3 subgroups improved between 24% and 40%.

CONCLUSIONS

Our findings consolidate G-CSF as a drug that both reduces infarct size and enhances functional recovery. These effects are presumably dose dependent. In contrast to most other neuroprotectants, a beneficial outcome may also be achieved when treatment is delayed.

The combination of granulocyte colony-stimulating factor and stem cell factor significantly increases the number of bone marrow-derived endothelial cells in brains of mice following cerebral ischemia

Granulocyte colony-stimulating factor (G-CSF) induces proliferation of bone marrow-derived cells. G-CSF is neuroprotective after experimental brain injury, but the mechanisms involved remain unclear. Stem cell factor (SCF) is a cytokine important for the survival and differentiation of hematopoietic stem cells. Its receptor (c-kit or CD117) is present in some endothelial cells. We aimed to determine whether the combination of G-CSF/SCF induces angiogenesis in the central nervous system by promoting entry of endothelial precursors into the injured brain and causing them to proliferate there. We induced permanent middle cerebral artery occlusion in female mice that previously underwent sex-mismatched bone marrow transplantation from enhanced green fluorescent protein (EGFP)-expressing mice. G-CSF/SCF treatment reduced infarct volumes by more than 50% and resulted in a 1.5-fold increase in vessel formation in mice with stroke, a large percentage of which contain endothelial cells of bone marrow origin. Most cells entering the brain maintained their bone marrow identity and did not transdifferentiate into neural cells. G-CSF/SCF treatment also led to a 2-fold increase in the number of newborn cells in the ischemic hemisphere. These findings suggest that G-CSF/SCF treatment might help recovery through induction of bone marrow-derived angiogenesis, thus improving neuronal survival and functional outcome.

Therapeutic pathways of adult stem cell repair

The use of adult stem cells as therapeutic agents to treat disease has become increasingly prevalent. During the last decade, isolated and expanded stem and progenitor cells have demonstrated the capacity to differentiate into multiple cell types. Early optimism that in vitro differentiation capacity would translate into in vivo tissue regeneration has lessened and identifying the mechanisms that underlie the benefit of stem cell repair is an emerging area of investigation. This review considers several of the pathways and mechanisms required for adult stem cell repair. These mechanisms include the mobilization and the homing of stem cells to sites of injury, immunomodulatory effect of stem cells, and the association of stem cells with increased vascularization of injured tissue. These data suggest that the unique properties of adult stem cells can be utilized to treat a wide variety of diseases that cannot be treated with existing pharmacological agents, and prompt new paradigms for the bio-pharmacokinetics of biological expressed by efficacious stem cells.

Fibronectin is elevated in the cerebrospinal fluid of patients suffering from bacterial meningitis and enhances inflammation caused by bacterial products in primary mouse microglial cell cultures

Toll-like receptors (TLR) play a key role in the recognition of pathogenic organisms. Fibronectin, an extracellular matrix protein, is considered a potent stimulator of the innate immune system through TLR4. In bacterial meningitis, several extracellular matrix proteins and bacterial compounds are elevated in the CSF. For this reason, we hypothesized that these molecules may jointly stimulate the innate immune system and increase neuronal damage in bacterial meningitis. Concentrations of fibronectin were elevated in the CSF of patients suffering from bacterial meningitis, but not in patients with multiple sclerosis, when compared with control patients without CSF abnormalities. In primary cultures of mouse microglial cells, co-administration of fibronectin at concentrations occurring in the CSF in bacterial meningitis (10 microg/mL) with defined TLR agonists [lipopolysaccharide (TLR4), the synthetic lipopeptide tripalmytoyl-cysteinyl-seryl-(lysyl)3-lysine (TLR2) and single-stranded unmethylated cytosine-guanosine oligodesoxynucleotide (TLR9)] led to an additive release of nitric oxide and tumor necrosis factor-alpha when compared with the release elicited by either compound alone. In conclusion, the inflammatory reaction to bacterial compounds can be aggravated by endogenous fibronectin at elevated levels during bacterial CNS infections. This additive or synergistic effect may contribute to neuronal damage during bacterial meningitis.

New targets for established proteins: exploring G-CSF for the treatment of stroke

Several recent reports describe the efficacy of the hematopoietic factor granulocyte-colony-stimulating factor (G-CSF) in models of stroke and neurodegeneration. Here, we discuss the role of G-CSF as a novel type of multifactorial drug with which to treat stroke, and describe aspects of its modes of action in stroke, in addition to the relationship between clinical trials and the preclinical dataset. Neuroprotective activity in stroke models seems to be based on a direct anti-apoptotic activity in neurons that is mediated by the neuronally expressed G-CSF receptor. Explanations for the long-term effects that improve recovery in different experimental models of stroke include the enhancement of neurogenesis in the adult brain and the stimulation of blood vessel formation. Additional beneficial effects might be based on systemic influences on immunocompetence and inflammation parameters, and the activation of bone-marrow-derived stem cells. Several clinical trials have been initiated in stroke patients, mainly to demonstrate the safety of G-CSF in this setting.

G-CSF and neuroprotection: a therapeutic perspective in cerebral ischaemia

In several experimental studies of cerebral ischaemia, G-CSF (granulocyte colony-stimulating factor) exerted neuroprotective effects through different mechanisms, including mobilization of haemopoietic stem cells, anti-apoptosis, neuronal differentiation, angiogenesis and anti-inflammation. Hence, G-CSF not only inhibits neuron death, but also generates ‘new’ neural tissue formation. A small pilot trial reports on the safety and feasibility of G-CSF therapy in stroke patients. According to this evidence, we can speculate that G-CSF, being used either alone or in combination with another agent, should have a dual activity beneficial both to acute neuronal protection and long-term plasticity after cerebral ischaemia, thus proposing that G-CSF is an ideal new drug for stroke and neurodegenerative diseases.