G-CSF protects human cerebral hybrid neurons against in vitro ischemia

A pilot study of neuroprotective effect of granulocyte colony-stimulating factor (G-CSF) in patients with carbon monoxide poisoning: a double-blind, randomized, placebo-controlled trial

Although neuroprotective effects of granulocyte colony-stimulating factor (G-CSF) have been shown in rats exposed to carbon monoxide (CO), this pilot clinical trial was performed to assess the feasibility of treatment with G-CSF in patients with acute CO poisoning. A double-blind, randomized, placebo-controlled pilot clinical trial was conducted on twenty-six patients with acute CO poisoning. G-CSF (90 μg/kg) was administered intravenously for 72 h. Demographic data, routine laboratory tests, differential blood counts, venous blood gas, and adverse reactions were recorded. The primary endpoint was brain ischemia improvement based on CT findings and the secondary endpoints examined improvements in the modified Rankin Scale (mRS), National Institutes of Health Stroke Scale (NIHSS), and Barthel Index as well as S-100β concentrations. Fourteen patients received G-CSF, and 12 received a placebo. Twenty-six were followed for 30 days and no one in both groups died during follow-up. Neurological complications, brain ischemic changes, Barthel, and mRS were compared between the two groups on determined days after the onset of therapeutic intervention, and no significant differences were observed between the two groups. Favorable results were achieved for treated patients by different measures; NIHSS was decreased 72 h after treatment (p = 0.046), and S-100β levels were significantly higher in the G-CSF group than in the control group, 12 h and 72 h after the treatment. G-CSF appears to have potential effects on several clinical parameters in patients with acute CO poisoning. The trial was registered at the Iranian Registry of Clinical Trials with the ID: (IRCT201607232083N7).

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.

Granulocyte-colony stimulating factor: a new player for the enteric nervous system

The enteric nervous system (ENS) controls and modulates gut motility and responds to food intake and to internal and external stimuli such as toxins or inflammation. Its plasticity is maintained throughout life by neural progenitor cells within the enteric stem cell niche. Granulocyte-colony stimulating factor (G-CSF) is known to act not only on cells of the immune system but also on neurons and neural progenitors in the central nervous system (CNS). Here, we demonstrate, for the first time, that G-CSF receptor is present on enteric neurons and progenitors and that G-CSF plays a role in the expansion and differentiation of enteric neural progenitor cells. Cultured mouse ENS-neurospheres show increased expansion with increased G-CSF concentrations, in contrast to CNS-derived spheres. In cultures from differentiated ENS- and CNS-neurospheres, neurite outgrowth density is enhanced depending on the amount of G-CSF in the culture. G-CSF might be an important factor in the regeneration and differentiation of the ENS and might be a useful tool for the investigation and treatment of ENS disorders.

Colony stimulating factors (including erythropoietin, granulocyte colony stimulating factor and analogues) for stroke

BACKGROUND

Colony stimulating factors (CSFs), also called haematopoietic growth factors, regulate bone marrow production of circulating red and white cells, and platelets. Some CSFs also mobilise the release of bone marrow stem cells into the circulation. CSFs have been shown to be neuroprotective in experimental stroke.

OBJECTIVES

To assess (1) the safety and efficacy of CSFs in people with acute or subacute ischaemic or haemorrhagic stroke, and (2) the effect of CSFs on circulating stem and blood cell counts.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched September 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 4), MEDLINE (1985 to September 2012), EMBASE (1985 to September 2012) and Science Citation Index (1985 to September 2012). In an attempt to identify further published, unpublished and ongoing trials we contacted manufacturers and principal investigators of trials (last contacted April 2012). We also searched reference lists of relevant articles and reviews.

SELECTION CRITERIA

We included randomised controlled trials recruiting people with acute or subacute ischaemic or haemorrhagic stroke. CSFs included stem cell factor (SCF), erythropoietin (EPO), granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage colony stimulating factor (GM-CSF), macrophage-colony stimulating factor (M-CSF, CSF-1), thrombopoietin (TPO), or analogues of these. The primary outcome was functional outcome at the end of the trial. Secondary outcomes included safety at the end of treatment, death at the end of follow-up, infarct volume and haematology measures.

DATA COLLECTION AND ANALYSIS

Two review authors (TE and NS) independently extracted data and assessed trial quality. We contacted study authors for additional information.

MAIN RESULTS

We included a total of 11 studies involving 1275 participants. In three trials (n = 782), EPO therapy was associated with a significant increase in death by the end of the trial (odds ratio (OR) 1.98, 95% confidence interval (CI) 1.19 to 3.3, P = 0.009) and a non-significant increase in serious adverse events. EPO significantly increased the red cell count with no effect on platelet or white cell count, or infarct volume. Two small trials of carbamylated EPO have been completed but have yet to be reported. We included eight small trials (n = 548) of G-CSF. G-CSF was associated with a non-significant reduction in early impairment (mean difference (MD) -0.4, 95% CI -1.82 to 1.01, P = 0.58) but had no effect on functional outcome at the end of the trial. G-CSF significantly elevated the white cell count and the CD34+ cell count, but had no effect on infarct volume. Further trials of G-CSF are ongoing.

AUTHORS' CONCLUSIONS

There are significant safety concerns regarding EPO therapy for stroke. It is too early to know whether other CSFs improve functional outcome.

Neuroprotective effect of a cell-free extract derived from human adipose stem cells in experimental stroke models

A recent study suggested that a cell-free extract of human adipose stem cells (hASCs-E) has beneficial effects on neurological diseases by modulating the host environment. Here, we investigated the effects of hASCs-E in several experimental models of stroke in vitro (oxygen and glucose deprivation, OGD) and in vivo (transient or permanent focal cerebral ischemia and intracerebral hemorrhage, ICH). Ischemia was induced in vitro in Neuro2A cells, and the hASCs-E was applied 24h before the OGD or concurrently. Focal cerebral ischemia was induced by unilateral intraluminal thread occlusion of the middle cerebral artery (MCA) in rats for 90min or permanently, or by unilateral MCA microsurgical direct electrocoagulation in mice. The ICH model was induced with an intracerebral injection of collagenase in rats. The hASCs-E was intraperitoneally administered 1h after the stroke insults. Treatment of the hASCs-E led to a substantially high viability in the lactate dehydrogenase and WST-1 assays in the in vitro ischemic model. The cerebral ischemic and ICH model treated with hASCs-E showed decreased ischemic volume and reduced brain water content and hemorrhage volume. The ICH model treated with hASCs-E exhibited better performance on the modified limb placing test. The expression of many genes related to inflammation, immune response, and cell-death was changed substantially in the ischemic rats or neuronal cells treated with the hASCs-E. These results reveal a neuroprotective role of hASCs-E in animal models of stroke, and suggest the feasible application of stem cell-based, noninvasive therapy for treating stroke.

Granulocyte-colony stimulating factor improves MDX mouse response to peripheral nerve injury

BACKGROUND

G-CSF has been shown to increase neuronal survival, which may positively influence the spinal cord microenvironment during the course of muscular dystrophies.

METHODOLOGY/PRINCIPAL FINDINGS

Male MDX mice that were six weeks of age received a left sciatic nerve transection and were treated with intraperitoneal injections of 200 µg/kg/day of G-CSF 7 days before and 7 days after the transection. The axotomy was performed after the cycles of muscular degeneration/regeneration, consistent with previous descriptions of this model of muscular dystrophy. C57BL/10 mice were used as control subjects. Seven days after the surgery, the animals were sacrificed and their lumbar spinal cords were processed for immunohistochemistry (anti-MHC I, anti-Synaptophysin, anti-GFAP and anti-IBA-1) and transmission electron microscopy. MHC I expression increased in both strains of mice after the axotomy. Nevertheless, the MDX mice displayed a significantly smaller MHC I upregulation than the control mice. Regarding GFAP expression, the MDX mice showed a stronger astrogliosis compared with the C57BL/10 mice across all groups. Both groups that were treated with G-CSF demonstrated preservation of synaptophysin expression compared with the untreated and placebo groups. The quantitative analysis of the ultrastructural level showed a preservation of the synaptic covering for the both groups that were treated with G-CSF and the axotomized groups showed a smaller loss of synaptic contact in relation to the treated groups after the lesion.

CONCLUSIONS/SIGNIFICANCE

The reduction of active inputs to the alpha-motoneurons and increased astrogliosis in the axotomized and control groups may be associated with the cycles of muscle degeneration/regeneration that occur postnatally. The G-CSF treated group showed a preservation of the spinal cord microenvironment after the lesion. Moreover, the increase of MHC I expression in the MDX mice that were treated with G-CSF may indicate that this drug performs an active role in regenerative potential after lesions.

Granulocyte-colony stimulating factor protects memory impairment in the senescence-accelerated mouse (SAM)-P10

OBJECTIVE

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with memory impairment in elderly people. At present, AD remains incurable. More and more evidences have suggested that granulocyte-colony stimulating factor (G-CSF) has important non-hematopoietic neuroprotective functions in central nervous system. The present study was designed to investigate the therapeutic potential of G-CSF in the senescence-accelerated mouse prone strain (SAM-P10) mice, a mouse model of senile dementia.

METHODS

Recombinant human G-CSF was administered subcutaneously in SAM-P10 mice once daily for consecutive 7 days. Morris water maze test was used to evaluate spatial memory of the mice. Immunohistochemistry analysis was done to elucidate the changes of apoptotic neurons in CA1 region of hippocampus of the mice.

RESULTS

In the present study, we found that administration of recombinant G-CSF significantly protected spatial memory impairment, and decreased the number of apoptotic (caspase-3-positive) and tumor necrosis factor related apoptosis-inducing ligand (TRAIL)-positive neurons in CA1 region of hippocampus of SAM-P10 mice, suggesting that G-CSF may protect spatial memory impairment through suppression of TRAIL-mediated apoptosis in neurons.

CONCLUSIONS

These findings highlight the therapeutic potential of G-CSF in AD.

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.

Neuroprotective effects of the beta-catenin stabilization in an oxygen- and glucose-deprived human neural progenitor cell culture system

β-Catenin stabilization achieved either via GSK-3β specific inhibition or involving canonical Wnt signalling pathway, contributes to neuroprotection in an oxygen-glucose deprivation (4h OGD) in vitro hypoxia model performed on human cortical neural progenitor cells previously differentiated into neurons and glia. Neuroprotection mechanisms include both acquiring tolerance to injury throughout preconditioning (72 h prior to OGD) or being pro-survival during 24h reoxygenation after the insult. Four hours of OGD induced apoptotic cell death elevation to 73 ± 1% vs. 12% measured in control and the LDH level, indicative of necrotic cell injury, elevation by 67 ± 7% (set to 100%). A significant reduction in apoptosis occurred at 24h reoxygenation with indirubin supplement which was 49 ± 6% at 2.5 μM BIO while LDH level was only 47 ± 5% of OGD. Kenpaullone was efficient in reducing both cell deaths at 5 μM (apoptosis 38 ± 1% and necrosis 33 ± 3% less than in OGD). Wnt agonist reduced apoptosis to 45 ± 3% at 0.01 μM, while LDH value was decreased to a level of 53 ± 5% of control. Our findings suggest that GSK-3beta inhibitors/β-catenin stabilizers may ultimately be useful drugs in neuroprotection and neuroregeneration therapies in vivo.

Efficacy of the coadministration of granulocyte colony-stimulating factor and stem cell factor in the activation of intrinsic cells after spinal cord injury in mice

Object

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic cytokine that induces undifferentiated stem cells from the bone marrow (BM) into the peripheral blood. Stem cell factor (SCF) is also a hematopoietic cytokine that stimulates the differentiation and proliferation of neural stem cells and has neuroprotective effects. In cerebrally infarcted mice, the combination of G-CSF and SCF promotes the differentiation of BM-derived cells into neural cells, stimulates the proliferation of intrinsic neural stem cells, and improves motor function. The object of this study was to investigate the effects of these cytokines on BM stem cells, intrinsic cells, and motor function recovery in spinal cord–injured mice.

Methods

For marking BM-derived cells, the authors induced contusive spinal cord injury in mice transplanted with BM cells from green fluorescent protein (GFP)–transgenic mice after whole-body irradiation. These mice were treated with G-CSF and SCF in the subacute injury phase. Bromodeoxyuridine (BrdU) was injected into these mice to label proliferating cells. The cell numbers and phenotype of the BM-derived cells were evaluated, and the change in intrinsic cells (proliferation, accumulation, and differentiation) was noted using immunohistological analysis at 4 weeks postinjury (wpi). A behavior analysis was conducted until 12 wpi using the Basso, Beattie, Bresnahan locomotor rating scale.

Results

In the SCF + G-CSF group, improvement in hindlimb motor function was significantly greater than in the SCF group, G-CSF group, and sham-treatment (vehicle) group after 8 wpi. At 4 wpi, the number of GFP+ BM-derived cells induced in the lesion did not significantly differ between groups. At 4 wpi, the authors evaluated perilesional GFP− intrinsic spinal cord cells. The number of GFP− and F4/80+ cells was significantly greater in the SCF + G-CSF group than in the other 3 groups. As compared with the sham group, the number of NG2+/BrdU+ cells was significantly increased in the SCF + G-CSF group.

Conclusions

In this study, the combined administration of SCF and G-CSF in traumatic spinal cord injury not only improved motor function, but also induced the accumulation of intrinsic microglia and the active proliferation of intrinsic oligodendrocyte precursor cells.

Granulocyte-colony stimulating factor ameliorates irradiation-induced suppression of hippocampal neurogenesis in adult mice

Granulocyte-colony stimulating factor (G-csf) is a member of the hematopoietic growth factor family and demonstrates neuroprotective functions in neurodegenerative diseases. This study evaluated the radioprotective effects of G-csf in the suppression of hippocampal neurogenesis in adult mice undergoing irradiation. The radioprotective effects were assessed using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay and immunohistochemical markers of neurogenesis, including the proliferating cell marker Ki-67 and the immature progenitor neuron marker doublecortin (DCX). Acute exposure to cranial irradiation (5Gy γ-rays) induced neural apoptosis and inhibited neurogenesis in the dentate gyrus (DG) of the adult mouse hippocampus. Pretreatment with G-csf (100μg/kg every 12h subcutaneously on three consecutive days) attenuated neural apoptosis and decreased the number of Ki-67- and DCX-positive cells in the DG of the irradiated mouse hippocampus. Therefore, G-csf inhibited the detrimental effects of irradiation on hippocampal neurogenesis, suggesting that G-csf administration has potential therapeutic utility in brain irradiation.

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 Delays PWI/DWI Mismatch Evolution and Reduces Final Infarct Volume in Permanent-Suture and Embolic Focal Cerebral Ischemia Models in the Rat

Background and Purpose— Granulocyte-colony stimulating factor (G-CSF) is used clinically to attenuate neutropenia after chemotherapy. G-CSF acts as a growth factor in the central nervous system, counteracts apoptosis, and is neuroprotective in rodent transient ischemia models.

Methods— We assessed the effect of G-CSF on ischemic lesion evolution in a rat permanent-suture occlusion model with diffusion- and perfusion-weighted magnetic resonance imaging and the neuroprotective effect of G-CSF in a rat embolic stroke model.

Results— With a constant perfusion deficit, vehicle-treated animals showed an expanding apparent diffusion coefficient lesion volume that matched the perfusion deficit volume at ≈3 hours, with the 24-hour infarct volume equivalent to the perfusion deficit. In G-CSF–treated rats, the apparent diffusion coefficient lesion volume did not increase after treatment initiation, and the infarct volume at 24 hours reflected the initial apparent diffusion coefficient lesion volume. In the embolic model, we observed a significant decrease in infarct volume in G-CSF–treated animals compared with the vehicle-treated group.

Conclusions— These results confirm the potent neuroprotective activity of G-CSF in different focal ischemia models. The magnetic resonance imaging data demonstrate that G-CSF preserved the perfusion/diffusion mismatch.

Autophagy is involved in the ischemic preconditioning

Autophagy is a key pathway for the clearance of damaged organelles. Ischemic preconditioning (IPC) and autophagy are enhanced by mild hypoxic insults, but the association between autophagy and IPC remains unclear. We investigated the existence and role of autophagy in IPC. In an in vitro PC12 cell model, IPC increased generation and degradation of autophagosomes, as revealed by increased LC3-II bands, cathepsin D positive cells, lysosomal activity and autophagic vacuoles on electron microscopy. Autophagic activity was blocked using 3-methyladenine during IPC, and cell viabilities were measured using FASC and WST-1 assays. Inhibition of autophagy, especially during reperfusion or lethal oxygen-glucose deprivation periods ameliorated the neuroprotective effects of IPC. Moreover, inhibiting autophagy also attenuated Hsp70 upregulation induced by IPC. These findings imply that autophagy participates in IPC-induced neuroprotection, and that autophagy might provide a means of neuroprotection against cerebral ischemia.

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.

Colony stimulating factors (including erythropoietin, granulocyte colony stimulating factor and analogues) for stroke

BACKGROUND

Colony stimulating factors (CSFs), also called haematopoietic growth factors, regulate bone marrow production of circulating red and white cells, and platelets. They have been shown to be neuroprotective in experimental stroke. Some CSFs also mobilise the release of bone marrow stem cells into the circulation.

OBJECTIVES

To assess the effects of CSFs on functional outcome and haematology measures in patients with acute or subacute stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched November 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2006), MEDLINE (1985 to June 2006), EMBASE (1985 to June 2006), and Science Citation Index (1985 to June 2006). In an attempt to identify further published, unpublished and ongoing trials we contacted manufacturers and principal investigators of trials (last contacted 2006). We also searched reference lists of relevant articles and reviews.

SELECTION CRITERIA

Unconfounded randomised controlled trials recruiting patients with acute or subacute ischaemic or haemorrhagic stroke were included. CSFs included stem cell factor (SCF), erythropoietin (EPO), granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage colony stimulating factor (GM-CSF), macrophage-colony stimulating factor (M-CSF, CSF-1), and thrombopoietin (TPO), or analogues of these. The primary outcome was functional outcome (assessed as combined death or disability and dependency using scales such as the modified Rankin Scale or Barthel Index) at the end of the trial. Secondary outcomes included safety at the end of treatment (death, impairment, deterioration, extension or recurrence), death at the end of follow up, and haematology measures (blood counts at or around day seven after treatment commenced).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality. Study authors were contacted for additional information.

MAIN RESULTS

No large trials were identified. EPO therapy was associated with a non-significant reduction in neurological impairment in one small trial (n = 40 participants) but had no significant effect on haematological measures. G-CSF was associated with a non-significant reduction in combined death and dependency in two small trials (n = 46 participants) although there was substantial heterogeneity in this result. G-CSF significantly elevated white cell count in three trials (n = 91). Further small trials of EPO and G-CSF are ongoing.

AUTHORS' CONCLUSIONS

No large trials of EPO, G-CSF or other colony stimulating factors have been performed and it is too early to know whether CSFs improve functional outcome.

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.

Pathophysiology of Acute Ischaemic Stroke: An Analysis of Common Signalling Mechanisms and Identification of New Molecular Targets

Stroke continues to be a major cause of death and disability. The currently available therapies have proven to be highly unsatisfactory (except thrombolysis) and attempts are being made to identify and characterize signalling proteins which could be exploited to design novel therapeutic modalities. The pathophysiology of stroke is a complex process. Delaying interventions from the first hours to days or even weeks following blood vessel occlusion may lead to worsening or impairment of recovery in later stages. The objective of this review is to critically evaluate the major mechanisms underlying stroke pathophysiology, especially the role of cell signalling in excitotoxicity, inflammation, apoptosis, neuroprotection and angiogenesis, and highlight potential novel targets for drug discovery.

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.

An extended window of opportunity for G-CSF treatment in cerebral ischemia

Background

Granulocyte-colony stimulating factor (G-CSF) is known as a powerful regulator of white blood cell proliferation and differentiation in mammals. We, and others, have shown that G-CSF is effective in treating cerebral ischemia in rodents, both relating to infarct size as well as functional recovery. G-CSF and its receptor are expressed by neurons, and G-CSF regulates apoptosis and neurogenesis, providing a rational basis for its beneficial short- and long-term actions in ischemia. In addition, G-CSF may contribute to re-endothelialisation and arteriogenesis in the vasculature of the ischemic penumbra. In addition to these trophic effects, G-CSF is a potent neuroprotective factor reliably reducing infarct size in different stroke models.

Results

Here, we have further delayed treatment and studied effects of G-CSF on infarct volume in the middle cerebral artery occlusion (MCAO) model and functional outcome in the cortical photothrombotic model. In the MCAO model, we applied a single dose of 60 μg/kg bodyweight G-CSF in rats 4 h after onset of ischemia. Infarct volume was determined 24 h after onset of ischemia. In the rat photothrombotic model, we applied 10 μg/kg bodyweight G-CSF daily for a period of 10 days starting either 24 or 72 h after induction of ischemia. G-CSF both decreased acute infarct volume in the MCAO model, and improved recovery in the photothrombotic model at delayed timepoints.

Conclusion

These data further strengthen G-CSF's profile as a unique candidate stroke drug, and provide an experimental basis for application of G-CSF in the post-stroke recovery phase.