Gerhard Vogt

Granulocyte Colony–Stimulating Factor in Patients With Acute Ischemic Stroke Results of the AX200 for Ischemic Stroke Trial

Background and Purpose— Granulocyte colony–stimulating factor (G-CSF; AX200; Filgrastim) is a stroke drug candidate with excellent preclinical evidence for efficacy. A previous phase IIa dose–escalation study suggested potential efficacy in humans. The present large phase IIb trial was powered to detect clinical efficacy in acute ischemic stroke patients. Methods— G-CSF (135 µg/kg body weight intravenous over 72 hours) was tested against placebo in 328 patients in a multinational, multicenter, randomized, and placebo-controlled trial (NCT00927836; www.clinicaltrial.gov). Main inclusion criteria were ⩽9-hour time window after stroke onset, infarct localization in the middle cerebral artery territory, baseline National Institutes of Health Stroke Scale score range of 6 to 22, and baseline diffusion-weighted imaging lesion size ≥15 mL. Primary and secondary end points were the modified Rankin scale score and the National Institutes of Health Stroke Scale score at day 90, respectively. Data were analyzed using a prespecified model that adjusted for age, National Institutes of Health Stroke Scale score at baseline, and initial infarct volume (diffusion-weighted imaging). Results— G-CSF treatment failed to meet the primary and secondary end points of the trial. For additional end points such as mortality, Barthel index, or infarct size at day 30, G-CSF did not show efficacy either. There was, however, a trend for reduced infarct growth in the G-CSF group. G-CSF showed the expected peripheral pharmacokinetic and pharmacodynamic profiles, with a strong increase in leukocytes and monocytes. In parallel, the cytokine profile showed a significant decrease of interleukin-1. Conclusions— G-CSF, a novel and promising drug candidate with a comprehensive preclinical and clinical package, did not provide any significant benefit with respect to either clinical outcome or imaging biomarkers. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00927836.

AXIS A Trial of Intravenous Granulocyte Colony-Stimulating Factor in Acute Ischemic Stroke

Background and Purpose— Granulocyte colony-stimulating factor (G-CSF) is a promising stroke drug candidate. The present phase IIa study assessed safety and tolerability over a broad dose range of G-CSF doses in acute ischemic stroke patients and explored outcome data. Methods— Four intravenous dose regimens (total cumulative doses of 30–180 &mgr;g/kg over the course of 3 days) of G-CSF were tested in 44 patients in a national, multicenter, randomized, placebo-controlled dose escalation study (NCT00132470; www.clinicaltrial.gov). Main inclusion criteria were a 12-hour time window after stroke onset, infarct localization to the middle cerebral artery territory, a baseline National Institutes of Health Stroke Scale range of 4 to 22, and presence of diffusion-weighted imaging/perfusion-weighted imaging mismatch. Results— Concerning the primary safety end points, we observed no increase of thromboembolic events in the active treatment groups, and no increase in related serious adverse events. G-CSF led to expected increases in neutrophils and monocytes that resolved rapidly after end of treatment. We observed a clinically insignificant drug-related decrease of platelets. As expected from the low number of patients, we did not observe significant differences in clinical outcome in treatment vs. placebo. In exploratory analyses, we observed an interesting dose-dependent beneficial effect of treatment in patients with DWI lesions >14–17 cm3. Conclusions— We conclude that G-CSF was well-tolerated even at high dosages in patients with acute ischemic stroke, and that a substantial increase in leukocytes appears not problematic in stroke patients. In addition, exploratory analyses suggest treatment effects in patients with larger baseline diffusion-weighted imaging lesions. The obtained data provide the basis for a second trial aimed to demonstrate safety and efficacy of G-CSF on clinical end points.

Initial Lesion Volume Is an Independent Predictor of Clinical Stroke Outcome at Day 90 An Analysis of the Virtual International Stroke Trials Archive (VISTA) Database

Background and Purpose— Age and National Institutes of Health Stroke Scale early after stroke onset have been identified as important determinants of final stroke outcome. We analyzed the Virtual International Stroke Trials Archive (VISTA) database to define the influence of infarct or hemorrhagic volume on clinical outcome after stroke. Methods— All patients were extracted from VISTA where infarct or hemorrhage volume information was available (n=2538; most images obtained by CT within 72 hours after stroke onset with a subset of MRI data included, volumes calculated by the ABC/2 approximation method). We used multivariate regression models to study the influence of age, National Institutes of Health Stroke Scale at baseline, and initial infarct/hemorrhage volume on clinical outcome (modified Rankin Scale, National Institutes of Health Stroke Scale, mortality) at day 90. Results— We find that in a large cohort of >1800 patients with ischemic stroke, initial lesion size is a strong and independent predictor of stroke outcome in a statistical regression model that also accounts for age and National Institutes of Health Stroke Scale at baseline (P<0.0001). The use of infarct/hemorrhage volume as an additional predictive factor further reduces the fraction of unexplained variance in outcome by approximately 15% (R2 of 0.41 versus 0.26 in a model without lesion volume). The predictive strength of initial lesion size is only marginally influenced by image modality or time point of image acquisition within the first 72 hours. The model was equally valid for both ischemic and hemorrhagic strokes. Conclusions— Infarct/hemorrhage volume at baseline together with age and National Institutes of Health Stroke Scale at baseline should be used in the effect analysis of future therapeutic stroke trials to improve power.

Kindling-induced overexpression of Homer 1A and its functional implications for epileptogenesis

Despite an extensive research on the molecular basis of epilepsy, the essential players in the epileptogenic process leading to epilepsy are not known. Gene expression analysis is one strategy to enhance our understanding of the genes contributing to the functional neuronal changes underlying epileptogenesis. In the present study, we used the novel MPSS (massively parallel signature sequencing) method for analysis of gene expression in the rat kindling model of temporal lobe epilepsy. Kindling by repeated electrical stimulation of the amygdala resulted in the differential expression of 264 genes in the hippocampus compared to sham controls. The most strongly induced gene was Homer 1A, an immediate early gene involved in the modulation of glutamate receptor function. The overexpression of Homer 1A in the hippocampus of kindled rats was confirmed by RT‐PCR. In order to evaluate the functional implications of Homer 1A overexpression for kindling, we used transgenic mice that permanently overexpress Homer 1A. Immunohistochemical characterization of these mice showed a marked Homer 1A overexpression in glutamatergic neurons of the hippocampus. Kindling of Homer 1A overexpressing mice resulted in a retardation of seizure generalization compared to wild‐type controls. The data demonstrate that kindling‐induced epileptogenesis leads to a striking overexpression of Homer 1A in the hippocampus, which may represent an intrinsic antiepileptogenic and anticonvulsant mechanism in the course of epileptogenesis that counteracts progression of the disease.

The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia

BackgroundThe different physiological repertoire of CA3 and CA1 neurons in the hippocampus, as well as their differing behaviour after noxious stimuli are ultimately based upon differences in the expressed genome. We have compared CA3 and CA1 gene expression in the uninjured brain, and after cerebral ischemia using laser microdissection (LMD), RNA amplification, and array hybridization.ResultsProfiling in CA1 vs. CA3 under normoxic conditions detected more than 1000 differentially expressed genes that belong to different, physiologically relevant gene ontology groups in both cell types. The comparison of each region under normoxic and ischemic conditions revealed more than 5000 ischemia-regulated genes for each individual cell type. Surprisingly, there was a high co-regulation in both regions. In the ischemic state, only about 100 genes were found to be differentially expressed in CA3 and CA1. The majority of these genes were also different in the native state. A minority of interesting genes (e.g. inhibinbetaA) displayed divergent expression preference under native and ischemic conditions with partially opposing directions of regulation in both cell types.ConclusionThe differences found in two morphologically very similar cell types situated next to each other in the CNS are large providing a rational basis for physiological differences. Unexpectedly, the genomic response to ischemia is highly similar in these two neuron types, leading to a substantial attenuation of functional genomic differences in these two cell types. Also, the majority of changes that exist in the ischemic state are not generated de novo by the ischemic stimulus, but are preexistant from the genomic repertoire in the native situation. This unexpected influence of a strong noxious stimulus on cell-specific gene expression differences can be explained by the activation of a cell-type independent conserved gene-expression program. Our data generate both novel insights into the relation of the quiescent and stimulus-induced transcriptome in different cells, and provide a large dataset to the research community, both for mapping purposes, as well as for physiological and pathophysiological research.

Granulocyte-colony stimulating factor (G-CSF) in stroke patients with concomitant vascular disease--a randomized controlled trial.

Background G-CSF has been shown in animal models of stroke to promote functional and structural regeneration of the central nervous system. It thus might present a therapy to promote recovery in the chronic stage after stroke. Methods Here, we assessed the safety and tolerability of G-CSF in chronic stroke patients with concomitant vascular disease, and explored efficacy data. 41 patients were studied in a double-blind, randomized approach to either receive 10 days of G-CSF (10 µg/kg body weight/day), or placebo. Main inclusion criteria were an ischemic infarct >4 months prior to inclusion, and white matter hyperintensities on MRI. Primary endpoint was number of adverse events. We also explored changes in hand motor function for activities of daily living, motor and verbal learning, and finger tapping speed, over the course of the study. Results Adverse events (AEs) were more frequent in the G-CSF group, but were generally graded mild or moderate and from the known side-effect spectrum of G-CSF. Leukocyte count rose after day 2 of G-CSF dosing, reached a maximum on day 8 (mean 42/nl), and returned to baseline 1 week after treatment cessation. No significant effect of treatment was detected for the primary efficacy endpoint, the test of hand motor function. Conclusions These results demonstrate the feasibility, safety and reasonable tolerability of subcutaneous G-CSF in chronic stroke patients. This study thus provides the basis to explore the efficacy of G-CSF in improving chronic stroke-related deficits. Trial Registration ClinicalTrials.gov NCT00298597

KIBRA (KIdney/BRAin protein) regulates learning and memory and stabilizes Protein kinase Mζ.

The WWC1 gene has been genetically associated with human episodic memory performance, and its product KIdney/BRAin protein (KIBRA) has been shown to interact with the atypical protein kinase protein kinase M ζ (PKMζ). Although recently challenged, PKMζ remains a candidate postsynaptic regulator of memory maintenance. Here, we show that PKMζ is subject to rapid proteasomal degradation and that KIBRA is both necessary and sufficient to counteract this process, thus stabilizing the kinase and maintaining its function for a prolonged time. We define the binding sequence on KIBRA, a short amino acid motif near the C‐terminus. Both hippocampal knock‐down of KIBRA in rats and KIBRA knock‐out in mice result in decreased learning and memory performance in spatial memory tasks supporting the notion that KIBRA is a player in episodic memory. Interestingly, decreased memory performance is accompanied by decreased PKMζ protein levels. We speculate that the stabilization of synaptic PKMζ protein levels by KIBRA may be one mechanism by which KIBRA acts in memory maintenance.

Granulocyte-Colony Stimulating Factor (G-CSF) Improves Motor Recovery in the Rat Impactor Model for Spinal Cord Injury

Granulocyte-colony stimulating factor (G-CSF) improves outcome after experimental SCI by counteracting apoptosis, and enhancing connectivity in the injured spinal cord. Previously we have employed the mouse hemisection SCI model and studied motor function after subcutaneous or transgenic delivery of the protein. To further broaden confidence in animal efficacy data we sought to determine efficacy in a different model and a different species. Here we investigated the effects of G-CSF in Wistar rats using the New York University Impactor. In this model, corroborating our previous data, rats treated subcutaneously with G-CSF over 2 weeks show significant improvement of motor function.

The hematopoietic cytokine granulocyte-macrophage colony stimulating factor is important for cognitive functions

We recently reported expression of hematopoietic growth factor GM-CSF and its receptor (GM-CSFR) in CNS neurons. Here we evaluated this system in learning and memory formation using GM-CSF deficient mice. In complementation, GM-CSF signalling was manipulated specifically in adult murine hippocampus by adeno-associated virus (AAV)-mediated GM-CSFR alpha overexpression or knock-down. GM-CSF ablation caused various hippocampus and amygdala-dependent deficits in spatial and fear memory while rendering intact basic parameters like motor function, inherent anxiety, and pain threshold levels. Corroborating these data, spatial memory of AAV-injected mice was positively correlated with GM-CSFRα expression levels. Hippocampal neurons of knock-out mice showed markedly pruned dendritic trees, reduced spine densities, and lower percentages of mature spines. Despite such morphological alterations, long-term potentiation (LTP) was unimpaired in the knock-out hippocampus. Collectively, these results suggest that GM-CSF signalling plays a major role in structural plasticity relevant to learning and memory.

Forced arm use is superior to voluntary training for motor recovery and brain plasticity after cortical ischemia in rats.

Background and purposeBoth the immobilization of the unaffected arm combined with physical therapy (forced arm use, FAU) and voluntary exercise (VE) as model for enriched environment are promising approaches to enhance recovery after stroke. The genomic mechanisms involved in long-term plasticity changes after different means of rehabilitative training post-stroke are largely unexplored. The present investigation explored the effects of these physical therapies on behavioral recovery and molecular markers of regeneration after experimental ischemia.Methods42 Wistar rats were randomly treated with either forced arm use (FAU, 1-sleeve plaster cast onto unaffected limb at 8/10 days), voluntary exercise (VE, connection of a freely accessible running wheel to cage), or controls with no access to a running wheel for 10 days starting at 48 hours after photothrombotic stroke of the sensorimotor cortex. Functional outcome was measured using sensorimotor test before ischemia, after ischemia, after the training period of 10 days, at 3 and 4 weeks after ischemia. Global gene expression changes were assessed from the ipsi- and contralateral cortex and the hippocampus.ResultsFAU-treated animals demonstrated significantly improved functional recovery compared to the VE-treated group. Both were superior to cage control. A large number of genes are altered by both training paradigms in the ipsi- and contralateral cortex and the hippocampus. Overall, the extent of changes observed correlated well with the functional recovery obtained. One category of genes overrepresented in the gene set is linked to neuronal plasticity processes, containing marker genes such as the NMDA 2a receptor, PKC ζ, NTRK2, or MAP 1b.ConclusionsWe show that physical training after photothrombotic stroke significantly and permanently improves functional recovery after stroke, and that forced arm training is clearly superior to voluntary running training. The behavioral outcomes seen correlate with patterns and extent of gene expression changes in all brain areas examined. We propose that physical training induces a fundamental change in plasticity-relevant gene expression in several brain regions that enables recovery processes. These results contribute to the debate on optimal rehabilitation strategies, and provide a valuable source of molecular entry points for future pharmacological enhancement of recovery.