Project description:Inflammation triggers secondary brain damage after stroke. The meninges and other CNS border compartments serve as invasion sites for leukocyte influx into the brain thus promoting tissue damage after stroke. However, the post-ischemic immune response of border compartments compared to brain parenchyma remains poorly characterized . Here, we deeply characterize tissue-resident leukocytes in meninges and brain parenchyma by flow cytometry, histology, and single cell transcriptomics after experimental stroke and discover that leukocytes respond differently to stroke depending on their site of residence. We thereby discover a unique phenotype of myeloid cells exclusive to the brain after stroke. These stroke-associated myeloid cells partially resemble neurodegenerative disease-associated microglia. They are mainly of resident microglial origin, partially conserved in humans and exhibit a lipid-phagocytosing phenotype. Blocking markers specific for these cells partially ameliorates stroke outcome thus providing a potential therapeutic target. The injury-response of myeloid cells in the CNS is thus compartmentalized, adjusted to the type of injury and may represent a therapeutic target.
Project description:Acute stroke triggers extensive changes to myeloid immune cell populations in the brain that may be targets for limiting brain damage and enhancing repair. Immunomodulatory approaches will be most effective with precise manipulation of discrete myeloid cell phenotypes in time and space. Here, we investigate how stroke alters mononuclear myeloid cell composition and phenotypes at single-cell resolution and key spatial patterns. Our results show that multiple reactive microglial states and monocyte-derived populations contribute to an extensive myeloid cell repertoire in post-stroke brains. We identify important overlaps and distinctions among different cell types/states that involve ontogeny- and spatial-related properties. Notably, brain connectivity with infarcted tissue underpins the pattern of local and remote altered cell accumulation and reactivity. Our discoveries suggest a global but anatomically governed brain myeloid cell response to stroke that comprises diverse phenotypes arising through intrinsic cell ontogeny factors interacting with exposure to spatially organized brain damage and neuro-axonal cues.
Project description:We have used microarrays to investigate the changes in gene expression at various times after stroke. Our findings reported that gene expression screening can detect known and unknown transcriptional features of stroke. Brain samples were obtained from 9 patients who died from stroke, with the approval of the local Ethics Committee. The patients were aged between 51 and 86 years and had survived between 2-37 days following stroke. Tissue samples were taken from infarct and peri-infarcted zones while controls were obtained from the contralateral hemisphere. We established mRNA expression profiles of the damaged brain tissues between 2 to 6 days, 9 to 20 days, and 26 to 37 days after stroke. RNA from three stroke patients was pooled for each patient survival group.
Project description:Genes upregulated in stroke infiltrating stem cells were compared against the parent non-infiltrated mouse stem cell line derived from immortomouseTM. Abstract Background and Purpose- Although the therapeutic potential of bone marrow-derived stem cells (SC) has been addressed in different experimental models of ischemic stroke, it is still unclear how SC induce neuroprotection following stroke. In this study, we describe a novel method for recovering SC infiltrating post-stroke brain tissue allowing the determination of genes which become persistently activated / or depressed (compared to their naïve counterparts) during SC-mediated neuroprotection. Methods- Ischemic stroke was induced in C57BL/6 mice by middle cerebral artery occlusion for 1 h, followed by reperfusion. SC were isolated from H-2Kb-tsA58 (immortomouseTM) mice, and were administered (i.v.) 24 h after reperfusion. At the onset of therapeutic improvement (14 days after ischemia), infarcted brain tissue was isolated and infarct-infiltratng SC cultured at 33°C. Microarray analysis and RT-PCR were performed to compare persistent differential gene expression between naïve and infiltrating SC populations. Results- Z-scoring revealed dramatic changes in extracellular genes of analyzed cells. Pair-wise analysis detected 80 extracellular factor genes that were up-regulated ( 2 fold, P<0.05, Benjamini-Hochberg correction) between naïve and infiltrated SC. Although several conventional neuroregenerative, nerve guidance and angiogenic factors (bFGF, bone morphogenetic protein, angiopoietins, neural growth factors were among the expressed genes detected we identified Cytokine receptor-like factor 1 (Crlf1), Fgf7, family with sequence similarity 19, member A5 (Fam19a5), Glypican 1 (Gpc1), Dickkopf homolog 2 (Dkk2), Endothelial cell-specific molecule 1, Osteopontin (OPN)35, Tissue factor pathway inhibitor 2, Masp3 mRNA for MBL-associated serine protease-3, Glial cell line derived neurotrophic factor (Gdnf), Bone morphogenetic protein 2 (Bmp2), Olfactomedin 1, Sushi-repeat-containing protein, X-linked 2 (Srpx2). Conclusions- SC infiltrating the post-i schemic brain assume a persistently altered pattern of expressed extracellular genes compared to naïve SC that contributes to neuroprotection, regeneration and angiogenesis in infarcts. Keywords: Gene activation / suppression study Comparison of persistent stem cell gene expression induced by stroke-infarct infiltration
Project description:We have used microarrays to investigate the changes in gene expression at various times after stroke. Our findings reported that gene expression screening can detect known and unknown transcriptional features of stroke. Keywords: time course, disease state analysis
Project description:Purpose: Signaling pathways mediated by microRNAs (miRNAs) represent one of the mechanisms that regulate stroke progression and recovery. The goal of this study is to investigate miRNA expression signatures in freshly removed human stroke brain tissue. Methods: Human brain samples (5 stroke and 3 non-stroke samples) obtained at 48-72 hours after stroke onset during craniectomy and stroke-ectomy, were subjected to histopathological and immunofluorescence microscopy analyses. NGS sequencing was performed by Qiagen company and analyses were carried out using QIAseq miRNA Quantification workflow and RNA-seq Analysis tools within CLC Genomics Workbench (version 20.0.2). Reads were normalized for expression analysis using trimmed mean of M-values method (TMM). miRNA profiling was performed using the EdgeR in Bioconductor package. Whole transcriptome RNA-sequencing Analysis: The unmapped reads from the NGS miRNA analysis were extracted, deduplicated and mapped to the genome. Gene expressions were calculated by counting number of reads mapping to the annotated gene loci. Human miR-155 Targets RT2 Profiler PCR Array (Qiagen) was performed using 3 RNA samples per stroke and control groups. The PCR Array Data analysis was performed using an automated PCR Analysis Web Portal and GeneGlobe Data Analysis (Qiagen). Results: Human stroke brain tissue was characterized by classic ischemic changes, including significant neuronal and vascular damage, and prominent edema. The absence of monocytes and notable neutrophil infiltration indicated the early stage of leukocyte response to ischemia. miRNA NGS analysis detected 36 miRNAs with significantly aberrant expression in stroke tissue, as compared to non-stroke samples. Of these miRNAs, 19 were previously identified in stroke patient blood and CSF, while dysregulation of 16 miRNAs was newly detected in this study. Bioinformatics pathway enrichment analysis demonstrated a strong association of the identified miRNAs with stroke-related biological processes and signaling pathways Conclusions: Dysregulated miRNAs detected in our study could be regarded as potential candidates for biomarkers and/or targets for therapeutic intervention. The obtained data will serve for better understanding of the molecular basis of stroke and provide valuable information for the future functional studies in the experimental models of stroke.
Project description:This program addresses the gene signature associated with brain (cortex) in the tMCAO rat model for stroke. The tMCAO stroke model profiling data was analyzed by identifying genes that were up- and down-regulated at selected p value and fold change in brain cortex of the Sprague Dawley rats following middle cerebral artery occlusion compared to the sham-operated controls.
Project description:Stroke is still a major cause of death and disability worldwide. A better comprehension of stroke pathophysiology is fundamental to reduce its dramatic outcome. Our aim was to identify and verify gene expression changes that occur in the human brain after ischemia.
Project description:It has been unclear whether ischemic stroke induces neurogenesis or neuronal DNA-rearrangements in the human neocortex. We show here that neither is the case, using immunohistochemistry, transcriptome-, genome- and ploidy-analyses, and determination of nuclear bomb test-derived 14C-concentration in neuronal DNA. A large proportion of cortical neurons display DNA-fragmentation and DNA-repair short time after stroke, whereas neurons at chronic stages after stroke show DNA-integrity, demonstrating the relevance of an intact genome for survival. Analyze of potential fusion transcripts in 13 samples, seven cortical ischemic stroke tissue and six control cortex, by deep sequencing using Illumina HiSeq 2000