Background and Purpose-Intra-arterial cell transplantation offers a novel therapeutic strategy for stroke; however, it remains unclear how the timing of cell administration affects cell distribution, brain repair processes, and functional recovery. Here, we investigate the hypothesis that the timing of cell transplantation changes the behavior of the cell graft and the host environment in a way that affects functional recovery. Methods-Rats received human mesenchymal stem cells via the internal carotid artery at 1, 4, or 7 days (D1, D4, or D7) after middle cerebral artery occlusion and reperfusion. Animals were euthanized at various time points to assess cell distribution, infiltration of activated microglia, expression of brain-derived neurotrophic factor, reactive astrocytes, angiogenesis, and functional recovery. Results-Human mesenchymal stem cells were widely distributed both in the peri-infarct and core in D1, and dominantly in the peri-infarct in D4. Very few cells were observed on D7. At day 7 poststroke, microglia activation was significantly suppressed in both the peri-infarct and core in D1, and predominantly in the peri-infarct in D4. At day 21 poststroke, brain-derived neurotrophic factor was widely distributed throughout the peri-infarct in D1 and D4, along with many reactive astrocytes and considerable angiogenesis. Motor function improved earlier in D1 and later in D4, but no recovery was obtained in D7. Conclusions-Our

Stroke induces network-wide changes in the brain, affecting the excitability in both nearby and remotely connected regions. Brain stimulation is a promising neurorestorative technique that has been shown to improve stroke recovery by altering neuronal activity of the target area. However, it is unclear whether the beneficial effect of stimulation is a result of neuronal or non-neuronal activation, as existing stimulation techniques nonspecifically activate/inhibit all cell types (neurons, glia, endothelial cells, oligodendrocytes) in the stimulated area. Furthermore, which brain circuit is efficacious for brain stimulation is unknown. Here we use the optogenetics approach to selectively stimulate neurons in the lateral cerebellar nucleus (LCN), a deep cerebellar nucleus that sends major excitatory output to multiple motor and sensory areas in the forebrain. Repeated LCN stimulations resulted in a robust and persistent recovery on the rotating beam test, even after cessation of stimulations for 2 weeks. Furthermore, western blot analysis demonstrated that LCN stimulations significantly increased the axonal growth protein GAP43 in the ipsilesional somatosensory cortex. Our results demonstrate that pan-neuronal stimulations of the LCN is sufficient to promote robust and persistent recovery after stroke, and thus is a promising target for brain stimulation.

Cell transplantation therapy offers great potential to improve impairments after stroke. However, the importance of donor age on therapeutic efficacy is unclear. We investigated the regenerative capacity of transplanted cells focusing on donor age (young vs. old) for ischaemic stroke. The quantities of human mesenchymal stem cell (hMSC) secreted brain-derived neurotrophic factor in vitro and of monocyte chemotactic protein-1 at day 7 in vivo were both significantly higher for young hMSC compared with old hMSC. Male Sprague-Dawley rats subjected to transient middle cerebral artery occlusion that received young hMSC (trans-arterially at 24 h after stroke) showed better behavioural recovery with prevention of brain atrophy compared with rats that received old hMSC. Histological analysis of the peri-infarct cortex showed that rats treated with young hMSC had significantly fewer microglia and more vessels covered with pericytes. Interestingly, migration of neural stem/progenitor cells expressing Musashi-1 positively correlated with astrocyte process alignment, which was more pronounced for young hMSC. Aging of hMSC may be a critical factor that affects cell therapy outcomes, and transplantation of young hMSC appears to provide better functional recovery through anti-inflammatory effects, vessel maturation, and neurogenesis potentially by the dominance of trophic factor secretion.

Background and Purpose-Recent studies have investigated plaque morphology to determine patients who are at high risk of carotid atherosclerosis. In this study, we investigated whether a difference in dynamic enhancement pattern in plaque components could be useful to assess plaque stability with multidetector CT angiography. Methods-Fifty-nine lesions with moderate to severe carotid atherosclerosis in 51 patients (33 symptomatic, 18 asymptomatic) were consecutively included. Early-and delayed-phase images were obtained in 3 equivalent axial slices with multidetector CT angiography. Hounsfield units (HU) in the early phase were subtracted from those in the delayed phase in plaques (⌬HU) and compared with clinical features, MRI-based plaque characteristics, and histological findings with 20 surgical specimens acquired from carotid endarterectomy. Results-The ⌬HU was significantly higher in asymptomatic than that in symptomatic presentation (Pϭ0.02). With MRI, a higher ⌬HU was negatively correlated with signal intensity on T1-weighted imaging (rϭϪ0.56, PϽ0.0001). Histology confirmed that ⌬HU was positively correlated with fibrous tissue (rϭ0.67, Pϭ0.001) and negatively correlated with a lipid-rich necrotic core with hemorrhage (rϭϪ0.70, PϽ0.001). Moreover, less neovascularization and inflammation was found in plaques with a higher ⌬HU. Conclusions-Delayed-phase images provide information regarding the dynamic change in contrast media from the early arterial phase. An increase in HU from the early phase on multidetector CT angiography indicates plaque stability with more fibrous tissue and a less lipid-rich necrotic core, intraplaque hemorrhage, and neovascularization. (Stroke. 2012; 43:393-398.)

Background and purpose Many restorative therapies have been used to study brain repair after stroke. These therapeutic-induced changes have revealed important insights on brain repair and recovery mechanisms, however, the intrinsic changes that occur in spontaneously recovery after stroke is less clear. The goal of this study is to elucidate the intrinsic changes in spontaneous recovery after stroke, by directly investigating the transcriptome of primary motor cortex in mice that naturally recovered after stroke. Methods Male C57BL/6J mice were subjected to transient middle cerebral artery occlusion. Functional recovery was evaluated using the horizontal rotating beam test. A novel in-depth lesion mapping analysis was used to evaluate infarct size and locations. Ipsilesional and contralesional primary motor cortices (iM1 and cM1) were processed for RNA sequencing (RNA-seq) transcriptome analysis. Results Cluster analysis of the stroke mice behavior performance revealed two distinct recovery groups: a spontaneously recovered and a non-recovered group. Both groups showed similar lesion profile, despite their differential recovery outcome. RNA-seq transcriptome analysis revealed distinct biological pathways in the spontaneously-recovered stroke mice, in both iM1 and cM1. Correlation analysis revealed that 38 genes in the iM1 were significantly correlated with improved recovery, while 74 genes were correlated in the cM1. In particular, ingenuity pathway analysis highlighted the involvement of cyclic adenosine monophosphate (cAMP) signaling in the cM1, with selective reduction of adenosine receptor A2A (Adora2a), dopamine receptor D2 (Drd2) and phosphodiesterase 10A (Pde10a) expression in recovered mice. Interestingly, the expressions of these genes in cM1 were negatively correlated with behavioral recovery. Conclusions Our RNA-seq data revealed a panel of recovery-related genes in the motor cortex of spontaneously-recovered stroke mice and highlighted the involvement of contralesional cortex in spontaneous recovery, particularly Adora2a, Drd2 and Pde10a-mediated cAMP signaling pathway. Developing drugs targeting these candidates after stroke may provide beneficial recovery outcome.