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Stroke is a leading cause of disability in the Western world. Current post-stroke rehabilitation treatments are only effective in approximately half of the patients. Therefore, there is a pressing clinical need for developing new rehabilitation approaches for enhancing the recovery process, which requires the use of appropriate animal models. Here, we demonstrate the use of nonlinear microscopy of calcium sensors in the rat brain to study the effects of ischemic stroke injury on cortical activity patterns. We longitudinally recorded from thousands of neurons labeled with a genetically-encoded calcium indicator before and after an ischemic stroke injury in the primary motor cortex. We show that this injury has an effect on the activity patterns of neurons not only in the motor and somatosensory cortices, but also in the more distant visual cortex, and that these changes include modified firing rates and kinetics of neuronal activity patterns in response to a sensory stimulus. Changes in neuronal population activity provided animal-specific, circuit-level information on the post-stroke cortical reorganization process, which may be essential for evaluating the efficacy of new approaches for enhancing the recovery process.

Stroke is a leading cause of disability in the Western world. Current post-stroke rehabilitation treatments are only effective in approximately half of the patients. Therefore, there is a pressing clinical need for developing new rehabilitation approaches for enhancing the recovery process, which requires the use of appropriate animal models. Here we study the activity patterns of multiple cortical regions in the rat brain using two-photon microscopy. We longitudinally recorded the fluorescence signal from thousands of neurons labeled with a genetically-encoded calcium indicator before and after an ischemic stroke injury, and found substantial functional changes across motor, somatosensory, and visual cortical regions during the post-stroke cortical reorganization period. We show that a stroke injury in the primary motor cortex has an effect on the activity patterns of neurons not only in the motor and somatosensory cortices, but also in the more distant visual cortex, and that these changes include modified firing rates and kinetics of neuronal activity patterns in response to a sensory stimulus. Changes in neuronal population activity provided animal-specific, circuit-level information on the poststroke cortical reorganization process, which may be essential for evaluating the efficacy of new approaches for enhancing the recovery process.

5-bromo-2′-dexoyuridine (BrdU) is often used in neuroscience research as a marker of newly-divided cells. However, several studies suggest that BrdU can produce unwanted side effects, including changes in animal behavior and cellular function. In this study, we investigated the effect of BrdU injections on locomotor behavior in a rodent model of ischemic stroke. Ischemic strokes were induced in adult rats, and 50 mg/kg BrdU was intraperitoneally injected over 5 days beginning 2 weeks post-stroke, while control animals received vehicle. Locomotor activity was evaluated by videotaping the rats in their home cages for 30 min, beginning one hour after BrdU injection. BrdU-injected rats showed a nearly three-fold increase in locomotor activity compared to control animals. These findings suggest that BrdU induces a hyperlocomotor effect in rats following brain injury, pointing to the need for caution when interpreting behavioral results in such studies.

Background Chronic deep brain stimulation of the rodent lateral cerebellar nucleus (LCN) has been demonstrated to enhance motor recovery following cortical ischemia. This effect is concurrent with synaptogenesis and expression of long-term potentiation markers in the perilesional cerebral cortex. Objective To further investigate the cellular changes associated with chronic LCN stimulation in the ischemic rodent by examining neurogenesis along the cerebellothalamocortical pathway. Methods Rats were trained on the pasta matrix task, followed by induction of cortical ischemia and electrode implantation in the contralesional LCN. Electrical stimulation was initiated 6 wk after stroke induction and continued for 4 wk prior to sacrifice. Neurogenesis was examined using immunohistochemistry. Results Treated animals showed enhanced performance on the pasta matrix task relative to sham controls. Increased cell proliferation colabeled with 5'-Bromo-2'-deoxyuridine and neurogenic markers (doublecortin) was observed in the perilesional cortex as well as bilateral mediodorsal and ventrolateral thalamic subnuclei in treated vs untreated animals. The neurogenic effect at the level of motor cortex was selective, with stimulation-treated animals showing greater glutamatergic neurogenesis but significantly less GABAergic neurogenesis. Conclusion These findings suggest that LCN deep brain stimulation modulates postinjury neurogenesis, providing a possible mechanistic foundation for the associated enhancement in poststroke motor recovery.

Ischemic stroke is one of the most common causes of death. A brain that has suffered a stroke is significantly damaged due to the transient interruption of blood supply. Stroke survivors suffer from stroke-induced cognitive, motor and psychiatric problems that require increased use of the health care system, which results in a very poor quality of life and a heavy emotional and financial burden for patients and their families. Although rehabilitation can ameliorate some behavioral abnormalities, it does not significantly improve stroke symptoms. Neuroregeneration may be the principle process for replenishing of lost brain functions. Stem cell therapy is a novel approach to restore neurological function following ischemic stroke. Our goal in this review is to first briefly introduce the pathophysiology of stroke then document the progress of stem cell research, including clinical trials, towards the treatment of ischemic stroke. We highlight the promising applications of biomaterials to enhance the therapeutic effect of stem cell therapy in stroke treatment. As biomaterials provide efficient scaffolds for the growth and differentiation of stem cells, they may guarantee the quality and yield of stem cells for grafting. Furthermore, biomaterials also provide a convenient method for delivering the stem cells to be transplanted. This review provides direction for future research to combine tissue engineering approaches with stem cell therapy for the treatment of stroke.

Background Many traumatic brain injury (TBI) survivors live with persistent disability from chronic motor deficits despite contemporary rehabilitation services, underscoring the need for novel treatment. Objective/Hypothesis We have previously shown that deep brain stimulation (DBS) of the lateral cerebellar nucleus (LCN) can enhance post-stroke motor recovery and increase the expression of markers of long-term potentiation in perilesional cerebral cortex. We hypothesize that a similar beneficial effect will be for motor deficits induced by unilateral fluid percussion injury (FPI) in rodents through long-term potentiation- and anti-inflammatory based mechanisms. Methods Male Long Evans rats with a DBS macroelectrode in the LCN underwent FPI over contralateral primary motor cortex. After 4 weeks of spontaneous recovery, DBS treatment was applied for 4 weeks, with the pasta matrix, cylinder, and horizontal ladder tests used to evaluate motor performance. All animals were euthanized and tissue harvested for further analysis by histology, immunohistochemistry, RNA microarray assay and Western Blot. Results LCN DBS-treated animals experienced a significantly greater rate of motor recovery than untreated surgical controls, with treated animals showing enhanced expression of RNA and protein for excitability related genes, suppressed expression of pro-inflammatory genes, suppressed microglial and astrocytic activation, but proliferation of c-fos positive cells. Finally, our data suggest a possible role for anti-apoptotic effects with LCN DBS. Conclusion LCN DBS enhanced the motor recovery following TBI, possibly by elevating the neuronal excitability at the perilesional area and mediating anti-apoptotic and anti-inflammatory effects.

Crossed cerebellar diaschisis (CCD) is a functional deficit of the cerebellar hemisphere resulting from loss of afferent input consequent to a lesion of the contralateral cerebral hemisphere. It is manifested as a reduction of metabolism and blood flow and, depending on severity and duration, it can result in atrophy, a phenomenon known as crossed cerebellar atrophy (CCA). While CCA has been well-demonstrated in humans, it remains poorly characterized in animal models of stroke. In this study we evaluated the effects of cerebral cortical ischemia on contralateral cerebellar anatomy using an established rodent model of chronic stroke. The effects of cortical ischemia on the cerebellar hemispheres, vermis and deep nuclei were characterized. Intracortical microinjections of endothelin-1 (ET-1) were delivered to the motor cortex of Long Evans rats to induce ischemic stroke, with animals sacrificed 6 weeks later. Naive animals served as controls. Cerebral sections and cerebellar sections including the deep nuclei were prepared for analysis with Nissl staining. Cortical ischemia was associated with significant thickness reduction of the molecular layer at the Crus 1 and parafloccular lobule (PFL), but not in fourth cerebellar lobule (4Cb), as compared to the ipsilesional cerebellar hemisphere. A significant reduction in volume and cell density of the lateral cerebellar nucleus (LCN), the rodent correlate of the dentate nucleus, was also noted. The results highlight the relevance of corticopontocerebellar (CPC) projections for cerebellar metabolism and function, including its direct projections to the LCN.

Clinical trials have demonstrated positive proof of efficacy of dual metabotropic glutamate receptor 2/3 (mGluR2/3) agonists in both anxiety and schizophrenia. Importantly, evidence suggests that these drugs may also be neuroprotective against glutamate excitotoxicity, implicated in the pathogenesis of Parkinson's disease (PD). However, whether this neuroprotection also translates into functional recovery is unclear. In the current study, we examined the neuroprotective efficacy of the dual mGluR2/3 agonist, 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate (2R,4R-APDC), and whether this is accompanied by behavioral recovery in a rodent 6-hydroxydopamine (6-OHDA) model of PD. We now report that delayed post lesion treatment with 2R,4R-APDC (10 nmol), results in robust neuroprotection of the nigrostriatal system, which translated into functional recovery as measured by improved forelimb use asymmetry and reduced (+)-amphetamine-induced rotation compared to vehicle treated animals. Interestingly, these beneficial effects were associated with a decrease in microglial markers in the SNc, which may suggest an antiinflammatory action of this drug.

The design of biomaterials and the sourcing for appropriate cells are two integrated aspects of tissue engineering to construct a tissue implant for clinical applications. During the past decades, many innovative biomaterials with desirable biological and mechanical properties have emerged, while stem cells have been shown to be a promising cell source to differentiate into many cell types. However, the testing of these bioartificial tissue constructs in the clinical trials is far from satisfactory. How microenvironments in the biomaterials regulate cellular signaling pathways and functions, how stem cell-derived target cells respond to extracellular cues presented by the biomaterials, and how implanted tissue constructs interact with host tissues remain to be investigated. The information of the interplay between cell and biomaterials would be helpful to guide us in improving our current strategy to refine the tissue constructs for effective tissue repair in regenerative medicine. In this special issue, we first present a thorough review by M. Ramamoorthi et al. on the efficacy of dental stem cell therapy in bone regeneration in preclinical in vivo and in vitro studies. They suggest that well-designed randomized animal trials are needed before moving into clinical trials. Then we introduce three types of innovative biomaterials: (1) bionanocomposites based on bacterial cellulose and magnetic nanoparticles (magnetite) for efficient chronic wounds healing reported by B. Galateanu et al.; (2) the elastomeric poly(e-caprolatone urethane) (PCLU) scaffolds using a high internal phase emulsion for bone tissue regeneration developed by S. Changotade et al.; and (3) a novel gelatin-alginate-polyacrylamide 3D interpenetrating network with superior performance in promoting chondrogenesis using human adipose-derived stem cells designed by S. Dinescu et al. Most importantly, our special focus will be given to the insight studies on the cell-biomaterial interactions. C.-H. Wang et al. demonstrate that the migration ability of bone marrow stem cells can be regulated by varying the porous structure of the artificial ligaments and this regulation is related to the RhoA/ROCK signaling pathway. M. Deng et al. demonstrate the endothelial differentiation of human adipose-derived stem cells on the polyglycolic acid/polylactic acid (PGA/PLA) mesh and propose the synergistic effect of 3D environments and biochemical signals such as growth factors on the acquisition of mature characteristic endothelial phenotype. S. Fu et al. have investigated the protective effect of neuropeptide Substance P on bone marrow stromal cells against apoptosis induced by serum deprivation through Wnt signaling. J. Michel et al. have reviewed a wide range of hydroxyapatite containing scaffolds and their interactions with mesenchymal stem cells in in vitro and in vivo contexts.