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Transplanted neurons derived from stem cells have been proposed to improve function in animal models of human disease by various mechanisms such as neuronal replacement. However, whether the grafted neurons receive functional synaptic inputs from the recipient's brain and integrate into host neural circuitry is unknown. Here we studied the synaptic inputs from the host brain to grafted cortical neurons derived from human induced pluripotent stem cells after transplantation into stroke-injured rat cerebral cortex. Using the rabies virus-based trans-synaptic tracing method and immunoelectron microscopy, we demonstrate that the grafted neurons receive direct synaptic inputs from neurons in different host brain areas located in a pattern similar to that of neurons projecting to the corresponding endogenous cortical neurons in the intact brain. Electrophysiological in vivo recordings from the cortical implants show that physiological sensory stimuli, i.e. cutaneous stimulation of nose and paw, can activate or inhibit spontaneous activity in grafted neurons, indicating that at least some of the afferent inputs are functional. In agreement, we find using patch-clamp recordings that a portion of grafted neurons respond to photostimulation of virally transfected, channelrhodopsin-2-expressing thalamo-cortical axons in acute brain slices. The present study demonstrates, for the first time, that the host brain regulates the activity of grafted neurons, providing strong evidence that transplanted human induced pluripotent stem cell-derived cortical neurons can become incorporated into injured cortical circuitry. Our findings support the idea that these neurons could contribute to functional recovery in stroke and other conditions causing neuronal loss in cerebral cortex. [ABSTRACT FROM AUTHOR]

Stroke is a leading cause of disability and currently lacks effective therapy enabling long-term functional recovery. Ischemic brain injury causes local inflammation, which involves both activated resident microglia and infiltrating immune cells, including monocytes. Monocyte-derived macrophages (MDMs) exhibit a high degree of functional plasticity. Here, we determined the role of MDMs in longterm spontaneous functional recovery after middle cerebral artery occlusion in mice. Analyses by flow cytometry and immunocytochemistry revealed that monocytes home to the stroke-injured hemisphere., and that infiltration peaks 3 d after stroke. At day 7, half of the infiltratingMDMsexhibited a bias toward a proinflammatory phenotype and the other half toward an anti-inflammatory phenotype, but during the subsequent 2 weeks, MDMs with an anti-inflammatory phenotype dominated. Blocking monocyte recruitment using the anti-CCR2 antibody MC-21 during the first week after stroke abolished long-term behavioral recovery, as determined in corridor and staircase tests, and drastically decreased tissue expression of anti-inflammatory genes, including TGFβ, CD163, and Ym1. Our results show that spontaneously recruited monocytes to the injured brain early after the insult contribute to long-term functional recovery after stroke. [ABSTRACT FROM AUTHOR]

Purpose: Induced pluripotent stem cells (iPSCs) improve behavior and form neurons after implantation into the stroke-injured adult rodent brain. How the aged brain responds to grafted iPSCs is unknown. We determined survival and differentiation of grafted human fibroblast-derived iPSCs and their ability to improve recovery in aged rats after stroke. Methods: Twenty-four months old rats were subjected to 30 min distal middle cerebral artery occlusion causing neocortical damage. After 48 h, animals were transplanted intracortically with human iPSC-derived long-term neuroepithelial-like stem (hiPSC-lt-NES) cells. Controls were subjected to stroke and were vehicle-injected. Results: Cell-grafted animals performed better than vehicle-injected recipients in cylinder test at 4 and 7 weeks. At 8 weeks, cell proliferation was low (0.7 %) and number of hiPSC-lt-NES cells corresponded to 49.2% of that of implanted cells. Transplanted cells expressed markers of neuroblasts and mature and GABAergic neurons. Cell-grafted rats exhibited less activated microglia/macrophages in injured cortex and neuronal loss was mitigated. Conclusions: Our study provides the first evidence that grafted human iPSCs survive, differentiate to neurons and ameliorate functional deficits in stroke-injured aged brain. [ABSTRACT FROM AUTHOR]

Abstract: Neural stem/progenitor cells (NSPCs) in subventricular zone (SVZ) produce new striatal neurons during several months after stroke, which may contribute to recovery. Intracerebral grafts of NSPCs can exert beneficial effects after stroke through neuronal replacement, trophic actions, neuroprotection, and modulation of inflammation. Here we have explored whether human fetal striatum-derived NSPC-grafts influence striatal neurogenesis and promote recovery in stroke-damaged brain. T cell-deficient rats were subjected to 1h middle cerebral artery occlusion (MCAO). Human fetal NSPCs or vehicle were implanted into ipsilateral striatum 48h after MCAO, animals were assessed behaviorally, and perfused at 6 or 14weeks. Grafted human NSPCs survived in all rats, and a subpopulation had differentiated to neuroblasts or mature neurons at 6 and 14weeks. Numbers of proliferating cells in SVZ and new migrating neuroblasts and mature neurons were higher, and numbers of activated microglia/macrophages were lower in the ischemic striatum of NSPC-grafted compared to vehicle-injected group both at 6 and 14weeks. A fraction of grafted NSPCs projected axons from striatum to globus pallidus. The NSPC-grafted rats showed improved functional recovery in stepping and cylinder tests from 6 and 12weeks, respectively. Our data show, for the first time, that intrastriatal implants of human fetal NSPCs exert a long-term enhancement of several steps of striatal neurogensis after stroke. The grafts also suppress striatal inflammation and ameliorate neurological deficits. Our findings support the idea that combination of NSPC transplantation and stimulation of neurogenesis from endogenous NSPCs may become a valuable strategy for functional restoration after stroke. [Copyright &y& Elsevier]

Reprogramming of adult human somatic cells to induced pluripotent stem cells (iPSCs) is a novel approach to produce patient-specific cells for autologous transplantation. Whether such cells survive long-term, differentiate to functional neurons, and induce recovery in the stroke-injured brain are unclear. We have transplanted long-term self-renewing neuroepithelial-like stem cells, generated from adult human fibroblast-derived iPSCs, into the stroke-damaged mouse and rat striatum or cortex. Recovery of forepaw movements was observed already at 1 week after transplantation. Improvement was most likely not due to neuronal replacement but was associated with increased vascular endothelial growth factor levels, probably enhancing endogenous plasticity. Transplanted cells stopped proliferating, could survive without forming tumors for at least 4 months, and differentiated to morphologically mature neurons of different subtypes. Neurons in intrastriatal grafts sent axonal projections to the globus pallidus. Grafted cells exhibited electrophysiological properties of mature neurons and received synaptic input from host neurons. Our study provides the first evidence that transplantation of human iPSC-derived cells is a safe and efficient approach to promote recovery after stroke and can be used to supply the injured brain with new neurons for replacement. S TEM C ELLS 2012;30:1120-1133 [ABSTRACT FROM AUTHOR]

Objectives: The aim of the present study was the experimental analysis of blood rheological disorders in the microcirculation during endotoxic shock. Methods: Experiments were carried out on 30 white laboratory rats of both sexes weighing about 200 g. The experimental animals were divided in two groups: the control group and the group undergoing experimental endotoxic shock. The following specific hemorheological properties were investigated in all animals during the experiments: red blood cells (RBC) aggregability, their deformability and the systemic hematocrit. Results: We found that all the investigated hemorheological parameters appreciably changed underconditions of endotoxic shock. The RBC aggregability index was increased by a mean of 136%. As to the RBC deformability index was found to be decreased by 71%, and the systemic hematocrit lowered by 31%, as compared to the same parameters in the control group. Conclusion: The data obtained provide us with evidence that the hemorheological derangements associated with the development of the heavy microcirculatory disorders during endotoxic shock, are most significant factors. [ABSTRACT FROM AUTHOR]

It has been unclear whether ischemic stroke induces neurogenesis or neuronal DNA rearrangements in the human neocortex. Using immunohistochemistry; transcriptome, genome and ploidy analyses; and determination of nuclear bomb test-derived 14C concentration in neuronal DNA, we found neither to be the case. A large proportion of cortical neurons displayed DNA fragmentation and DNA repair a short time after stroke, whereas neurons at chronic stages after stroke showed DNA integrity, demonstrating the relevance of an intact genome for survival. [ABSTRACT FROM AUTHOR]

Ischemic stroke triggers neurogenesis from neural stem/progenitor cells (NSPCs) in the subventricular zone (SVZ) and migration of newly formed neuroblasts toward the damaged striatum where they differentiate to mature neurons. Whether it is the injury per se or the associated inflammation that gives rise to this endogenous neurogenic response is unknown. Here we showed that inflammation without corresponding neuronal loss caused by intrastriatal lipopolysaccharide (LPS) injection leads to striatal neurogenesis in rats comparable to that after a 30 min middle cerebral artery occlusion, as characterized by striatal DCX + neuroblast recruitment and mature NeuN +/BrdU + neuron formation. Using global gene expression analysis, changes in several factors that could potentially regulate striatal neurogenesis were identified in microglia sorted from SVZ and striatum of LPS-injected and stroke-subjected rats. Among the upregulated factors, one chemokine, CXCL13, was found to promote neuroblast migration from neonatal mouse SVZ explants in vitro . However, neuroblast migration to the striatum was not affected in constitutive CXCL13 receptor CXCR5 −/− mice subjected to stroke. Infarct volume and pro-inflammatory M1 microglia/macrophage density were increased in CXCR5 −/− mice, suggesting that microglia-derived CXCL13, acting through CXCR5, might be involved in neuroprotection following stroke. Our findings raise the possibility that the inflammation accompanying an ischemic insult is the major inducer of striatal neurogenesis after stroke. [ABSTRACT FROM AUTHOR]