Mesenchymal Stem Cell Therapy Modulates the Inflammatory Response in Experimental Traumatic Brain Injury

Therapy with mesenchymal stem cells (MSCs) has showed to be promising due to its immunomodulatory function. Traumatic brain injury (TBI) triggers immune response and release of inflammatory mediators, mainly cytokines, by glial cells creating a hostile microenvironment for endogenous neural stem cells (NSCs). We investigated the effects of factors secreted by MSCs on NSC in vitro and analyzed cytokines expression in vitro in a TBI model. Our in vitro results show that MSC-secreted factors increase NSC proliferation and induce higher expression of GFAP, indicating a tendency toward differentiation into astrocytes. In vivo experiments showed that MSC injection at an acute model of brain injury diminishes a broad profile of cytokines in the tissue, suggesting that MSC-secreted factors may modulate the inflammation at the injury site, which may be of interest to the development of a favorable microenvironment for endogenous NSC and consequently to repair the injured tissue

Thyroid hormone treated astrocytes induce maturation of cerebral cortical neurons through modulation of proteoglycan levels

Proper brain neuronal circuitry formation and synapse development is dependent on specific cues, either genetic or epigenetic, provided by the surrounding neural environment. Within the sesignals, thyroid hormones (T3 and T4) play crucial role in several steps of brain morphogenesis including proliferation of progenitor cells, neuronal differentiation, maturation, migration, and synapse formation. the lack of thyroid hormones during childhood is associated with several impair neuronal connections, cognitive deficits, and mental disorders. Many of the thyroid hormones effects are mediated by astrocytes, although the mechanisms underlying these events are still unknown. in this work, we investigated the effect of 3,5,3'-triiodothyronine-treated (T3-treated) astrocytes on cerebral cortex neuronal differentiation. Culture of neural progenitors from embryonic cerebral cortex mice onto T3-treated astrocyte monolayers yielded an increment in neuronal population, followed by enhancement of neuronal maturation, arborization and neurite outgrowth. in addition, real time PCR assays revealed an increase in the levels of the heparan sulfate proteoglycans, Glypican 1(GPC-1) and Syndecans 3 e 4 (SDC-3 e SDC-4), followed by a decrease in the levels of the chondroitin sulfate proteoglycan, Versican. Disruption of glycosaminoglycan chains by chondroitinase AC or heparanase III completely abolished the effects of T3-treated astrocytes on neuronal morphogenesis. Our work provides evidence that astrocytes are key mediators of T3 actions on cerebral cortex neuronal development and identified potential molecules and pathways involved in neurite extension; which might eventually contribute to a better understanding of axonal regeneration, synapse formation, and neuronal circuitry recover.Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)Conselho Nacional para o Desenvolvimento Cientifico e TecnologicoCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ Fed Rio de Janeiro, Inst Ciencias Biomed, BR-21949590 Rio de Janeiro, RJ, BrazilUniv Fed Rio de Janeiro, Inst Bioquim Med, BR-21949590 Rio de Janeiro, RJ, BrazilUniv Fed Rio de Janeiro, Hosp Univ Clementino Fraga Filho, BR-21949590 Rio de Janeiro, RJ, BrazilUniversidade Federal de São Paulo, Dept Bioquim, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Bioquim, São Paulo, BrazilWeb of Scienc

Polarized Signaling Endosomes Coordinate BDNF-Induced Chemotaxis of Cerebellar Precursors

During development, neural precursors migrate in response to positional cues such as growth factor gradients. However, the mechanisms that enable precursors to sense and respond to such gradients are poorly understood. Here we show that cerebellar granule cell precursors (GCPs) migrate along a gradient of brain-derived neurotrophic factor (BDNF), and we demonstrate that vesicle trafficking is critical for this chemotactic process. Activation of TrkB, the BDNF receptor, stimulates GCPs to secrete BDNF, thereby amplifying the ambient gradient. The BDNF gradient stimulates endocytosis of TrkB and associated signaling molecules, causing asymmetric accumulation of signaling endosomes at the subcellular location where BDNF concentration is maximal. Thus, regulated BDNF exocytosis and TrkB endocytosis enable precursors to polarize and migrate in a directed fashion along a shallow BDNF gradient

Injection of SDF-1 loaded nanoparticles following traumatic brain injury stimulates neural stem cell recruitment.

Recruiting neural stem cell (NSC) at the lesion site is essential for central nervous system repair. This process could be triggered by the local delivery of the chemokine SDF-1. We compared two PLGA formulations for local brain SDF-1 delivery: SDF-1 loaded microspheres (MS) and SDF-1 loaded nanoparticles (NP). Both formulations were able to encapsulate more than 80% of SDF-1 but presented different release profiles, with 100% of SDF-1 released after 6days for the MS and with 25% of SDF-1 released after 2 weeks for NP. SDF-1 bioactivity was demonstrated by a chemotactic assay. When injected in mouse brain after traumatic brain injury, only SDF-1 nanoparticles induced NSC migration to the damage area. More neuroblasts (DCX+ cells) could be visualized around the lesions treated with NP SDF-1 compared to the other conditions. Rostral migratory stream destabilization with massive migration of DCX+ cell toward the perilesional area was observed 2 weeks after NP SDF-1 injection. Local injection of SDF-1-loaded nanoparticles induces recruitment of NSC and could be promising for brain injury lesion

Upregulation of E2F1 in cerebellar neuroprogenitor cells and cell cycle arrest during postnatal brain development

In the developing cerebellum, proliferation of granular neuroprogenitor (GNP) cells lasts until the early postnatal stages when terminal maturation of the cerebellar cortex occurs. GNPs are considered cell targets for neoplastic transformation, and disturbances in cerebellar GNP cell proliferation may contribute to the development of pediatric medulloblastoma. At the molecular level, proliferation of GNPs is regulated through an orchestrated action of the SHH, NOTCH, and WNT pathways, but the underlying mechanisms still need to be dissected. Here, we report that expression of the E2F1 transcription factor in rat GNPs is inversely correlated with cell proliferation rate during postnatal development, as opposed to its traditional SHH-dependent induction of cell cycle. Proliferation of GNPs peaked at postnatal day 3 (P3), with a subsequent continuing decrease in proliferation rates occurring until P12. Such gradual decline in proliferating neuroprogenitors paralleled the extent of cerebellum maturation confirmed by histological analysis with cresyl violet staining and temporal expression profiling of SHH, NOTCH2, and WNT4 genes. A time course analysis of E2F1 expression in GNPs revealed significantly increased levels at P12, correlating with decreased cell proliferation. Expression of the cell cycle inhibitor p18 (Ink4c) , a target of E2F1, was also significantly higher at P12. Conversely, increased E2F1 expression did not correlate with either SMAC/DIABLO and BCL2 expression profiles or apoptosis of cerebellar cells. Altogether, these results suggest that E2F1 may also be involved in the inhibition of GNP proliferation during rat postnatal development despite its conventional mitogenic effects.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)INCT-CETGENCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ São Paulo, Ctr Estudos Genoma Humano, Dept Genet & Biol Evolut, Inst Biociencias, BR-05508090 São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Neurol Expt, Dept Neurol Neurocirurgia, São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Biol Mol, Dept Bioquim, São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Neurol Expt, Dept Neurol Neurocirurgia, São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Biol Mol, Dept Bioquim, São Paulo, BrazilWeb of Scienc

Decreased viability and neurite length in neural cells treated with chitosan-dextran sulfate nanocomplexes.

CXCL12 is a chemokine known to regulate migration, proliferation, and differentiation of neural stem cells (NSCs) and to play a neuroprotective role in ischemic stroke. Chitosan-dextran sulfate nanocomplexes (Ch/DS NC) are known nanoparticulated systems used to efficiently deliver heparin-binding factors. Here we evaluate Ch/DS NC as carriers for CXCL12 in a mouse model of stroke. Free CXCL12 reduced the size of the ischemic brain lesion. However, when Ch/DS NC were administrated, the stroke volume increased. Neurotoxic screening revealed that Ch/DS NC reduced neuronal viability, decreased the extension of neurites and impaired NSC migration in vitro. To the best of our knowledge, neurotoxicity of Ch/DS NC has not been reported and further screenings will be needed in order to evaluate the biological safety of these nanocomposites. Our results add new data on nanoparticle neurotoxicity and may help us to better understand the complex interactions of the nanostructures with biological components

Fast preparation of free-standing nanohydroxyapatite-vertically aligned carbon nanotube scaffolds

We present a simple, low cost, and fast method to produce free-standing nanohydroxyapatite/carbon-based scaffolds. We electrodeposited nanohydroxyapatite onto vertically aligned carbon nanotube flakes and reticulated vitreous carbon bars. We prepared a highly crystalline and homogeneous thin film without any post-thermal treatment, and our results evidence that we can control the nanohydroxyapatite crystal formation according to the substrate employed. Immersion tests using simulated body fluid showed that these new nanobiomaterials had in vitro bioactivity. the free-standing nanohydroxyapatite/carbon-based scaffolds have been shown to be a suitable surface for mesenchymal stem cell adhesion with active formation of membrane projections and cell monolayer formation.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ Vale Paraiba, Lab Biomed Nanotechnol, Inst Res & Dev, BR-12224000 São Paulo, BrazilInst Nacl Pesquisas Espaciais, Lab Associado Sensores & Mat, BR-12227010 São Paulo, BrazilUniversidade Federal de São Paulo, Neurobiol Lab, BR-04039032 São Paulo, BrazilUniversidade Federal de São Paulo, Neurobiol Lab, BR-04039032 São Paulo, BrazilFAPESP: 2011/17877-7FAPESP: 2013/07696-0FAPESP: 2011/20345-7CNPq: 202439/2012-7Web of Scienc