1,720,971 research outputs found
Exosomes from mesenchymal stem cells: experimental assessment of an innovative therapeutic approach for ALS
No full textLa sclerosi laterale amiotrofica (SLA) è una patologia neurodegenerativa progressiva caratterizzata da progressiva paralisi muscolare e degenerazione dei motoneuroni nella corteccia motoria primaria, tronco encefalico e midollo spinale. Mutazioni nel gene superossido dismutasi 1 (SOD1) rappresentano uno dei maggiori contributi genetici di SLA. Diverse strategie terapeutiche sono state testate in modelli in-vitro e in-vivo della patologia, ma al momento non esiste trattamento in grado di curare o di migliorare la qualità di vita dei pazienti. Le cellule staminali rappresentano un approccio terapeutico promettente nella cura delle malattie neurodegenerative e il loro effetto benefico sembra esplicarsi, tramite un’azione paracrina, attraverso il rilascio di vescicole extracellulari, in particolare esosomi.In questa tesi di dottorato sono riportati gli studi effettuati per valutare il possibile effetto neuroprotettivo di esosomi, ottenuti da cellule staminali adipose (ASC), in modelli in vitro ed in vivo di SLA e il protocollo per marcare gli esosomi al fine di monitorarne l’accumulo dopo somministrazione in vivo.Riguardo gli esperimenti in vitro, la somministrazione di esosomi in seguito a stress ossidativo (H2O2) ai danni della linea cellulare di motoneuroni NSC-34 naive e trasfettata con il gene umano SOD1 portante diverse mutazioni note per essere correlate alla patologia (G93A, G37R, A4V), protegge le cellule dal danno ossidativo, con un significativo aumento della vitalità cellulare. Riguardo agli esperimenti in vivo, l’iniezione intravena di esosomi nel modello murino SOD(G93A) dall’onset clinico fino alla fase terminale di malattia determinano un ritardo nella progressione dei sintomi e aumentano la durata di vita degli animali trattati. I risultati ottenuti dimostrano che gli esosomi isolati dalle cellule staminali adipose hanno un effetto neuroprotettivo nei modelli in vitro ed in vivo di SLA, indicando una possibile strategia terapeutica per questa malattia neurodegenerativa. Inoltre, abbiamo identificato un nuovo protocollo per marcare gli esosomi con nanoparticelle di ferro superparamagnetiche, grazie al quale sarà possibile valutarne il tracking e l’accumulo in vivo con tecniche non invasive, quali la risonanza magnetica nucleare.Amyotrophic lateral sclerosis (ALS) is a fatal progressive neurodegenerative disease characterized by progressive muscular paralysis and degeneration of motoneurons in the primary motor cortex, brainstem and spinal cord. Mutations in superoxide dismutase 1 (SOD1) gene are one of the genetic contributor to ALS. Therapeutic strategies for ALS are actually minimally effective on patients’ survival and quality of life. Stem cells represent a promising therapeutic approach in the treatment of neurodegenerative diseases and their beneficial effect seem to be due through a paracrine effect via the release of extracellular vesicles, in particular exosomes.In this doctoral thesis, I describe the studies to assess the neuroprotective effect of exosomes derived from syngeneic adipose stem cells (ASC) on in vitro and in vivo models of ALS, and the protocol for exosomes labeling to monitor the accumulation of exosomes after their in vivo administration.In in vitro experiments, the administration of ASC-exosomes after oxidative insult (H2O2) on motoneuron-like cell line (NSC-34) naïve and transfected with different human mutant SOD1 gene (G93A, G37R, A4V), protected cells from oxidative damage, with a significantly increase of cell viability. In in vivo experiments, the intravenous injection of ASC-exosomes in SOD1(G93A) mice at clinical onset until terminal stage point out that exosomes delay symptoms progression and postpone lifespan of treated animals. Our results demonstrate that ASC-exosomes have a neuroprotective effect in in vitro and in vivo models of ALS, indicating a possible new strategy as therapy in this neurodegenerative disease. Moreover, we set up a new protocol to label exosomes with superparamagnetic iron oxide nanoparticles, that allow to evaluate their tracking and their accumulation in vivo with a non-invasive technique, as magnetic resonance imaging
ALS Pathogenesis and Therapeutic Approaches: The Role of Mesenchymal Stem Cells and Extracellular Vesicles
Full text linkAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive muscle paralysis determined by the degeneration of motoneurons in the motor cortex brainstem and spinal cord. The ALS pathogenetic mechanisms are still unclear, despite the wealth of studies demonstrating the involvement of several altered signaling pathways, such as mitochondrial dysfunction, glutamate excitotoxicity, oxidative stress and neuroinflammation. To date, the proposed therapeutic strategies are targeted to one or a few of these alterations, resulting in only a minimal effect on disease course and survival of ALS patients. The involvement of different mechanisms in ALS pathogenesis underlines the need for a therapeutic approach targeted to multiple aspects. Mesenchymal stem cells (MSC) can support motoneurons and surrounding cells, reduce inflammation, stimulate tissue regeneration and release growth factors. On this basis, MSC have been proposed as promising candidates to treat ALS. However, due to the drawbacks of cell therapy, the possible therapeutic use of extracellular vesicles (EVs) released by stem cells is raising increasing interest. The present review summarizes the main pathological mechanisms involved in ALS and the related therapeutic approaches proposed to date, focusing on MSC therapy and their preclinical and clinical applications. Moreover, the nature and characteristics of EVs and their role in recapitulating the effect of stem cells are discussed, elucidating how and why these vesicles could provide novel opportunities for ALS treatment
Effect of physical exercise and anabolic steroid treatment on spinal motoneurons and surrounding glia of wild-type and ALS mice
No full textMotoneuron degeneration is the hallmark of amyotrophic lateral sclerosis (ALS). The cause and predisposing factors for sporadic ALS are still unknown. Exposure to a specific environmental risk factors in subjects with a susceptibility genotype may increase the risk of the disease. The role of physical activity and the use of anabolic steroids are still debated in epidemiological studies on patients and murine models of ALS. To assess at the cellular level the role (beneficial or detrimental) of physical exercise and the use of anabolic steroid, we here investigated, in SOD1(G93A) (mSOD1) mice and wild-type littermates, changes in the ventral horn after regular exercise, treatment with the anabolic androgenic steroid 19-nortestosterone (nandrolone), and their combination, compared with matched control sedentary mice. The experiments were pursued for several weeks until symptom onset in mSOD1 mice. Lumbar motoneurons, astrocytes and microglia were analyzed. In wild-type mice, cytological alterations of motoneurons were observed especially after nandrolone treatment. The following main findings were observed in treated mSOD1 mice versus untreated ones: i) nandrolone treatment markedly enhanced motoneuron loss; this detrimental effect was reverted by the combination with exercise, resulting in increased motoneuron survival; ii) astrocytic activation was most marked after nandrolone treatment when motoneuron damage was most severe;iii) microglia activation was most marked after physical exercise when motoneuron damage was less severe. The results indicate a vulnerability of mSOD1 motoneurons to nandrolone treatment, a potential neuroprotective effect of physical exercise, and a modulation by glial cells in the ALS murine model in the examined paradigms
Exosome derived from murine adipose-derived stromal cells: Neuroprotective effect onin vitromodel of amyotrophic lateral sclerosis
No full textTherapeutic strategies for the fatal neurodegenerative disease amyotrophic lateral sclerosis (ALS) have not yet provided satisfactory results. Interest in stem cells for the treatment of neurodegenerative diseases is increasing and their beneficial action seems to be due to a paracrine effect via the release of exosomes, main mediators of cell-cell communication. Here we wished to assess, in vitro, the efficacy of a novel non-cell therapeutic approach based on the use of exosomes derived from murine adipose-derived stromal cells on motoneuron-like NSC-34 cells expressing ALS mutations, and used as in vitro models of disease. In particular, we set out to investigate the effect of exosomes on NSC-34 naïve cells and NSC-34 cells overexpressing human SOD1(G93A) or SOD1(G37R) or SOD1(A4V) mutants, exposed to oxidative stress. The data presented here indicate for the first time that exosomes (0.2μg/ml) are able to protect NSC-34 cells from oxidative damage, which is one of the main mechanism of damage in ALS, increasing cell viability. These data highlight a promising role of exosomes derived from stem cells for potential therapeutic applications in motoneuron disease
Acetylation state of RelA modulated by epigenetic drugs prolongs survival and induces a neuroprotective effect on ALS murine model
Full text linkDysregulation in acetylation homeostasis has been implicated in the pathogenesis of the amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder. It is known that the acetylation of transcriptional factors regulates their activity. The acetylation state of NF-kB RelA has been found to dictate the neuroprotective versus the neurotoxic effect of p50/RelA. Here we showed that the pro-apoptotic acetylation mode of RelA, involving a general lysine deacetylation of the subunit with the exclusion of the lysine 310, is evident in the lumbar spinal cord of SOD1(G93A) mice, a murine model of ALS. The administration of the HDAC inhibitor MS-275 and the AMPK/sirtuin 1 activator resveratrol restored the normal RelA acetylation in SOD1(G93A) mice. The SOD1(G93A) mice displayed a 3 weeks delay of the disease onset, associated with improvement of motor performance, and 2 weeks increase of lifespan. The epigenetic treatment rescued the lumbar motor neurons affected in SOD1(G93A) mice, accompanied by increased levels of protein products of NF-kB-target genes, Bcl-xL and brain-derived neurotrophic factor. In conclusion, we here demonstrate that MS-275 and resveratrol restore the acetylation state of RelA in the spinal cord, delaying the onset and increasing the lifespan of SOD1(G93A) mice
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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