Enriched Differentiation of Human Otic Sensory Progenitor Cells Derived From Induced Pluripotent Stem Cells

Age-related neurosensory deficit of the inner ear is mostly due to a loss of hair cells (HCs). Development of stem cell-based therapy requires a better understanding of factors and signals that drive stem cells into otic sensory progenitor cells (OSPCs) to replace lost HCs. Human induced pluripotent stem cells (hiPSCs) theoretically represent an unlimited supply for the generation of human OSPCs in vitro. In this study, we developed a monolayer-based differentiation system to generate an enriched population of OSPCs via a stepwise differentiation of hiPSCs. Gene and protein expression analyses revealed the efficient induction of a comprehensive panel of otic/placodal and late otic markers over the course of the differentiation. Furthermore, whole transcriptome analysis confirmed a developmental path of OSPC differentiation from hiPSCs. We found that modulation of WNT and transforming growth factor-β (TGF-β) signaling combined with fibroblast growth factor 3 (FGF3) and FGF10 treatment over a 6-day period drives the expression of early otic/placodal markers followed by late otic sensory markers within 13 days, indicative of a differentiation into embryonic-like HCs. In summary, we report a rapid and efficient strategy to generate an enriched population of OSPCs from hiPSCs, thereby establishing the value of this approach for disease modeling and cell-based therapies of the inner ear

Modifiers of Neural Stem Cells and Aging: Pulling the Trigger of a Neurogenic Decline

International audienceThe adult mammalian central nervous system contains resident neural stem cells able to self-renew and to generate new neurons throughout life, as well as other neural cell types. Progressive changes in adult neural stem cells accompany the aging process, which may contribute to a progressive decline in regenerative capacities, tissue degeneration, and functional impairments. For example, accelerated and pathological declines in neural stem cell functions have been associated with age-related brain diseases. Therefore, identifying and better understanding the age-associated molecular events involved in the deterioration of adult neural stem cell homeostasis is of high interest. To date, several intrinsic and extrinsic factors have been identified as putative drivers for age-related dysfunctions in brain stem cell niches. This review aims to provide a concise overview of the age-associated changes that have been reported in mammalian adult neural stem cells as well as the underlying events able to trigger those changes

Potentiel thérapeutique des cellules souches adultes de la Lamina Propria olfactive humaine (caractérisation et évaluations dans des modèles de déficits mnésiques)

Les cellules souches, considérées comme l'un des éléments clés de la future médecine régénérative, sont utilisées pour le développement de nouvelles approches thérapeutiques. Dans ce cadre, nous avons étudié les cellules souches humaines de la lamina propria olfactive chez l'adulte. Nos travaux ont identifié ces cellules comme un sous-type de cellules souches mésenchymateuses mais elles s'en distinguent in vitro par des capacités neurogéniques plus élevées. Ces données ont permis d'envisager leur utilisation dans le cadre de transplantations cellulaires faisant suite à des pertes de substance nerveuse. Nos résultats ont montré que la transplantation de ces cellules, dans un hippocampe lésé de souris, rétablit les performances mnésiques et l'intégrité du circuit trisynaptique hippocampique. La mise en évidence de ce potentiel thérapeutique peut être corrélée avec la survie, la migration, l'installation de ces cellules exogènes (de phénotype neuronal) dans les couches cellulaires endommagées et un accroissement de la neurogenèse hippocampique endogène. Ces résultats ont été reproduits en utilisant d'autres voies d'administrations des cellules (intra-thécales et intra-veineuses) démontrant leur capacité à traverser des barrières biologiques. Ces premiers travaux ont été pour partie confirmés en réalisant des greffes dans d'autres structures cérébrales lésées (cortex frontal). Les résultats obtenus au cours de cette thèse convergent, tous, pour décrire les cellules souches de la lamina propria olfactive comme un outil majeur pour la thérapie cellulaire. On peut en effet envisager de les utiliser pour des greffes autologues destinées à réparer le système nerveux.AIX-MARSEILLE1-BU Sci.St Charles (130552104) / SudocSudocFranceF

Conversion of pericytes to neurons:a new guest at the reprogramming convention

International audienceReprogramming strategies allow for the generation of virtually any cell type of the human body, which could be useful for cell-based therapy. Among the different reprogramming technologies available, direct lineage conversion offers the possibility to change the phenotype of a cell type to another one without pushing cells backwards to a plastic/proliferative stage. This approach has raised the possibility to apply a similar process in vivo in order to compensate for functional cell loss. Historically, the cerebral tissue is a prime choice for developing cell-based treatments. As local pericyte accumulation is observed after central nervous system injury, it can be reasoned that this cell type might be a good candidate for the conversion into new neurons in vivo. In this article, and by focusing on recent observations from Karow and colleagues demonstrating the possibility to convert human brain-derived pericytes into functional neurons, we present a brief overview of the state of the art and attempt to offer perspective as to how these interesting laboratory findings could be translated in the clinic

The labyrinth of nuclear reprogramming

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[Resetting Parkinson's disease patient-derived cells to unveil new pathological marks]

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[Nose at the bedside of the brain]

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Developmental vitamin D deficiency alters learning in C57Bl/6J mice

International audienceEpidemiological studies have highlighted a season of birth effect in multiple sclerosis and schizophrenia. As a result, low prenatal vitamin D has been proposed as a candidate risk factor for these brain diseases, with cognitive impairments. In order to further investigate the long-term consequences of a transient gestational hypovitaminosis D, we used a mouse developmental vitamin D (DVD) deficiency model. Female C57Bl/6J mice were fed a vitamin D-free diet for 6 weeks prior to conception and during gestation. At birth, dams and their offspring were fed a normal vitamin D-containing diet. The adult offspring underwent a learning test based on olfactory cues, at 30 weeks and 60 weeks of age. In addition, using magnetic resonance imaging (MRI), volumes of cerebrum, hippocampus and lateral ventricles were measured at 30 weeks and 70 weeks of age. We found that DVD-deficient mice, when compared to control animals at Week 30, displayed impaired learning and smaller lateral ventricles. At Weeks 60-70, both groups deteriorated when compared to young mice and no significant difference was observed between groups. This study confirms that transient prenatal vitamin D deficiency alters brain development and functioning and induces cognitive impairments in the young adult offspring

Le resvératrol peut-il par son effet anti-oxydant protéger contre le vieillissement ?

International audienceD'après la théorie de Harman, le vieillissement vasculaire est dû notamment au stress oxydant, déséquilibre entre les systèmes anti-oxydants et pro-oxydants de l'organisme. L'accumulation de collagène et la calcification artérielle engendrées vont conduire à la formation de plaques d'athéromes et à l'artériosclérose. Les vaisseaux vont alors se rigidifier et s'épaissir. L'un des systèmes oxydants est l'enzyme NADPH-oxydase, comprenant la sous-unité p47phox. La thiorédoxine, quant à elle, est une enzyme anti oxydante. Dans cette étude, afin de prévenir la dégradation vasculaire, le resvératrol, polyphénol retrouvé en quantité notable dans le vin, est administré à des souris. Des données d'épaisseur, de distensibilité, de concentration en collagène et en calcium ainsi que les quantités de p47phox et de thiorédoxine sont étudiés au niveau de l'aorte. La comparaison entre des souris jeunes et des souris âgées ne recevant aucun traitement permet d'observer, lors d'un vieillissement aortique physiologique, une augmentation de l'épaisseur, une diminution de la distensibilité, une augmentation des teneurs en collagène et en calcium associés à une augmentation de la concentration en NADPH-oxydase et une diminution de celle de la thiorédoxine. D'après cette étude, le resvératrol permettrait de diminuer la concentration en p47phox et donc de diminuer le stress oxydant, sans pour autant influer sur la concentration en thiorédoxine. Les souris âgées traitées par resvératrol ont également, au niveau aortique, une épaisseur non-augmentée, une distensibilité conservée et une concentration en collagène inchangée par rapport aux souris jeunes. Le polyphénol ne semble pas influer sur la concentration aortique en calcium. Le resvératrol semble donc être une piste intéressante pour la prévention du vieillissement vasculaire

Perseveration related to frontal lesion in mice using the olfactory H-maze

International audienceThe delayed reaction paradigm, consisting to discover two different rules consecutively (delayed alternation and non-alternation task) followed by a delayed reversal task, is a specific marker for the functioning of primate prefrontal cortex. Although several works in rodents report the use of operant delayed alternation tasks, in none of the studies mice with lesion of the prefrontal cortex were used in this paradigm. In the current study, mouse experiments were conducted using a new, totally automated device, the olfactory H-maze. Here, we show that unilateral lesion of the dorsomedial prefrontal cortex in mice induced similar deficits to those observed after frontal lesions in monkeys and humans. These pronounced learning deficits seem to come from difficulty elaborating a new rule and the inability to inhibit the previous rule, characterized by perseveration after prefrontal cortex lesion. The present results demonstrate that this very simple experimental paradigm using the olfactory H-maze presents the advantage to be fast (one training session) and well suited to assess the frontal functions in mice. It should be useful for testing pharmacological or stem cell approaches in order to reduce organic damages or gain insight into the cognitive functions of the frontal cortex using transgenic or gene-targeting mice. (C) 2009 Elsevier B.V. All rights reserved