Aberrant iPSC-derived human astrocytes in Alzheimer's disease

The pathological potential of human astroglia in Alzheimer's disease (AD) was analysed in vitro using induced pluripotent stem cell (iPSC) technology. Here, we report development of a human iPSC-derived astrocyte model created from healthy individuals and patients with either early-onset familial AD (FAD) or the late-onset sporadic form of AD (SAD). Our chemically-defined and highly efficient model provides >95% homogeneous populations of human astrocytes within 30 days of differentiation from cortical neural progenitor cells (NPCs). All astrocytes expressed functional markers including; glial fibrillary acidic protein (GFAP), excitatory amino acid transporter 1 (EAAT1), S100B and glutamine synthetase (GS) comparable to that of adult astrocytes in vivo. However, induced astrocytes derived from both SAD and FAD patients exhibit a pronounced pathological phenotype, with a significantly less complex morphological appearance, overall atrophic profiles, and abnormal localisation of key functional astroglial markers. Furthermore, NPCs derived from identical patients did not show any differences, therefore, validating that remodelled astroglia are not as a result of defective neuronal intermediates. This work not only presents a novel model to study the mechanisms of human astrocytes in vitro, but also provides an ideal platform for further interrogation of early astroglial cell-autonomous events in AD and the possibility of identification of novel therapeutic targets for the treatment of AD

Embryogenic suspensions of adult cork oak: the first step towards mass propagation.

Abstract Protocols have been established to clone adult cork oak trees by somatic embryogenesis using semisolid medium. However, for economically viable mass propagation, embryogenic cultures in liquid medium need to be developed. In this study, suspension cultures were initiated from embryo clusters obtained by secondary embryogenesis on a gelled medium lacking plant growth regulators. After 6 days of culture, these embryo clusters generated high cell density suspensions that also contained small organized structures (embryos and embryogenic clumps). As the culture duration increased, tissue necrosis and fewer embryogenic structures were observed and the establishment of suspension cultures failed. An alternative method was found adequate for initiation of embryogenic suspensions: embryo clusters from gelled medium were briefly shaken in liquid medium and detached cells and embryogenic masses of 41?800 lm were used as inoculum. Maintenance of embryogenic suspensions was achieved using a low-density inoculum (43 mg l-1) by subculturing four embryogenic clumps of 0.8?1.2 mm per 70 ml of medium. Proliferation ability was maintained for almost 1 year through ten consecutive subcultures. The initiation and maintenance protocols first developed for a single genotype were effective when tested on 11 cork oak genotypes

Reinvigoration treatments for the micropropagation of mature chestnut trees

Crown material from five adult chestnut trees was given different reinvigoration treatments, such as 6-benzylaminopurine (BA) applications (spray or pulse) to forced cuttings, and juvenile grafting alone or combined with BA sprays, then used for the establishment in vitro. The in vitro performance, in terms of establishment, multiplication and rooting, of both untreated and treated material was compared. Grafting alone or in combination with BA spray greatly increased the in vitro reactivity of crown-derived explants. By combining in vivo pretreatments and a horizontal reculturing system, crown-derived microshoots exhibited maximum rooting rates, similar to those found for cultures from basal shoots of the same tree in previous work.Traitements de rajeunissement de châtaigniers adultes. Pour faciliter l'établissement in vitro du châtaignier, différents traitements, tels que des applications de 6-benzylaminopurine (BA, pulvérisation ou trempage de 2 h), le greffage sur porte-greffe juvénile, seul ou combiné avec des pulvérisations de BA, ont été appliqués au matériel prélevé dans la couronne de cinq châtaigniers adultes. On a comparé le comportement durant l'établissement, la multiplication et l'enracinement in vitro, du matériel non traité (témoin) et du matériel rajeuni. Durant l'établissement in vitro, la réactivité du matériel témoin a été relativement faible pour tous les clones (variations entre 0 et 22 %). Le greffage, seul ou combiné avec des pulvérisations de BA, augmente significativement la réactivité des explants provenant de la cime des arbres, atteignant 94 % pour le clone HV. En ce qui concerne la phase de multiplication, les meilleurs résultats ont été obtenus avec les microboutures dérivées du matériel provenant de la couronne, pulvérisé avec BA (C+S), ainsi qu'avec ceux des greffes pulvérisées avec BA (G+S). Dans les deux cas, on a obtenu des valeurs bien supérieures à celles du témoin. Un comportement similaire a été observé dans leur aptitude à l'enracinement. Ces résultats montrent que les traitements C+S et G+S induisent un certain rajeunissement du matériel adulte. En combinant les prétraitements in vivo avec un système de culture répétée des explants in vitro en position horizontale (recyclage), les microboutures dérivées de la couronne présentent un taux de multiplication significativement supérieur à celui des explants en position verticale et/ou horizontale non recyclés. De plus, avec ce système on a obtenu des taux d'enracinement (63 et 28 % pour les clones 431 et HV, respectivement) similaires à ceux précédemment trouvés dans des cultures dérivées de rejets de la base du même arbre

Cold storage of in vitro cultures of wild cherry, chestnut and oak

Shoot cultures of chestnut, oak and wild cherry have been stored at low temperature (2°C) for 3, 6, 9 and 12 months. Cultures were stored immediately after the last subculture or 10 d later. Survival and morphogenetic parameters have been recorded at the end of each period of storage. Both survival and proliferation capacity of the explants were influenced by the timing of the transfer. When the explants were stored 10 d after the subculture, higher percentages of survival and multiplication rates were obtained. The 4 species studied may be maintained at 2°C for up to 1 year without subculturing.Conservation au froid de pousses in vitro de merisier, châtaignier et chêne. Des pousses en culture in vitro de châtaignier, de chêne et de merisier ont été conservées à basse température (2°C) pendant 3, 6, 9 et 12 mois. Ces pousses furent stockées juste après le dernier repiquage ou 10 j plus tard. Les taux de survie et les caractéristiques morphologiques ont été déterminées à la fin de chaque période de conservation. La survie comme la capacité de prolifération des explants sont influencées par la durée de la phase de transfert (tableaux I, II ; fig 1). Le stockage des explants 10 j après le repiquage s'est traduit par de forts taux de survie et de multiplication. Les 4 espèces étudiées peuvent être maintenues à 2°C pendant plus d'une année sans repiquage