Guided self-organization and cortical plate formation in human brain organoids.

Three-dimensional cell culture models have either relied on the self-organizing properties of mammalian cells or used bioengineered constructs to arrange cells in an organ-like configuration. While self-organizing organoids excel at recapitulating early developmental events, bioengineered constructs reproducibly generate desired tissue architectures. Here, we combine these two approaches to reproducibly generate human forebrain tissue while maintaining its self-organizing capacity. We use poly(lactide-co-glycolide) copolymer (PLGA) fiber microfilaments as a floating scaffold to generate elongated embryoid bodies. Microfilament-engineered cerebral organoids (enCORs) display enhanced neuroectoderm formation and improved cortical development. Furthermore, reconstitution of the basement membrane leads to characteristic cortical tissue architecture, including formation of a polarized cortical plate and radial units. Thus, enCORs model the distinctive radial organization of the cerebral cortex and allow for the study of neuronal migration. Our data demonstrate that combining 3D cell culture with bioengineering can increase reproducibility and improve tissue architecture

Phosphodiesterase 4 inhibition in the treatment of psoriasis, psoriatic arthritis and other chronic inflammatory diseases

Agents which increase intracellular cyclic adenosine monophosphate (cAMP) may have an antagonistic effect on pro-inflammatory molecule production so that inhibitors of the cAMP degrading phosphodiesterases have been identified as promising drugs in chronic inflammatory disorders. Although many such inhibitors have been developed, their introduction in the clinic has been hampered by their narrow therapeutic window with side effects such as nausea and emesis occurring at sub-therapeutic levels. The latest generation of inhibitors selective for phosphodiesterase 4 (PDE4), such as apremilast and roflumilast, seems to have an improved therapeutic index. While roflumilast has been approved for the treatment of exacerbated chronic obstructive pulmonary disease (COPD), apremilast shows promising activity in dermatological and rheumatological conditions. Studies in psoriasis and psoriatic arthritis have demonstrated clinical activity of apremilast. Efficacy in psoriasis is probably equivalent to methotrexate but less than that of monoclonal antibody inhibitors of tumour necrosis factor (TNFi). Similarly, in psoriatic arthritis efficacy is less than that of TNF inhibitors. PDE4 inhibitors hold the promise to broaden the portfolio of anti-inflammatory therapeutic approaches in a range of chronic inflammatory diseases which may include granulomatous skin diseases, some subtypes of chronic eczema and probably cutaneous lupus erythematosus. In this review, the authors highlight the mode of action of PDE4 inhibitors on skin and joint inflammatory responses and discuss their future role in clinical practice. Current developments in the field including the development of topical applications and the development of PDE4 inhibitors which specifically target the subform PDE4B will be discussed

Widespread arc-related melting in the mantle section of the northern Oman ophiolite as inferred from detrital chromian spinels

<p>We examined detrital chromian spinels, in recent river beds, derived from the mantle section to deterrmine whether the mantle peridotite of the northern Oman ophiolite is of oceanic or arc origin. The Cr-number (= Cr/(Cr + Al) atomic ratio) of the detrital chromian spinels mostly ranges from 0.4 to 0.8, and more than 60% of them have Cr-numbers higher than 0.6. This indicates a significant extent of island-arc nature because chromian spinels seldom have Cr-numbers higher than 0.6 in ocean-floor rocks. The high-Cr-number (>0.6) spinels, which are also low in TiO₂ (<0.3 wt%), are probably derived from an arc setting. Lherzolite with spinel Cr-numbers <0.2 is absent except near the base of the section. The high-Cr-number detrital chromian spinels are more abundant from the mantle section with more frequent discordant dunite pods. Post-deformational discordant dunite and adjacent harzburgite include the high-Cr-number spinels in outcrops. The upper mantle of the northern Oman ophiolite was formed at a fast-spreading ridge and was later modified by island-arc magmatism in a subduction-zone environment. This switch of tectonic setting from a mid-oceanic ridge to an island arc is essential in the explanation of obduction of a slice of oceanic lithosphere onto a continental margin as an ophiolite. </p