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Spatial and temporal organoid control Stem cell–derived organoids form through self-organization and serve as models for organ development, function, and disease, with potential applications in drug development and personalized medicine. However, in the absence of external guidance, developmental processes are stochastic, resulting in variable end products that differ significantly from the native organ. Gjorevski et al . developed approaches for specifying the initial organoid geometry to build intestinal organoids of defined shape, size, and cell distributions, forming structures that are predictable, more similar to normal organs, and reproducible (see the Perspective by Huycke and Gartner). These methods identify symmetry-breaking mechanisms in intestinal morphogenesis and have potential for standardizing organoid-based therapies and facilitating the refinement of mechanistic studies. —BAP

Organoids derived from epithelial stem cells have emerged as powerful platforms to model development and disease in a dish1-3. However, the current mismatch in anatomy, lifespan and size between native organs and their in vitro counterparts severely limits their applicability4. In particular, the closed, cystic architecture of most epithelial stem cell-derived organoids makes experimental manipulation and assay development cumbersome. Here we describe how tissue engineering and cellular self-organization can be combined to guide in vitro organogenesis into openly accessible, functional intestinal tubes termed ‘mini-guts’. Intestinal stem cells (ISCs) rapidly generate simple columnar epithelia when propagated inside basal lamina-like hydrogel scaffolds that feature a tubular and crypt-containing, in vivo-like anatomical structure. Using a microfluidic perfusion system, dead cells shed into the lumen can be continuously removed from the mini-guts. This increases tissue lifespan to months, establishing a homeostatic organoid culture system in which cell proliferation (in crypts) is balanced with cell death (in villus-like domains). The approach developed here can be extended to generate functional tissue/organ models from other epithelial cell types, including primary human stem/progenitor cells from the small intestine, colon or airway, permitting reconstitution of complex organ-level physiology and disease in a personalized manner.

Рязанский государственный медицинский университет им. акад. И.П. Павлова, г. Рязань В статье рассмотрены современные представления о роли свободно-радикальных процессов в физиологии роговицы и микроорганизмов. Обсуждается роль окислительного стресса в патогенезе бактериальной язвы роговицы. Делается обзор исследований по применению антиоксидантов для лечения бактериальной язвы. Ключевые слова: окислительный стресс, антиоксиданты, бактериальная язва роговицы.

Embryo implantation into the uterus marks a key transition in mammalian development. In mice, implantation is mediated by the trophoblast and is accompanied by a morphological transition from the blastocyst to the egg cylinder. However, the roles of trophoblast-uterine interactions in embryo morphogenesis during implantation are poorly understood due to inaccessibility in utero and the remaining challenges to recapitulate it ex vivo from the blastocyst. Here, we engineer a uterus-like microenvironment to recapitulate peri-implantation development of the whole mouse embryo ex vivo and reveal essential roles of the physical embryouterine interaction. We demonstrate that adhesion between the trophoblast and the uterine matrix is required for in utero-like transition of the blastocyst to the egg cylinder. Modeling the implanting embryo as a wetting droplet links embryo shape dynamics to the underlying changes in trophoblast adhesion and suggests that the adhesion-mediated tension release facilitates egg cylinder formation. Light-sheet live imaging and the experimental control of the engineered uterine geometry and trophoblast velocity uncovers the coordination between trophoblast motility and embryo growth, where the trophoblast delineates space for embryo morphogenesis.

Implantation marks a key transition in mammalian development. The role of embryo-uterus interaction in peri-implantation development is however poorly understood due to inaccessibility in utero. Here, we develop an engineered uterus-like microenvironment to recapitulate mouse development ex vivo up to E5.25 and discover an essential role of integrin-mediated trophoblast adhesion to the uterine matrix. Light-sheet microscopy shows that trophoblast cells undergo Rac1-dependent collective migration upon implantation, displacing Reichert's membrane and generating space for egg cylinder growth. The key role of coordination between trophoblast migration and embryo growth is verified by experimentally manipulating the migration velocity and geometry of the engineered uterus. Modeling the implanting embryo as a wetting droplet links the tissue shape dynamics to underlying changes in trophoblast adhesion and suggests that the corresponding tension release facilitates egg cylinder formation. Together, this study provides mechanisms by which dynamic embryo-uterus interactions play an essential role in peri-implantation development.

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