3 Minute 3Rs October 2019

3 Minute 3Rs

The October episode of 3 Minute 3rs, brought to you by the NC3Rs (www.nc3rs.org.uk), the North American 3Rs Collaborative (www.na3rsc.org), and Lab Animal (www.nature.com/laban).Papers1. Modelling human hepato-biliary-pancreatic organogenesis from the foregut–midgut boundaryhttps://www.nature.com/articles/s41586-019-1598-02. Automated Platform for Long-Term Culture and High-Content Phenotyping of Single C. elegans Worms https://www.nature.com/articles/s41598-019-50920-83. Analysis of vertebrate vision in a 384-well imaging system. Thorn RJ. Sci Rep. https://www.ncbi.nlm.nih.gov/pubmed/31562366Transcript[LA] Organoids are three dimensional structures derived from human cells. Unlike traditional cell cultures that are grown flat on petri dishes, multicellular organoids can offer researchers a little extra physiological context. But, an organoid of one organ still exists in isolation. A new paper published last month in the journal Nature starts to put some organoids together.The team, led by Takanori Takebe at Cincinnati Children’s Hospital, wanted to study organagenesis, the process by which organs form. They took human skin cells, reverted them to pluripotent stem cells, and meticulously guided those to become small balls called spheroids that mimicked foregut and midgut. The team then put the two kinds of spheroids together in a special medium and let them grow. The structure that ultimately formed recapitulated functions of the liver, bile ducts, and pancreas. Such an integrated system is another step forward for organoid research. [NA3RsC] The worm, C. elegans, is an increasingly popular model for drug discovery and screening. For example, adverse effects of compounds can easily be detected by looking for changes in how fast the C. elegans grow, how big they get, and once they are larvae - how they move. Atakan and colleagues present a platform for automating the process of phenotyping single C elegans from the embryo to the adult. The platform overcomes many of the challenges of prior systems. It automates the painstaking process of distributing embryos into individual chambers and can expose the worms to up to 8 different chemical conditions in a single experiment. The phenotypes, including growth and movement, are measured automatically through analysis of 10 second videos captured every four hours across the worms’ life cycle. To validate the platform, C. elegans were exposed to increasing concentrations of tetramisole and the known negative effects on growth and motility were demonstrated. The continued progress toward automating C. elegans studies with platforms, such as this one, will allow scientists to discover new opportunities for using the worm in early drug discovery. [NC3Rs] Automated behavioural monitoring can reveal subtle changes in an animal’s vision before they can be detected physically. While these tests can be applied to rodents in the lab, each animal must be individually trained to use the system and only one animal can be monitored per cage, making it impractical for high throughput studies. In search of an alternative approach, Robert Thorn and colleagues at Brown University turned to zebrafish larvae at five days post-fertilisation. In their recent Scientific Reports paper, the team describe imaging 384 larvae at once in four 96-well plates, monitoring their response to moving visual stimuli. They found that diazepam significantly reduced their response, while flumazenil, a diazepam antidote, reversed this effect, illustrating that the larvae can be used to detect clinically relevant changes in the visual system, With three percent of the world’s population affected by visual impairment, this new tool could speed up the screening and development of treatments while also replacing mammalian models.

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