Scientists Grew a Synthetic Mouse Embryo With a Brain and a Beating Heart

An anonymous reader quotes a report from ScienceAlert: In a monumental leap in stem cell research, an experiment led by researchers from the University of Cambridge in the UK has developed a living model of a mouse embryo complete with fluttering heart tissues and the beginnings of a brain. The research advances the recent success of a team comprised of some of the same scientists who pushed the limits on mimicking the embryonic development of mice using stem cells that had never seen the inside of a mouse womb. In the past, researchers in embryology have focused largely on plucking choice stem cells from parts of an embryo that would grow into an animal and encouraging them to proliferate in glassware full of specially selected nutrients. Over the years, this method has resulted in clumps of cells containing the basic starting structures of a gut and a fold of tissues called the neural tube. What the so-called 'gastruloid' model contains in form, however, it lacks in function. Many features expected to develop alongside these tissues aren't present, making it harder to draw parallels between the model and an authentic growing embryo. There are ways to encourage brain-like structures to appear, as well as functioning heart tissue and a more complex gut tube. Yet workarounds based on comparatively simple hormonal soups can only go so far. Mixing stem cells representative from these three major tissue groups and improving on previous methods for their development in vitro (that means in a dish) into an embryoid, the team found their model could progress under its own steam to develop a nervous system equivalent to a natural mouse embryo at 8.5 days post-conception. The step is a small one, equivalent to just a single day of development for an unborn mouse. But a lot can happen in that 24 hours of gestation. The synthetic embryoid also contained foundational heart tissue that twitched out a beat and the beginnings of a gut, as well as the start of structures that in an actual embryo could build parts of the skeleton, muscles, and other tissues beneath the skin. On its own, the model wouldn't continue to develop into anything like a thriving baby mouse. Science is far from able to produce anything so advanced as a functional organ from stem cells alone, let alone an entire animal. While the resemblance is quite significant in research, it is -- so to speak -- only skin deep, lacking the signals that would see it transform into the fully-formed organism it models. Having a collection of tissues that authentically reflects development outside of a body provides researchers with the opportunity to not only observe, but ethically test genetic changes that could help improve our understanding of how our bodies grow. The findings appear in a study published in the journal Nature.

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