An anonymous reader quotes a report from ScienceAlert: Mini brains grown in a lab from stem cells have spontaneously developed rudimentary eye structures scientists report in a fascinating new paper. On tiny, human-derived brain organoids grown in dishes, two bilaterally symmetrical optic cups were seen to grow, mirroring the development of eye structures in human embryos. This incredible result will help us to better understand the process of eye differentiation and development, as well as eye diseases. Brain organoids are not true brains, as you might be thinking of them. They are small, three-dimensional structures grown from induced pluripotent stem cells — cells harvested from adult humans and reverse engineered into stem cells, that have the potential to grow into many different types of tissue. In this case, these stem cells are coaxed to grow into blobs of brain tissue, without anything resembling thoughts, emotions, or consciousness. Such ‘mini brains’ are used for research purposes where using actual living brains would be impossible, or at the very least, ethically tricky — testing drug responses, for example, or observing cell development under certain adverse conditions.
Previous work in the development of organoids showed evidence of retinal cells, but these did not develop optic structures, so the team changed their protocols. They didn’t attempt to force the development of purely neural cells at the early stages of neural differentiation, and added retinol acetate to the culture medium as an aid to eye development. Their carefully tended baby brains formed optic cups as early as 30 days into development, with the structures clearly visible at 50 days. This is consistent with the timing of eye development in the human embryo, which means these organoids could be useful for studying the intricacies of this process. There are other implications, too. The optic cups contained different retinal cell types, which organized into neural networks that responded to light, and even contained lens and corneal tissue. Finally, the structures displayed retinal connectivity to regions of the brain tissue. The research has been published in the journal Cell Stem Cell.
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