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Tiny brains grown in the lab from plant cells suddenly developed eye-like features, scientists report in an outstanding paper in 2021.
On small human brain organs grown in plates, two identical eye plates were observed growing, simulating development. eyes on human embryos.
This amazing result will help us to better understand the process of eye differentiation and development, as well as eye diseases.
“Our work highlights the remarkable ability of brain organoids to create highly specialized structures that are lightweight and compact, similar to those found in the body,” says neuroscientist Jay Gopalakrishnan the University Hospital Düsseldorf in Germany.
“These organoids can help to study brain-eye interactions during infant development, model congenital retinal disorders, and generate patient-specific retinal cell types for specialized drug testing and therapeutics.”
Brain organoids are not real brains, as you might think. Small, three-dimensional structures grown from induced pluripotent stem cells – cells harvested from adults and transplanted into cells, can develop into many types different tissues.
In this case, these cells are encouraged to grow and become brain cells, without anything resembling thoughts, feelings, or knowledge.
Such ‘mini brains’ are used for research purposes where a real living brain cannot be used, or at the very least, artificially. the experiment – testing the response of drugs, for example, or monitoring the development of cells under certain conditions bad situation.
This time, Gopalakrishnan and his colleagues sought to monitor the development of eyes.
In previous research, other scientists used embryonic cells to create eye cups, the structures that grow inside. almost the entire globe of the eye during embryonic development. And other studies have created glass-like structures from induced pluripotent cells.
Instead of growing these structures directly, Gopalakrishnan’s team wanted to see if they could be grown as part of an integrated brain organoid. It will be more useful to see how the two species can coexist, rather than just developing the same mesh structures.
“The development of the eye is a complex process, and the light can allow the molecular establishment of early retinal diseases,” the researchers wrote in their paper.
“Therefore, it is very important to study the optic vesicles of the primordium of the eye that is attached to the closest part of the eye, which is necessary for the proper formation of the eyes.”
Previous work on the development of organoids showed evidence of retinal cells, but these did not develop eye structures, so the team changed their rules. They did not try to encourage the development of pure neural cells at the beginning of neural differentiation, and added retinol acetate to the culture to help the development of eyes.
Their carefully nurtured baby brains formed eye cups as early as 30 days of development, with clear vision at 50 days. This is consistent with the eye development time in the human embryoThis means that these organoids can be useful for studying the complexity of this process.
There are other effects as well. The optic cups contained different types of retinal cells, which are organized into neural networks that respond to light, and even the lens and eye tissue. Finally, the structures revealed the retinal connection in the brain regions.
“In the mammalian brain, nerve fibers of retinal ganglion cells reach out to connect with their brain targets, a feature that has not been demonstrated before in an in vitro system,” Gopalakrishnan said.
And it can be reproduced. Of the 314 brain organoids that the team grew, 73 percent developed optic discs. The team hopes to develop strategies for maintaining these structures that are possible over long periods of time for the implementation of in-depth studies with greater capacity, the researchers said.
“Optic vesicle-containing brain organoids show specialized neuronal cell types that can develop, paving the way to produce specialized organoids and retinal pigment epithelial sheets for implantation,” they wrote in their paper.
“We believe that (now) the next generation of organoids will help in the diagnosis of retinopathies that arise from early neurodevelopmental disorders.”
The study is published in Cell Stem Cell.
A version of this article was originally published in August 2021.