Scientists at Heinrich-Heine-University's Institute for Human Genetics in Düsseldorf, Germany, used stem cells to enable mini human brains to develop rudimentary eyes that can detect light and send signals to the brain.
These eyes are also called the optic cups, which are at their earliest stage of eye formation and will eventually develop at about five weeks old. According to Daily Mail, researchers used stem cells to create these cerebral organoids that can duplicate the function of any other somatic cell.
German Chancellor Angela Merkel listens to researcher Zoe Mendelsohn explain her work involving brain organoids from stem cells at the new Berlin Institute for Medical Systems Biology of the Max-Delbrück Center for Molecular Medicine as Scientific Director Nikolaus Rajewsky (3rd from L) and scientist Martin Lohse (R) look on on February 26, 2019, in Berlin, Germany. The new center, located in the center of Berlin, brings together researchers from all over the world to advance the science of personalized medicine. (Photo by Sean Gallup/Getty Images)
Remarkable Cerebral Organoids
The news outlet reported that the mini human brains are only about 3 mm (0.1 inch) wide, while the optic cups only measure about 0.2 mm (0.008 inches) each. The optic cups grow as identical pairs with real eye parts, such as retinas, corneas, lenses, and nerve cells that allow them to sense light and communicate to the brain.
In their study titled "Human Brain Organoids Assemble Functionally Integrated Bilateral Optic Vesicles," published in the journal Cell Stem Cell, the researchers wrote that they detected electrical signals traveling along the neural pathways of the optic cups when they were exposed to the light, suggesting that visual information was transmitted.
Small blobs of human brain grown in a dish have been coaxed into forming rudimentary eyes, which respond to light by sending signals to the rest of the brain tissue [read more: https://t.co/yOdlu4onQl] pic.twitter.com/0uReuJgq6V
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"In the mammalian brain, nerve fibers of retinal ganglion cells reach out to connect with their brain targets, an aspect that has never before been shown in an in vitro system," senior study author Jay Gopalakrishnan said in a statement in Cell Press via EurekAlert!
He added that their work highlights the remarkable ability of the cerebral organoids to generate the primitive sense of sight and harbor cell types that are similar to somatic cells. As reported by Daily Mail, researchers hope that the mini human brains will help study brain-eye interactions during the early stages of development and model congenital retinal conditions.
Around 3/4 of the 314 mini human brains developed optic cups after 60 days, equivalent to their appearance in human embryos. However, they are short-lived due to the lack of blood supply. The organoids also raised ethical concerns because the brain waves detected are similar to those two-month-old human embryos.
Nonetheless, researchers believe that the mini human brains with optic cups present potential in developing artificial retinas for people who lost their vision.
ALSO READ: Are Human Cell Transplants and Brain Organoids Experiments in Animals Ethical?
How Did the Mini Human Brains Develop Their Eyes?
According to Live Science, scientists have been growing individual optic cups in the past. However, this is the first time that cerebral organoids have been introduced with optic cups.
The scientists have used a technique they previously developed for transforming stem cells into neural tissues to create the mini human brains with optics cups.
First, the stem cells developed into the organoids, and then optic cups appeared as early as 30 days and matured on the 50th day. They observed that the retina developed in a similar timeframe as it should in human embryos.
As to why they are making mini human brains with eyes, researchers said that they hope their experiment could be useful in studying human brain development and related diseases.
They hope to develop new batches in which the optic cups could last for a long time so they can use them to research the mechanisms behind retinal disorders.
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