Organoid "three in one"
The mini-brain grown in the laboratory independently connected with the muscles
Scientists from the Laboratory of Molecular Biology in Cambridge have grown a cerebral organoid in a Petri dish – a miniature likeness of the brain, which turned out to be able to communicate with spinal fibers and send nerve impulses to the muscles.
Figure from the press release of the MRC Laboratory of Molecular Biology Cerebral organoids at the air-liquid interface generate nerve traces with functional output – VM.
Primitive miniature analogues of real organs grown from cell cultures have become much more sophisticated in recent years. Scientists were able to obtain analogs of the heart, kidney, brain, stomach, lungs, retina, large and small intestines in laboratory conditions. They have groups of differentiated cells similar to those found in full-sized organs.
Such organoids are used to test new therapies, for example, recently glioblastoma, one of the most aggressive tumors, was grown on mini-brains in order to find the best way to combat it.
In the current experiment, scientists were able to achieve the most advanced development of a cerebral organoid grown from human stem cells. It corresponds to the brain of an embryo at 12-16 weeks of pregnancy. In previous experiments, the size of the mini-brain was limited by the lack of nutrients that occurs when the organoid reaches a certain size. After that, the neurons in its central part lost access to oxygen and nutrition obtained from the culture medium, and died. Now scientists have grown an organoid, divided it into layers half a millimeter thick and placed it on a membrane floating in a liquid rich in nutrients. Each of the fragments had access to nutrition and oxygen, and at the same time the mini-brain cells were able to form connections with each other. The development of the organoid continued for a year.
While a fully developed adult brain has 80-90 billion neurons, there are only about two million of them in the organoid grown by scientists, so in terms of gray matter it occupies an intermediate place between a cockroach and a danio rerio fish. Nevertheless, already at this level, the organoid has shown new properties. Scientists placed a fragment of a mouse spinal cord about a millimeter long and part of the surrounding muscles in a culture medium next to it. During the experiment, the mini-brain grew nerve processes to connect with the spinal cord, and through it with muscle tissues. Then muscle contractions were observed under the control of this organoid.
Scientists note that in the future such systems can be used to study how the human brain and nervous system develop and what is disrupted in their interaction with diseases such as motor neuron disease or epilepsy.
The results are published in the journal Nature Neuroscience (Giandomenico et al., Cerebral organoids at the air–liquid interface generate diverse nerve traces with functional output).
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