Scientists have successfully transplanted human brain tissue into the brains of newborn mice for the first time, changing the behavior of these rodents.
The results were published Wednesday in an article detailing the study. in nature.
— New York Post (@nypost) October 12, 2022
“We found that human neurons respond very quickly to capillary stimulation that we did,” Sergio B. Pasca, professor of psychiatry at Stanford University and co-author of the study, told NBC News.
Scientists have fused human brain tissue with the brain of Baby Rats https://t.co/NSa4R0ash4
— ScienceAlert (@ScienceAlert) October 12, 2022
The Associated Press reported that the team designed a brain experiment to shed light on human brain development and neurological disease.
Unfortunately, while “disorders like autism and schizophrenia are uniquely human,” studying them in the human brain has not been easy, according to Baska.
To overcome this hurdle, the Stanford University Center for Brain Trust decided to create organelles (miniature copies of human organs) by turning skin cells into stem cells, which then turn into several types of brain cells.
These cells multiply to form the organelles of the human cerebral cortex, an area of the brain responsible for functions ranging from memory to thinking and emotions. In other words, they made human brain tissue “out of focus.”
Finally, the scientists injected artificial human brain tissue into the somatosensory cortex—areas involved in processing sensations such as touch or pain—in two to three-day-old rats whose brain connections were still forming.
The neural connection was immediate. “More than 70 percent of human neurons fire into some form of activity about a second after such stimulation, and this tells us that they are probably connected,” Pasca explained. He added that human neurons “glisten with electricity under the microscope,” noting that they “will become part of the brains of mice.”
Within eight months, human neurons doubled in size by about six times, making up a third of the brains of mice, becoming part of the decision-making and bodily reactions of rodents.
The transfer of the brain between species has influenced rodent behavior, and the team trained mice to lick a faucet to get water when the lights are on. Then, when the scientists noticed the hybrid brain, the mice began licking the tube for water, which meant that the human cells had integrated well enough to drive the behavior of the animals. What’s more, when the scientists stimulated the whiskers of mice, they found that human cells in the sensory cortex fired in response, indicating that the cells are capable of capturing sensory information.
Pasca considered the work to be “the most advanced human brain circuitry ever made from human skin cells and evidence that transplanted human neurons can influence animal behavior.”
As an added moral bonus, neurologically enhanced rodents had no health issues such as seizures, while more than 70% were alive after brain conduction.
To test practical applications, the scientists implanted the organoids in both hemispheres of rats. One was made from the cells of a healthy person, and the other was made from a person with Timothy syndrome, a rare genetic disorder similar to autism.
They found dramatic differences in the amount of electrical activity between the two hemispheres of the brain. Meanwhile, the neurons of the patient with Timothy’s syndrome were much smaller and did not form as many connections as healthy ones.
In the future, scientists hope to conduct similar experiments with organelles made from the cells of people with autism or schizophrenia.
Source: New York Post.