To study diseases, scientists use human brain cells in rats

scientists have transplanted human brain cells into the brains of baby rats, where the cells grew and formed connections.

The research is part of an effort to study the development of the human brain and diseases that affect this most complex of organs.

dr Sergiu Pasca of Stanford University in California was the lead author of a study describing the work. It recently appeared in the publication Nature.

“Many disturbances such as autism and schizophrenia are likely unique Man,” said Pasca. But the human brain has not been very easy to study. Research that doesn’t involve taking tissue from the human brain is a “promising” area to deal with these diseases, Pasca added.

The research builds on the team’s previous work on creating “organoids” in the brain. These organoids are very small structures that resemble human organs. Organoids were made to represent organs such as the liver, kidneys, and prostate.

To create the brain’s organoids, Stanford University scientists engineered human skin cells into stem cells. Then they caused the stem cells to become several types of brain cells. These cells then grew to form organoids that resemble the cerebral cortex, the outermost layer of the human brain. The cerebral cortex is associated with memory, thinking, learning, reasoning, and emotions.

Scientists transplanted these organoids into baby rats that were two to three days old. Brain connections are still forming at this age. The organoids grew to eventually occupy a third of the hemisphere of the rat brain where they were implanted. Neurons from the organoids formed working connections with the brain.

Human neurons have previously been transplanted into rodents, but into adult animals, usually mice. Pasca, a professor at Stanford School of Medicine, said this is the first time these organoids have been placed in the brains of baby rats.

To study how the idea might be useful for studying human health, scientists transplanted organoids into both sides of a rat’s brain. One side had organoids made from the cells of a healthy person and the other side had cells from a person with Timothy syndrome, a rare genetic condition linked to heart problems and autism.

Five to six months later, they saw the effects of the disease on the activity of the neurons. There were differences in the electrical activity of the two sides, and the neurons of the person with Timothy syndrome were much smaller and didn’t grow as many processes that pick up signals from nearby neurons.

The researchers, whose study was partially funded by the National Institutes of Health, said they could do the same experiments using organoids made from the cells of people with disorders like autism or schizophrenia. Such studies could help them learn new things about how these disorders affect the brain.

dr Flora Vaccarino of Yale University said the study advances the field.

“It’s extreme impressive what they’re doing here in terms of what these cells can actually show us in terms of theirs progressive Development…in the rat,” said Vaccarino, who was not involved with the study.

I’m John Russell.

Laura Ungar covered this story for the Associated Press. John Russell adapted it for VOA Learning English.

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words in this story

transplantation – v. medical : to move an organ or other part (such as a cell) of something and insert it into something else

Disturbance – n. medical : a physical or mental condition that is not normal or healthy

unique – adv. pertaining to or associated with just one specific thing

stem cell – n. a simple cell in the body that can develop into any of several types of cells (e.g. blood cells, skin cells, etc.)

impressive – adj. Earning attention, admiration, or respect: making a good impression

progressive – adj. far in a course of progress or development