美国国家公共电台 NPR 'Minibrains' Could Help Drug Discovery For Zika And For Alzheimer's

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'Minibrains' Could Help Drug Discovery For Zika And For Alzheimer's

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Some tiny brains are making big news this week at the world's largest neuroscience meeting. Minibrains are these lab-created clusters of living human brain cells that mimic² some of the functions of actual, fully³ developed brains. As NPR's Jon Hamilton reports, they are helping⁴ scientists answer questions about everything from early brain development to infection with the Zika virus.

JON HAMILTON, BYLINE⁵: Unlike real brains, minibrains are made in laboratories - labs like this one at Johns Hopkins University in Baltimore. Hongjun Song, the scientist in charge, takes me to a small, windowless room with a powerful air filtration system. He opens an incubator the size of a dorm fridge and points inside.

HONGJUN SONG: So this is the device we've developed.

HAMILTON: The device is only a bit larger than a cell phone, but Song says it's a complete minibrain factory. The lower half looks like a miniature muffin pan with a dozen separate compartments⁶.

SONG: Yeah, we can grow up to five to 10 minibrain in each one.

HAMILTON: These minibrains aren't just random⁷ clumps⁸ of human brain cells. They contain many of the structures and connections found in real brains. And figuring out how to grow them has taken a lot of work. About three years ago, scientists in Europe showed how to coax⁹ brain cells into specializing and organizing much the way a developing brain does. The Hopkins team has streamlined and improved the process. Guo-Li Ming, a professor at Hopkins, says each minibrain is just big enough to see with the naked eye.

GUO-LI MING: It's basically, like, a ball of cells clustering together. But if you open it up, you really see something very similar to the early embryonic¹⁰ brain.

HAMILTON: It's not just that they look like embryonic brains. They also grow the way a brain does in the womb. And that led to a big discovery with a minibrain just a few months ago. It involved the Zika virus, which was suspected of derailing brain development in early pregnancy¹¹. Ming says she and Hongjun Song, who are married, thought their minibrains might offer a way to figure out what was happening. And by chance, the couple knew a researcher at Florida State University who was studying the Zika virus.

MING: So Hongjun called him right away, saying, well, we have the perfect system to work. Do you have the Zika? And he said yes.

HAMILTON: That call led to experiments in minibrains that showed how the infection was attacking certain critical brain cells. The Hopkins team described this research Sunday during a press conference at the Society for Neuroscience meeting in San Diego. Elsewhere at the meeting, scientists are presenting minibrain research on a range of other diseases and disorders¹², including brain cancer and Down syndrome¹³. Thomas Hartung from Hopkins Bloomberg School of Public Health says minibrains may offer a better way for drug companies to test new products.

THOMAS HARTUNG: One company after the other failed on things like stroke, multiple sclerosis, but also new degenerative diseases, like Alzheimer's and Parkinson's.

HAMILTON: Those drugs worked on animals but failed with people. Hartung says that's because animal brains aren't like human brains.

HARTUNG: We need human systems to tell us about humans, and that's why this is such a big step forward.

HAMILTON: One potential obstacle for minibrain research is public acceptance. Hartung says when people hear about scientists growing brains in a lab, they sometimes imagine a fully functioning organ. And in some ways, he says, the clusters are like real brains.

HARTUNG: These cells are communicating. These neurons are talking to each other. You could say it's a primitive¹⁴ type of thinking.

HAMILTON: But Hartung says these brains contain thousands of cells, not billions like a real brain. And even if they could get bigger, they wouldn't be conscious.

HARTUNG: This has nothing to do with consciousness. This has nothing to do with any type of information which is digested here by these cells because they have no input¹⁵.

HAMILTON: So they don't have anything to think about. Jon Hamilton, NPR News.