ADRIAN FLORIDO, HOST:
Human brain development remains one of the most complex mysteries in biology. Often, scientists look to animal models to study this process. But lab animals, like mice, are not ideal for running experiments over many years or decades or studying complicated disorders like autism or schizophrenia. Now, scientists have found a new way around those problems by growing special structures called organoids. NPR's Rachel Carlson reports.
RACHEL CARLSON, BYLINE: Organoids are tiny clumps of human cells. They are derived from stem cells and scientists use them to study human brain development in the lab because they reveal a little more about how cells work inside the body. But organoids usually don't last very long. They typically die within months, maybe a year or two. That means they only show researchers very early stages of the human brain. But in a recent study in the journal Nature, scientists managed to make some organoids grow for five years. Dr. Guo-li Ming is a neuroscientist at the University of Pennsylvania. She wasn't involved in the current study but says this is the longest lifespan of organoids to date.
GUO-LI MING: This is a technology breakthrough.
CARLSON: She says this means researchers could potentially use organoids in longer-term studies of human brain development. Andrea Beckel-Mitchener is the acting director of the National Institute of Mental Health, which funded grants that supported this research. She says the scientists found the organoids age similarly to cells inside a human body over the five-year period, showing characteristics of a fetal brain, then a newborn, all the way up to a 4-year-old brain.
ANDREA BECKEL-MITCHENER: And they retain characteristics of cells that would be in a living brain of the same age.
CARLSON: The study authors also mixed cells of different ages and saw the older cells continued to look like older cells instead of assimilating with the younger ones. Ming says this means the cells seem to have some kind of internal clock.
MING: Basically, they have a timestamp. They know what time or in what process they have been through.
CARLSON: Beckel-Mitchener says organoids don't replace the study of actual human brains. But she thinks this is a step towards using organoids to test drug therapies, gene therapies and figuring out the right time in a cell's life for those treatments.
Rachel Carlson, NPR News.
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