The brains are about as big as the eye of a housefly!
Animal rights activists will be thrilled to learn that scientists have grown “mini-brains” —
effectively little balls of neurons and human support cells — which could be used to replace animal testing in labs within the year.
“Ninety-five percent of drugs that look promising when tested in animal models fail once they are tested in humans, at great expense of time and money,” says study leader Thomas Hartung, professor of evidence-based toxicology at Johns Hopkins University’s Bloomberg School of Public Health.
Since the mini-brains are made from human cells, the researchers are confident that they would offer a significant improvement from the current methods with mice and rats.
“While rodent models have been useful, we are not 150-pound rats,” Hartung says. “And even though we are not balls of cells either, you can often get much better information from these balls of cells than from rodents. We believe that the future of brain research will include less reliance on animals, more reliance on human cell-based models.”
The researchers created the mini-brains using induced pluripotent stem cells — cells tailored to become any type of specialized cell in the body. In this case, the scientists genetically reprogrammed adult skin cells and stimulated them to grow into brain cells.
The team used skin cells from healthy adults, but interestingly, Hartung says that using cells from people with specific diseases or genetic traits could be used to better study them. For example, mini-brains can be grown to study particular diseases like Alzheimer’s, Parkinson’s, and even autism.
The mini-brains truly are mini, sizing in at 350 micrometers in diameter, which is about the size of the eye of a housefly! The scientists can produce hundreds to thousands of exact copies in each batch, and about a hundred mini-brains can easily grow in the same petri dish.
The mini-brains developed four types of neurons and two types of support cells — astrocytes and oligodendrocytes — after about two months of growth. Oligodendrocytes serve an important function because they eventually go on to create myelin, which insulates the neurons’ axons allowing them to communicate quicker.
“We don’t have the first brain model nor are we claiming to have the best one,” says Hartung, who also directs the Bloomberg School’s Center for Alternatives to Animal Testing. “But this is the most standardized one. And when testing drugs, it is imperative that the cells being studied are as similar as possible to ensure the most comparable and accurate results.”
The researchers are applying for a patent for their mini-brains and are also developing a commercial entity to begin producing the mini-brains in 2016 if all goes according to plan.
“Only when we can have brain models like this in any lab at any time will we be able to replace animal testing on a large scale,” Hartung says.
Less animal testing and more accurate results? Sounds like a win-win.