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Mini-Brains Made to Order

Cell-Culturing Technique Developed by JHSPH Scientists Could Revolutionize Neurological Drug Development

When it comes to developing new drugs for neurological disorders such as Alzheimer’s, multiple sclerosis and Parkinson’s disease, failure is an all-too-common outcome.


“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 Thomas Hartung, MD, PhD, the Doerenkamp-Zbinden Professor and Chair for Evidence-based Toxicology at the Bloomberg School.

“95% of drugs that look promising when tested in animal models fail once they are tested in humans."

There are myriad reasons why seemingly promising drugs fail when tested on humans, but the most intractable problem is also the most obvious. “While rodent models have been useful,” observes Hartung, “we are not 150-pound rats.”

Hartung and colleagues took the search for a better drug-testing model to a new level with the February 12, 2016 announcement at the American Association for the Advancement of Science conference in Washington, D.C. that his team had created “mini-brains,” cell cultures that mimic the structure of the human brain. The hope is that “mini-brains”—which have the two types of cells that make up the main structure of the human brain—will allow scientists to assess the effects of drugs that come into contact with the cell cultures, ultimately reducing the use of animals in scientific research. 

The mini-brains start as human fibroblasts, which are reprogrammed into stem cells. The cells are then cultured and grown into neural cells over a 10-week period, emerging as a “mini-brain,” a tiny white bundle of cells no larger than a snowflake.

The researchers have plans to share the cell-growth technique worldwide through a tech venture, with the goal of mass-producing mini-brains to order. It would allow neurological scientists to grow everything from healthy brains to brains with disorders such as Down syndrome, potentially leading to dramatic reductions in cost and in the time required for drug development. 

“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,” says Hartung.