Scientists Grow 'Model Brain' From Stem Cells
The tiny 'organoids' have many of the same tissues as nine-week-old fetal brains
"In ours, we don't have that spatial organization. We have those regions, but they're not spatially organized in that manner," she said.
And while researchers found some evidence that the different brain regions were functioning, they don't think the organoids were fully wired and connected the way mature adult brains are, because that kind of connection is something that happens at later developmental stages.
"It's sort of like manufacturing all the transistors and resistors in a radio, but not actually wiring it all up so you can listen to the radio," said Amy Bernard, director of structured science for the Allen Institute for Brain Science in Seattle. "But certainly getting those building blocks set in is the first step."
However, "it's very impressive to see the level of differentiation that's achieved in this model," added Bernard, who was not involved with the study.
To further prove the value of watching early brain development this way, the researchers took stem cells from an individual with microcephaly, a developmental problem that affects about 25,000 of the roughly 4 million children born in the United States each year.
They treated the stem cells with chemicals to return them to an embryonic state and then watched them as they began to grow into an early brain.
Compared to the way previous organoids had grown, the stem cells from the individual with microcephaly stopped dividing earlier, so they had fewer total stem cells with which to build a brain, resulting in a smaller overall brain size.
"So in this, we understand how microcephaly developed in one individual patient," Lancaster said.
Their hope is that by studying the process of microcephaly and other developmental problems in many individuals, they will find new ways to diagnose and perhaps treat these kinds of conditions.