'Mini-brain' grown in test tubes

Scientists have grown miniature human brains in test tubes, creating a "tool" that will allow them to watch how the organs develop in the womb.
They hope the findings will increase their understanding of neurological and mental problems.
Just a few millimetres across, the "cerebral organoids" are built up of layers of brain cells with defined regions that resemble those seen in immature, embryonic brains.
The scientists say the organoids will be useful for biologists who want to analyse how conditions such as schizophrenia or autism occur in the brain.
The organoids are also expected to be useful in the development and testing of drugs.
Researchers at the Institute of Molecular Biotechnology in Vienna started with stem cells and grew them into    brain cells in a nourishing gel-like matrix that recreated conditions similar to    those inside the human womb.
After several months the cells had formed spheres measuring about 3-4mm in diameter.
"The cerebral organoids display discrete regions that resemble different areas of the early developing human brain. These include the dorsal cortex identity -- the dorsal cortex is the largest part of the human brain.
"They also include regions representing the ventral forebrain and even the immature retina," said Madeline Lancaster, who was first author of the paper published in Nature on Wednesday.
Jürgen Knoblich, who was part of the team that created the organoids, said that tests on the brain cells in the structures showed that they were functional.
He said the team's goals included growing larger organoids and modelling more brain diseases.
Knoblich added the intention of the research was not to grow replacement brain parts or an entire brain in culture.