Miniature "human brains" have been grown in a lab in a feat scientists hope will transform the understanding of neurological disorders. The pea-sized structures reached the same level of development as in a nine-week-old foetus, but are incapable of thought.
They used either embryonic stem cells or adult skin cells to produce the part of an embryo that develops into the brain and spinal cord - the neuroectoderm. This was placed in tiny droplets of gel to give a scaffold for the tissue to grow and was placed into a spinning bioreactor, a nutrient bath that supplies nutrients and oxygen.
The cells were able to grow and organise themselves into separate regions of the brain, such as the cerebral cortex, the retina, and, rarely, an early hippocampus, which would be heavily involved in memory in a fully developed adult brain.
The "mini-brains" have survived for nearly a year, but did not grow any larger. There is no blood supply, just brain tissue, so nutrients and oxygen cannot penetrate into the middle of the brain-like structure.
The technique could also be used to replace mice and rats in drug research as new treatments could be tested on actual brain tissue.
"Now it's not thinking, it's not communicating between the areas in the way our brains do, but it gives us a real start and this is going to be the kind of tool that helps us understand many of the major developmental brain disorders."
The team has already used the breakthrough to investigate a disease called microcephaly. People with the disease develop much smaller brains. By creating a "mini-brain" from skin cells of a patient with this condition, the team were able to study how development changed…… They showed that the cells were too keen to become neurons by specialising too early. It meant the cells in the early brain did not bulk up to a high enough number before specialising, which affected the final size of even the pea-sized "mini-brains".
The team in Vienna do not believe there are any ethical issues at this stage, but Dr Knoblich said he did not want to see much larger brains being developed as that would be "undesirable".