Scientists have grown miniature human brains from skin cells in a laboratory for the first time as part of a study into the development of the most complex of all our organs, and the ultimate source of human creativity and consciousness.
The mini-brains are less than 4mm across but researchers say that they are equivalent in development to the brain of a human foetus at about nine weeks’ gestation, and even have the complex three-dimensional structure of a real embryonic brain.
Previous attempts at growing brain tissue in a laboratory dish have focused on culturing the nerve cells in two dimensions on a flat plate of nutrients, but the latest study used a droplet of nutrient gel as a three-dimensional scaffold on which the growing brain cells organised themselves into the miniature organ.
The scientists have called the primitive brains “cerebral organoids” and have emphasised that the living structures are still far from being described as true human brains with a potential for self-awareness or consciousness – a threshold of development that would be ethically wrong to cross, they said.
Dr Knoblich said that the organoids have already shed light on a condition called microcephaly, when the brain fails to grow to its correct size in the womb, and also could eventually help research into conditions such as autism and schizophrenia, which both involve unknown malfunctions in early brain development.
“There have been numerous attempts recently to model human brain tissue from human cells. [Scientists] have gone on to generate an eye, a pituitary gland and even a human liver, but so far the most complex of all human organs, which is the brain, has not been susceptible to these kinds of cultures,” Dr Knoblich said.
“[This technique] allows us to study the human-specific features of brain development. We can analyse the function of individual genes in a human setting. We have been able to model one disease, microcephaly, but ultimately we’d like to move to more common disorders such as schizophrenia or autism,” he said.
“So far drug testing has been done on animal models and isolated human cells. These organ-culture models offer the possibility of testing drugs directly without animal experiments to get more informed results,” he added.