Brain tissue from stem cells

Functioning brain tissue has been produced from stem cells, in a world first experiment, offering insights into a number of neurodegenerative disorders and, ultimately, the possibility of improved treatments.

Japanese researchers, based at the government funded research institute Riken in Kobe induced human embryonic stem cells (ES cells) to become neural cells with a cocktail of chemicals. When cultured in a specially adapted bioreactor with a rotating wall that supports three-dimensional growth, the cells self-organised into four distinct zones resembling a 7-8 week fetal cerebral cortex - the thin but complex layer of tissue that covers the fore brain. Most excitingly for researchers, the cells conducted electrical signals, a sign of neuroactivity.

'In regenerative therapy, only a limited number of diseases can be cured with simple cell transplants. Transplanting tissues could raise hopes for greater functional recovery', said Yoshiki Sasai, who led the research. 'Cultivated tissues are still insufficient and too small to be used to treat stroke patients. But study of in-vitro cultivation of more mature cortex tissues, such as those with six zones like in the adult human brain, will be stepped up', he added.

The cerebral cortex is vital to memory, attention, perceptual awareness, thought, language, and consciousness and its expansion is seen as playing a major role in separating us from our closest evolutionary ancestors.

The result was initially achieved using human ES cells - the source of much controversy - but has since been repeated on induced pluripotent stem cells (iPS cells) and mouse ES cells. iPS cells are produced from adult somatic cells transformed via the introduction of four genes into their genome into a pluripotent state (the capacity to transform into a number of tissues).

Scientists hope iPS cells they provide a less contentious and more freely accessible source of stem cells, and this study would seem to consolidate the view that they have a similar level of pluripotency to ES cells.