Scientists grow 'pure' nerve stem cells

A team of Italian and Scottish researchers has managed to grow pure batches of human nerve stem cells in the laboratory, using embryonic stem cells (ES cells). Previous nerve stem cell lines grown in this way are actually a mixture of ES cells and nerve stem cells, which limits their usefulness. The scientists, based at the Universities of Edinburgh and Milan, say the new cells will enable them to work out how ES cells differ from nerve stem cells. The cell-lines will also be invaluable for testing out new drugs for diseases that affect the brain, such as Alzheimer's and Parkinson's disease.

ES cells are the body's 'master cells', capable of growing into any type of body tissue. Other types of stem cell have a more specialised role, and can renew themselves and produce a limited range of different cell types. Nerve stem cells can produce both neurons - brain cells that communicate with each other using electrical signals - and other sorts of brain cells that support and nourish neurons.

Many scientists hope that research on ES cells will lead to new cell-based treatments for a range of diseases. However, such therapies will require the development of 'pure' cell-lines that can renew themselves and which remain capable of growing into specialised cell types. Previous attempts to grow nerve stem cells using ES cells have resulted in cell-lines that are a mixture of ES cells, nerve stem cells, neurons and supporting brain cells. In the latest study, published in the open-access journal PLoS Biology, the researchers obtained pure nerve stem cell lines from both mouse and human ES cells.

The scientists first grew nerve stem cells from mouse ES cells, in the presence of two key proteins - epidermal growth factor (EGF) and fibroblast growth factor (FGF). They then successfully repeated the process with human nerve stem cells. In both cases, they obtained pure nerve stem cell-lines, free from ES cells.

In the short term, the researchers want to use the cells to study the 'basic biology' of stem cells. 'It's a good opportunity to understand what the difference is between an embryonic stem cell, which can make anything, and a brain stem cell, which can just make brain', said team member Steve Pollard. Stem Cell Science, the company that has an exclusive license to commercialise the research, has already been approached by several pharmaceutical firms interested in using the cells to test and develop new drugs.

Eventually, nerve stem cell transplants could be used to replace damaged parts of the brain, but this is a long way off. Team leader Austin Smith says that although the cells would survive if put into the brain 'whether they can do anything useful is a much more complicated question'.