Blood hope.

AN assortment of six different types of white blood cell has been created in the laboratory by scientists.

The cells, produced from embryonic stem cells, could be valuable tools for studying cancer and other diseases. One day they may also provide life-saving treatments for patients with blood cancers and damaged immune systems. The most immediate use of the cells is likely to be safety screening of new drugs. "Toxicity to the blood-forming system is a key limit on drug development, so these cells could be used for safety testing in any drug development," said research leader Dr Igor Slukvin from the University of Wisconsin-Madison in the US. Stem cells are immature cells with the ability to develop into different kinds of tissue. Those extracted from early stage embryos have the potential to become virtually any kind of cell in the body. The technique used to create the blood cells works equally well with true embryonic stem cells and adult cells re-programmed into an embryonic state.

Dr Slukvin and his team got the cells to develop along particular pathways by exposing them to specific biological signalling molecules.

Among the cells they produced were osteoclasts, large white cells involved in the brittle bone disease osteoporosis, and eosinophils, which play a role in allergy and asthma.