Stem cells are a great new hope for medicine.
The variety known as embryonic stem cells have the potential to become any kind of cell in the body. But researchers have had trouble controlling them. These cells can develop into any cell, but the problem is trying to direct how they develop. If this could be done, experts agree they could be used as tissue transplants, for basic research and perhaps even to grow entire organs for transplant. They hope their findings could eventually lead to a way to manipulate human stem cells for use in treating Parkinson's and other brain diseases.