First trial of embryonic stem cells in humans
US doctors have begun the first official trial using human embryonic stem cells in patients after getting the green light from regulators.
The Food and Drug Administration has given a license to Geron to use the controversial cells to treat people with spinal injuries.
The cells have the potential to become many of the different cell types found in the body, including nerve cells.
The trials at a hospital in Atlanta will check if the treatment is safe.
Fergus Walsh reports.