Scientists have used injections of human stem cells to heal spinal injuries in paralyzed mice, allowing them to walk normally again.
The research, which was funded by the Christopher Reeve Paralysis Foundation, suggests that stem cells could be used to repair spinal damage in people who have suffered damaging accidents or disease, although further studies, including safety tests, are needed before the treatment can go into human trials.
Neuroscientist Aileen Anderson and her team at the Reeve-Irvine Research Center at the University of California, Irvine, used stem cells taken from the neural tissue of aborted fetuses. When injected into the body, they can develop into any type of nervous tissue.
The researchers simulated common spinal cord injuries in mice by bruising their backbones at a specific point.
"Immediately after the injury, nerve cells inside die and others lose their ability to pass on signals," said Anderson, whose work appears in the Proceedings of the National Academy of Sciences today.
In tests, half of the 68 mice used were injected with around 75,000 stem cells above and below the injury site. The animals' behavior was then assessed over the next few months.
"Animals that didn't get stem cells could only walk a little, and even though they improved slightly over the first two to three weeks, they were really struggling," Anderson said. "The mice that got stem cells go from stepping just occasionally to stepping all the time."
Tests showed that the stem cells had formed new neurons and coatings that allow the nerves to send signals properly.