Scientists in the US have succeeded in producing nerve cells by using stem cells taken from bone marrow: a breakthrough that could help people with Alzheimer's or Parkinson's disease, or spinal cord injuries.
If the findings are borne out, this could in time enable doctors to take cells from a patient's bone marrow, turn them into nerve cells, and then inject them into the patient's brain and spinal cord, replacing injured cells.
The research, conducted at the University of Medicine and Dentistry of New Jersey and the MCP Hahnemann University in Philadelphia, was funded in part by the Christopher Reeve Paralysis Foundation, which was set up after the Hollywood actor who played Superman was paralysed in a horse-riding accident.
Stem cells are stored in various organs and grow naturally into the specific types of cells needed by those organs. Stem cells from foetal tissue can grow into any type of cell; the latest study suggests the same may be true for adult stem cells.
Dr Ira Black of the University of Medicine and Dentistry of New Jersey reported that the stem cells, treated with growth factors and antioxidants in tissue culture experiments, quickly divided into another stem cell and a nerve cell.
By altering the chemical signals he used to stimulate the conversion, Dr Black and colleagues were able to turn 80 per cent of the bone-marrow cells taken from rats and humans into nerve cells. He said he transplanted rat nerve cells to the brains and spinal cords of rats and found that they formed connections with other neurons and survived.
Stem cells could be drawn from the patient being treated, eliminating the problem of adding tissue the immune system might attack, said Dr Darwin Prockop, of Tulane University's medical school, who co-wrote the research.
It could be years before the technique is tested in humans, however, since studies and tests in animals will be required first. Nonetheless, other researchers were impressed by the possibilities.
"Clearly, it is important to generate neurons from other tissues," said a neuroscientist, Dr Ronald McKay, of the National Institutes of Health. "We have to demonstrate that these cells will perform specific functions" in the brain and spinal cord, and not behave like stem cells only in the lab, he added.
"It's really beautiful," said Dr William Greenough, a neuroscientist at the University of Illinois. "I see this as a truly significant step along the way toward developing new technologies for the repair of the damaged brain."