WASHINGTON, May 11 (UPI) -- Scientists have restored the ability to walk in paralyzed rats using a treatment derived from human embryonic stem cells, the first direct demonstration the controversial cells can regenerate tissues damaged by spinal cord injuries.
"We're very excited with these results," Hans Keirstead, lead author of the study, said in a statement. Keirstead is an assistant professor of anatomy and neurobiology at the University of California at Irvine's Reeve-Irvine Research Center.
The findings "underscore the great potential that stem cells have for treating human disease and injury (and) suggests one approach to treating people who've just suffered spinal cord injury, although there is still much work to do before we can engage in human clinical tests," Keirstead added.
Other researchers in this field were impressed by the results.
"This is an impressive study," Dr. Robert Lanza told UPI. He is vice president of medical and scientific development at Advanced Cell Technology in Worcester, Mass., a company focusing on turning embryonic stem cells into disease treatments.
"It's an exciting first step toward treating spinal cord injuries with human embryonic stem cells," Lanza said. He added human clinical trials probably are "not far down the pike and could happen as soon as next year."
Although the consensus among scientists is that embryonic stem cells have the potential to regenerate damaged tissues and treat disease in people, the research is controversial and opposed by some because it requires the destruction of a human embryo.
In 2001, the Bush administration sought a compromise and limited federal funding to 78 lines of stem cells already in existence, a move that scientists and patient advocacy groups have criticized for stifling progress in this field.
Despite the limitations, the research has forged ahead in other countries and even in the United States. Some U.S. states have endorsed it, with the most notable being California, which passed legislation that provides $3 billion in funding over the next 10 years.
Lanza said the stem cell field has had a resurgence of attention and funding in recent months.
"I think you're going to see more and more studies like this, more applications from stem cell research now that money for this research is starting to flow," he said.
In addition to funding from the states, private investors have also started pumping more money into it.
"Our own company is a good example," Lanza said, and noted they have been able to hire five new stem cell scientists with the additional capital recently poured into the company.
In the study, which appears in the May 11 issue of the Journal of Neuroscience, Keirstead and colleagues enticed embryonic stem cells to develop into specialized cells called oligodendrocytes. These cells help form myelin, which wraps around nerve cells, providing insulation. Myelin is critical for proper function of the central nervous system and when it is damaged, paralysis can be the result.
The researchers injected the oligodendrocytes into rats that had their spinal cords injured and were unable to walk properly.
In rats that had been injured seven days earlier, the cells formed into functioning oligodendrocytes that gave rise to myelin around the damaged cells of the spinal cord. By two months, the rats showed significant improvements in walking ability compared to rats who received no stem cell treatment.
However, the treatment was less successful in mice that had been injured 10 months before treatment. Although oligodendrocytes formed in the right location of the spinal cord, they were unable to generate myelin.
Keirstead's team thinks this could be due to scar tissue that may have built up in that area or other factors that may inhibit the formation of myelin. Either way, it suggests stem cell-derived treatments will have to be initiated early after a spinal cord injury if they are to restore function.
