A breakthrough in stem cells could lead to a treatment for muscular dystrophy, a study has found.
An Italian-French team found that transplanting stem cells into dogs with a version of the disease significantly improved their symptoms. Writing in Nature, the team says the research paves the way for future human trials. Scientists said it was an important step forward that strengthened the idea that stem cells could be used to treat muscular dystrophy.
Muscular dystrophy is a group of genetic diseases that causes the muscles of the body to gradually weaken over time and to lose the ability to move. It shortens life expectancy and currently has no cure. The researchers, led by a team at the San Raffaele Scientific Institute in Milan, Italy, looked at the most common form of the disease, Duchenne muscular dystrophy.
The incidence of this disease, which only affects boys, is about one in every 3,500 male births and it is caused by mutations in a certain gene that cause a lack of dystrophin, a protein involved in maintaining muscle integrity. The team members had previously gotten promising results when they injected stem cells into mice with a version of the disease, but switched to dogs for their next experiment because they copy the muscular dystrophy more accurately.
The ability to move back
The researchers used a form of stem cells collected from blood vessels, called mesoangioblasts, which are "programmed" to become muscle cells. They isolated the stem cells from both healthy dogs and dogs with muscular dystrophy, with the diseased dogs' stem cells then modified to "fix" the mutated gene.
The scientists then injected these different types of stem cells into dogs with muscular dystrophy. They found that transferring the stem cells five times at one-month intervals produced the best results. Overall, injection of stem cells taken from healthy dogs showed the most improvement.
In four of the six dogs that received these stem cells, dystrophin returned and with it muscle strength. In one dog that was injected in the early stage of the disease, the ability to walk returned and in two dogs that were injected in the late stage of the disease, the ability to move returned. Of the two remaining dogs, one died early and the other, the scientists think, did not receive enough cells.
The experiment of injecting dogs with muscular dystrophy with their own "repaired" stem cells was less successful, although the dystrophin protein returned. This approach was studied because if the stem cell treatment were to be transferred to humans, it would mean that it would be possible to inject patients with their own cells, thereby reducing the chances of rejection and preventing the need for taking drugs that suppress the immune response.
The researchers wrote: "The work reported here establishes the logical premise for starting clinical trials that may lead to an effective treatment for Duchenne muscular dystrophy."
'Great job'
Dr. Marita Pohlschmidt, research director at the Muscular Dystrophy Campaign, UK, said: "We are encouraged by the study because the results provide preliminary evidence that we may be one step closer to treating Duchenne muscular dystrophy using stem cells." Dr. Steven Minger, a stem cell researcher at King's College London, said: "This is excellent work that shows a significant functional improvement in a disease that occurs naturally in dogs and is very similar to the disease in humans.
"Although it will probably be some time before this work can be transferred to humans, this is nevertheless important research in the development of treatments for muscular dystrophy."
Professor Dominic Wells, from the Gene Focus Group at Imperial College London, said: "This is another example of the vital contribution of animal research to the development of treatments for human diseases. "This is the first study that convinced me that stem cell therapy can play a role in the treatment of dosha muscular dystrophy."
Kay Davies of the Medical Research Council's Functional Genetics Unit, University of Oxford, said: "The use of stem cells to treat human disease holds great promise, but the view is that such treatment will only be available in practice for many years." The data, she said, changed that opinion. However, she added that the researchers need to find out why not all dogs reacted positively.
