PULLMAN, Wash., July 28 (UPI) -- The breakdown of muscle often accompanies chronic or long-term disease, making disease worse and sometimes hastening death, and doctors have no way to stop or slow it.
Researchers at Washington State University devised a method of delivering gene therapy to stop muscle wasting without affecting other functions of the body, according to a newly published study, which may help improve the results of other disease treatment.
Muscle wasting is the atrophy of muscles when movement is limited or lacking, and often accompanies diseases from muscular dystrophy and cancer to malnutrition and old age.
Conditions like cachexia, associated with cancer, is induced by a lack of nutrients and movement. Researchers in the new study say that while cancer kills people, many patients die because their muscles have shrunk beyond functional use, such as when heart muscle has wasted and can no longer function properly.
Previous attempts at treating muscle wasting have proven to be unsafe, the researchers say, because the hormones causing the condition, specifically one called myostatin, is important to other bodily functions. They found that targeting genetic fixes at muscles, though, stops their breakdown while not affecting the rest of the body.
"Others have tried and failed to develop treatments for muscle wasting," Dan Rodgers, a researcher at Washington State University and director of the Washington Center for Muscle Biology, said in a press release. "Some drugs have even caused serious safety problems. Our targeted approach only affects muscle and completely avoids these problems, which is why we think we have a solution."
For the study, published in the journal Science Translational Medicine, the researchers loaded an adeno-associated virus targeted at heart and skeletal muscle with the DNA signaling protein Smad7, with the hope of blocking the signaling proteins Smad2 and Smad3, both of which are activated by muscle-wasting hormones.
In a group of mice with tumors, the treatment effectively prevented the wasting of skeletal muscles and the heart regardless of how many tumors they had. In healthy mice, the treatment built muscle.
Researchers at Washington State University have started a company to develop their research into usable treatments, which will have to be tested for safety and efficacy in humans.
Rodgers said, however, that the potential to improve muscle condition in cancer patients may give them 10 or 15 years to fight the disease, rather than one, and potentially see more people cured because their bodies are fighting fewer battles.
"Chronic disease affects more than half of the world's population," Rodgers said. "Most of those diseases are accompanied by muscle wasting. It occurs with chronic infection, muscular dystrophy, malnutrition and old age. About half the people who die from cancer are actually dying from muscle wasting and there's not one single therapy out there that addresses it."