While promoting muscle growth and strength has long been a primary goal of body-builders and other athletes, many people have degenerative muscle disorders that make it impossible to gain strength; in fact they gradually lose both mass and strength over time.
Now researchers have come a step closer to safe and effective stimulation of muscle growth and strength. In a study published in the November issue Science Translational Medicine, scientists at the Nationwide Children's Hospital in Ohio were able to enhance muscle growth and strength in the quadriceps of cynomolgus macaques by means of an injection of a spliced human follistatin, a glycoprotein found ubiquitously in the body of almost all higher animals. Follistatin has been found to be safe and effective in mice but until now tests in primates had yet to be conducted. Follistatin inhibits the growth of myostatin, a beta protein that inhibits the differentiation and growth of muscles. Animals that lack myostatin tend to have much larger muscles than those that do not lack the protein.
After the macaques had been injected with follistatin, the scientists observed significant and long lasting increases in the size and strength of the quadriceps muscles. At the same time, there were no abnormal changes in the shape or function of internal organs, which indicated that gene therapy by means of an intramuscular injection was a safe and effective method for stimulating muscular growth.
"Our studies indicate that this relatively non-invasive approach could have long-term effects, involve few risks and could potentially be effective in various types of degenerative muscle disorders including multiple forms of muscular dystrophy," said the study's corresponding author, Brian Kaspar, PhD, principal investigator in the Center for Gene Therapy of The Research Institute at Nationwide Children's Hospital.
As of yet, no human clinical trials of this gene therapy have been conducted, but the research team is conducting formal studies for backing the initiation of human clinical trials.
This low-risk and relatively non-invasive procedure could see applications in treating many types of muscular dystrophy, muscular atrophy due to disease or inactivity, such as when a limb is placed in a cast to repair broken bones, and muscle loss due to injury or surgery.