Researchers here have moved on past myostatin and further down the chain of signals and molecular mechanisms to find a novel place to intervene in order to boost muscle growth in mice and humans. So far results are promising: if this treatment turns out to produce few to no side-effects, it is the sort of thing that everyone could benefit from. That said, again, it doesn’t address root causes of degenerative muscle loss with aging – something that needs to be accomplished in order to reliably and most effectively extend healthy life.
The new compound (BYM338) acts to prevent muscle wasting by blocking a receptor that engages a cellular signaling system that exists to put the brakes on muscle development when appropriate. But sometimes those brakes are activated inappropriately, or are stuck on.
A variety of signals can activate the receptor. Prior to development of BYM338, compounds developed to block these molecules were blunt instruments, either trapping all incoming signals (which stimulated muscle growth but also caused harmful side effects) or blocking just a single receptor activator (providing only tepid growth stimulation.) BYM338 was designed to be in the Goldilocks zone (just right.)
In the study the compound boosted muscle mass 25 to 50 percent and increased strength in animal models. Those gains were significantly superior to those of compounds that blocked a single receptor activator. Clinical trials are currently underway.
BYM338 dramatically increases skeletal muscle mass in mice, beyond sole inhibition of myostatin as detected by comparing the antibody with a myostatin inhibitor. A mouse version of the antibody induces enhanced muscle hypertrophy in myostatin-mutant mice, further confirming a beneficial effect on muscle growth through blockade of ActRII ligands beyond myostatin inhibition alone.