Blocking Myostatin Didn’t Damage Hearts of Mice

Mice lacking myostatin don’t develop enlarged hearts, an abnormality that some researchers had feared might occur, reports a group that included MDA grantee Kathryn Wagner at Johns Hopkins University in Baltimore. Blocking myostatin, which may cause skeletal muscle fibers to enlarge, is a strategy currently being pursued for the treatment of muscular dystrophies. Wyeth Pharmaceuticals is testing MYO-029, a myostatin blocker, in three MDs.

On the other hand, in mice missing both myostatin and dystrophin, with a disease resembling Duchenne muscular dystrophy (DMD), a lack of myostatin didn’t prevent the development of scar tissue in the heart, which some researchers had hoped it might.

The researchers, who reported their findings online March 1 in Neuromuscular Disorders, say their data “do not support a cardiac effect in the complete absence of myostatin and therefore would not predict a significant impairment nor improvement in the cardiac function of patients treated with myostatin inhibitors such as are now in clinical trials.”

They add, however, that extending these mouse findings to human patients must be done with extreme caution, because humans treated with myostatin inhibitors will have had myostatin during their development; and because mouse DMD and human DMD are somewhat different.