Myostatin inhibitors may improve recovery of wartime lim...( Inhibiting a growth factor that keep...),Health

Inhibiting a growth factor that keeps muscles from getting too big may optimize recovery of injured soldiers, researchers say.

They are studying two myostatin inhibitors in mice with limb injuries, first to see which works best and then to identify the best delivery mechanism, says Dr. Mark Hamrick, bone biologist in the Medical College of Georgia Schools of Graduate Studies and Medicine.

"Fifty to 60 percent of the injuries occurring in Iraq are to the limbs, and the average injury requires five surgeries," Dr. Hamrick says. "Myostatin inhibitors are known to improve muscle regeneration and we have evidence that they also increase bone formation. We believe these inhibitors will result in a stronger, more rapid recovery for these soldiers and other victims of traumatic limb injuries."

A $1.2 million grant from the Office of Naval Research to Dr. Hamrick is enabling laboratory studies of two experimental myostatin inhibitors: a decoy receptor and a binding protein, both developed by MetaMorphix, Inc. of Beltsville, Md. Both inhibitors have been shown effective in muscle regeneration, but this is the first trial that looks at their impact on bone.

Two delivery mechanisms also will be studied. "Is the best approach a single injection bolus that circulates everywhere or just localized delivery?" Dr. Hamrick says.

Study collaborators include Dr. Li Liang of the life sciences company MetaMorphix, who will oversee development of the inhibitors; Dr. Xuejun Wen, bioengineer at Clemson University in Clemson, S.C.; and David Immel, radiographic imaging expert at Savannah River National Laboratory in Aiken, S.C., who will provide three-dimensional, high-resolution computerized tomography scans of injured limbs before and after treatment.

Myostatin is primarily produced by muscle cells. Females tend to produce more myostatin receptors, which helps explain why men tend to have greater muscle mass. Dr. Hamrick's
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