The human body can heal itself, but only up to a point. If an injury removes 20% or more of a muscle — as can happen in car accidents, certain surgeries or explosions in combat zones — natural processes can’t, on their own, replace it. Instead, the wound seals up, covered by scar tissue. “The body sees this extensive loss of tissue as an insurmountable void,” says Jonathan Grasman, an assistant professor of biomedical engineering.
His lab is developing implants to boost muscles’ regenerative power and provide a more effective option than the surgeries currently used to treat these injuries. The material he and his colleagues are developing mimics the internal scaffolding that organizes muscle, serving as a template for healing.
“I like to describe it as tricking the body into thinking that it has a smaller injury,” Grasman says. After more minor damage, including that caused by a strenuous workout, muscle fiber-forming cells known as myoblasts arrive to heal damaged muscle fibers and produce new ones. But this repair mechanism falls short in more traumatic injuries, such as those involving volumetric muscle loss.
To treat these bigger wounds, doctors remove muscle from elsewhere in the body, typically from within large muscles such as the quadriceps of the thigh, or the back’s broad latissimus dorsi. They then graft this muscle into the wound. This surgery has some significant drawbacks: Grafting creates a second injury with all the accompanying risks, is prone to complications, and, even when successful, leaves patients with reduced control over fine movement. Scar tissue, for example, is composed of aligned collagen fibers that don’t contract like myofibers, thus limiting functionality within muscle. To read the full story.