Corporal Isais Hernandez shows off his healing thigh muscles.

The strange sensation in his right thigh muscle began as a faint pulse. Slowly, surely, it was becoming more pronounced. Some people would have thought it impossible. But Corporal Isaias Hernandez could feel his quadriceps getting stronger. The muscle was growing back.

When he first arrived in the trauma unit of San Antonio’s Brooke Army Medical Center in December 2004, Hernandez’s leg looked to him like something from KFC. “You know, like when you take a bite out of the drumstick down to the bone?” Hernandez recalls. The 19-year-old Marine, deployed in Iraq, had been trying to outfit his convoy truck with a makeshift entertainment system for a long road trip when the bomb exploded. The 12-inch TV he was clutching to his chest shielded his vital organs; his buddy carrying the DVDs wasn’t so lucky. 

The doctors kept telling Hernandez he would be better off with an amputation. He would have more mobility with a prosthetic, less pain. When he refused, they took a piece of muscle from his back and sewed it into the hole in his thigh. He did all he could to make it work. He grunted and sweated his way through the agony of physical therapy with the same red-faced determination that got him through boot camp. He even sneaked out to the stairwell, something they said his body couldn’t handle, and dragged himself up the steps until his leg seized up and he collapsed.


Generally people never recovered from wounds like his. Flying debris had ripped off nearly 70 percent of Hernandez’s right thigh muscle, and he had lost half his leg strength. Remove enough of any muscle and you might as well lose the whole limb, the chances of regeneration are so remote. The body kicks into survival mode, pastes the wound over with scar tissue, and leaves you to limp along for life.

For Hernandez, it had been three years and there was no mistaking it: He had hit a plateau. Lately the talk of amputation had cropped up again. The pain was constant, and he was losing hope. Then his life took another radical turn. He saw a science documentary on the Discovery Channel (no relation to this magazine) that told the story of a war veteran in Cincinnati named Lee Spievack whose fingertip had been severed by the propeller of a model airplane. Spievack’s brother, a surgeon in Boston, had sent him a vial of magic powder—the narrator called it “pixie dust”—and told him to sprinkle it onto the wound. Lee was to cover his hand with a plastic bag and reapply the powder every other day until his supply ran out. After four months, Lee’s fingertip had regenerated itself, nail, bone, and all.

Hernandez recalled that one of his own doctors—Steven Wolf, then chief clinical researcher for the United States Army Institute of Surgical Research in Texas—had once mentioned some kind of experimental treatment that could “fertilize” a wound and help it heal. At the time, Hernandez had dismissed the therapy as too extreme. The muscle transplant sounded safer, easier. Now he changed his mind. He wanted his leg back, even if it meant signing himself up as a guinea pig for the U.S. Army.

So Hernandez tracked down Wolf, and in February 2008 the two got started. First, Wolf put Hernandez through another grueling course of physical therapy to make sure he had indeed pushed any new muscle growth to the limit. Then he cut open Hernandez’s thigh and inserted a paper-thin slice of the same material used to make the pixie dust: part of a pig’s bladder known as the extracellular matrix, or ECM, a fibrous substance that occupies the spaces between cells. Once thought to be a simple cellular shock absorber, ECM is now understood to contain powerful proteins that can reawaken the body’s latent ability to regenerate tissue.

A few months after the surgery healed, Wolf assigned the young soldier another course of punishing physical therapy. Soon something remarkable began to happen. Muscle that most scientists would describe as gone forever began to grow back. Hernandez’s muscle strength increased by 30 percent from what it was before the surgery, and then by 40 percent. It hit 80 percent after six months. Today it is at 103 percent—as strong as his other leg. Hernandez can do things that were impossible before, like ease gently into a chair instead of dropping into it, or kneel down, ride a bike, and climb stairs without collapsing, all without pain.