A U.S. Marine whose leg muscles were mostly destroyed in a mortar attack in Afghanistan is reportedly able to walk again after treatment that helped his body re-grow the lost tissue.

Cpl. Isaias Hernandez was 19 when he lost 70 percent of the muscles in his right thigh, and doctors initially recommended amputation, according to a report in the Australian. But Hernandez worked with researchers at the McGowan Institute for Regenerative Medicine at the University of Pittsburgh, who were able to seed his remaining muscles with a cocktail of proteins and growth factors derived from pig bladders, the Australian reports.

Stephen F. Badylak and J. Peter Rubin at Pitt are working with funding from the Defense Department to develop an implantable extracellular matrix that can re-grow tissue. The matrix is a biological scaffold, enriched with proteins and growth factors, which recruits stem cells and other cell precursors to the site of the injury, according to the McGowan Institute’s website. The therapy stimulates further tissue regeneration, essentially rebuilding the lost muscle.

Skeletal muscle does not normally regenerate after an accident, so the ability to re-grow this tissue, complete with nerve branches and tendons, would be a real breakthrough.