A possible strategy for regrowing muscle lost to injury: "Cpl. Isaias Hernandez was 19 when he lost 70 percent of the muscles in his right thigh, and doctors initially recommended amputation ... 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. ... [Researchers are working 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. ... 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. ... Before injecting the extracellular matrix, doctors had him perform a rigorous exercise regimen to build up his remaining leg muscle ... Then surgeons made an incision in his thigh and inserted the matrix. After a few weeks, Hernandez's leg began growing 'in bulk and strength.'" This is a similar strategy to that used to regenerate a fingertip some years ago - a result that hasn't been replicated to date. This may renew interest in the work in the broader research community.