ROCHESTER, Minn. — A new discovery by Mayo Clinic researchers could mean more donor hearts are available for heart transplant, giving more people a second chance at life. In findings published in Nature Cardiovascular Research, a team led by Mayo Clinic cardiac surgeon Paul Tang, M.D., Ph.D., identified a biological process that contributes to donor heart injury during cold storage. The researchers found that a drug already used to treat heart conditions can prevent this…