Doctors in Baltimore have transplanted a genetically-modified pig heart into a patient in a last-ditch effort to save his life, in a medical first. Three days later, David Bennett, 57, is said to be recovering and doing well after the nine-hour procedure. Experts say it is too soon to know if the operation really will work, but it marks a step forward in the decades-long quest to one day use animal organs for life-saving transplants. Bennett is breathing on his own without a ventilator, but is still using a Extracorporeal Membrane Oxygenation (ECMO) machine that helps pump blood throughout his...