For several years, scientists have used a person’s own stem cells to slowly grow replacement organs in an artificial environment (Live Science, September 24, 2013). Simple organs like skin, tracheas and bladders, with a person’s own DNA, have been grown and transplanted into patients—with no rejection effects! Regenerative medicine is now developing 3D printers to rapidly make new organs. The goal is to make complex organs like hearts, livers, and kidneys (ibid.).