Catalan scientists from the Bellvitge Biomedical Research Institute (IDIBELL) have, for the first time, created a piece of heart tissue that can grow, mature, and survive long-term inside an animal. Until now, these types of experiments failed because these tissues are very complex, and if they don't receive enough blood and nutrients, they don't mature properly and eventually die. Now these researchers have achieved this goal using a 3D bioprinter: they have created small blood vessels with this tool, allowing the tissue to integrate perfectly into the circulatory system and survive for a month after implantation. Until now, the life expectancy of these tissues was no more than two weeks, so the researchers believe that using this technique, heart patches could be manufactured to replace affected parts of a patient's organ and help the patient regain its functionality.