The Integrated Tissue and Organ Printing (ITOP) System can 3D print living tissues and organs that may be used for medical transplants. So far, it has printed ear, bone, and muscle structures, which in preclinical trials matured into living tissue and developed a system of blood vessels and nerves. The ultimate goal for the printer is to create tissue that can be safely implanted in humans. The ITOP System was developed over a 10-year period by scientists at the Institute for Regenerative Medicine. For the research reported in Nature Biotechnology, three printing nozzles were used to deposit: 1. bio-degradable, plastic-like materials to form the tissue “shape” 2. a water-based gel that contains the cells 3. a temporary outer structure to help maintain the tissue shape during printing