For many years people expected the future of medical technology would probably have something to do with cloning. Growing new organs from cells harvested from the patient would make rejection unlikely, and whole stockpiles of human parts could be created to save lives. Now it seems more likely that AM will provide the organs that social mores and certain types of paranoia combined to keep cloning on the sidelines.
A number of institutes around the world are experimenting with bioprinting. The process uses inkjet based 3D printers and an “ink” made of human cells (as with cloning, using the patient’s own cells are the best bet) mixed with a dissolvable gel, often cellulose. From there, the process is similar to other AM techniques. The printer puts down a layer, which is then cured with heat, chemicals or UV light, before moving on to the next layer. Finally, the printed part is placed in a bioreactor, where it is subjected to the processes it is meant to facilitate (blood is pumped through heart valves, liquid through a liver, etc.).