"Forget 3-D printable moonbases or even the Million Dollar Bionic Man: British scientists have achieved something amazing: For the first time they've proved a 3-D printing technique that uses human embryonic stem cells to create complex, living structures. The printer used a "micro valve" head which allowed it to squirt out a tiny amount of human stem cell matter in a pre-programmed pattern. The stem cells remained alive and--critically--their ability to be modified into any other human body cell was intact (the reason stem cells hold such promise).
The new breakthrough is said to prove the eventual viability of crafting complex 3-D organ structures through a 3-D printing process where stem cells are then modified into cells compatible with, for example, human hearts. For now the researchers are championing the success as a way to speed up drug testing without needing risky in-vivo experiments with volunteers."