This is yet another incredible discovery. Researchers at Harvard have created Human heart tissue in which the cells are able to beat on their own.

http://3dprint.com/1676/3d-printing-...g-heart-cells/

They used a new type of hydrogel called MeTrogel which allows for a more elastic consistency to the tissue. This incredible progress in the field of medicine is all with the help of 3D printing. They used a 3d printer to etch the gel so that the cells were lined up perfectly, allowing the tissue to form currectly.