Such a futuristic dream remains far from reality, but university labs and private companies have already taken the first careful steps by using 3D-printing technology to build tiny chunks of organs.

Regenerative medicine has already implanted lab-grown skin, tracheas and bladders into patients body parts grown slowly through a combination of artificial scaffolds and living human cells. By comparison, 3D-printing technology offers both greater speed and computer-guided precision in printing living cells layer by layer to make replacement skin, body parts and perhaps eventually organs such as hearts, livers and kidneys.

"Bioprinting organs for human uses won't happen anytime soon," said Tony Atala, director of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, N.C. "But for tissues we've already implanted in patients structures we've made by hand we're now going back to those tissues and saying 'We know we can do better with 3D printing.'" [7 Cool Uses of 3D Printing in Medicine]