Think your printer produces lifelike images? Gabor Forgacs created one that prints the stuff of life--specifically "bio ink," a liquid made up of cells. The cells cluster together and grow, and as he adds layers of bio ink, a 3-D structure takes shape. Last year, Forgacs, 61, printed the first branching vascular tissue and successfully implanted a nerve graft into an animal. For now, he can do only simple tissues, such as blood vessels, but these advances are the first step to printing and growing replacement skin, muscle, and eventually organs. "Within 5 or 10 years, there will be a spectacular breakthrough," Forgacs says. "Don't push me to be more specific." Forgacs will most likely be involved. Organovo, a company he cofounded, just began making "bio printers."