The article is at http://www.smithsonianmag.com/science-nature/What-Lies-Ahead-for-3-D-Printing-204136931.

Carlos Kengla, a slim young man wearing statement eyeglasses and a four-inch-long soul patch, could easily pass for a hipster Maker of small-batch bourbon or bespoke bicycles. But Kengla has spent the last few years focusing on the production of ears, which he prints using cells that are taken from human ear cartilage and then propagated in the lab. Kengla’s fellow scientists at the Wake Forest Baptist Medical Center’s Institute for Regenerative Medicine are developing, in collaboration with other labs, processes to systematically print muscle tissue, skin, kidneys, cartilage and bones. For years, researchers have been building organs by hand, pipetting progenitor cells—which have the capacity to differentiate into specific types of cells—onto degradable scaffolds. They’ve had varying levels of success: Handmade bladders have been functioning in a handful of patients for many years; a miniature kidney implanted in a cow successfully excreted urine. But constructing organs by hand is laborious and plagued by human error. Rapid prototyping, with cartridges of cells squirting from a print head and guided by a computer, Kengla says, “is faster and more precise, to the micron. It allows us to place different types of cells in specific shapes and in intricate patterns.”