Researchers at the University of Pennsylvania and MIT have developed a new technique for creating blood vessel networks using a 3D printer and some sugar. The two are used to build a template for the vessel network — first scientists design the network, before feeding the design into a RepRap 3D printer, which then builds it using sugar. Once the sugar gets suitably hard it's coated with a gel containing liver cells. Then, after the gel sets, the sugar is flushed out through the vessels, leaving behind a functional vascular network.

"This new technology, from the cell's perspective, makes tissue formation a gentle and quick journey," says researcher Christopher Chen. The team managed to pump both "nutrient-rich media" and blood through the printed vessels, and the networks could eventually be used to keep engineered living tissues alive. You won't be seeing them used in human patients anytime soon, though — the team's goal is to create organs that can be implanted in animals for study.