Researchers at the University of Pennsylvaniahave developed a technique to print living tissue using a 3D printer.
The problem with constructing living tissue in three dimensions is a simple one: as you build out the tissue, how will oxygen and other nutrients reach the cells in the center of the mass? In nature, the body uses vascular tissue as highways to supply these nutrients. In 3D printing, that's not an option.
Using a RepRap printer modified to print sugar, the researchers found a way over the hurdle. First, they printed a three-dimensional sugar lattice. Then, they encased the lattice in a gel embedded with living cells. By dissolving the sugar, the researchers created hollow capillaries in the gel -- pathways through which those nutrients can flow.