Other tissue engineers have tried printing 3D structures, using modified ink-jet printers which spray cells suspended in liquid. Now Forgacs and a company called Sciperio have developed a device with printing heads that extrude clumps of cells mechanically so that they emerge one by one from a micropipette. This results in a higher density of cells in the final printed structure, meaning that an authentic tissue structure can be created faster.

Cells seem to survive the printing process well. When layers of chicken heart cells were printed they quickly begin behaving as they would in a real organ. "After 19 hours or so, the whole structure starts to beat in a synchronous manner," says Forgacs.

Most tissue engineers trying to build 3D structures start with a scaffold of the desired shape, which they seed with cells and grow for weeks in the lab. This is how Anthony Atala of Wake Forest University and his colleagues grew the bladders which he successfully implanted into seven people. But if tissue engineering goes mainstream, faster and cheaper methods will be a boon. "Bioprinting is the way to go," says Vladimir Mironov, a tissue engineer at the Medical University of South Carolina in Charleston.

So much cooler than the CakeJet.