Sitting in a culture dish, a layer of chicken heart cells beats in synchrony. But this muscle layer was not sliced from an intact heart, nor even grown laboriously in the lab. Instead, it was "printed", using a technology that could be the future of tissue engineering.

The "bioprinting" technique developed by Gabor Forgacs, a biophysicist at the University of Missouri in Columbia, relies on droplets of "bioink", clumps of cells a few hundred micrometers in diameter, which Forgacs has found behave just like a liquid, says an article in New Scientist:

Droplets placed next to one another will flow together and FUSE, forming layers, rings or other shapes, depending on how they were deposited. To print 3D structures, Forgacs and his colleagues alternate layers of supporting gel, dubbed "biopaper", with the bioink droplets. To build tubes that could serve as blood vessels, for instance, they lay down successive rings containing muscle and endothelial cells, which line our arteries and veins. "We can print any desired structure, in principle," Forgacs told the meeting.

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.

"When layers of chicken heart cells were printed they quickly begin behaving as they would in a real organ."

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. (photo University of Utah)