The technology is the same as that of the simple inkjet printer found in homes and offices, but Japanese scientist Makoto Nakamura is on a mission to see if it can also produce human organs.

The idea is for the printer to jet out thousands of cells per second, rather than ink droplets, and to build them up into a three-dimensional organ.

"It would be like building a huge skyscraper on a micro level using different kinds of cells and other materials instead of steel beams, concrete and glass," he said.

"Ultimately I hope to make a heart," said Dr Nakamura, professor at the graduate school of science and technology for research at the state-run University of Toyama.

While Dr Nakamura says it would take him some 20 years to develop a heart, the feat could pave the way to mass produce "good hearts" for patients waiting for transplants.

A heart made of cells originating from the patient could eliminate fears that the body would reject it.

In the emerging field of organ printing, Dr Nakamura bills his work as the world's finest printed 3D structure with living cells.

The technology works a bit like dealing with sliced fruit: an organ is cut horizontally, allowing researchers to see an array of cells on the surface.

If a printer drops cells one by one into the right spots and repeats the process for many layers, it creates a 3D organ.

Much like a printer chooses different colours, the machine can position different types of cells to drop.

Dr Nakamura has succeeded in building a tube with living cells.

It measures one millimetre in diameter and has double walls with two different kinds of cells, similar to the three-layer structure in human blood vessels.

He has also made a smaller single-wall hydrogel tube that measures one-tenth of a millimetre, as narrow as human hair.

The tubes are made by a 3D inkjet bioprinter that Dr Nakamura's team developed in a three-year project completed earlier this year at Kanagawa Academy of Science and Technology, a foundation based south-west of Tokyo.

The printer can adjust where to drop cells in the order of one-thousandth of a millimetre and produce a tube at a speed of 3 centimetres per two minutes.

- AFP