The technology behind printing documents is being used to create 3D living tissue.

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Artificial tissue? Press print...
Thursday, 23 January, 2003, 11:07 GMT

The technology behind printing documents is being used to create 3D living tissue.

The technique could eventually be used to create "mini" organs, which could be used to test drugs. Scientists even hope it could one day be used to create whole organs.

The technique uses conventional printing technology.

When a document is printed, ink is distributed in a specific pattern on the paper.

To create three dimensional tissue structures, US researchers modified printers to use a cell solution instead of ink.

They then repeatedly "printed" layers, creating a 3D structure.

Experts in the UK said the use of cells instead of a polymer was a significant step forward.

However, the use of the technology in medical treatment is still a long way off, they warned.

Fusion

In the technique, developed by South Carolina`s Medical University and Clemson University, conventional ink cartridges were washed out and refilled with cell solutions.

Then the software that controls how the fluids being discharged from the cartridges behave, including properties such as resistance and temperature, was reprogrammed.

To create the 3D structures, a non-toxic biodegradable gel designed by University of Washington scientists was used as the "paper".

The gel is liquid below 20°C and solidifies above 32°C.

Researchers printed alternative layers of the gel, and hamster ovary cells, building up 3D structures.

If thin layers of tissue are placed close enough they will fuse together.

In this research, scientists found that as long as the layers were thin enough for the clumps to come into contact with each other, the bits of tissue would fuse.

The gel can then be easily removed, leaving the 3D structure.

The research team, led by Dr Vladimir Mironov, from the Medical University of South Carolina, said the printing technique enabled tissue to be created faster than the existing technique where a "scaffold" is made, and cells seeded onto it.

He told BBC News Online: "The problem with that is you can never create an organ with a blood supply.

"We can print tissue which is five centimetres thick in two hours, and we can print a blood vessel system simultaneously.

"A kidney is five centimetres thick."

He said: "The next stage is to print a very small element of an organ, called a structural functional unit.

"It would contain all the necessary elements which reflect the function of the organ."

Dr Mironov added: "These could be used as drug-testing systems, or to test what treatment is best for a patient.

"For example, a biopsy from a tumour could be taken and drugs tested to see which is most suitable for the patient."

Whole organs

Anthony Atala, a leading tissue engineer at Harvard University, said: "This is extremely exciting technology that has the potential to overcome some of the major obstacles we have seen in the past."

He said growing whole organs was the ultimate aim.

"It`s been the holy grail of tissue engineering, to be able to create adequate circulatory networks for complex organs."

Professor Tim Hardingham, director of the UK Centre for Tissue Engineering told BBC News Online said: "The printing technology has a lot of promise.

"But there`s as much work to know how we can actually apply it."

Zentek International