Scientists are taking the idea of 3D computer printing and catapulting it into the realms of something more suited to science fiction. The idea of printing a human heart, liver or kidney is becoming closer to reality every day. Several teams of researchers around the world are working on the process. And one company, Organovo from San Diego in California has taken on the challenge of using 3D printing technology to create human tissue. They work with one of the world’s first bio-printers. The NovoGen MMX is capable of reproducing human tissue in three dimensions. The idea is ultimately to print entire organs that can be transplanted. The company’s CEO, Keith Murphy, said: “It prints materials from two deposition heads, cells from one side and gel from the other, with plus or minus 20 microns precision. So you print cells and the cells join together in three dimensions to make one piece of tissue.” Thirty or so engineers and biologists work on improving every aspect of the technique. They create what they call ‘bio-ink’ from stem cells that have been grown on fatty tissue or bone marrow. They are further cultured in flasks, because the process needs several million of them to create just one millimetre of tissue. They print the cells and a fixing gel layer by layer to form a shape that is controlled by computer. After that nature takes over and the cells organise themselves into living tissue. In the lab they can print fragments of heart and lung tissue and blood vessels, but creating an entire organ is still some way off. Murphy explained: “If you don’t have the ability to create blood vessels inside the system, you’re limited in how thick those can be. So our real limit right now is making things smaller than a millimetre. Over time, as we can print blood vessel networks into larger structures, then we can think about making larger tissues.” The big advantage of this type of treatment is that the risk of rejection would be eliminated, because the original cells would come from the patient. In the end it is hoped this technology could ease the shortage of donor organs. Michael Renard, the company’s vice-president, said: “It is very hard to know how many years it might take. Obviously there is a lot of research and work that have to be done. Obviously there is equal amounts (sic) of experimentation (and) clinical study, things like this do take time.” Right now it is the pharmaceutical industry which is the biggest consumer, using printed samples to test new drugs and treatments. For the moment, this cutting edge technology is still very futuristic.