Here is a popular science article on the topic of bioprinting complex tissues, which at this stage is largely used to provide small living tissue structures for research and development. These represent a great improvement in cost and efficiency when compared with the other options of cell culture and animal studies. Nonetheless, this is but a stepping stone on the path to the greater goal of tissue engineered organs assembled to order via 3-D printing technologies:
Just like you would hope, something very cool was revealed at the 2015 Experimental Biology conference in Boston: the biomedical company Organovo showed off its technique for 3D printing human kidney tissue. Organovo has been working on printing functional human tissue since being incorporated in 2007, and first printed a cellular blood vessel in 2010. Since January 2014, it has offered bioprinted liver tissue for companies to use in drug trials and disease modeling, and it looks as though its bioprinted human kidney tissue will be used for the same tasks, starting sometime in the latter half of 2016. "The product that we intend to build from these initial results can be an excellent expansion for our core customers in toxicology, who regularly express to us an interest in having better solutions for the assessment of human kidney toxicity."
So far Organovo's 3D-printed liver tissue is used for preclinical drug trials because the tissue responds like a real life human liver would for 42 days. That's much longer than the single layers of cells previously used in tests, which wilt in a few days. There are mixed views on how far off printing functional organs for transplant is. Growing tissue is one thing, but growing an organ and integrating it into a living body is another. "Everybody's dream is the 3D-printed organ. Are we ever going to get there?" asked Gabor Forgacs, whose research forms the basis of Organovo's method. Forgacs argued that there was no reason functional organs couldn't be made eventually, but that printing replacement organs on demand was still decades away.