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Some labs and private companies have already taken the first steps by using 3D-printing technology to build tiny chunks of organs.

Regenerative medicine has already implanted lab-grown skin, tracheas and bladders into patients, body parts grown slowly through a combination of artificial scaffolds and living human cells. By comparison printing technology offers both greater speed and computer guided precision in printing living cells. The ultimate goal is to make replacement skin, body parts and eventually organs such as hearts, livers and kidneys.

There are four levels of complexity in building organs with 3D printing. Skin and similar flat structures with mostly one type of cell represent the easiest organs so they are in first group. In second group we can put blood vessels and any other structures with two major cell types. After this two follow more difficult third level. This group includes hollow organs such as the stomach or bladder every with more complicated functions and interactions with other organs. Most complicated organs with main role such as heart, liver or kidneys are members of fourth level and they represent ultimate goal for bioprinting.

Scientists previously built lab grown organs by creating artificial scaffolds and seeding the scaffold with living cells. The technique they used for grow was first implanted in patients in 1999. Last decade they were busy with building 3D printers that can at the same time print both an artificial scaffold and living cells. Some other labs and scientists think they can bypass the artificial scaffolds by harnessing living cells tendencies to self organize. Scientists have experimented with building tiny slices of livers by first creating "building blocks" with the necessary cells. Then they can situate the building blocks in layers that allow the living cells to start growing together. Stem cells taken from a patient's fat or bone marrow can provide the material for making an organ that the body won't reject.