Organovo can print strips of human liver tissue in its labs in about 45 minutes, and it takes another two days for the cells to grow and mature, CEO Keith Murphy told CNN recently. The models can then survive for about 40 days. Organovo has also built models of human kidneys, bone, cartilage, muscle, blood vessels and lung tissue, Murphy said.

It may be a while until 3D printers are spitting out spare parts for humans; then again, it's part of Organovo's 10-year plan.

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— Norbert Sparrow