A mixture of three cell types self-assembles into a liver bud that can be seen with the naked eye.

In work that will raise hope that organs could be repaired or even grown from scratch using a patient’s own tissue as the raw material, Japanese researchers have created functioning liver tissue from stem cells and successfully transplanted them into mice.

The researchers found that a mixture of human liver precursor cells and two other cell types can spontaneously form three-dimensional structures dubbed “liver buds.” In the mice, these liver buds formed functional connections with natural blood vessels and perform some liver-specific functions such as breaking down drugs in the bloodstream.