A functioning human liver has been successfully grown in a mouse by scientists in Japan, opening up the prospect of a future where replacement organs are grown on demand.
The ground-breaking research, published in the latest edition of Nature, involved the scientists creating a liver "bud" in a laboratory using stem cells and then transplanting it into the rodent.
The tiny but functioning human liver matured after being transplanted into the mouse, developing a vascular system and performing liver-specific functions.
Takanori Takebe and Hideki Taniguchi, of the Yokohama City University Graduate School of Medicine, said the breakthrough proved the concept of organ bud transplantation for the first time.
"Although efforts must ensue to translate these techniques to treatments for patients, this proof-of-concept demonstration of organ-bud transplantation provides a promising new approach to study regenerative medicine," the researchers said.
Tests on the mouse showed the minute liver, which measured just half a centimetre, was able to perform liver-specific functions such as protein production and human-specific drug metabolism.
"These results highlight the enormous therapeutic potential using in vitro-grown organ-bud transplantation for treating organ failure," the study concluded.