To grow their mini livers, the researchers took human skin cells donated by volunteers and reverted them to a stem cell state, known as induced pluripotent stem cells, from which other kinds of cell types can be derived.
While it ordinarily takes two years for a human's liver to mature from the moment of their birth, the researchers were able to grow their miniature analogues in only a matter of weeks, seeding the grown cells on a rat liver scaffold that had been stripped of its rat cells.
While previous experimental liver graft research has incorporated rodent cells onto the scaffold, here the researchers used the human stem cells to populate the liver's functional tissue, along with its vascular system and bile duct network.