The key reason for the success of this technique was using stem cells together with cells from the umbilical cord and bone marrow, the researchers said.
How he did it
Takebe and his team grew the organ using induced pluripotent stem cells (iPS), created by reprogramming human skin cells to an embryo-like state. The researchers placed the cells on growth plates in a specially designed medium; after nine days, analysis showed that they contained a biochemical marker of maturing liver cells, called hepatocytes.
At that key point, Takebe added two more types of cell known to help to recreate organ-like function in animals: endothelial cells, which line blood vessels, taken from an umbilical cord; and mesenchymal cells, which can differentiate into bone, cartilage or fat, taken from bone marrow. Two days later, the cells assembled into a 5-millimeter-long, three-dimensional tissue that the researchers labelled a liver bud an early stage of liver development.