Tiny human livers successfully grown in lab have been transplanted into rats

Miniature human livers have been successfully grown in a lab by scientists – who then transplanted them into rats.

Human volunteers donated skin cells which researchers then developed into fully-functional mini-livers in a laboratory.

Livers take up to two years to mature naturally, but the researchers managed to engineer similar results in under a month.

Researchers hope that their new technique might be a step towards one day replacing organ donation.

Study senior author Dr. Alejandro Soto-Gutierrez, at Pittsburgh University, said: “Seeing that little human organ there inside the animal – brown, looking like a liver – that was pretty cool.

“This thing that looks like a liver and functions like a liver came from somebody’s skin cells.”

The “made-to-order” livers secrete bile acids and urea just like their natural equivalents, the team explained.

The researchers created their mini livers by reprogramming human skin cells into different types of liver stem cells.

Then they seeded those human liver cells into a rat liver which had been stripped of its own cells.

As the ultimate test, the researchers transplanted their mini livers into five rats, which had been specially bred to resist organ rejection.

Four days after the transplant, researchers investigated how the implanted organs were faring.

Blood flow problems had developed within and around the graft, but the rats had human liver proteins in their blood serum proving that the transplants had worked.

The team is optimistic that their research is not merely a stepping-stone towards growing replacement organs in a lab, but also a useful tool in its own right.

Dr. Soto-Gutierrez, a pathology specialist, added: “The long-term goal is to create organs that can replace organ donation, but in the near future, I see this as a bridge to transplant.

“For instance, in acute liver failure, you might just need hepatic boost for a while instead of a whole new liver.”

But he conceded that there are significant challenges to overcome, including the organs’ long-term survival and several safety issues.

The study results were published in the journal Cell Reports.