Miniature human livers grown from skin cells are successfully transplanted into rats for the first time - offering hope for 'made-to-order' organ replacements in the future

• Researchers took human skin cells and then reprogrammed them into stem cells
• They then managed to coax these new stem cells into converting into liver cells 
• The liver cells were then implanted into a rat and grew into a mini human liver 

Fully functional mini human livers have been created from skin cells and transplanted into rats for the first time - giving hope for future organ transplants.

Researchers from the University of Pittsburgh School of Medicine reprogrammed skin cells into stem cells that they then coaxed into forming liver cells. 

These mini livers secrete bile acids and urea, just like a normal liver, except they're made-to-order in the lab using cells taken from the patient set to get the organ.

Organs grown from the DNA of a human recipient could pave the way for alternatives to current donor transplants, researchers claim.

The team say the lab-made organs survived for four days inside their animal hosts. 

These mini livers secrete bile acids and urea, just like a normal liver, except they're made-to-order in the lab using cells taken from the patient set to get the organ

The team reprogrammed human skin cells into stem cells and then coaxed those cells to become various types of liver cells that could grow into a functional liver.

It's hoped in future this technique can be scaled up to produce organs for humans on demand and using the patients own DNA to reduce the risk of rejection. 

'Seeing that little human organ there inside the animal - brown, looking like a liver - that was pretty cool,' said senior author Alejandro Soto-Gutierrez.

'This thing that looks like a liver and functions like a liver came from somebody's skin cells,' said the associate professor of pathology 

The development could lay the groundwork for future treatments to address terminal liver failure - something that kills 40,000 people in the US every year. 

The team were even able to speed up the growth of the liver - from the two years it usually takes the liver to mature in a human - to under a month.

As an ultimate test, the researchers transplanted their lab-grown mini livers into five rats, who were bred to resist organ rejection. 

The team effectively seeded the grown human liver cells on to a rat liver scaffold that had been stripped of the rat liver cells. 

Four days after the transplant, researchers investigated how well the implanted organs were faring and found they had worked.

In all cases, blood flow problems had developed within and around the graft, but the transplanted mini livers worked - the rats had human liver proteins in their blood.

It's hoped the technique can help in all forms of transplant in the future - as donor supply is limited and the procedure is expensive. 

+2

As an ultimate test, the researchers transplanted their lab-grown mini livers into five rats, who were bred to resist organ rejection

Soto-Gutierrez is optimistic this research is not merely a stepping-stone on the path toward growing replacement organs in a lab, but also a useful tool in its own right.

'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,' Soto-Gutierrez said. 

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

The approach would effectively temporarily augment failing liver function in patients and lengthen their lives while they wait for a donor organ to be available.

That is a situation currently facing about 14,000 Americans and the majority won't ever receive an organ, according to the research team. 

But there are significant challenges to overcome, he noted, including long-term survival and safety issues. 

'I believe it's a very important step because we know it can be done,' Soto-Gutiérrez said. 

'You can make a whole organ that can be functional from one cell of the skin.' 

The findings have been published in Cell Reports.