Scientists say the advance offers early-stage progress towards developing liver tissue implants for people. It could also reduce the need for animals in research by providing a tool for studying human diseases and testing drugs in the lab.
Researchers at the University of Edinburgh produced the implants by turning stem cells into cells with characteristics of liver cells in the lab.
The cells grew into tiny balls in a dish for up to a year, but did not adopt the 3D structure of liver tissue.
The team worked with chemists and engineers to identify scaffold materials that could be used to provide a 3D backbone for the cells.
They identified one such material, which is already approved for implants in people. The material was spun into a fibre mesh that formed a scaffold one centimetre square and just a few millimetres thick.
Liver cells grown from human stem cells were grown in the lab for 60 days before loading on to the mesh scaffold to form a 3D structure.
When the implants were placed under the skin of mice, blood vessels grew into the scaffolds. The mice had human liver proteins in their blood, indicating that the tissue was functioning and had successfully integrated with the circulatory system.
The researchers tested the implants in mice with a potentially fatal genetic disease called tyrosinaemia, which causes defects that prevent the liver from breaking down toxic products.
Mice with the liver implants showed fewer signs of liver damage than those that were implanted with an empty scaffold. They lost less weight and had fewer toxins in their blood.
These results are an important early step. We need to conduct longer-term studies to fully establish the safety of this technique and to scale up and optimise the performance of the liver tissue.
Professor David Hay, Group Leader at the MRC Centre for Regenerative Medicine
Liver disease is the fifth biggest killer in the UK. A transplant is the only treatment for liver failure but many people die while waiting for an organ to become available.
The study, published in Archives of Toxicology, was funded by the UK Regenerative Medicine Platform and the Chief Scientist Office of Scotland.
Showing that such stem-cell derived tissue is able to reproduce aspects of liver function in the lab also offers real potential to improve the testing of new drugs where more accurate models of human tissue are needed.
Dr Rob Buckle, Chief Science Officer, Medical Research Council
Source: University of Edinburgh