Organ testing

A model liver that works outside the body is being developed by researchers at the Fraunhofer Institute as a viable alternative to animal drug testing.

Prof Heike Mertsching and Dr Johanna Schanz are currently trialling the model, which uses pig intestines and human cells to simulate activity in the human liver.

Schanz told The Engineer Online: ‘There are very few simple liver tests based on human test systems. This is because if you take liver cells out of their natural environment they lose most of their function within 48 hours. What we’re developing is a biological vascular network that keeps cells working over a longer period of time.’

The system uses a section of a pig’s intestine (around 10 to 15cm) with the blood vessels preserved so that human cells can be seeded into their structure. In order to simulate blood circulation, the researchers place the model into a computer-controlled bioreactor that allows the drugs to be carried in the same way as human veins and arteries.

According to Schulz, this allows the cells to be active for up to three weeks, which is enough time to analyse the drug’s effects on the liver. The model is expected to provide valuable early-stage information to the pharmaceutical industry as many drugs are only metabolised into their therapeutic form after they are broken down, while others develop toxic substances.

So far the research has focused on a liver model, however the applications are wide ranging. Schulz said: ‘We are also looking at the development of skin, intestine and windpipe models. We have already developed a skin model without vascularity and will be begin work on the vascularised versions in the near future.’

Ellie Zolfagharifard