Mechanical engineering helps research into the liver

Artificial glass livers being developed at the University of Leeds could help those suffering from liver failure, and improve understanding of how the organ works, researchers believe.

Dr Peter Walker of mechanical engineering is leading Leeds’ contribution to a three-year £320,000 project that aims to replicate the geometry of the liver, using glass and liver cells.

“The liver is a very complex organ, which we still don’t fully understand,” said Dr Walker. “If we can mimic closely how it’s constructed and how the cells function within it, we should ensure an effective ‘replacement’. It may also provide an alternative to animal testing for hepatic drugs and bring us one step closer to being able to engineer liver tissue.”

The artificial liver – to be used like a dialysis machine – will be constructed of tiny hexagonal glass plates with channels running from their edges to the centre.

Glass is the ideal substance for etching the channels – less than 1/200 of a millimetre wide – which are lined with liver cells which reproduce the cleaning work of the organ.

The blood flows to the edge of each hexagon and down the channels, cleaned by cells as it goes, before exiting through a central ‘vein’. The liver is the only organ in the body where blood from veins and arteries is mixed together.

The arterial blood, fresh from the lungs, provides the cells with the oxygen they need to function, while venal blood contains the impurities for the liver to clean out.

A major problem with artificial livers is that as the blood runs through, it loses too much oxygen, so cells at the end of the line are no longer effective. “Reproducing the exact layout of the liver should overcome this problem, as cells will behave as they do in the natural liver, performing different cleaning functions dependent on their position and the level of oxygen they receive,” said Dr Walker.

He is creating computer simulations to model the liver, so optimum channel size, flow rate and density of cells can be calculated as accurately as possible, before the artificial liver is constructed in the laboratory.

The project, funded for three years by the EPSRC, is in collaboration with the Rutherford Appleton Laboratory in Oxfordshire – which is etching the glass plates – and the University of Nottingham.