By Jeremy Manier
You’d rather not live without any organ, but some are easier than others to replace with technology. Kidney fails? Get dialysis. Diabetes saps your pancreas? Take insulin. Heart gives out suddenly? Try a left ventricular assist device.
But the liver poses a special problem. Its biochemistry is so complex that no one understands all the functions it serves, or the details of how it works. We do know it’s essential for blood clotting and for removing a wide range of toxins from the bloodstream. Acute liver failure can lead to death within 48 hours. Yet even the liver’s well-defined functions are difficult to mimic completely. Then there are the thousands of proteins the liver produces, many of which have poorly understood roles in the body.
All of that makes it hard for artificial livers to do much more than help patients survive a few more hours while they wait for a donor organ. Even the term “artificial liver” is a bit misleading, because most of the devices rely on liver cells of some kind. Duplicating their function from scratch is just too difficult. (Imagine if heart assist devices had to use actual heart muscle cells.)
As this Forbes piece observes, several companies have gone out of business trying to make artificial livers. One of the rare success stories that the story cites is a University of Chicago patient, Amy Petrovic, who nine years ago survived on a synthetic liver for a few days – long enough for her condition to improve so she could survive a liver transplant operation.
Attempts to make reliable devices keep coming – one company this week announced plans for a new Phase III trial of an artificial liver system, and a separate trial started last month. But stories like Petrovic’s also underscore the immensity of this challenge, and the limits of medical knowledge. Many hurdles in medicine are purely technological in nature. In this case, researchers don’t know exactly where the technological intervention should start, because they don’t fully grasp the underlying biology.