Several years ago, MIT tissue engineer Linda Griffith set out to build an artificial liver that could eliminate the need for donated organs for transplant. Then she had a realization: the most common reason for needing a liver transplant is a hepatitis C infection, and "if it were me, I'd rather not have a liver transplant. I'd rather the doctor said, Here, take these drugs; you will be cured of hepatitis C; you'll go on and lead a happy life; and you'll stay out of the operating room.'" But researchers have a hard time developing drugs for hepatitis C and other ailments because animal experiments don't always reveal what happens in humans, and human cells in a petri dish don't always function the way they would in the body. Indeed, hepatitis viruses don't even infect human liver cells in a petri dish. So Griffith and her team are putting their tissue-engineering expertise to work building what's essentially a miniature human liver on a silicon chip. It won't serve as a replacement part but rather as an amazingly realistic model of the natural organ. "What we're trying to do is replicate the structure, as well as the mechanical forces, so that we can hopefully replicate the function," she explains. Mass produced, such a chip could be a boon not only to companies developing drugs for hepatitis and other diseases, but also for scientists investigating liver cancer and gene therapy, and even chemical firms testing the toxicity of new materials. Griffith and graduate student Albert Hwa showed Technology Review senior editor Rebecca Zacks how to build a little liver.

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