It worked: the more toxic a drug was known to be, the more toxic its effect was on her mini-livers. Indeed, one of the drugs that showed up as highly toxic in her tests had already been pulled from the market after causing problems in humans.

Bhatia is not the only researcher working on using liver cells to better predict toxicity. Companies such as Hurel of Beverly Hills, CA, and RegeneMed of La Jolla, CA, have developed toxicology screenings that also use liver cells.

One of Bhatia's colleagues at MIT, Linda Griffith, along with research scientist Karel Domansky, has built a system that encloses three-dimensional liver tissue and perfuses it with nutrients using microfluidics. Griffith's cells also retain their functions over time, and so could also be used to test for chronic toxicity. Her lab is working with DuPont on evaluating the system for commercialization

Although Bhatia's current liver model is promising, it's not a panacea, according to the FDA's Dragan. "It's a wonderful model," she says, especially because it can screen for chronic toxicity. But Dragan cautions that "it's still derived from a single human liver." This means Bhatia's model might fail to predict how people with genetic differences or unusual medical histories would react to a drug.

Bhatia says that future screenings could incorporate different livers. For now, says Dragan, "It will not substitute for human trials. But it will be useful for screening out bad actors."