A lab-grown liver stand-in may better predict bad responses to drugs than animal testing does.

A human “liver chip” — liver cells grown on a membrane along with several types of supporting cells — formed structures reminiscent of bile ducts and reacted to drugs similarly to intact livers, researchers report November 6 in Science Translational Medicine. Similar rat and dog liver chips also processed drugs like normal livers in those species, allowing scientists to compare human liver cells’ reactions to drugs to those of the other species.

Rats, dogs and other animals are often used to test whether drugs are toxic to humans before the drugs are given to people. But a previous study found that the animal tests correctly identified only 71 percent of drug toxicities.

The liver chip is designed to catch bad drug reactions that animal tests might miss. For instance, bosentan, a high blood pressure drug, doesn’t harm rats’ livers, but causes bile salts to build in humans’ livers, damaging the organ. Those effects were mimicked by the chips, Kyung-Jin Jang of the Boston-based company Emulate Inc., which makes the chips, and her colleagues found.

Some drugs that were toxic to dogs and rats might not harm people, the human liver chip tests also suggest. Development of one experimental compound called JNJ-2 was discontinued because it caused liver fibrosis, or scarring in rats. But the human liver chip didn’t show any bad reactions, suggesting it might be safe for people.