Typically, animals are the first stop in seeing how a drug works, and researchers use them to see how well it is absorbed, distributed and metabolized in the body. But animal testing often doesn’t translate well to humans, and it also carries a high financial—and ethical—cost.

In 2010 a team at the Wyss Institute at Harvard offered an alternative with their first “organ on a chip.” The devices are the size of a computer memory stick and contain living cells from human organs. Those cells are cultured on one side of a porous membrane, and vascular tissue cells line the other, allowing the two compartments to exchange molecules—including drugs—as they would in the human body.

In early 2020, the teams hit their target to have a complete human “body on chips,” which would consist of at least ten types of organs. By sending fluids from one chip to another—which is done by a device they call “the interrogator”—the researchers can explore the multisystem effects of drugs on real human tissues. The model has already delivered critical insights about how particular compounds might work in the body and where they might prove toxic. Their use in the future as a first stop for experimental drugs may pay big dividends, improving the success rate of those that make it into human clinical trials.