First she dotted glass slides with liver cells to study infection. Now her larger assemblies of cells, in a disc about the diameter of a soda can, are being implanted into rodents to carry out most of the liver’s 500 different tasks. Thinking big but starting small, Sangeeta Bhatia is closing in on her ambitious goal: growing human livers in the lab from scratch.

“We hope we’re on the way to growing big pieces of liver for people,” says Bhatia, an HHMI investigator who has pioneered sophisticated methods of removing cells and keeping them happy and behaving much as they would in their natural habitats. It’s been a formidable challenge. “Primary liver cells are difficult to culture,” she says. “When you take them out of the body, they lose all their functions.”

Since the 1950s, scientists have probed the molecular secrets of cells plucked from the body and grown in the laboratory on flat plates or Petri dishes. These standard cultures have taught us about normal cell biology, cancer, and other diseases.

From a cell’s point of view, however, these two-dimensional (2-D) habitats—dubbed “plastic palaces” by one researcher—are a poor substitute for real life. Scientists have come to realize that a cell’s surrounding microenvironment plays a much larger role in directing its growth and shaping its behavior than anyone understood 10 or 20 years ago.

Illustration: Steve Wilson