Anthony Atala makes bladders. Not the plastic-model kind but actual living, human organs. Step into his office at Wake Forest University’s Institute for Regenerative Medicine (IRM), where the 48-year-old tissue engineer is director, and you’ll find a suite of climate-controlled chambers the size of hotel mini fridges.

Inside, spheres of human bladder cells resembling deflated pink balloons divide and grow. Culled from patients with incontinence problems, these cells will assemble themselves over time, forming into brand-new replacement bladders for the cell donors.

Atala has been developing the procedure for 16 years, but he became the toast of the industry this year when he announced the first successful transplant of lab-grown organs into humans. Seven volunteers received the organs—new bladders—beginning in 1999, and today all report improved urinary control. Although the bladder is perhaps the simplest organ to replicate because it lacks blood vessels, Atala’s achievement paves the way for creating far more complex body parts, such as livers and kidneys. “The current organ shortage is a public health crisis,” he says. “People are living longer, and there aren’t enough organs to go around. That brings up the question, ‘Can we grow them instead?’”

Atala has been wrestling with that very question for 20 years. The soft-spoken researcher attended medical school at the University of Louisville, where he specialized in urology. Struck by the ineffectiveness of standard bladder-repair procedures—intestinal tissue grafts that heightened cancer risks—he resolved to improve on the technique. In 1990 he became a research fellow at Children’s Hospital in Boston and set about developing a prototype for the first homegrown bladder. Like others working on similar tissue-engineering projects, he kept facing the same bugaboo: When he tried to grow bladder cells outside the body, they would divide and grow for only a few days or weeks before dying off. After years of trial and error, he hit on a solution: harvesting younger cells. “We used the layer of cells at the very, very base of the bladder,” he explains. “Once we started working with them, we were able to grow enough bladder cells to cover a football field in 60 days.”

The IRM is now collaborating with local biotech company Tengion, which is bankrolling large-scale clinical trials of Atala’s bladders and hopes to manufacture them eventually. Meanwhile, Atala is busy replicating more than 20 kinds of tissues and organs, including hearts and livers. But because the vast snarls of blood vessels inside these organs are exceedingly difficult to grow in the lab, he thinks it might be decades before his work yields commercially viable treatments. “Rushing may be OK when you’re trying to get a widget or a videogame on the market,” he says, “but not when you’re dealing with patients’ lives.”