Anthony Atala

If a salamander can grow a new limb, Dr. Anthony Atala likes to say, why can't a person? It's hardly an idle question. Atala, 50, is at the forefront of the study of growing human tissue, an emerging field also known as regenerative medicine. He made headlines around the world in 2006 when he announced that he had grown a handful of human bladders in the lab and that the patients who'd received them were still healthy after five years. No one had bio-engineered an organ before, much less implanted one. But today, Atala and his staff at North Carolina's Wake Forest Institute for Regenerative Medicine, the world's largest such facility, are working to replicate their success with other body parts. They're currently growing 22 different tissues -- from heart valves to muscle to fingers.

When Atala began trying to bioengineer organs nearly 20 years ago, there was little interest in such speculative work. "The National Institutes of Health wouldn't fund this research," he says. "If you called it 'regenerative medicine,' people said, 'What is that?' " These days, there are plenty of believers. Every day, 17 people in the United States die while awaiting an organ transplant. By growing a replacement from a patient's own tissue or from stem cells, doctors could eliminate the shortage and reduce the risk of rejection.

Money is now pouring into the field. Tengion, a Philadelphia startup, has licensed Atala's technology (he is chairman of its scientific advisory board) and has already completed the first Phase II clinical trials for bladders, one step closer to FDA approval. And last year, the Army announced the creation of a $250 million Armed Forces Institute of Regenerative Medicine (AFIRM), which draws on the research of 27 institutions to accelerate work to help wounded soldiers. Atala is the codirector -- and the inspiration for the collaboration. "When I saw what he was doing growing tissue, I was knocked out," says Colonel Bob Vandre, AFIRM's project director. "This is not science fiction. It's happening right now."

Atala became interested in bioengineering as a pediatric urological surgery resident at Harvard. "I thought, If you need new tissue, you can make it, since it regenerates inside the body when you have an injury inside the body," he says. "It was naive of me. But being naive helped me not accept the current dogma that tissue can't grow outside the body."

Atala started out targeting adult bladder cells, but they wouldn't survive in the lab no matter how much he tinkered with the biological growth factors, or "soup," used to feed the cells. So he turned to young progenitor cells, which eventually did grow. After that milestone, he spent several more years customizing the soup for different cell types.

To form a bladder, he built a mold out of biomaterial and sprayed on the corresponding cells that would multiply to form the inner and outer lining. Next, an incubator acclimated the new organ to the body's temperature, and oxygen and carbon-dioxide levels. From biopsy to implantation takes just six to eight weeks.

After proving that the man-made bladder functioned in animals, he moved on to humans -- nine children with spina bifida, a spinal birth defect that also compromises the bladder. Along the way, he made another significant discovery: Stem cells from amniotic fluid and the placenta also will make tissue that the body doesn't reject and that doesn't form tumors. This sidesteps the controversial use of embryonic stem cells. According to Atala, it would take only 100,000 specimens from placentas and amniotic fluid to give 99% of the U.S. population a genetic match.

Despite making enormous advances -- and being featured in biology textbooks as a medical pioneer -- Atala remains focused on what he has yet to figure out: how to grow nerve, liver, and pancreas cells. The difference now, compared with 20 years ago, is that he's no longer alone. "We have more than 170 people at this institute and thousands of investigators around the world doing this work," he says. "We're taking major leaps now." -- by Chuck Salter