Lured by the promise of finding work, hundreds of people in India have instead lost their kidneys. Some of the victims had been taken to a clinic in Gurgaon, just outside New Delhi, where they were reportedly knocked out by injection, and then learned they were missing a kidney when they awoke. In late January of this year, police raided the clinic as part of an effort to break up an organ transplant racket that authorities believe may have sold as many as 500 kidneys.

Growing hope: Bladder engineering (shown) represents one of many new advances. Credit: Associated Press/Brian Walker

This illegal ring, one of the most extensive ever uncovered, highlights the desperate need for organs. In the United States alone, more than 98,000 patients are currently listed with the United Network for Organ Sharing; but only about 26,000 received transplants between January and November 2007.

“Transplantation currently does not come close to meeting the need for organ replacement,” says John Scandling, director of the kidney transplant program at the Stanford University Medical Center in Palo Alto, California. “There aren't enough organs to go around.”

Advances in organ transplant research could help fill those gaps. Recently, two vastly different approaches—one that involves reducing organ rejection and another in which organs are grown from scratch—have shown good results in a handful of individuals.

On 23 January 2008 researchers reported that they could transplant kidneys without the need for immunosuppressive drugs, which weaken the body's ability to fight infection and tumors. Most transplant patients must take these drugs for the rest of their lives because their immune systems react against the foreign human leukocyte antigen (HLA) proteins within the transplanted organ.

Five patients at the Massachusetts General Hospital (MGH) in Boston received kidney transplants from donors whose HLA proteins did not match their own. Researchers partially destroyed each patient's bone marrow with radiation—wiping out the T cells that typically attack the foreign organ—and replaced it with bone marrow from the donor before attaching the new kidney (New Engl. J. Med. 358, 353–361; 2008). As the immune system recovers, the donor marrow generates new T cells in the recipient. Four of the five individuals have gone for at least five years without drugs. Doctors still aren't exactly sure how this approach works, but they think that it's because the recipient's T cells lose their reactivity against the donor's cells.

Scandling and his colleagues have achieved similar success by transplanting both bone marrow and a kidney from one man to his brother (New Engl. J. Med. 358, 362–368; 2008).

Another completely different approach also enjoying preliminary success involves growing body parts from patients' own cells. In early February a team of doctors at the University of Tampere in Finland announced at a news conference that they had replaced part of a man's jaw with one grown inside his abdomen from stem cells taken from his fat. The researchers have submitted a report on the procedure to a journal for review.

Previously, a team led by Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine in Winston-Salem, North Carolina, showed that it's possible to grow a new bladder by seeding a biodegradable bladder scaffold with cells from a patient, placing the cell-seeded mold in an incubator, and then inserting the lab-grown organ into the individual (Lancet 367, 1241–1246; 2006).

But scientists say the biggest advantage that both this technique and the bone marrow transplant approach offer is the promise of sidestepping the threat of organ rejection by the immune system.

Still, each method faces significant hurdles, and it's unclear whether the organs will hold out over time. “That's the big question,” says urologist Steve Chung of Northwestern University in Chicago. “Everybody wants to know, several years out, are they going to need a new bladder, or will it stay robust and functional?”

With the organ engineering approach in particular, experts question whether scientists will be able to grow more complex organs. “I think the technology, while exciting, is still a ways off,” says David Sachs, senior author of the new paper from MGH and head of the hospital's Transplantation Biology Research Center. “To make all the different integral parts for a kidney, for example, is just going to take a lot of time.” Atala and his colleagues are working toward this goal by tackling what he sees as the major limiting factor: forming new blood vessels for complex organs such as the pancreas and heart.

Routinely using bone marrow grafts in transplanting kidneys and other organs without the use of immunosuppressants is also a way off. Because researchers get rid of all mature T cells, which help defend against pathogens, “infection is a worry until the immune system comes back,” says Sachs.

The extent to which either approach will help solve the organ transplant crisis remains unknown. In the meantime, “it's encouraging to know that there are parallel avenues,” says Atala.