Pig-Baboon Transplant A Success Results First Step To Putting Animal Hearts Into Humans

Scientists who grafted pig hearts into baboons say they have taken a major step toward the routine transplant of animal organs into people, a high-tech answer to the shortage of human organs.

The pig hearts carried proteins that markedly reduced damage from an initial and normally devastating assault by the immune system.

This attack, called hyperacute rejection, has been considered the biggest barrier to routine transplants of animal organs into people, and the new work shows it has been overcome, researcher Jeffrey Platt said.

Platt is a professor of experimental surgery, pediatrics and immunology at the Duke University Medical Center in Durham, N.C. The study, done with colleagues at Duke and the biotechnology company Nextran in Princeton, N.J., is reported in the May issue of Nature Medicine.

About 90,000 people a year in the United States could benefit from transplants, but the potential human supply is only 8,000 to 14,000 donors annually, said Roger Evans of the Mayo Clinic in Rochester, Minn.

In hyperacute rejection, the immune system unleashes proteins that can destroy a transplanted organ’s usefulness within minutes. This process is different from the longer-term rejection that transplant recipients stave off by taking drugs.

Most experiments with transplanting animal organs into people used chimps or baboons as donors. Organs from those animals are less susceptible to hyperacute rejection than are organs from pigs, Platt said.

But there are too few of those animals to meet the demand for transplants, their organs are too small for human adults and they pose a risk of dangerous infections, Platt said. So scientists have turned to pigs.