The scientists describe their procedure in this week's electronic version of the journal Nature . He points out that this method created five healthy piglets last March, as opposed to one. Efficient cloning may become an important factor in the future if and when scientists are able to use pig organs for human transplant. About 180,000 people around the world are estimated to be waiting for an organ transplant, but fewer than one in three will receive one because of the widening gap between supply and demand. Many see organs derived from pigs as a solution to the problem.
Research is already under way to manipulate genes responsible for organ rejection.
Once scientists find a way to turn off organ-rejecting genes, they hope to clone pigs with genetic material that is missing those genes. But as a Nature study points out this week, organ rejection isn't the only concern. Transferring pig organs may also introduce contagious diseases to humans. Danger of Disease Daniel Salomon of the Scripps Research Institute in La Jolla, Calif., and colleagues found that human cells can be infected with viruses that exist in all pig cells, called porcine endogenous retroviruses or PERVs. Guidelines surrounding xenotransplantation research by the U.S. Food and Drug Administration have stiffened since 1996 because of such fears.