Researchers in China claim to have figured out a way to coax cells from any part of a pig's body -- they used cells from a pig's ear and bone marrow -- into any type of cell in the body, just like embryonic stem cells.
The breakthough could set the stage for pigs being raised to grow organs for humans for transplantation, the researchers say.
Lead researcher Dr Lei Xiao, of the Shanghai Institute of Biochemistry and Cell Biology, said many other attempts had been made to transform adult cells from animals such as pigs into "pluripotent" stem cells, but they had failed.
He said: "Therefore, it is entirely new, very important and has a number of applications for both human and animal health."
Dr Xiao's team reprogrammed cells taken from a pig's ear and bone marrow, using a cocktail of chemicals introduced into the cells via a virus.
Tests showed that the reprogrammed cells were capable of becoming any of the cell types that make up the three layers in a developing embryo.
Dr Xiao said pigs were a potentially ideal source of organs for transplant, as their organs were similar in function and size to those found in humans.
In its blog,the American Journal of Bioethcis quipped that the breakthrough could help save the pig's reputation after the swine flu scare.
Medical researchers have long looked to pigs as a potential source of human organs in a field known as xenotransplantation, saying it could help with chronic shortages of organs from transplant.
Professor Chris Mason, an expert in regenerative medicine at University College London, said: "This breakthrough to produce pig stem cells potentially reinvigorates the quest to grow humanised pig organs such as pancreases for diabetics and kidneys for chronic renal failure.
"The clinical use of humanised porcine tissues and organs (xenografts) has moved a long way forward in recent months with successful small-scale clinical trials.
There's a certain "yuck" factor for many people, however, and animal rights activists and religious groups have objected to the idea.
Dr Sebastien Farnaud, science director of the Dr Hadwen Trust for Humane Research, said: "Persisting with highly speculative research that would see us use sentient animals as little more that living organ grow-bags, is not only ethically unsupportable but also scientifically dubious.
"Creating pig stem cells does not necessarily remove the risk of organ rejection but even more worrying is the risk of infecting patients and the wider public with pig viruses."