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May 4, 2010


By Miriam Falco
CNN Medical Managing Editor

Scientists appear to have broken another barrier in stem cell research by creating a better research model to study human illnesses ? a pig ? actually 34 pigs.

It?s an important advance for research because pigs are much more like humans than other lab animals are.

The scientists did not clone the pigs ? instead they adapted a procedure used in mice and human stem cell researchand were able to grow a specific kind of cell, induced pluripotent stem cells, or IPS cells.

Pluripotent stem cells have the ability to turn into any cell in the body. IPS cells were first developed about five years ago by Shinya Yamanaka, who used four genes to coax a regular mouse cell into acting like an embryo. Creating stem cells with this method is less controversial than harvesting them from an embryo, which destroys the fertilized egg in the process.

According to Dr. Steve Stice, director of the University of Georgia Regenerative Bioscience Center, his team took a bone marrow cell from a pig and injected six new genes, which caused it turn into an embryo-like cell. Pluripotent stem cells were harvested from this embryo-like cell and injected in another pig embryo.

The first piglets carrying these new stem cells were born September 3, 2009.

So far human embryonic stem cell research has not actually found its way into the human body. Most of the research is still in mice. But mice aren't the best animal models to get more accurate data on how a treatment may affect a person. For example, mice hearts beat four times faster than a human heart and mice don't get atherosclerosis (clogged arteries) ? but pigs do. That's why pigs are much better animal models says Stice. "Physiologically, pigs are much closer to a human," he says.

The researchers also found that unlike mouse embryonic stem cells, which can turn into cancer cells, none of the pigs developed any signs of tumors.

But it has been very difficult to harvest embryonic pluripotent stem cells from pigs. Stice credits his research assistant Franklin West with finding a way to make the existing IPS technology work in pigs.

Now researchers hope to find many different applications for these new pig stem cells and the pigs they can produce. They are already working with scientists at Emory University to develop insulin-producing pancreatic islet cells, which might be transplanted into people with diabetes.

Stice thinks this new method can also be used to genetically engineer healthier livestock for other tissue transplants and food consumption. He suggests these stem cells may someday be used to make "artificial bacon," which would eliminate the need to slaughter pigs.

The research will be published in the online journal "Stem Cell and Development."