Pig stem cells could make 'humanised' organs

• 23:00 02 June 2009 by Andy Coghlan
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The world's first pig stem cells have been created from porcine ear and bone-marrow cells.

Researchers at the Institute of Biochemistry and Cell Biology in Shanghai, China, say they are the first to achieve this in hoofed animals.

Induced pluripotent stem (iPS) cells have the potential to turn into all types of body tissue. The big advantage, though, is that they can be genetically manipulated in the lab, and then cloned to create animals with new traits.

By adding or deleting certain genes, for example, researchers could produce pigs whose organs can be transplanted into patients without them being recognised and rejected. Efforts to do such xenotransplants have already been under way for at least a decade, but iPS cells are easier to genetically engineer and grow in the lab than pig embryos, opening up new possibilities for xenotransplantation.

Similar species

"The pig species is significantly similar to humans in its form and function, and the organ dimensions are largely similar to human organs," says head of the research team, Lei Xiao.

"We could use these cells to modify the immune-related genes in the pig to make the pig organ compatible to the human immune system," says Xiao. "Then we could use these pigs as [sources of organs] that won't trigger an adverse reaction from the patient's own immune system."

Xiao and his colleagues say that they made the iPS cells by using a virus to load ear or bone marrow cells with special reprogramming factors. These "rewound" the cells to the embryonic-like state of iPS cells.

Swine flu protection

As well as working towards improved organs for xenotransplantation, Xiao and his colleagues intend to produce pigs that are resistant to diseases, includingswine flu. "We could do this by finding and manipulating a gene that has anti-swine flu activity, or which inhibits growth of the swine flu virus," says Xiao.

And in agriculture, pigs could be engineered to produce better, healthier meat – with less fat, for example.

Chris Mason, an expert in regenerative medicine at University College London, said the breakthrough will boost the quest for "humanised" pig organs.

"While [using pig organs] may not necessarily be the long-term solution, it may represent a major step change in the treatment of organ failure, which potentially could deliver real benefit to millions of patients within a decade."