A line of pigs with severe combined immunodeficiency (SCID, pronounced “skid”) could contribute to new research in cellular biology that could change human and animal medicine, according to a report by the American Society of Animal Science in Friday’s “Taking Stock.”
In a talk on Sept. 23, Chris Tuggle, professor in the Department of Animal Science at Iowa State University, will share news from his research on the SCID pig at Innovate 2013.
This line of pigs lacks a functional immune system. Tuggle compares the SCID pig to the famous “bubble boy” who had to remain in a sterile environment to live.
“Essentially, that’s the status of this pig—they cannot survive long after weaning,” Tuggle says.
The SCID pig could help researchers test drug treatments and learn more about the fundamentals of the immune system, he says. Researchers often use mice to study diseases, but Tuggle says pigs may be more useful because the way pigs respond to disease is closer to the human response.
“What we’re hoping is that the SCID pig could be a better model,” Tuggle says. “That’s really the exciting part.”
For example, researchers could use the SCID pig to test treatments for HIV. Tuggle says researchers could start with “humanization” of the SCID pig’s immune system. This means they would inject human immune stem cells into the pig.
“The human immune cells will go and take residence in the bone marrow,” Tuggle says. “Because there’s no pig immune system, the recipient animal can’t fight off those cells.”
Humanization would give the pig an immune system that would react to human viruses. If scientists then infected the humanized pig with HIV, they could test new treatments or learn more about the course of the disease.
“That’s not been done in the pig yet, but we hope to attempt such experiments soon,” Tuggle says.
According to the Iowa State researcher, animal scientists could also use the SCID pig line to improve animal health.
The immune system is made up of different kinds of cells that have different roles in fighting disease. By studying individual parts of the immune system, scientists could better understand how the different cells work together.
For example, Tuggle says, researchers could implant only cytotoxic T cells in a SCID pig. These T cells attack damaged cells and virus-infected cells. If a pig only had cytotoxic T cells, researchers would likely see “rampant” inflammation, as T regulatory cells would be absent.
Tuggle’s colleagues, Jack Dekkers at Iowa State University and Bob Rowland at Kansas State University, discovered the SCID pig line in 2011, so this collaborative group is just getting started. Right now they are locating the exact gene responsible for the SCID mutation.
The researchers have also “reconstituted” the immune system of a SCID boar by implanting bone marrow from a non-SCID pig. This boar is genetically SCID, but it now has a functioning immune system donated by his tissue-matched littermate.
“That’s a pretty unique thing,” Tuggle says. “We’re collecting his semen every week so we can regenerate this line whenever we need to.”
To learn more about the SCID pig line, register for Innovate 2013. The conference will be heldSept. 22 to 24 in Braselton, GA.
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