Pig stem cells discovered by two animal science researchers at the University of Georgia reveal a better way to determine the safety of future stem cell therapies than rodent-based models.

Rodent studies are likely inadequate for testing many human therapies including pharmaceuticals, since 50 percent of all chemicals test positive as carcinogens, regardless of their source or identity, according to Thomas Hartung a professor in the Bloomsburg College of Public Health at Johns Hopkins University.

He suggests that these rodent studies may be no better than a coin toss. As an example, some components in coffee appear to be carcinogenic in rodents, but in humans moderate coffee consumption may reduce the risk of cancer.

In 2010, UGA’s Steve Stice and Franklin West introduced to the world 13 pigs that show promise to unlocking the path to new therapies. The pigs today produced another positive finding: These adult-cell-sourced stem cells don’t form tumors in pigs.

“Pluripotent stem cells have significant potential for stem cell therapies,” said West, an animal science researcher in the UGA College of Agricultural and Environmental Sciences. “However, tests in mice often resulted in tumor formation that frequently led to death.”

Tackling tumors

This has raised concerns about the safety of induced pluripotent stem cells, or iPSCs, and cells derived from these stem cells. Until now, all iPSC safety studies have been performed only in rodent models.

“To address the concern, our research team studied tumor formation in pigs generated from pig iPSCs. Brain, skin, liver, pancreas, stomach, intestine, lung, heart, kidney, muscle, spleen and gonad tissues from all 11 pigs tested showed no evidence of tumors,” West said.