Cystic fibrosis is the most common genetic disease in Caucasians. The median lifespan for those with the disease is 36 years, and lung disease is the major cause of mortality.
For years, scientists have studied cystic fibrosis using mice in which the cystic fibrosis gene was altered. However, mice do not develop lung disease like humans with cystic fibrosis. Now, researchers at the University of Missouri and the University of Iowa have taken the first step in developing a porcine cystic fibrosis model that may more faithfully mimic the disease in humans.
"When you make the same genetic mutations in mice that people have, mice don't get the lung disease that's associated with cystic fibrosis, so no model currently exists to research lung disease caused by cystic fibrosis," said Randy Prather, distinguished professor of reproductive biotechnology in the MU College of Agriculture, Food and Natural Resources. "Compared to mice, pigs may be a good model for human genetic diseases because their anatomy, biochemistry, physiology, size and genetics are more similar to those of humans."
Prather collaborated with Michael Welsh from the Howard Hughes Medical Institute at the University of Iowa. To create the genetic defect in pigs, a team led by Welsh made genetic modifications in pig cells. Prather's group then generated the genetically modified pigs from the cells using a method called nuclear transfer. With the genetic modifications, the researchers hope they will be able to mimic the lung disease that afflicts humans who have cystic fibrosis.
However, the pigs that were generated only carried one copy of the mutated gene. Since these pigs do not have both copies of the mutant gene, they do not show signs of cystic fibrosis. So Prather bred the pigs naturally and the researchers are expecting animals in Spring 2008 that should have both copies of the affected gene. Both researchers said they will have to wait to see if the pigs that carry both copies of the defective gene display symptoms related to those associated with cystic fibrosis in people.