In both cases, researchers “knocked out” the pig gene that sticks sugar molecules onto the surface of organs; the human immune system attaches to those sugars, recognizes the organ as foreign and rejects it. PPL’s five little piggies and Immerge’s original seven (four survive) could therefore be important first steps in breeding swine to be organ donors, especially for pancreatic islet cells, hearts, kidneys and lungs. But Randall Prather, the University of Missouri biologist who cloned the pigs for Immerge, thinks gene knockouts will find even wider use. Eliminating a cow’s kappa-casein gene could let it produce pricey goat’s milk; knocking out the myostatin gene eliminates the brake on muscle growth and could yield meatier pigs and steers; knocking out the cystic fibrosis gene could create a pig that gets the disease and thus serves as a model for scientists researching a cure.
