Randy Prather, a professor of reproductive biotechnology at the University of Missouri, Columbia, is one of the researchers in the forefront of the creation of transgenic swine for medicine. He often uses GFP and its yellow mutant YFP as a marker to show that foreign genes can be expressed in transgenic swine. The photo below shows two pigs, the one on the right is a regular piglet, a little cleaner than your typical piglet, but no different from the piglets you find on a hog farm. The one on the left is clearly very different to any pig we have ever seen before. It is a transgenic YFP cloned pig created by Professor Prather. It was formed to show that it is possible to produce a transgenic clone. In the words of Prather: “These animals prove that we can make genetic modifications to express desired traits. For xenotransplantation, this is a large step because it means it’s possible to change the genetic makeup of the cells to prevent the body’s rejection of transplanted organs.” Sky News summed up the research in the following way: “Scientists have developed the first pig with a fluorescent yellow snout and trotters using jellyfish DNA. Researchers in the US say the work is a step towards growing animal organs for transplants – which could save thousands of human lives. But opponents have said the work is a freak show and a perversion of science.”

Update: CRISPR used to edit pigs for xenotransplantation.

And

2022: First pig heart transplanted into human.