I remember, some years ago, on 'Holby City', where two surgeons, Rick Griffin and a friend of his played by Adrian Edmondson, transplanted a pig's kidney into a patient. Pioneering surgery! The operation didn't take place in the hospital, might have been in Rick's kitchen but I don't recall. It was not legal of course but they did it and the patient survived a bit longer than he would have done without it. All very exciting, or so I found it at the time and I've never forgotten it.
It must be fairly easy to obtain bits of a pig, we do eat them after all, but I'm not sure of the ethics of growing organs in pigs for human use, or more precisely putting human organs in pigs for later use. The pigs will have to undergo quite difficult operations and be on anti-rejection drugs, steroids etc. Not pleasant I'm sure.