On the last day of March, surgeons at Massachusetts General Hospital began an operation that they hoped might lead to a permanent change in how kidneys are transplanted in people.

That morning’s patient was not a person. It was a pig, lying anesthetized on a table. The pig was missing one kidney and needed an implant.

While kidneys typically must be transplanted within 24 to 36 hours, the kidney going into the pig had been removed 10 days before, frozen and then thawed early that morning.

Never before had anyone transplanted a frozen organ into a large animal. There was so much that could go wrong.

“I think there is about a 50 percent chance that it will work,” Korkut Uygun, a professor of surgery and a leader of the team, said before the surgery. Dr. Uygun is on the scientific advisory board of Sylvatica Biotech Inc., a company that is developing freezing methods to preserve organs.

But the promise from freezing and storing organs is great.

There is a severe and ongoing shortage of kidneys for transplants — more than 92,000 people are on waiting lists. One reason is that the window of 24 to 36 hours is so brief that it limits the number of recipients who are good matches.