LANSING, Mich. (WLNS) — Doctors at the University of Maryland Medical Center transplanted a genetically modified pig heart into a 57-year-old man.

So far, it seems to be working.

Cardiologists from both Sparrow and Spectrum Health say using an organ from an animal and putting it in a human is a breakthrough.

Because the operation is still in the early stages, doctors say more research needs to be done.

“This pig heart has performed so far very well, even beyond our expectations,” said Dr. Muhammad Mohiuddin.

Doctors from the University of Maryland Medical Center placed a genetically altered pig heart into David Bennet.

“My first thought was, is this real? We in the transplant field have known about the idea of xenotransplantation, but to see a story being realized in the united states is something that I didn’t anticipate,” said Dr. Sangjin Lee, the Chief of Heart Transplantation with Spectrum Health.

Dr. Lee interacts with heart transplant patients every day.

“Their quality of life is is very poor. They can’t do their usual activities. Everyone wants to get a transplant sooner and they’re sick. They want to get back to their usual quality of life,” said Lee.

But what could this breakthrough mean for the thousands of patients waiting on the transplant list?

“I think that we have to still look very carefully to see if it can be realized in a more ubiquitous manner. I think there’s still a lot of questions that need to be answered,” said Lee.

Doctors at sparrow hospital agree.

“We really want to know how these patients are going to do in the long term follow up and hopefully these patients will do well,” said Dr. Mohammed Quintar of Sparrow Hospital.

Overall, doctors say it’s a step in the right direction.

“There’s a lot of technology, a lot of innovation that’s ongoing. And with a structural heart as a specialty that’s kind of leading the way,” said Dr. Nam Cho, a cardiologist at Sparrow Hospital.