Researchers have made new progress in making pig heart transplants available to humans by putting the hearts of genetically engineered pigs into baboons.

A baboon has lived a year so far with a pig heart in its abdomen, which is a great sign considering that many baboons of the past have rejected the pig hearts within six months.

The new hearts that are being used are from pigs genetically engineered to have less pig genes and more human genes. Pigs are already a great candidate because anatomy-wise human and pig hearts are very similar. Heart valves from pigs and cows are actually already being used in human surgeries.

Combining genetically engineered hearts with medication that suppresses what could be a deadly immune response to the donors could be the trick for making these transplants available for humans. Having pig heart transplants available would lessen the gap between heart transplants needed and hearts available to be transplanted.

“The developments may instill a new ray of hope for thousands of patients waiting for human donor organs,” said Muhammad Mohiuddin of the Cardiothoracic Surgery Research Programme at the National Heart, Lung, and Blood Institute in the US.

The genetically engineered hearts have already proven to be a good start considering that baboons given non-genetically engineered hearts rejected them within a day. Now that the hearts have been proven to be safe within the baboon’s bodies, the next step is to test them out as actual heart replacements.

It could be years before pig hearts are available to humans, but it seems to be off to a great start.