The first person who received a genetically modified pig kidney died almost two months after the surgery.

There was no indication the transplant was the cause, according to Massachusetts General Hospital, which performed the surgery.

In March, Richard “Rick” Slayman, who was suffering from end-stage kidney disease, underwent critical surgery.

At least two years was predicted as the lasting time of the pig kidney by the surgeons, according to Interesting Engineering.

The surgery performed on Slayman was claimed as a historic milestone because in the past, transplants of other organs from genetically modified pigs have failed.

“The Mass General transplant team is deeply saddened at the sudden passing of Rick Slayman. We have no indication that it was the result of his recent transplant,” said MGH in a statement.

“Slayman will forever be seen as a beacon of hope to countless transplant patients worldwide and we are deeply grateful for his trust and willingness to advance the field. Our family is deeply saddened about the sudden passing of our beloved Rick but take great comfort knowing he inspired so many,” said Rick’s family in a statement.