Chinese researchers are reporting new steps in the quest for animal-to-human organ transplants. Researchers at Xijing Hospital in China say a pig kidney transplant recipient continues to recover nearly three weeks after that surgery.

These advances have made it possible for scientists to create pigs with organs that are more compatible with human biology, thus reducing the chances of rejection. One common edit, for instance, removes a pig’s ability to produce alpha-gal, a sugar that the human body doesn’t make.

Doctors in China have become the first to report details about a transplant of a genetically modified pig liver into a human.