Surgical teams at NYU Langone Health performed the world's first genetically modified pig kidney transplants into a human body in September and November 2021, and then transplanted two pig hearts in the summer of 2022. These procedures were done in patients declared dead based on neurologic criteria (decedents) and maintained on ventilators with the consent of their families. Demonstrating the field's progress, NYU Langone in April 2024 transplanted a pig kidney into a living patient.

Now two new analyses, one published online on May 17 in Nature Medicine and the other May 21 in Med , reveal changes at the single-cell level in the organs and recipient's bodies before, during, and just after the xenotransplantation surgeries in the decedents. Teams of scientists had worked alongside the surgeons, taking blood and tissue samples to analyze changes in tens of thousands of collected cells. Led by researchers at NYU Grossman School of Medicine and the Broad Institute of MIT and Harvard, the Med paper tracked the genetic and cellular activity in the two pig kidneys transplanted into humans, and compared them against pig kidney samples that had not been translated.

To do so, the research team used several techniques, including single-cell RNA sequencing, which determined the order (sequence) of the molecular letters making up the pig and human genes active in various cell types during the procedures. The study showed that the transplanted pig kidneys, while not rejected outright by .