The first clinical trial is getting underway to see if transplanting pig kidneys into people might really save lives.

United Therapeutics, a producer of gene-edited pig kidneys, announced Monday that the study’s initial transplant was performed successfully at NYU Langone Health.

It’s the latest step in the quest for animal-to-human transplants. A second U.S. company, eGenesis, is preparing to begin its own pig kidney clinical trial in the coming months. These are the first known clinical trials of what is called xenotransplantation in the world.

To protect the study participant’s identity, researchers aren’t releasing information about when the NYU surgery was performed or further patient information.

NYU’s Dr. Robert Montgomery, who led the transplant team, told The Associated Press his hospital has a list of other patients interested in joining the small trial, which will initially include six people. If all goes well, it could be expanded to up to 50 as additional transplant centers join.

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