Putting pig organs in people is OK in the US, but growing human organs in pigs is not – why is that?

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Monika Piotrowska, University at Albany, State University of New York

(THE CONVERSATION) In a New York operating room one day in October 2025, doctors made medical history by transplanting a genetically modified pig kidney into a living patient as part of a clinical trial. The kidney had been engineered to mimic human tissue and was grown in a pig, as an alternative to waiting around for a human organ donor who might never come. For decades, this idea lived at the edge of science fiction. Now it’s on the table, literally.

The patient is one of six taking part in the first clinical trial of pig-to-human kidney transplants. The goal: to see whether gene-edited pig kidneys can safely replace failing human ones.

A decade ago, scientists were chasing a different solution. Instead of editing the genes of pigs to make their organs human-friendly, they tried to grow human organs – made entirely of human cells – inside pigs. But in 2015 the National Institutes of Health paused funding for that work to consider its ethical risks. The pause remains today.

As a bioethicist and philosopher who has spent years studying the ethics of using organs grown in animals – including serving on an NIH-funded national working group...