Male Rat Was Made Pregnant and Had Pups. Result: Outrage

Arthur L. Caplan, PhD


June 25, 2021

This transcript has been edited for clarity.

Hi. I'm Art Caplan. I'm at the Division of Medical Ethics at the New York University Grossman School of Medicine.

Should men ever, through medical intervention, be permitted or given the capacity to have a baby? Any time this subject comes up, there is enormous interest. People who think that such a thing would fundamentally be a violation of the laws of nature pay close attention. Everybody is just interested in something that crosses boundaries.

Very recently, a team of scientists in China at the Naval Medical University in Shanghai tried to create a model to test the hypothesis that you could get a male rat to deliver babies. They published this paper and reported some success. It has created almost a predictable firestorm to the point where they're thinking of retracting the paper.

What did they do? Something called heterosexual parabiosis. They took a male and a female rat and literally joined their blood circulation to get female hormones into the male bloodstream. Then they transplanted the uterus of the female rat into the male rat. They created a space, put it there, then they put in embryos transferred from the female that they had created in vitro. Lo and behold, the male with the transplanted uterus and the donated embryos gave birth to 10 rat cubs, and they seemed normal.

The interesting thing about this model is it's obvious that it wouldn't be used in humans. It would be a violation, if you will, of a number of principles, not the least trying to tie together a male and a female and then having to put them down at the end of the study since they can't go on this way for life. You would have all kinds of immunologic and other problems. This isn't anything that anybody's going to do tomorrow, next week, next year, or hopefully ever.

The point of principle — that if you had the right hormones, you had the uterus bathed in the right blood circulation and chemicals, and you somehow were able to get embryos in there you could make the whole system work — does raise at least one baby step toward thinking about how you might be able to modify a male body with a transplanted uterus, artificially put in the right hormones, and maybe have a C-section–type delivery.

Even the prospect of doing all this set off a firestorm. Many people online began to say this is a violation of the rules of God or the rules of nature. It's created a firestorm in Asia, and in particular in China. People wanted to know who approved this study, to which the answer is probably nobody because this is basic animal research. Human ethics committees wouldn't be involved in giving permission to do it.

Even if human ethics committees had been involved, I suspect it would have been approved because it's just a basic physiology model, as bizarre as it sounds. As long as the animals didn't suffer, I don't think review boards are going to be thinking that this could be abused in 10, 15, or 20 years — or if you take the position that it's okay, that it could be used — not just abused — in humans to help males become mothers.

Nonetheless, the researchers were so freaked out by the hostile response that this physiologic experiment created that they are talking about retracting the paper.

I think that's unfortunate. I think this basic physiology model is something that can be tested, not because it's a set-up that's going to be used in humans, but just as a proof of concept that you can take the elements physiologically for reproduction and arrange them in a way that might work in a male.

Whether we choose to do that and whether it's right to let men reproduce are bigger issues that ought to go way beyond scientists. I think it's time to form an international committee to start thinking about that kind of a question regarding limits on reproductive technology, giving advice, and guidelines. We need society to agree where we might go in terms of who can have a baby, under what circumstances, and with what medical assistance — not a review committee.

I wouldn't stop the basic science, but it's time to start thinking harder about the ethics of where reproductive technology can take us.

I'm Art Caplan at the New York University Grossman School of Medicine. Thanks for watching.

Arthur L. Caplan, PhD, is director of the Division of Medical Ethics at New York University Langone Medical Center and School of Medicine. He is the author or editor of 35 books and 750 peer-reviewed articles as well as a frequent commentator in the media on bioethical issues.

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