illustration for Michael Gusmano illustration

 Illustration by Luis Toledo

The Ethics of Xenotransplantation  

Michael Gusmano examines the ethics and politics of animal-to-human organ transplants.  

Story by

Kelly Hochbein

In January 2022, surgeons at the University of Maryland Medical Center implanted the heart of a genetically modified pig into a 57-year-old man in a procedure known as xenotransplantation (XTx). XTx is an experimental treatment in which a human receives a whole organ from a nonhuman animal. XTx currently is performed on an emergency basis with FDA approval. With the first in-human clinical trials anticipated in the near future, XTx, if successful, could provide desperately needed donor organs for some of the more than 100,000 patients on the national transplant waiting list. However, many critical questions remain. 

Michael Gusmano, a professor of health policy in Lehigh’s College of Health, has partnered with colleagues from bioethics research institute The Hastings Center, Northwestern University and Rutgers University to ask those questions, with the goal of providing up-to-date ethical and policy guidance to patients, clinical teams, and the Institutional Review Boards (IRB) and regulators involved with XTx clinical trials. 

To assess perceptions and concerns about ethical and policy issues, Gusmano and his colleagues are conducting in-depth interviews with transplant patients and clinicians, as well as transplant and human subjects ethics regulators. The researchers will use the information they gather to develop innovative XTx decision aids for stakeholders and provide recommendations for the ethical translation of XTx clinical trials. The four-year project, “Informing Ethical Translation of Xenotransplantation Clinical Trials,” is funded by the National Institutes of Health (NIH). 

Illustration for Gusmano research

Illustration by Luis Toledo

“We have been able to identify what we consider to be a number of either unanswered or underexplored ethical issues that need to be answered before first in-human clinical trials ought to take place,” says Gusmano. “These include basic questions about informed consent and how we ought to be describing the benefits and burdens of participation in these trials.”

Among the questions: Who gets an animal organ? Should clinical trials prioritize patients most likely to die before a human organ becomes available? A patient on the transplant waiting list would receive a human organ when it becomes available and if it’s a “match,” but no such system exists for animal organs. 

Patients who participate in clinical trials should be aware of the risks and uncertainty of participation, Gusmano says. The patient who received the pig heart at the University of Maryland Medical Center died two months after the surgery. “You are contributing to science by doing this, but we can't tell you that you will benefit from it clinically. That's the whole point of the trial: to find out what works.” 

Some basic methodological questions related to trial design also give rise to ethical questions. For example, Gusmano says, different companies are developing genetically modified pigs for transplant purposes, with each using a different brand of pig and modifying the pigs in different ways. At the same time, clinical teams are proposing different forms of immunosuppression regimes for transplants. 

“There's a real concern that we may have multiple trials that are using different pigs, different genetic modifications and different suppression all at the same time,” he explains. “It is more difficult to learn from the trials under those circumstances. You can think of it as a methodological problem, but you can also think about it as an ethical issue. To what extent should we standardize trial design to overcome those problems?”

And what if, for example, a pig kidney transplant fails but the patient survives? 

“What does it mean for your ability to then get a human kidney down the road? Should [trial participation] increase your probability or would that be coercive? We haven’t sorted that out,” Gusmano says. 

The past two decades have brought advances to XTx, but the guidance addressing related ethical and policy challenges has not changed. This study will provide much-needed updates. 

“[XTx is] an interesting question for me because it involves clear ethical concerns, issues around fairness and justice, and a major public health problem,” he says. “So in any small way our study can contribute and make sure that the science moves forward in a way that's responsible, that will be great.” 


Michael Gusmano’s research focuses on health and social policy in the U.S. and abroad. He received his Ph.D. in political science from the University of Maryland College Park and an M.A. in public policy from the State University of New York at Albany. Gusmano serves as a research scholar at The Hastings Institute and is co-director of the World Cities Project. 

Story by

Kelly Hochbein

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