CMDA's The Point

Who is Juan Carlos Izpisúa Belmonte?

August 15, 2019
Oil Bubbles July 31, 2018

by D. Joy Riley MD, MA (Ethics)

Dr. Juan Carlos Izpisúa Belmonte is trained in pharmacy and biochemistry and is a professor at the Salk Institute for Biological Studies in La Jolla, California, in the Gene Expression Laboratories. He has been at the Salk Institute since 1993. He also held a position in Spain during 10 of those years. He helped found the Barcelona Regenerative Medicine Center (CMRB), a stem cell research institution, in 2004. He left the CMRB director’s post in 2014, citing lack of funding and support from the government. Of the center’s 21 projects, he took 18 with him, for they were his intellectual property.

Dr. Izpisúa Belmonte served on the combined National Academy of Sciences and National Academy of Medicine’s “Committee on Human Gene Editing: Scientific, Medical, and Ethical Considerations.” Their task was to produce a report that would serve as “a framework based on fundamental, underlying principles that may be adapted by any nation considering the development of guidelines for human gene-editing research, with a focus on advice for the U.S.” The committee was formed in 2015 and released its report on Human Genome Editing in February 2017.

A Scientific American article in 2016 described Dr. Izpisúa Belmonte’s interest in “coaxing human tissue to grow inside animal embryos”—in a word, chimeras. According to the Cambridge Dictionary, chimeras are organisms that “contain cells or tissues from two or more different species.” In the Scientific American telephone interview, Dr. Izpisúa Belmonte described the possibility of human cells integrating in not only the pig embryo, but also cow and sheep embryos. He mentioned ethical considerations briefly:

“We are entering into an ethical [area]. Because there are some people who think that we shouldn’t mix human cells with other animals and there are others who don’t care, so to speak. Here in California, we have gone through the different committees and they allow us to have a pig embryo develop for a month. Which is one third of their gestation. At that point you can see already all of the major organ primordia.

“There are other countries. I’m from Spain and Spain has been quite open to this field of stem cell research. And they have allowed us to go until the animal is born. So in theory we could have a pig born with the human organ. It was not easy. Even though Spain is quite open to this stem cell research area, at the same time, Spain is a very Catholic country, so we had to go through the Pope. He very nicely said yes. This is to help people.”

Dr. Izpisúa Belmonte described a further worry: that the human neurons could colonize the recipient animal’s brain. Spain allowed the pig to be born and then sacrificed, but the scientist was unhappy with that situation, concerned there would be ethical criticism. He reported working to engineer the cells with a toxin so any cell that became a neuron would be destroyed in the embryo. He explained, “My feeling is that we still need to better understand these issues of cell competence, of mixing cells in embryogenesis—the rules of development, so to speak.”

In 2017, his team used CRISPR to produce rat-mouse chimeric embryos that were not brought to birth. Fast-forward to the July 31, 2019 announcement that he led a group that created human-monkey chimera embryos. The team of scientists from the Salk Institute in California and the Murcia Catholic University (UCAM) in Spain did not do this in the United States or in Spain. Instead, the experiment was done in China. The 14-day rule was observed, with such embryos not allowed to live beyond that time, project collaborator Estrella Núñez assured El Pais. She explained, “The ultimate goal would be to create a human organ that could be transplanted, but the path itself is almost more interesting for today’s scientists.”

It also appears to be very lucrative. According to Núñez, the research in China has been largely financed by UCAM, to the tune of “many hundreds of thousands of euros.”

What about the ethical considerations? Director of CMRB Dr. Ángel Raya raised several: “What happens if the stem cells escape and form human neurons in the brain of the animal? Would it have consciousness? And what happens if these stem cells turn into sperm cells?”

Dr. Raya is correct to ask these questions. More of us, including the Pope, should be asking such. The assurances of programmed human neuronal self-destruction and the prohibition of chimeras coming to birth are rather thin ethical gruel.

Dr. Izpisúa Belmonte is one of a cadre (number unknown) of bright, well-trained scientists for hire, and his group’s use of lax ethical boundaries in China to produce human-animal chimeras is of grave concern. Desire trumping ethics is not a new phenomenon, sadly. Accountability, however, would be. An international moratorium on such work is needed. Reining in such behavior is essential not only to good science, but also to human flourishing.

While mitigating the human organ shortage is a worthwhile goal, purely utilitarian calculus is wholly inadequate. Figuring out how to do a thing should not precede understanding what should be done. Considering what it means to be made in the image of God is not just a lofty ideal. Understanding this is imperative to right acting. It is not clear what portion of a human genome is necessary for an entity to be a human. To glibly state that the human-animal chimeras will be sacrificed before the 14-day limit, or before gestation is complete, is unhelpful. If these are humans, then researchers need to understand precisely what they are doing. Moral consequences of wrong acting accrue, whatever laws and regulations may allow. Forming human-monkey chimeras seems more akin to the desecration of the imago Dei than exercising sound stewardship of resources.

D. Joy Riley MD, MA (Ethics)

About D. Joy Riley MD, MA (Ethics)

Dr. Riley is executive director of The Tennessee Center for Bioethics & Culture and serves on the ethics committee of a Nashville-area hospital. Board certified in internal medicine, her writing and lecture topics include medical ethics, organ transplantation ethics, stem cell research, genetics, end-of-life issues and assisted reproductive technologies. With Scott B. Rae, she co-authored Outside the Womb: Moral Guidance for Assisted Reproduction, and with C. Ben Mitchell, Christian Bioethics.


  1. Avatar Ofelia Barletta-Chacon on April 16, 2021 at 12:08 am

    Science for hire is diabolic. There are other options to this. Try in vitro culture. Obviously, it is easy to suspect that his group went to China for help because they have no ethics, nor care for humankind.