The idea of using animal cells, tissues, and organs in human transplantation efforts — today known as xenotransplantation — is an old one. In the 1600s, French doctor and physician to King Louis 14th of France, Jean-Baptiste Denys, began transferring blood from lambs into people. Remarkably, this didn’t always prove fatal, and we know that a 15-year-old boy survived this procedure. Others, however, were not so lucky. Eventually, Denys was banned from performing further experiments by a French court (with the backing of the Paris Faculty of Medicine), and then by the French Parliament. Following France’s lead, the British government banned such transfers shortly after.
In the 1900s, several attempts to cure people’s ills using animal materials were attempted, to varying degrees of… well, success isn’t the word; let’s say not failure. Serge Voronoff thought xenotransplantation could cure aging and its associated effects on men’s sex drives. His method involved implanting bits of monkey testicles into the scrotum of willing participants in the hope of restoring those men’s lost vigor. John R. Brinkley tried a similar procedure, but rather than use monkey tissue, he would implant bits of goat testicles. Voronoss and Brinkley made a lot of money from offering these procedures, with the latter going on to have a modestly successful career in radio and politics.
However, not all modern attempts at xenotransplantation involve the restoration of sexual vigor. In 1963-64, surgeon Keith Reemtsma conducted thirteen chimpanzee-to-human kidney transplants. None of these were what we’d probably call successful, with no patient surviving beyond nine months. Most died shortly after the operations, but the fact that a reputable surgeon even tried them was remarkable.
Then there was the case of Baby Fae, who, having been born with hypoplastic left heart syndrome, in 1984, received a baboon heart in a last-ditch attempt to save her life. Fae survived the surgery but died 21 days later. While failing to save her life, this single operation, conducted at Loma Linda University, changed the perceptions of xenotransplantation. No longer was it the preserve of quack scientists or charities hoping to find fame and fortune. Instead, it was a theoretically possible solution to one of the biggest problems within medicine, both then and now — the organ shortage crisis.
Now, xenotransplantation is not a new subject here at The Prindle Post, with Goodwine and Arnet having written about it before. But, given the advancements that have been made in the practice over the past couple of years, I wanted to draw the Post back into the xeno-world.
Arguably, the most significant change in the past few years has been the success rate. Gone are the days when fringe scientists (or pretenders to the title) would implant whichever bit of animal they thought would cure whatever problem the patient in front of them had. Today, it is gene-edited pigs that provide the bulk of organs being used by researchers and surgeons. These pigs, raised in clinical conditions to control for variables, have their genetics altered so that, when an organ, like a kidney, is removed from them and put into a person, that person’s immune system doesn’t immediately reject the transplanted organ. And, while this practice is still very experimental and most often performed on compassionate grounds, it has started showing results.
To illustrate the rapid pace of development in this field, let’s look at two cases that, while relatively close in terms of time, are fields apart in terms of results.
On March 16th, 2024, 62-year-old Richard “Rick” Slayman underwent surgery to receive a kidney from a genetically altered pig. Slayman had been suffering from end-stage kidney disease, which meant that he had to regularly undergo dialysis. In addition to this, he also had Type 2 diabetes and hypertension and had previously received a transplant from a human donor in 2018. However, this organ began to fail five years after implantation. So, in a last-ditch effort to save his life, and knowing that his actions could help future generations of people who may find themselves in similar predicaments, he underwent the experimental procedure. At first, things seemed to go well, with Slayman no longer needing to be in dialysis as the new kidney began to function. Sadly, however, on May 12th, 2024, Slayman died; less than two months after surgery. A recent paper in the New England Journal of Medicine claims that Slayman died of cardiac causes and that there was evidence of organ rejection.
Fast forward to January 26th, 2025, and Towana Looney becomes the world’s longest-surviving xeno-graph recipient. Like Slayman, Looney needed a new kidney but had exhausted all other options. She, however, was lucky in that others, like Slayman, had gone before her, and the procedures that they underwent provided knowledge that Looney’s surgical team could learn from to improve her chances of survival. As far as I’m aware, Looney is still alive. This change signifies a remarkable change in outcomes in less than a year. And if the hype is to be believed, similar organs could one day be rolled out to those who need them. Indeed, the US Food and Drug Administration (FDA) has been so swayed by these compassionate applications of xenotransplantation that, earlier this year, they gave the green light for the United Therapeutics Corporation to begin clinical trials. This regulatory approval marks a notable change in circumstances and perceptions from the days of Denys, Voronoff, and Brinkley.
But it is not all sunshine and rainbows with xenotransplantation. Putting aside the significant additional suffering that pigs must endure to be suitable for our needs, substantial risks come with rolling out this biotechnology, much like there are with them all.
For my part, one of the biggest concerns is the perverse incentives businesses will have to maximize profits when it comes to producing these genetically altered organisms. Once large corporations start to profit from the production of pigs for xenotransplantation, they will be highly resistant to change their practices for any other reason than the securement of more profit. Any bad practices that get baked into the system at the early stage will be problematic to modify unless there is a saving in dollar form for the companies producing these organisms. This, in turn, will make it difficult for any issues regarding animal welfare, present at this sector’s genesis, to be purged. If this position is a little too pessimistic for you, I would urge you to look at the farming sector and the incredible efforts it takes to make only the smallest changes, which, while improving animal welfare, harm corporate profits.
Businesses exist to make money, and they resist anything that will prevent them from doing so as efficiently as possible. In the context of xenotransplantation, once companies start to make money from rearing pigs and selling their organs, they will resist changes that might hurt their bottom dollar, even if such a change is better for the pigs or even everyone else. A similar pattern can be seen in other areas of the health sector, where multinational conglomerates lobby lawmakers to enact policy decisions and changes which, while having broad appeal, would constrain those companies from making as much money as possible. As noted in a paper by Bobier, Merlocco, Rodger, Hurst, and myself:
the pharmaceutical industry spent hundreds of millions of U.S. dollars to try and prevent the passage of the Inflation Reduction Act of 2022, which allows Centers for Medicare and Medicaid Services to negotiate drug prices, regulate insulin prices, and cap out-of-pocket spending for Medicare recipients, all of which would promise to reduce national health spending and help individuals afford health care.
Ultimately, while xenotransplantation would likely prove hugely beneficial for those needing the organs, it could act as a barrier to further, more systemic changes necessary for the betterment of all. After all, while it would be great to meet the organ shortage, it would be even better to identify why so many organs are necessary and solve the issue at the cause. However, doing so would likely impact the interests of the companies that stand to gain from xenotransplantation’s rollout.
So, then, the question I want to leave you with is this: is it better to use xenotransplantation to meet the organ shortage crisis and save countless lives, or would we be better served by trying to deal with the socio-economic, political, health, and environmental factors that mean so many of us need organs in the first place? The latter may seem like the correct choice, but as the stories of Slayman and Looney illustrate, it’s far easier to change the nature of an organ than it is the churn of our economic system.