by Anisha Rajaselvam
On January 7th, surgeons from the University of Maryland School of Medicine (UMSOM) successfully performed the first pig-to-human heart transplant. David Bennett, the 57 year old recipient, had ventricular fibrillation and advanced heart failure. His own negligence of high blood pressure and other health issues made him ineligible for a human heart, as physicians must deem a patient responsible enough to receive this extremely valuable human organ. Fortunately for Bennett, The UMSOM had been working with Revivicor, a company that creates modified pig hearts, for years. Successful experiments with pig hearts on baboons, and the fact that the consenting patient would have otherwise died, led to “compassionate use” authorization from the FDA.
Although his long term health remains unpredictable, Bennett is currently doing well in recovery. This medical achievement is a significant step in establishing a potential solution to human transplant organ shortages and related deaths.
Xenotransplantation: what it is, how it works, and why we need it
Transferring cells, tissues, or organs between two different species is described as xenotransplantation. The first heart xenotransplant was in 1964, when a terminally ill patient received a chimpanzee heart and died shortly after. A more famous case is that of baby Fae, the first infant patient to ever receive a heart xenotransplant from a baboon, back in 1984, but tragically passed away three weeks later. On the brighter side, 2021 saw the first successful pig-to-human kidney xenotransplants, and promising research is looking into lung xenotransplants.
Technology enabling xenotransplantation has come a long way since the 1960s. In this most recent heart xenotransplant, genetic engineering was used to address the problem of organ rejection. altered pig cells, which had four genes knocked out and six human genes knocked in, were used to create embryos that were raised in a heavily controlled environment. With the help of immunosuppressant drugs, the patient becomes less likely to reject the ‘disguised’ foreign organ.
Xenotransplantation has been heavily invested in because of the devastating shortage of human organ donations. In Canada alone, hundreds of patients on indefinitely growing waiting lists die waiting for a second chance that isn’t there. The ability to provide readily available organs to the critically ill would save the lives of many who would have had no other option than wait in vain.
The applications of this technology extends beyond just organ transplants. It could prove useful to people suffering from all sorts of conditions ranging from neurodegenerative diseases such as Alzheimer’s, where a cellular transplant will do, to skin conditions caused by burns, where whole tissues may be repurposed. While xenotransplantation is currently not prohibited in Canada, the United States and Great Britain have approved various clinical trials as a result of all these possibilities.
This sort of medical innovation is bound to undergo rigorous ethical debate. While the UMSOM team has received well-deserved praise for their groundbreaking accomplishment, there has also been heavy backlash from animal rights activists, some religious individuals, and other political figures.
First, there is the potential risk for the recipient. Xenosis, or human infection by viruses or bacteria derived from animals, can occur after xenotransplantation. Blood clotting around the site of xenotransplant is another possible postoperative outcome that must be avoided to keep the new organ alive. The high levels of immunosuppression required for xenotransplantation to be supported leaves the patient extremely vulnerable to infectious diseases and certain cancers. There is also, despite all efforts with genetic modifications and immunosuppression, the open possibility that the human body may reject the organ. These are just a few of the many dangers that patients face, but considering they may have no other option to survive, these risks can be outweighed by the benefits, such as in the case of Mr. Bennett.
Second, there is the issue of animal rights. On what basis should we validate the objectification of other living creatures? In other words, what makes a human life more valuable than that of any other being? While there is obviously no simple answer to these questions, crucial to scientific discourse as they are, some would argue they should be dismissed as unfounded and even hypocritical in the context of saving a human life. By no stretch of the imagination could we argue that we live in a world where animals are not already used for human material gain, most of these uses are much more trivial than that of extending a 57 year old’s life. On top of this, thorough ethical clearance for research projects must be obtained before working with animals. One tenet of such ethics boards is to ensure that excessive cruelty is avoided. There are legitimate and clear arguments on both sides, but one requires the reconstruction of our entire society in a way that many people, including some making those broad animal rights arguments, may not be prepared to accept. As long as we live in a world where pigs are slaughtered to fulfill hotdog cravings, saving human lives becomes a relatively easier case to defend.
Third, we have to acknowledge the cultural and religious objections to such procedures. A senior London rabbi and Egypt’s Dar al-Ifta have both expressed approval of the procedure. And while they obviously don’t speak for the personal opinions or beliefs of every individual Jew or Muslim, it does mean that there is some religious acceptance of the idea. There seems to be general consensus that human life remains the number one priority, even if it requires animal material. even if this isn’t the case for certain cultural or religious groups, there is nothing forcing individuals of those groups to participate. Any objections can therefore be separated from the choices made by suffering patients with no alternatives. While everyone has the right to not support xenotransplantation for their own reasons, they arguably don’t have the right to impose that belief on others, and by extension, impede ongoing research in the field.
Finally, there are more abstract objections to genetic engineering and the specific process of xenotransplantation as a whole. This sort of experimentation has led us to question the extent to which we have the right to ‘play God’. Is the intentional creation of an intricately designed life (such as that of a genetically modified pig), just to kill it for our benefit, ever morally justifiable? If we consider the protection of human life the most important obligation in medical science, what can we get away with? General concerns around genetic technology are important to impose some pressure for transparent and effective ethics policies. As we simultaneously advance technologically and navigate the moral grey, there will be a continuous, conscious, and collective effort to uphold ethical duties while moving forward in medicine.
There has always been controversy around innovation, and no one person has the right to decisively establish which side, if any, is right. But at the end of the day, the UMSOM team saved the life of a man who would have otherwise died of heart failure using cutting edge technology. Regardless of where the event lands on the moral spectrum, it seems worth talking about.