The public is numb to claims of scientific breakthrough because the term is so overused. False claims of breakthrough are used to market products and treatments that are not very good. It's difficult to know when an advance is a breakthrough and will change the world in a significant way. We can't really know in the future. I am going to go out on a limb and say that this is a significant step, if not a genuine breakthrough.
David Bennett received a heart transplant from a pig. This is a technology that we have been anticipating for a long time, and it is not ready for prime time yet, but the first such bio engineered xenotransplant in a living recipient definitely crosses an important line. I think this is a first test-tube baby type moment.
The pig heart was provided by a company. They made news last summer when they provided a pigKidney to connect to a human recipient. The recipient was brain dead and the only thing they had left was their blood supply. This is a pre-clinical study to determine if the kidneys will be rejected. It worked, making urine and filtering blood. The safety test lasted 54 hours.
The pig heart that David Bennett received from Revivicor had ten genetic modifications, four of which were silenced, three of which were to reduce rejection, and six of which were human genes. Modifications are used to make the pig's immune system more like a human's, so that the recipient's body won't reject them. The strength of immune rejection depends on how close a genetic match the donor and recipient are. Genetic matching is important in the human species. The goal is to make the pig donor's immune markers closer to that of a human.
Bennett is getting an anti-rejection drug that will suppress his immune system. The drug was developed by Kiniksa Pharmaceuticals and the director of the University of Maryland School of Medicine who did the surgery. The technique of adapting the pig heart to the human system was developed by Bartley P Griffith. This operation is a triple experiment, testing the viability of the genetically modified pig heart, a new anti-rejection drug, and the surgical techniques used to adapt a pig heart to a human. The FDA gave emergency use authorization for the entire procedure on December 30th.
Bennett had terminal cardiac arrhythmia and was being kept alive on a heart machine, which is why the FDA cleared the experimental treatment. He had exhausted his treatment options and was not a candidate for a human donor, so he had to have an experimental procedure or die. What does his treatment mean for the future?
There is a great unmet need for organ transplants. In the US alone, more than 100,000 people are on the waiting list for an organ, and 17 of them will die before they can get that organ. The ability to make or grow organs would be a game-changing technology. The technology that seems to have the greatest chance of success is the use of non-human donors. Several companies are working on this technology. George Church, a Harvard geneticist, co-founded eGensisis, a company that is developing bio engineered pigs for organ transplantation.
The learning curve is steep for a technology that is still very experimental. This research can be done many times more quickly thanks to the use of genetic modification technology. Bennett received a pig heart, which is a non-human organ, and it is likely that we will see more elaborately engineered non-human organs in the future. It is possible that such genetic tinkering can go beyond making humanized donors, to tweaking the genetics to be a match for a specific donor. Human donated organs may be superior to bio engineered organs in the end.
In cases such as Bennett where all other options have been exhausted, such transplants will remain in the realm of experimental use. Once the technology is established, they will likely be approved for general use. This technology will change the world of organ transplantation. Incremental improvements will make the technology better. The approach of non-human organ donors allows science to ride the wave of genetic technology.
The usual pushback from predictable ideological groups will likely occur. Some will question the ethics of donating animals. We already grow over 100 million pigs every year to slaughter for food, and growing even a million extra to save lives doesn't feel like an ethical line. There will be a luddite response that such treatments are not natural or violate some natural code. I think these objections will have the same effect as protests against in-vitro fertilization. Demand for this technology will overwhelm criticism once it starts saving lives.
Steven Novella is an academic clinical neurologist at the Yale University School of Medicine. He is the host and producer of the popular weekly science show, The Skeptics' Guide to the Universe, as well as the author of the daily neuroscience news and opinion website, the Neuro LogicaBlog. The Skeptics Guide to the Universe was published by Dr. Novella, as well as two courses with The Great Courses.
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