The first foreign transplant of the human heart: a milestone in medicine, whether it was successful or not

Author: Dr. Triana Abel Encarnacion

Earlier this week, news broke that surgeons at the University of Maryland had performed a heart transplant. This heart transplant was different because it was the first with pig cells to be performed in a patient. As a last hope, after being ineligible for a donor heart, 57-year-old patient David Bennett had two options: undergo an experimental procedure or never know what would have happened.

Its donor, a pig, was genetically modified to be compatible with changes in its genome to have a heart size similar to the recipient’s heart and introduced four human genes to modulate the immune response to accept this new tissue. In the three stages of transplant rejection, we can say that this patient is past the hyperacute stage, and it is still necessary to monitor how the patient reacts to the following acute and chronic stages, both of which are important to consider the triumph of this procedure.

It is essential to remember that although this is the first heart transplant, it is not the first transplant of heart tissue. Since the 1960s, during the development of mechanical heart valve prostheses, biological prostheses appeared, a less thrombotic option that avoided being at the mercy of aggressive treatment with anticoagulants. Among these biological prosthetics, the most successful today are those of porcine origin preserved with glutaraldehyde and containing antimetallic substances that delay the calcification process. Moving heart valve transplants to the traditional method was a process that took several decades and is still in development, which means that something similar awaits humanity with organ transplantation, with the difference that in 2020 we know the human genome and we have CRISPR-Cas9 technology.

More than 600,000 people in the United States have end-stage heart disease. Most of these die off waiting lists because they are ineligible for a transplant or cannot find a compatible donor. Although this procedure has yet to yield results on its long-term impact on a patient’s quality of life, it is “the blueprint” that brings hope to the thousands of families who no longer have it. We hope this achievement will mean a shift in access to implants, not only in the United States but worldwide.