Xenotransplantation

January 21, 2022

Hidden in the middle of the front section of my local paper this morning I came across an article on xenotransplantation.  Xenotransplantation refers to putting live tissue or organs from a non-human animal source into the human body.  Pigs have long been considered a potential source for transplants as the organs are similar in size to human organs, but rejection by the host has always been a problem.  Recent advances have allowed genetically engineered pigs to provide a heart for a man in Baltimore last month and two kidney transplants last September were given to different brain-dead recipients.  The development of xenotransplantation is primarily driven by the demand for human organs for clinical transplantation.  Currently 10 – 20 patients a day die in the US waiting for an organ transplant.

When I looked online, I found from early 2000 the introduction of Gal-knockout (galactosyltransferase) pigs, has made prolonged survival possible in heart and kidney xenotransplantation.  However, the remaining antibody barriers to non-Gal antigens continued to be a hurdle.  The production of genetically engineered pigs was difficult and required a long time.  Recent advances in gene editing have made the production of genetically engineered pigs easier and more available, and clinical trials have received an international consensus.  Although the potential benefits are considerable, xenotransplantation has raised concerns regarding the potential for infection of recipients and possible subsequent infection into the general human population.  Of public health concern is the potential for cross-species infection by retroviruses, which may be latent and lead to disease years after infection.  Who would believe cross-species viral infection could ever happen?

A related article reported the man who received the pig-heart xenotransplantation once stabbed a man leaving him paralyzed.  The victim’s sister told the BBC’s Today show she thought the recipient was unworthy of the surgery.  The transplant team said a person’s criminal past could never be grounds for refusing treatment.  The University of Maryland Medical Centre said, “It is the solemn obligation of any hospital or health care organization to provide lifesaving care to every patient who comes through their doors based on their medical needs.  Any other standard of care would set a dangerous precedent and would violate the ethical and moral values that underpin the obligation physicians and caregivers have to all patients in their care.”  The attack took place in April 1988 and the man was found guilty of battery and carrying a concealed weapon and was sentenced to 10 years in prison.

Thoughts:  While the xenotransplantation of a pig heart was reported on the national news, the kidney xenotransplantation came to light months later after it was published as a scientific paper.  The heart prolonged the recipient’s life, but the kidney transplants were considered test trials as both recipients were clinically dead.  Most human transplants involve death, but xenotransplantation is growing and harvesting the organs.  Organs are given according to strict rules that consider physical matching, tissue and blood type matching, medical criteria, waiting time, and severity of illness, and is blind to name, race, sex, and wealth.  Two principles determine who gets a transplant: (1) urgency, the sickest or most likely to die are prioritized, and (2) effectiveness, organs go to those with the greatest chance of success.  This clearly requires consideration of the “ethical and moral values” of the administrators.  Follow the science.  Do the work.  Change is coming and it starts with you.

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