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Medicine Science

Pig Heart Transplant Failure: Doctors Detail Everything That Went Wrong (arstechnica.com) 61

An anonymous reader quotes a report from Ars Technica: Earlier this year, news broke of the first experimental xenotransplantation: A human patient with heart disease received a heart from a pig that had been genetically engineered to avoid rejection. While initially successful, the experiment ended two months later when the transplant failed, leading to the death of the patient. At the time, the team didn't disclose any details regarding what went wrong. But this week saw the publication of a research paper that goes through everything that happened to prepare for the transplant and the weeks following. Critically, this includes the eventual failure of the transplant, which was triggered by the death of many of the muscle cells in the transplanted heart. But the reason for that death isn't clear, and the typical signs of rejection by the immune system weren't present. So, we're going to have to wait a while to understand what went wrong.
[...]
After death, the team performed an autopsy on the transplanted heart. They found that it had nearly doubled in weight, largely because of fluid (and some red blood cells) leaking out of blood vessels in the absence of clotting. There was significant death of heart muscle cells, but that was scattered across the heart, rather than being a general phenomenon. Critically, most of the indications of a strong immune rejection were missing. The presence of an apparent pig cytomegalovirus was worrying, but the researchers indicate there's some question about whether the tests that picked it up might have been recognizing a closely related human virus -- one that's often associated with organ transplant problems.

So, for now, it's not clear what happened with this transplant or what the significance of the apparent viral infection is. Obviously, the team has lots of material to work with to try to figure out what went on, and there's a long, long list of potential experiments to do with it. And there are also additional xenotransplant trials in the works, so it may not be long before we have a better sense of whether this was something specific to this transplant or a general risk of xenotransplantation.

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Pig Heart Transplant Failure: Doctors Detail Everything That Went Wrong

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  • important step (Score:3, Informative)

    by TheMeuge ( 645043 ) on Saturday June 25, 2022 @08:11AM (#62649764)

    This is a very important line of research. Unfortunate that it went wrong, but I strongly believe that immunogenically humanized pigs probably represent the best chance we have of developing adapted organs for transplantation instead of relying on deceased donors. Given that human CMV can cause myocarditis, I can see how this may have come about. I hope that tools will be developed to allow for rapid alteration of immunological antigens in the pig embryo, allowing to grow a donor heart that will avoid risk of rejection and thus negating the need for immunosuppressive drugs in the future, possibly extending the lifespan of transplant recipients significantly, and increasing organ availability.

    • 3D printed organs from your own cloned cells are another prime candidate, though probably significantly further away for most organs - though I seem to recall some great success stories for relatively simply organs like bladders and ears (does the external ear count as an organ?).

      More complex organs like livers and kidneys though apparently have issues both with re-creating the complexity, and with maintaining their structure while incomplete - though it's believed that microgravity should help dramaticall

      • does the external ear count as an organ?

        I can't see why not. It has reasonably clearly defined functions (directing sound, even if that's vestigial in most humans; keeping dirt out with a complex shape) ; it's tissues are distinct from it's neighbouring tissues ; I can't think of any other parts of a definition of "organ".

        A popular trick question in quizzes is "what is the largest organ in the human body?", with popular answers being the liver, or the lungs (but rarely the brain). The correct answer is "th

        • I can't see why not. It has reasonably clearly defined functions (directing sound, even if that's vestigial in most humans.

          Known as the "auricle" it is not remotely "vestigial" in humans [wikipedia.org]. It performs very important and specific filtering operations to assist (for one thing) in interpreting speech sounds as well as in sound localization. If someone loses an auricle, it is not just cosmetic, it impairs their ability to hear quite significantly.

          • Agreed. We don't have swiveling ears for precise sound tracking like many mammals do - but what we have instead is is optimized for more omni-directional sound collection, and applying directional distortions that our brain learns to interpret as positional cues.

    • Better would be to grow or 3D-print the organ in a lab in a petridisch, so no animals are used. At least in the near future.
    • Maybe the pig heart suffered an infection by the same disease that the human had, which killed his own heart.
    • by gweihir ( 88907 )

      Well, for something like this it was a huge success that the patient made it for quite a while. Of course, there were a lot of unknowns so it was unlikely to be a longer-term success, but there was a chance and as long as the patient gives informed consent and has no other hope, I am fine with this. Also remember that this was a patient that did not qualify for a regular transplant, so the chances were pretty bad right from the start.

  • Somebody help me out here; I know it's an old movie, but I read the book. There was the cowardly lion, and there was the tin man. Was there a prequel?

  • Aren't we on the verge of having these things? Surely in the next few years, there won't be a need for transplanting organs from animals. We'll simply be able to clone or 3D print our own.
    • Surely not - if we are talking about living tissue. We don't have any sort of printed organ available yet, not even the lowest bar of a simple secretory organ, or replacement tissue layer. It is all research.

      A simple secretory organ, or other static structure (the auricle of the ear), would be candidates for near term availability but still years off.

      Despite one 3D printing advocacy site I found asserting that:

      "Contrary to what you might think, the heart is one of the most biologically simple organs in the body. It only has one function — to pump blood around the body. This should make it one of the easiest 3D printed organs to bioprint and transplant."

      This reveals a stunning level of ignorance and unfamiliarity with the actual difficulties in this

    • Why would anyone want a 3D Printed organ? Given the quality of what comes off most 3D printers, I wouldn't want that anywhere near my body especially replacing a critical organ.
  • This was not the first experimental xenotransplantation. One of the first was in 1984 [wikipedia.org].

  • What a prescient episode.
  • The first heart transplant patient dies 18 days later from lung infection and pneumonia.
    Things like this happen when doing things for the first time, ad I am sure the patient was informed of the risk.
    I just hope this doesn't needlessly slow down progress of this important technology.

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