David Bennet Sr, the 57-year-old American man who received a ground-breaking heart transplant from a pig died of a pig virus, his transplant surgeon has said.
The surgeon, Bartley Griffith, who led the transplant revealed this at a webinar hosted by the American Society of Transplantation.
Bennet, a handyman who suffered from heart failure, had in January received a heart transplant from a genetically modified pig at the University of Maryland medical Centre.
But two months after the surgery, Bennet died. The hospital had initially said that his condition had worsened over a few days but did not provide an exact cause of death.
But speaking at the webinar, Griffith said that the pig’s heart was infected with a porcine virus known as porcine cytomegalovirus, which may have contributed to Bennett’s death.
According to a report by The Guardian (UK), Griffith was quoted as saying “We are beginning to learn why he passed on. “(The virus) maybe was the actor, or could be the actor, that set this whole thing off.”
“If this was an infection, we can likely prevent it in the future,” Griffith said during the webinar.
Griffith also noted that “the biggest challenge in animal-to-human organ transplants is the resilience of the human immune system, as it can attack foreign cells in a process called rejection and trigger a response that will ultimately destroy the transplanted organ or tissue.
“As a result, companies have been biologically engineering pigs by removing and adding various genes to help conceal their tissues from potential immune attacks.
“The heart used in Bennett’s case came from a pig that underwent 10 gene modifications carried out by Revivicor, a biotechnology company.”
Griffith and his team had frequently monitored Bennett’s recovery through various blood tests.
In one of the tests, doctors examined Bennett’s blood for traces of various viruses and bacterias and found a little blip that indicated the presence of porcine cytomegalovirus.
However, because its levels were so low, the doctors assumed that the result could have been an error.
Griffith also said that because the special blood test was taking approximately 10 days to carry out, doctors were unable to know that the virus was already beginning to multiply rapidly.
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This, experts say, may have triggered a reaction that Griffith now believes was likely a ‘cytokine explosion,’ a storm of exaggerated immune response that can cause serious issues.
On the 43rd day of the experiment, doctors discovered that Bennett was breathing hard and warm to the touch.
“He looked really funky. Something happened to him. He looked infected,” said Griffith, adding, “He lost his attention and wouldn’t talk to us.”
According to The Guardian report, in attempts to fight Bennett’s infection while keeping his immune system under control, doctors provided him with intravenous immunoglobulin as well as cidofovir, a drug sometimes used in Aids patients. Bennett displayed signs of recovery after 24 hours before his condition worsened again.
“I personally suspect he developed a capillary leak in response to his inflammatory explosion, and that filled his heart with edema, the edema turned into fibrotic tissue, and he went into severe and non-reversing diastolic heart failure,” Griffith was quoted to have said at the webinar.
