No link between the patient’s death and the virus in question has been established so far, but doctors still want to know the end of the story.
Last January, the University of Maryland announced the first successful pig heart transplant in a human patient, hospitalized with end-stage heart disease which he had no chance of surviving, as he was ineligible for a standard transplant.
The person concerned unfortunately died two months after this first xénogreffe successful (see our post). Since then, the doctors who piloted the experiment have been trying to determine the exact causes of death to judge the relevance of this transplant. And by performing a heart scan, they determined that the transplanted organ was in fact harboring an animal virus.
No obvious link to the patient’s death
In this case, it is a porcine strain of cytomegalovirus, or CMV. They therefore tried to find out if this virus could have played a role in the death of the patient. After the transplant, he obviously remained very weak, but the surgeons explained that he had tolerated the operation well.
But a few days later, he began to show symptoms characteristic of an infection. Despite extensive examinations and a heavy course of antibiotics and antivirals, doctors were unable to reverse the trend. According to Bartley Griffith, the surgeon in charge of the operation quoted by the Associated Press, the heart continued to fill with fluids until it stopped working completely.
Still, doctors couldn’t find any traces of active infection afterward. There is therefore no evidence that this virus caused or even accelerated the process. “What could this virus have done – assuming it did anything – to cause these swellings? Honestly we don’t know”, concedes the specialist.
The preferred route therefore remains that of rejection of the graft. But this reaction is also not typical of a rejection, and therefore the mystery remains.
A crucial investigation for the future of xenografts
There is also another important question unanswered: where could this virus come from, when the pork came from an ultra-controlled sector where it was tested on numerous occasions?
It could therefore be a dormant virus, which means that it can travel from host to host without necessarily causing an active infection; this is called latent infection. These viruses therefore do not represent a threat as long as they remain in this state. But the situation can change under certain conditions, with potentially devastating consequences.
Researchers therefore continue to pay particular attention to these dormant viruses. At the moment, they are therefore working on the development of new, more sophisticated detection techniques. The objective:make sure you don’t miss this kind of virus”, said Dr. Muhammad Mohiuddin, director of xenografting at the University of Maryland.
In any case, it will be important to shed light on the exact circumstances of the patient’s death, even if the latter was obviously condemned. The conclusions of this investigation will be very important so that the rest of the researchers can repeat the experiment under better conditions. Because it is on the basis of work of this type that we may one day be able to revolutionize the supply of grafts; a new paradigm that could mean the difference between life and death for tens of thousands of patients awaiting transplants.