A big step forward in the field of transplants comes from China. For the first time, in fact, a pig liver has been implanted in a living patient suffering from a liver tumor too serious to justify a conventional transplant. And the operation can be considered, at least in part, a success: the patient, destined to die shortly at the time of the transplant, survived for almost six months after the operation. And although death still occurred in the end, the experiment made it possible to collect extremely important data to make liver xenotransplantations a clinical reality in the future.
The solution to the lack of donors
Xenotransplants (transplants of animal organs in our species) is a field that has only really begun to take its first steps in recent years. But it has already achieved good results in the case of the heart and kidneys. The liver, however, is a more complex organ: it does not simply pump blood or filter urine, but secretes fundamental substances for a myriad of processes in our organism. And it is therefore more difficult to think of being able to replace it with that of another species. Achieving this, obviously, would be of extraordinary importance: the liver is one of the organs that are transplanted most often throughout the world, and given the chronic shortage of organs coming from donations, many patients die every year waiting for a transplant.
The procedure
Until now, the procedure had only been attempted on brain-dead patients, to test how compatible the pig organ was with human physiology. Researchers at the Affiliated Hospital of Anhui University, China, instead subjected a 71-year-old man suffering from hepatitis B cirrhosis and hepatocellular carcinoma to the procedure: he needed a new liver to survive, and quickly.
The patient agreed to undergo the experiment, and as described in a study just published on Journal of Hepatologyunderwent surgery to remove a large part of the liver affected by the tumor, and replace it with an organ from a miniature pig, generically modified to reduce the risk of relapses, and make the organ more compatible with human physiology.
A partial success
For about a month after surgery, the porcine liver functioned effectively: it produced bile, synthesized clotting factors, and maintained the patient’s metabolic parameters without signs of acute rejection. However, after 38 days, a serious complication forced the removal of the graft. However, the man survived for another 133 days, showing reasonable liver function, before dying due to recurrent bleeding in the stomach, which the researchers say may not have been caused by the pig’s organ, but rather by previous damage suffered by the patient’s liver.
Regardless of the cause of death, the man survived for six months from the time of the transplant, and this is considered at least a partial success by Chinese doctors. The patient’s liver also appears to have partially regenerated during the month the implant remained in his system, which is likely why he was able to survive another five months after it was removed. This detail is interesting and could show an alternative path for liver xenotransplantation: the possibility that it helps heal the original liver could make it perfect as a bridging solution for patients waiting for a human organ to become available.
The data collected during the experiment will be invaluable in making pig transplants a concrete alternative to those from human donors in the future. However, the Chinese researchers warn that the road is still long: at least another ten years of research will be needed before turning liver xenotransplants into a clinical reality.