Surgeons in China have brought a pig lung into a person for the first time. The body worked for nine days in a patient who had been declared brain death, according to the study published on Monday in Nature Medicine. After those nine days, the patient was taken from the ventilation at the request of the family and the experiment was terminated.
The lung transplantation is the latest scientific breakthrough in the field of exchanging organs between animals and people. Earlier hearts, souls and livers from pigs were transplanted to people. The scientists warn that after this first study much still has to be done before pigs were able to be transplanted to people safely and successfully in the future.
The patient, a 39-year-old man whose brains were irreversibly damaged by a brain haemorrhage, received the left lung from a pig that was specially bred for organ transplantation. These so-called Bama Xiang pigs have organs the size of human organs.
They grow up in a completely sterile environment, so that the organs are free from pathogens, and there is crafted on their genetic material. Three specific pig genes that can start a immune response in people have been disabled in these pigs, and three human genes have been added to prevent the risk of severe bleeding and the formation of blood clots after transplantation.
The patient, who also held a long lung, received a cocktail from medicines that oppressed his immune system in advance, so that his immune cells would not be too aggressively tackling the foreign organ.
Fluid in the lungs
The good news: the patient did not stop the organ right away and there were still no signs of infections after nine days. The researchers say that they have overcome two ‘large hordes’ that transplanted lungs from animal to person so far.
The bad news: the lung was damaged because in the second instance an immune response started against the organ. The immune response became stronger and stronger in the course of the days, but decreased slightly after day six. The immune -suppressing medicines were not the right or not enough, the researchers concluded afterwards. That should be better investigated in the future.
In addition, moisture in the lungs occurred in the hours after the operation and the oxygen uptake of the organ declined sharply. That is, the researchers suspect, due to a phenomenon that is common just after a lung transplantation, also known as ischemia reperfusion damage: in tissue that has not had a blood supply for a long time, inflammatory reactions and other harmful processes will start as soon as that blood supply is restored. It is also in patients who get a human donor lung the biggest reason for the failure of the transplant.
More infections
Lungs are more difficult to transplant from animal to human than, for example, a heart or kidney, because the chance of an infection is particularly high: the lungs are in direct contact with the outside world through the inhaled air, and therefore with all kinds of pathogens. The researchers call that the patient did not get any infection for nine days in this case a “crucial safety breakthrough.”
Conversely, the immune system in the lungs is extremely sensitive due to all the threat from outside. That also increases the chance of a rejection of a non-body-like lung than with other organs. Due to the severe immune response of the patient in the Nature-Study the body suffered considerable damage. The researchers even warn that this damage may be even greater in patients who do not have a long lung to compensate for the damage in the pig -long, as was the case here.
Heart valves of pigs have been successfully used for heart patients for about thirty years, but for entire organs that is a different story. To date, only one American patient is familiar with a working pork.