Organ transplantation is one of the greatest achievements of medicine, but it faces a major problem, as the available human organs are not enough for the number of patients in need.
To solve this problem, scientists are working on using animal organs instead of human ones. This field, called "interspecies transplantation," has made new progress thanks to the world's first successful transplant of a liver and two kidneys from a pig to a human.
A team of scientists in China performed a complete liver and two kidney transplant from a pig into a deceased human (with the family's consent). Simultaneously, the deceased's own liver was harvested for transplantation into a living patient in need.
The pig's organs continued to function inside the deceased's body for five days, according to the study.
Until now, all organ transplants between humans and animals (whether from living or deceased donors) have involved only one organ at a time. Doctors had never before attempted a complete liver transplant with two kidneys simultaneously, because the more organs involved, the more complex the surgery and the greater the risk of complications. This procedure proved that it is possible.
In the past, attempts to transplant animal organs failed because the human body would immediately attack the foreign organ, a process known as immune rejection. But today, scientists are using advanced gene-editing technology.
In this case, six genes were modified in both the liver and the two kidneys used: some genes were disabled, and others were added to make the organ “human” enough that the body would not attack it.
After the transplants, the team analyzed the organs' functions and found they were closer to those of human organs than to those of pig organs. This means, according to the experts, that the human and pig liver and kidney systems are very similar physiologically and histologically.
However, some early signs of rejection appeared as early as 36 hours after surgery, in the form of an increase in a specific type of immune cell. Scientists say these cells could be targeted with specific drugs to reduce the risk of rejection in the long term.
The scientists emphasize that these results are based on only one individual, and that they followed the case for only five days, in accordance with the family's wishes regarding the burial. Therefore, further research involving a larger number of cases is needed.
The study was published in the scentific journal Nature .
