Repair of donor lungs
The damaged lungs were restored by connecting with live pigs
Sergey Vasiliev, Naked Science
For patients with advanced lung diseases (including severe forms of Covid-19), it is extremely difficult to find a replacement for a transplant. As a rule, donor organs themselves are too damaged, and doctors have only a few hours left to use them. During this time, they can be preserved, for example, thanks to the ex vivo pulmonary perfusion method, when the lungs are placed in a sterile box, connected to pumps, fans and filters, pumping a solution saturated with oxygen and nutrients through them. This allows you to maintain vitality for several hours and even slightly correct impaired lung functions.
However, doctors from Columbia University have found a new unusual way that allows not only to preserve the lungs longer, but at the same time to restore them by connecting them to the circulatory system of a live pig. "The use of biological recovery mechanisms," says John O'Neill, one of the authors of the work, "allows us to repair seriously damaged lungs that cannot be saved in other ways." The article by O'Neill and his colleagues was published in the journal Nature Medicine (Hozain et al., Xenogeneic cross-circulation for extracorporeal recovery of injured human lungs).
Previously, scientists have already demonstrated that pig lungs, "connected" to the circulatory system of another pig, not only remain viable for several days, but also restore lost functions under the action of the animal's own repair mechanisms. Now similar conclusions have been confirmed for human lungs. The authors conducted experiments with six donor organs that were rejected during transplantation and became unnecessary, including one with severe damage that could not be repaired by conventional perfusion.
These organs were connected to the circulatory system of live pigs under deep anesthesia, five of which also received immunosuppressants so that the immune system would not attack the lungs associated with them. The sixth pig was not injected with these drugs, using it as a control. The scientists left the blood circulating for a day, monitoring the physiological parameters of the donor organs. As one might expect, the "control" lungs did not last long: soon they developed inflammation, blood clots and all other signs of rejection. But the dynamics of the other experimental organs looked much better.
Partial restoration of a severely damaged lung connected to the circulatory system of a live pig / ©Hozain et al., 2020.
Despite the fact that all of them were already damaged, their functions were quickly restored. This was especially evident in the case of the most damaged lung. This organ, extracted from the donor, remained on ice for more than 22 hours, underwent five hours of ex vivo perfusion, after which the right lung was successfully transplanted, but the left lung was recognized as too badly destroyed, and the transplant centers refused it. However, a day of experimental "therapy" did the impossible with him: the half-dead organ began to recover.
The authors emphasize that the innovative technique is still far from clinical application and should be considered more as a demonstration of the approach. The animals needed for such a procedure must be special, laboratory, which makes such treatment even more difficult and expensive. But perhaps scientists will be able to develop this method: for example, to learn how to connect the lungs with the circulatory system of the very future recipient for preliminary "adaptation" and recovery.
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