Researchers heal human lungs by attaching them to pigs

A new breakthrough from researchers at Columbia University could dramatically increase the number of lungs available for transplant.

One of the biggest challenges for lung transplants is that the organs can only survive for a short period of time. However, a new breakthrough aims to extend the shelf-life of donated lungs by attaching them to pigs. If successful, researchers believe it could increase the number of lungs available for transplant by a factor of three. It’s an unfortunate reality of lung disease that there are many more patients than available lungs. By connecting damaged or deteriorated lungs to animals, this breakthrough has the potential to significantly increase the supply of transplnt ‘fit’ organs, giving many terminal patients a fighting chance of survival.

The study by Hozain et al, shows that an experimental technique in which lungs are connected to the circulatory system of live pigs could repair damaged lungs intended for transplant within 24 hours [1].  

Currently, health practitioners try to recover lungs using ex vitro lung profusion which pumps air and fluid through the lungs. This can keep lungs stable and repair them a little, but it can only be conducted up a maximum of eight hours, which limits the time for repair functions to kick-in and recipient patients readied.

Severely damaged human lungs ‘can be successfully recovered for transplant’ (Credit: Ahmed Hozain and John O’Neill/Columbia Engineering)

The new approach from Columbia works in a similar way by maintaining the lung at body temperature and delivering a supply of oxygen. Researchers successfully repaired five damaged human lungs by connecting them to pigs including one which had failed to recover using EVLP. Immunosuppressant drugs were used to prevent the donor lung being rejected by the body. A sixth control lung was connected to a pig without the use of drugs.

“It is the provision of intrinsic biological repair mechanisms over long-enough periods of time that enabled us to recover severely damaged lungs that cannot otherwise be saved,” said the study’s lead authors, Ahmed Hozain (surgical research fellow at Columbia Engineering) and John O’Neill (adjunct associate research scientist at Columbia Engineering). [2]

Before moving on to transplanting the lungs into humans, the team wants to repeat the experiment with more samples. For all the benefits, the procedure carries a number of risks such as white blood cells from the pigs triggering dangerous immune reactions in human recipients.

Some lungs may also be beyond repair even with the surrogate pigs. However, as co-author Gordana Vanjak Novakovic told the New Scientist, “if you can salvage two out of every four that are rejected, you can increase the number of lungs available to patients by three times.” [3]

Human lung that failed on EVLP (left) and then recovered on cross-circulation (right). (Credit: Ahmed Hozain and John O’Neill/Columbia Engineering)

The procedure will also require medical-grade animals which will not be cheap. However, it is a demonstrable step toward xenotransplantation where organs from (predominantly) pigs can be transplanted into humans. One promising study using baboons shows that this can be successful [4].