- Organ donation is life-saving, but besides a lack of donors, lungs from donors can also be unsuitable for transplant
- A new experiment connected damaged lungs to the blood supply of a pig
- The lungs were revived within 24 hours
Organ donation has saved and prolonged many lives, but it can be a race against time to ensure that donated organs reach the patient before deterioration sets in.
By the time organs are obtained from the deceased, the team may also discover that there is already significant damage (whether from injury or underlying illness) and that those organs are not fit to be transplanted.
Most donated lungs can only “live” outside a body for a couple of hours. And even then, they might have deteriorated so much that a safe transplant cannot be guaranteed. According to the American Lung Association, only 28% of donor lungs fit the criteria. But now, researchers at Columbia and Vanderbilt have managed to revive six damaged lungs within 24 hours. Their solution? Blood supply from a pig.
Not a large enough donor pool
Currently, many patients across the world are awaiting lung transplants. Severe lung damage caused by Covid-19 might increase those numbers.
Even with willing organ donors, the criteria for donor lungs are extremely strict. Dr Gordana Vonjak-Novakovic from Columbia University in New York have been pondering about how to grow the pool of potential donors for a while. This led her to investigate whether lungs would do better if they were immediately attached to a living blood supply, where vital nutrients can be delivered and harmful substances reduced.
Revived after 24 hours
Vonjak-Novakovic and her team obtained previously rejected lungs from six human donors (both single lungs and pairs). These lungs were badly damaged already – one lung failed even after being connected on an EVLP (ex vivo lung perfusion) device for five hours.
They then connected the lungs to the circulatory system of an anaesthetised live pig for 24 hours with tubes that “fed” the human lungs with blood from the blood vessels in the pig’s neck. The pig’s circulatory system also contained immunosuppressant drugs to prevent any “foreign” tissue being rejected by the immune system.
According to Vunjak-Nokavic, the lungs were already filled with fluid and already turning white, suggesting that the cells and tissues were dying. But after 24 hours of being connected to the pigs, the lungs started to look healthy, even though one of the lungs had already been outside a human body for two days.
“My expectation would be that that lung would be destroyed, but actually it doesn’t look like that at all. [The lungs] are not 100% normal, but they’re close enough,” she said.
The findings of this experiment were published in the journal Nature Medicine.
Would this be a viable method for the future?
Even though the lungs looked “normal enough” to use in a transplant in theory, the experiment needs to be repeated with several more lungs before this would be considered as an option in clinical practice.
Currently, the goal is to be able to revive lungs using a human blood supply, instead of that of pigs. Vunjak-Novakovic does state that medical-grade pigs should be used, as there will be a decreased risk of pathogens that could be transmitted to people and make them ill. And even though medical pigs eliminate the risk of pathogens, the lungs in the experiment still contained some white blood cells from pigs, which could potentially cause an unwanted immune response.
But despite this, experts are optimistic that it is a start. “If there were a way to use even 40% of donated lungs for a transplant, instead of the current 20%, the waiting list for lungs could be eliminated,” stated Dr Matthew D. Bachetta, lung transplant surgeon at Vanderbilt, and one of the lead authors of the paper, in the New York Times.
“This paper really demonstrates that it [the experiment] probably does and can work,” Dr Baschetta said.
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