A group of researchers from the University of Texas Medical Branch were able to construct bioengineered lungs and transplant them into adult pigs with no medical complications. This technique could possibly be used in the future to respond to the shortage of organs for transplantation.
As reported in Science Translational Medicine, the team built these viable lungs from the scaffolding of a donated organ. The donated lung was from an unrelated pig and was cleaned with a mixture of sugar and detergent to eliminate all the blood and cells, leaving just the scaffolding proteins behind.
The team then bioengineered this structure by placing the scaffolding in a tank filled with nutrients, with the recipient animal's own cells added to the mixture. The lungs were grown in a tank for 30 days and then transplanted. The animals were studied at different times after the transplant. There were no signs of rejection, even without using immunosuppressants. Already at two weeks, the bioengineered lung had integrated itself into the blood system and was colonized by the bacteria that make up the natural biome of the lung.
“The vascular system of the bioengineered lung connected to the vascular system of the animal and there was no leakage of blood in the vessels of the bioengineered lung,” lead author Dr Joan Nichols told IFLScience. "Animals also survived and did not have any indications of respiratory distress. There was also no rejection of the bioengineered lungs."
The obvious interest of this research is how this translates into medical applications for human transplants. The team led by Dr Nichols has already approached the problem of human lung scaffolding (here and here) for both adults and children.
“In these studies, we talk about producing human lungs using human scaffolds," Dr Nichols explained. "We discard large numbers of lungs each day that do not meet the requirements for transplantation. These can be used to produce scaffolds or, if there are still cells, we can bank the lung and vascular cells from these lungs to bioengineer new lungs."
But the road to these kinds of transplants in humans is still a long way away. The team is currently planning its next stage of investigations to confirm that this approach is safe in the long term.
“The next step is a long-term survival study where 10-15 pigs are given one bioengineered lung using this procedure and then they are sent back to the farm for a year.” Dr Nichols stated. “After 6 months to a year, we can bring the animals back, anesthetize them and block off their normal lung, forcing them to breathe and oxygenate using only the bioengineered lung.”