Scientists at the University of Texas Medical Branch in Galveston have succeeded in growing human lungs in the laboratory, using components from the lungs of deceased children.
Stem cell specialists have been working on growing lung tissue for some years, but the lung is a complex organ, which presents more problems than regenerating other organ tissue, such as human skin.
The University of Texas Medical Branch (UTMB) first announced their solution for growing lungs in 2010.
"In terms of different cell types, the lung is probably the most complex of all organs - the cells near the entrance are very different from those deep in the lung," UTMB researcher Dr. Joaquin Cortiella said at that time.
"People ask us why we're doing the lung, because it's so hard. But the potential is so great, and the technology is here. It's going to take time, but I think we're going to create a system that works."
"If we can make a good lung for people, we can also make a good model for injury," researcher Dr. Joan Nichols suggested, adding that:
"We can create a fibrotic lung, or an emphysematous lung, and evaluate what's happening with those, what the cells are doing, how well stem cell or other therapy works. We can see what happens in pneumonia, or what happens when you've got a hemorrhagic fever, or tuberculosis, or hantavirus - all the agents that target the lung and cause damage in the lung."
The 2010 research involved destroying the cells of rat lungs by repeatedly freezing and thawing and then "reseeding" the lungs with embryonic stem cells from mice.
Following that work up with similar but more large-scale experiments on pig lungs, the researchers now applied the same regenerative engineering principles to human lungs.
Human lungs grown in a 'fish tank' using cells from deceased children
Taking lungs from two children who had died from trauma (most likely a car accident), the researchers stripped one of the lungs down to a bare "skeleton" of just collagen and elastin - the main proteins in connective tissue.
The lab-grown lung before and after being reseeded with cells. Image credit: UTMB
Using this stripped-down lung as a "scaffold," they then harvested cells from the other lung, which were applied to the scaffolding.
This lung structure was then placed in a chamber filled with a nutritious liquid, which Nichols describes as "resembling Kool-Aid."
After 4 weeks of immersion, the team extracted a complete human lung from the liquid - "just pinker, softer and less dense." The team then successfully replicated the process using a second set of lungs.
It is UTMB's Dr. Michael Riddle who is credited with accelerating the procedure for growing the lungs, and he did so by improvising new equipment out of the most everyday of home furniture.
"He's the one who went home and actually built using - I'm not kidding - a fish tank that he went and bought from a pet store," Dr. Nichols says.
Can lab-grown lungs be used in transplants?
Lung transplants are often the only treatment for incurable lung disorders such as cystic fibrosis and chronic obstructive pulmonary disease (COPD). But successful lung transplants are rare, as finding matching donors is very difficult - many patients die while on a waiting list for transplants.
UTMB's work represents a landmark in regenerative engineering, but the reality of lab-engineered lungs being used in transplants could be at least 12 years away, Nichols says. The next phase of the research will be to test lab-grown lungs in pigs.
Although the science fiction-type nature of the research sounds incredible, UTMB were reluctant to announce their results. Indeed, the team grew the lungs a year ago, but the story has only just been picked up by the media.
"It's taken us a year to prove to ourselves that we actually did a good job with it. You don't run out immediately and tell the world you have something wonderful until you've proved it to ourselves that we really did something amazing," Dr. Nichols says.