Don't reach for the cigarettes yet, but human lungs have been created in the lab for the first time.

The reason you need to keep taking care of your current lungs is that the creation, while a big step forward, still leaves us a long way from being able to replace a malfunctioning organ. Perhaps unsurprisingly, construction of something so complex lags behind replacement tracheas , the second recipient of which is still alive five years after the operation

As with most organs, lung transplants are currently hampered both by the shortage of suitable donations and the body's immune response to anything it considers foreign. Artificial lungs built using cells from the recipient's own body would avoid the former problem and reduce the latter if not eliminating it entirely.

The lungs were created at the University of Texas Medical Branch (UTMB) using surviving tissue from badly damaged lungs of two children who had died. Cells from one lung were placed on a scaffolding of collagen and elastin left behind when most of the material of the other lung had been stripped.

After four weeks immersed in a nutritional liquid a lung was produced that is softer and less dense than normal human lungs. It's also a long way from being ready to be transplanted into a human body. The lung responds when air is pumped in, but it's still unknown whether it would work in a human body. "My students will be doing the work when I'm old and retired and can't hold a pipette anymore," says team leader Professor Joan Nichols, predicting it will be more than a decade before the work will save lives. Successful transplantation into animals will be required before anyone can even think about working on humans.

Still, progress is faster than it might have been. Growing the tissue was taking months until one of the student members of the team, Michael Riddle, created equipment that would accelerate the process out of an aquarium he bought at a pet store and worked on at home.

Even if artificial lungs are a long way off, the work may help speed progress on other organs. “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,” says UTMB's Dr Joaquin Cortiella.

Long before the first human recipient gets a lung made from their own cells grown on an artificial scaffold the work may produce superior testing grounds for disease treatments. “If we can make a good lung for people, we can also make a good model for injury,” said Dr. Nichols. “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.”