The team accomplished this by creating a lung scaffold from the organ of another animal using both detergent and sugar to wipe out all the cells and blood -- only the proteins were left. After that, they immersed the scaffold in a tank filled with nutrients, and added the pigs' own lung tissue cells using a "carefully designed protocol or recipe." It took 30 days to foster the organs before they were ready for transplants, but they didn't need infusions to keep working.
There's still a while to go before human transplants are an option. In addition to the question of functionality, long-term viability is also a concern. The scientists only tracked the progress of the organs for two months, or just long enough to spot immediate trouble. They'll need more studies to see how the lab-made lungs fare years down the road. Even so, the research group believes it could grow human-ready lungs in the next five to 10 years. That could prove invaluable to hospitals, which could end shortages of viable organs and improve their long-term transplant survival rates.