First Working Replacement Lung Created in Lab

Ker Than in National Geographic:

For the first time scientists have reconstructed working lungs in the lab and transplanted them into a living animal.

The achievement is a breakthrough in biomedical engineering that could lead to replacement lungs for humans in the near future, experts say.

Currently, the only way to replace diseased lungs in adults is a lung transplant, a high-risk procedure that's vulnerable to tissue rejection.

In a new study, researchers took lungs from a living rat and used detergents to remove lung cells and blood vessels, revealing the organ's underlying matrix.

This lung "skeleton"—made of flexible proteins, sugars, and other chemicals—consists of a branching network that divides more than 20 times into smaller and smaller structures. (See an interactive graphic of lung structure.)

The researchers placed these "decellularized" lungs into a bioreactor, a machine filled with a slurry containing different types of lung cells extracted from rat fetuses.

Within several days, the fetal cells naturally attached to the lung matrix and formed a functional lung.

"By and large, the correct subsets of cells went to their correct anatomical locations," explained study leader Laura Niklason, a biomedical engineer at Yale University. "It appears that the lung matrix has cues, or 'zip codes,' that tell the cells where to land."

When the team implanted the engineered lungs into an adult rat for short periods of time—between 45 minutes and two hours—the lungs exchanged oxygen and carbon dioxide in the same way as natural lungs.