o The life of the pig and its lung was published Wednesday in Science Translational Medicine. The organ did not exchange oxygen like normal lungs. But in the study, researchers demonstrated they could grow lungs that better recreate the intricate system of blood vessels than their bioengineered predecessors — a technical hurdle that has vexed scientists for years. Previous attempts at implanting bioengineered lungs in small animals like rats ended after the organs clotted with blood or swelled with excess fluid. We tried “replicating the exact nature of the milieu of the cells themselves when they are in the lung,” said Joaquin Cortiella, the senior author of the study and professor of anesthesiology at the University of Texas Medical Branch. “We wanted to produce something very similar to the real thing.”