Bioartifical organs differ from, well, plain ol' artificial organs because they consist of biomaterials and cells. And while bioartificial livers are becoming increasingly commonplace, it's only recently that working lungs have been grown in a lab. Working at the Massachusetts General Hospital and Harvard Medical School in Boston, researchers removed the left lungs from rats and stripped them of cells with a process that left the blood vessels, airways, and connective tissues intact. Using all that as a sort of scaffolding, lung cells were regrown on the scaffolding in a bioreactor. The cultivation of the lungs took less than a week, and once they'd been run through their paces in culture, they were transplanted into rats. At this point, the lungs did their job for about six hours, after which "they failed through accumulation of fluid inside the lung and resultant capillary leakage," according to PhysOrg. According to the man in charge, Mass General's Harald C. Ott, if work continues at the current pace we might begin to see regenerated organs for human patients within the next ten years. To see the thing in action, hit up that source link.