Dr. Eggman writes "Nature Medicine brings us news of the latest success in the regeneration of the gas exchanging tissues [abstract is free; the full paper requires subscription or payment] of the lungs of a rat. Led by Harald C. Ott, researchers from Massachusetts General Hospital and Harvard Medical School in Boston used decellularization to produce a cellular scaffolding to serve as the basis of the transplant lungs. You may recall the previous achievements in use of this cellular scaffolding technique by Yale University. This latest announcement comes with the excellent news that the rat's airway and respiratory muscles performed the necessary ventilation (as a normal rat's would), and that they provided gas exchange for up to 6 hours after extubation, up from the previous 2 hours. They eventually failed due to capillary leakage resulting in the accumulation of fluids in the lungs. Although there's much work to be done, as not all the cell types found in the lung were regenerated, Ott and his team remain optimistic and estimated we might see regenerated organs for use in human patients within 5 to 10 years." PhysOrg has videos of the lungs doing their thing.