NPR interviews Paolo Macchiarini, who leads the group working on transplanted tissue engineered tracheas: "How was the scaffold for the synthetic trachea built? Well, basically, by the same fibers that everybody of us has, nanofibers; very, very small fibers that are composed and native to the human trachea. So when we wanted to transplant this organ, we thought what is best. And the best would be to just replicate what human nature has done. And this is the reason why we use these very thin fibers. ... So I imagine you could try to do this with other organs in the body, other things. ... Well, we are starting to learn what happens with this still experimental therapy. So I'm not so pessimistic to try to do the same with other tissues or organs. And since I'm a thoracic surgeon, I deal with organs of the chest. So I would think of the esophagus at the chest wall, at the liver - at the lung, and eventually at the heart. Yes. ... depending on the degree of difficulty of the three dimensional aspect of the tissue, you can produce a trachea, for instance, just the tube, in two days. And a bifurcated trachea in 10 days. So now - then you need two days for getting the cells, reseeding the grafts, or in two weeks you have an entire trachea. ... And perhaps you might extend your work further, because you deal in this and possibly into the lungs. ... Well, ideally, yes. But to me my dream would be another one. It would be rather than replacing the lung or replacing the heart, you use cell therapy to treat these organs before they ultimately do not work anymore. so rather than doing a transplantation, just when we have the first signs of insufficiency, whether to treat these organs with the patient's stem cells, probably targeting the defect that they have, so prolonging and extending their life." This last point is the likely future of tissue engineering - not to build outside the body and require major surgery, but rather regenerate in situ by issuing commands to existing stem cell populations, or repair those stem cells where they are deficient.