A 36-year-old man is recovering after surgeons implanted the world's first wholly lab-grown organ into his body.
The synthetic trachea, or windpipe, was created by seeding the patient's own stem cells on to an artificial "scaffold".
British scientists helped design and built the structure, an exact replica of the man's original windpipe. Windpipes have been grown from stem cells before, but only using the collagen "skeletons" of donated tracheas.
Using an entirely synthetic scaffold means patients do not have to wait for a suitable donor organ. This is especially important for children, for whom donor tracheas are much more difficult to find.
The patient, an African student living in Iceland, had been suffering from life-threatening tracheal cancer. He is said to be doing well and is due to be discharged from hospital on Friday.
Spanish regenerative medicine pioneer Professor Paolo Macchiarini led the groundbreaking operation at Karolinska University Hospital in Sweden. In 2008 he carried out the world's first tissue-engineered tracheal transplant on a 30-year-old Spanish woman, Claudia Costillo.
Professor Alexander Seifalian, from University College London, worked with Prof Macchiarini to produce the synthetic trachea scaffold.
The Y-shaped structure was made from a plastic-like "nanocomposite" polymer material consisting of microscopic building blocks. The material had previously been developed and patented by Prof Seifalian. To guide the process, CT (computerised tomography) scan images were obtained of the patient's damaged trachea. These were used to produce a glass mould for the nanocomposite structure.
The scaffold was taken to Sweden, where it was "seeded" with stem cells from the patient's own body. The prepared trachea was then placed in a "bioreactor", a device providing the right environment for growth. After just two days the stem cells had grown into tracheal cells ready for transplantation. Since the organ was built from cells originating from the patient, there was no risk of it being rejected by his immune system.
Prof Seifalian said: "Professor Macchiarini has previously performed successful transplants of tissue-engineered tracheas, but on those occasions the tracheas used were taken from organ donors and then reseeded with the patient's own stem cells. What makes this procedure different is it's the first time that a wholly tissue-engineered synthetic windpipe has been made and successfully transplanted, making it an important milestone for regenerative medicine. We expect there to be many more exciting applications for the novel polymers we have developed."