Nov 2008 - The first artificial trachea (windpipe), created by using the patient's own stem cells, was successfully transplanted into a young woman with a failing airway in June 2008. The operation was carried out at the Hospital Clinic, Barcelona, by Professor Paolo Macchiarini of the University of Barcelona. The bio-engineered trachea immediately provided the patient with a normal functioning airway which saved her life.

Previous attempts to correct the problem with traditional artificial stents had failed, and so the 30 year old woman in Spain, was grown a new section of airway for transplant using her own cells.

The pan-European team from the universities of Barcelona, Bristol, Padua and Milan report on this pioneering work in an article in The Lancet.

To begin with, the team started with a 7 centimetre tracheal segment which was donated by a 51-year-old transplant donor who had who had died of cerebral haemorrhage. Spain has a policy of assumed consent for organ donation. Using a new technique developed in Padua University, the trachea was decellularised over a six-week period, leaving just the extracellular matrix. A biopsy was taken of the recipient's lung tissue and bone marrow, and these samples were used to culture epithelial and chondrocytic cells respectively.

The matrix was placed in a bioreactor and the patient's cells were then seeded onto the matrix; the chondrocytes on the outside, and the epithelial cells on the inside. This was fairly important as you want the epithelial cells to be present on the lumen of the airway and not the outside, although examination revealed that both chondrocytes and epithelial cells had migrated fully throughout the matrix.

The design of the bioreactor allowed the matrix to be rotated with a small motor, which provided necessary sheer stress to the growing cells, and after 96 hours in the reactor the graft was ready for implantation. Four days after being implanted, tests revealed that the graft was well vascularized and by one month was indistinguishable from the patient's native airways.

Since the cells used to seed the matrix were the patient's own, there was no need for any form of immunosuppression, as the cells present in the graft all expressed the right host antigens, meaning there was no danger of an immune reaction. The implanted graft successfully opened up the patient's airway and saved her lung, so this study represents a major success for the bioengineering of replacement tissues.

Once downside of this case is that a donor organ from a dead patient was still needed to create the scaffold meaning that this technique alone will not solve the shortage of donor organs. Another possibility is that scientists will use the method to re-seed the patient's own faulty organ with new stem cells to regenerate it or patch it up, avoiding the need for a transplant altogether.

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