Patients may one day be able to grow their own organs to replace diseased or damaged body parts - offering a potential solution to the global donor shortage crisis - says one of the world's leading transplant surgeons.
Professor Paolo Macchiarini, who pioneered the first transplant of a whole organ grown from a patient's own cells four years ago, says the technology of regenerative medicine has advanced to the point where it was possible to contemplate transplants with no human donors, no problems of rejection and no need for lifelong treatment with immuno-suppressive drugs.
The new technique involves the creation of an artificial "scaffold" - which could in future be made from animal organs that have been stripped of their living cells - into which the patients' own stem cells are inserted. The cells then grow to create a fully functioning organ ready for transplant.
"Such an approach has already been used successfully for the repair and reconstruction of complex tissues such as the trachea, oesophagus, and skeletal muscle in animal models and human beings," Professor Macchiarini says.
"Guided by appropriate scientific and ethical oversight, [this] could serve as a platform for the engineering of whole organs and other tissues, and might become a viable and practical future therapeutic approach to meet demand after organ failure," he adds.
Although such predictions have been made before, they have been given added impetus by Professor Macchiarini's own work. In 2008, he and his team transplanted a trachea into a 30-year-old woman in Barcelona grown from her own cells. Claudia Castillo had contracted TB, which had damaged her windpipe and left her unable to breathe.
In her case, the trachea was taken from a donor, stripped of all its living cells and reseeded with cells taken from the patient's bone marrow before being grown in a "bioreactor".
In a second operation carried out at Great Ormond Street Hospital, London, in 2010, a British team assisted by Professor Macchiarini performed a similar operation on a 10-year-old boy, who had been born with a narrow windpipe. In his case, the donor trachea was transplanted into his chest as soon as it had been reseeded with stem cells taken from his bone marrow, using his own body as the bioreactor.
The organ donor crisis is intensifying around the world as demand from ageing populations for replacement body parts rises, but the supply of donors is failing to keep pace.
In the UK, 3740 transplants were carried out in the year to March 2011, but 7587 patients are on the waiting list.
Writing in The Lancet, the professor and colleagues say the artificial "scaffolds" necessary for the transplants could in future be obtained from animals, removing the need for human donors.
As their living cells would be stripped away, before being repopulated with the patient's own cells, there would be no problem of rejection.
The trachea, composed of cartilage, is a relatively simple organ. Growing lungs, livers or kidneys will pose a much greater challenge, but progress has been made.
Several research groups have taken lungs from mice, stripped them of their respiratory cells, leaving the "scaffold" of bronchioles and blood vessels, and then repopulated them with rat cells and transplanted the regrown tissue into rats. The transplanted tissue functioned for a few hours like a lung, absorbing oxygen from the air.
Professor Macchiarini warns that many hurdles - technical, financial and ethical - lie ahead.
"The pressure to advance this technique, driven by demand, the race for prestige, and the potential for huge profits, mandates an early commitment be made to establish the safety of various strategies ... particularly when there are so many potential patients and doctors who are desperate for any remedy that offers hope."Independent