London – British and Italian doctors have carried out groundbreaking surgery to rebuild the windpipe of a 10-year-old British boy using stem cells developed within his own body, they said.

In an operation Monday lasting nearly nine hours, doctors at London's Great Ormond Street children's hospital implanted the boy with a donor trachea, or windpipe, that had been stripped of its cells and injected with his own.

Over the next month, doctors expect the boy's bone marrow stem cells to begin transforming themselves within his body into tracheal cells -- a process that, if successful, could lead to a revolution in regenerative medicine.

The new organ should not be rejected by the boy's immune system, a risk in traditional transplants, because the cells are derived from his own tissue.

"This procedure is different in a number of ways, and we believe it's a real milestone," said Professor Martin Birchall, head of translational regenerative medicine at University College London.

"It is the first time a child has received stem cell organ treatment, and it's the longest airway that has ever been replaced."

More clinical trials were needed to demonstrate that the process worked, he said, but if it did, it could lead to other organs such as the larynx or oesophagus being transplanted in hospitals around the world.

The boy, who has not been named, was born with a life-threatening condition called long segment tracheal stenosis, which meant he had a tiny windpipe that would not grow -- described by the team as like breathing through a straw.

Although he received various treatments, his condition deteriorated in November and his doctors called in Professor Paolo Macchiarini, a stem cell pioneer at the Careggi University Hospital in Florence.

Macchiarini led the surgery in Spain two years ago on 30-year-old Claudia Castillo, the first person to receive a transplant organ created from stem cells.

In her case, the new tissue was developed outside her body, but it is far less complicated to grow it within the body. The boy is only the second patient and the first child to have such a procedure.

Cardiothoracic surgeon Professor Martin Elliott, director of tracheal services at Great Ormond Street, said the boy was recovering well.