Windpipe defect repaired in womb

The cells grew to form new windpipe tissue

Stem cells from amniotic fluid have been used to repair windpipe defects in unborn lambs while still in the womb.

A team at the Children's Hospital Boston used the cells to grow sections of cartilage tube, which were then implanted into the unborn lambs.

Details were presented at an American Academy of Pediatrics conference.

Windpipe defects in humans are rare, but life-threatening - requiring immediate surgery to cut the risk of neurological complications.

Surgeons have tried various fixes, such as grafting in pieces of the baby's rib or pelvic bone, or using synthetic substances like Teflon.

However, these have had only limited success and carry a risk of complications, such as infection or narrowing of the windpipe.

The new technique is one of several tissue-engineering approaches pioneered by the Boston team to create patches to fix birth defects - but the first to be tested on embryos.

The team chose to work on lambs as they grow quickly and are similar in size to human babies.

Collecting cells

They collected a small quantity of mesenchymal stem cells from the amniotic fluid.

These cells have the potential to develop into many different tissues, such as muscle, bone and cartilage.

Cells were 'seeded' on to a scaffold

The cells were cultured in the lab, "seeded" onto biodegradable tubes and exposed to growth factors to stimulate them to differentiate into cartilage tissue.

Once the grafts had matured they were used to reconstruct defective windpipes in seven foetal lambs.

Five lambs survived to term, all were able to breathe spontaneously at birth - four of them with no sign of respiratory distress.

Lead researcher Dr Dario Fauza said the windpipe is not needed before birth, so this would be an ideal time to carry out repairs.

He added: "Foetal healing is very good - it's better than adult healing."

In addition, using the body's own stem cells to grow a graft minimises the risk of rejection.

Dr Fauza has submitted an application with the US Food and Drug Authority to grow grafts from cells taken from human amniotic fluid.

Dr John Moore-Gillon, a lung specialist at Bart's hospital in London and president of the British Lung Foundation, said: "Defects in the trachea of new-born babies can be extremely difficult to deal with and may cause death or life-long disability.

"This is still very early days in the development of new treatments but we may be seeing the beginnings of a brighter future for the tiny sufferers of these terrible problems."