Trachea Tissue-Engineered by Researchers

In a new study, researchers have used tissue engineering to reconstruct defective tracheas in fetal lambs, using cells from the amniotic fluid to grow sections of the cartilage tube and then implanting those living grafts into the lambs while still in the womb.

Amniotic fluid is easy to collect during pregnancy and contains mesenchymal stem cells that can make many of the tissues needed for repairs, according to Dario Fauza, M.D., a pediatric surgeon who led the study. The study results, from the Children's Hospital Boston (MA, USA), were reported at the annual meeting of the American Academy of Pediatrics in Washington (DC, USA) in October 2005.

Tracheal defects are rare but life-threatening. Surgeons have tried various ways to fix defects but have had limited success. Dr. Fauza's team multiplied the amniotic mesenchymal cells in culture, then "seeded” them onto biodegradable tubes of the required dimensions and shape. After exposure to growth factors, the cells differentiated into cartilage cells. When these grafts were ready, they were used to reconstruct defective tracheas in seven fetal lambs. When the lambs were born, all five that survived to term were able to breathe spontaneously at birth.

Although many congenital defects can be safely repaired after birth, Dr. Fauza's goal is to fix tracheal defects in utero, eliminating the complications of intubation and ventilation. "The fetus doesn't need the trachea, so the repair would have time to heal in utero,” he explained. "And fetal healing is very good--it's better than adult healing.”

Since the grafts are made from the baby's own cells, there is no risk of the immune system rejecting the tissues. Furthermore, amniotic fluid is readily available. Less than two tablespoons provide enough fetal cells to repair a malformation.






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