PEORIA, Ill. — Using plastic fibers and human cells, doctors have built and implanted a windpipe in a 2 ½-year-old girl — the youngest person ever to receive a bioengineered organ.

The surgery, which took place on April 9 here at Children’s Hospital of Illinois and will be formally announced Tuesday, is only the sixth of its kind and the first to be performed in the United States. It was approved by the Food and Drug Administration under rules that allow experimental procedures when otherwise the patient has little hope of survival.

Dr. Paolo Macchiarini, a specialist in the field of regenerative medicine who developed the windpipe and led the complex nine-hour operation, said the treatment of the Korean-Canadian toddler, Hannah Warren, made him realize that this approach to building organs may work best with children, by harnessing their natural ability to grow and heal.

“Hannah’s transplant has completely changed my thinking about regenerative medicine,” said Dr. Macchiarini, a surgeon at the Karolinska Institute in Stockholm. He said he would like to proceed with a clinical trial in the United States, something that critics of his approach have called for.