The patients' cells were left to grow on a scaffold in the lab.
"We then create a 3 dimensional model that looks like the organ that would fit into that specific patient. We coat that mold with the patient's own cells. We then place the structure in an oven like device to let it cook if you will, it has the same conditions as the human body," said Dr. Anthony Atala, Director of the Wake Forest Center for Regenerative Medicine.
The four teenage women who received the organs all had a rare genetic condition.
Swiss scientists are also reporting a step forward in tissue engineering.
They created human cartilage from a patient's cells, rebuilding the damaged nostrils of five skin cancer patients.
With a major shortage of organs, researchers hope their work in the lab will someday help relieve the crisis.