In April, a 2-year-old girl named Hannah Warren became the sixth patient in the world to receive a windpipe transplant made from her stem cells.
The nine-hour surgery was pioneered by Dr. Paolo Macchiarini, the director of the Advanced Center for Translational Regenerative Medicine at the Karolinska Institute in Stockholm. His procedure was approved by the FDA as an experimental operation for patients with very little hope of surviving. Macchiarini has performed all the previous transplants of bioengineered windpipes. So far, one of his patients, Christopher Lyles, has died. Last year, describing Lyles’ operation, TIME’s Alice Park wrote:
Macchiarini has been perfecting the process of using stem cells to seed bioengineered scaffolds for organs like the trachea since 2008; in his first such procedure, he used a donor trachea to replace that of a Spanish woman, stripping the organ of its cells and coating it with the woman’s own stem cells. But using a completely synthetic, bioengineered matrix such as the one transplanted in Lyles, he says, makes the transplant safer for the patient, potentially sparing him the complications that can arise if he can’t accept the new organ.
Exactly how the windpipe, made of stem cells, works in the body is not totally clear, but since stem cells are capable of becoming all different types of body cells, it’s likely they react to the environment they are transplanted into and start developing the appropriate tissue.
The research is not only promising for developing much needed organs, but for understanding how to tamp down rejection to transplantable devices.
MORE: Young Girl Receives Lifesaving Windpipe Transplant Made From Her Stem Cells