Hannah Warren was born without a trachea but now has one made from plastic fibers and a stew of her own stem cells . The 2-year-old Korean Canadian has spent every day of her life in intensive care , kept alive by a tube that substituted for the windpipe that was supposed to connect her mouth to her lungs . But nearly a month after her transplant , the toddler is mostly breathing on her own and is responding to doctors and nurses . The surgery , pioneered by Dr. Paolo Macchiarini , director of the Advanced Center for Translational Regenerative Medicine at the Karolinska Institute in Stockholm , was only the sixth performed in the world , and Hannah was the youngest patient and first to receive the transplant in the United States . The procedure was approved by the FDA as an experimental operation for patients with very little hope of survival ; being born without a trachea is fatal in 99 % of cases . TIME.com : Stem cell therapies may cure chronic conditions . Macchiarini performed the nine-hour operation on April 9 at the Children 's Hospital of Illinois after carefully creating the windpipe using stem cells from Hannah 's bone marrow that were saturated over a matrix of plastic fibers shaped into a tube . Exactly what happens to the windpipe after it is transplanted is n't clear , but researchers believe that placing stem cells , which are capable of developing into different types of body cells , can pick up signals from their environment and integrate with existing tissues . Macchiarini told the New York Times that the body 's regenerative capabilities may help such bioengineered organs to integrate with existing tissues . Children may make the ideal patients for these procedures since they have natural and active abilities to heal and grow . `` Hannah 's transplant has completely changed my thinking about regenerative medicine , '' he told the Times , adding that he wants to conduct a clinical trial in the United States . For children born with a windpipe defect or without one , and for others with defective or diseased organs , manipulating stem cells to generate healthy tissues or organs could be their only chance at survival . TIME.com : Cancer patient receives a man-made windpipe . Macchiarini performed all five of the previous transplants of the bioengineered windpipes ; four of the patients have done well , while one , Christopher Lyles , who received his trachea in Stockholm , died . Last year , in 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 ca n't accept the new organ . `` Researchers have used similar stem-cell-seeding techniques to create other organs . Dr. Anthony Atala at Wake Forest University generated bladders and a urethra using scaffolds and patients ' stem cells . '' Because of the small number of patients he has treated , his critics say it 's hard to determine how valid Macchiarini 's bioengineering technique is in treating patients like Hannah . But he plans to conduct a clinical trial to properly assess the risks and benefits of the procedure , and document how bodies react to the transplanted devices . Hopefully those trials will show that it 's possible to regenerate not just organs but hope as well . This story originally published on TIME.com .
Hannah Warren spent the first two years of her life in the intensive care unit . A month after her windpipe transplant , the toddler is mostly breathing on her own . Hide Caption 2 of 7 Photos:Photos: The miracle baby