Only three months after she became the youngest person to receive a bioengineered organ, two-year-old Hannah Warren has died.

In an announcement posted online Monday, the Children's Hospital of Illinois — where Hannah underwent a groundbreaking windpipe implant — confirmed the sad turn of events. "Although regenerative medicine remains in the early stages for pediatric patients, progress is being made," the statement reads. "Hannah, and the physicians caring for her, helped advance this area of medical practice which is only at its very beginning stages."

Hospital representatives didn't specify exactly what caused Hannah's death, but their statement points to "additional health issues." According to The New York Times, complications due to an esophageal surgery — which was performed in tandem with the windpipe procedure — are to blame. "The trachea was never a problem," Dr. Paolo Macchiarini, the surgeon who led Hannah's procedure, told the Times. "It was her native tissue that was very fragile."

Hannah had defied all medical odds

Ever since being born without a windpipe, Hannah had defied all medical odds: the scenario is deadly in 99 percent of cases, and only five similar windpipe implants had been performed worldwide prior to her surgery. Prior to undergoing the nine-hour procedure, Hannah was unable to breathe, eat, drink, or swallow independently. Surgeons had hoped that the engineered windpipe, made of a synthetic scaffold and Hannah's own stem cells, would change that.

Despite the burgeoning promise of the windpipe implants that Dr. Macchiarini has pioneered, they remain extremely risky. Some experts have criticized the procedures as too experimental, or called for clinical trials to better evaluate their longterm efficacy. One other patient, an American man, has also died following the surgery.

"Our hearts are broken."

But controversial or not, the surgery was widely seen as Hannah's best shot at survival. "Our hearts are broken," reads a statement from her family. "We will forever miss her infectious personality and miraculous strength and spirit."