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Paolo Macchiarini, a surgeon who transplanted artificial windpipes, has been found not guilty of scientific misconduct.

Paolo Macchiarini, a surgeon who transplanted artificial windpipes, has been found not guilty of scientific misconduct.

Staffan Larsson/Karolinska Institute

Artificial trachea pioneer cleared in first of two misconduct cases

A thoracic surgeon who attracted widespread attention for transplanting artificial tracheae into patients—and then faced scientific misconduct charges—has been found not guilty in the first of two investigations into his work. The decision, announced today, was made on 7 April by the Karolinska Institute’s vice-chancellor, Anders Hamsten, on the basis of an internal investigation by the institute’s ethics council. The council concluded that the issues raised are of a “philosophy-of-science kind rather than of a research-ethical kind.”

“We all felt terrible [about the investigation] because it affected our credibility, the credibility of my team,” says the accused, Paolo Macchiarini, a visiting professor at the Karolinska Institute in Stockholm. “We are now happy that everything has been cleared.” Pierre Delaere, a head and neck surgeon at UZ Leuven in Belgium who brought the case against Macchiarini, says he is "stunned about such outright injustice.”

Macchiarini produced artificial windpipes by taking a polymer scaffold and “seeding” it with stem cells from the recipient, which he claimed colonized the scaffold and eventually grew into a living organ. Delaere argues that Macchiarini's claims of success were exaggerated and that he misrepresented his results in several papers in The Lancet. Delaere first e-mailed Harriet Wallberg-Henriksson, then-president of the Karolinska Institute, about his concerns in 2011; he made a formal complaint to the institute in June 2014, which led to the current investigation. In its report, the council rejected all the issues Delaere had raised.

Delaere charged that Macchiarini’s claim to regenerate tracheae from patients’ stem cells was impossible, but the council concluded instead that it was a “miscommunication” about the meaning of the word regenerative. Delaere also charged that Macchiarini’s claim that blood vessels had regrown around the tracheae was impossible, but the council decided that “current evidence indicates that it is actually working.” The council found no evidence of fabricated data.

The council noted that hype is a general problem, not particular to Macchiarini. Delaere’s response: “The whole stem cell story has to come down to Earth,” but the artificial trachea story “is an extreme form.” The council's report, he adds, is "so wrong, it couldn’t be wronger.”

Another ongoing investigation against Macchiarini was launched after four surgeons at the affiliated Karolinska University Hospital charged that he did not get properly informed consent from patients—a charge Macchiarini has denied. A representative for the Karolinska Institute says the timing for this case is uncertain, as the vice-chancellor is waiting for a report from an outside expert.

Macchiarini says his team has paused its transplantations of tracheae, while they evaluate a new biomaterial. Splitting his time between the Karolinska Institute and Kuban State Medical University in Krasnodar, Russia, Macchiarini says he is now also engineering tissues of the lung, heart, and other thoracic organs for transplantation. The team also works on cell therapy to assist local regeneration of tissues, such as restoring lung function in newborns and adults.

*Correction, 20 April, 2:40 p.m.: A previous version of this story said that Macchiarini’s team no longer works on tracheae. They have only paused the transplant operations.