Last year, an investigation by the Institute, where Macchiarini is a visiting professor, cleared him of scientific misconduct following accusations from colleagues that he had falsified his results in scientific papers.
This week the vice-chancellor Anders Hamsten, who led that investigation, resigned after a television documentary broadcast in Sweden brought renewed interest to the details of Macchiarini's conduct.
The documentary provided evidence that Macchiarini had not informed his patients of the risks of his highly experimental trachea-replacement surgeries, several of whom died following the procedures.
'We are now endeavouring to investigate this information thoroughly and arrange an independent examination. But there is much to indicate that the judgement reached by KI last summer should be amended to scientific misconduct, which in plain language means research fraud,' Hamsten wrote in a piece for the newspaper Dagens Nyheter.
In January, an article appeared in Vanity Fair, in which Macchiarini's former fiancée claimed that he had falsified his qualifications and experience on his CV. Subsequently, the Karolinska Institute said they were launching an inquiry into the accuracy of the information Macchiarini had given them prior to his employment in 2010.
But less than a week later, a three-part documentary called The Experiments appeared on Swedish television. It revealed that Macchiarini may have misled patients by not notifying them of the risks of the procedure, and reassuring them that experiments in animals had been successful when in fact none had taken place.
The procedure involves the replacement of a damaged trachea with a polymer scaffold embedded with the patient's own stem cells that will then grow and form tissue to replace the trachea. Macchiarini performed three such procedures at the Karolinska Institute and its associated hospitals.
Two of the three patients who Macchiarini operated on at the Karolinska Insitute have since died, including the subject of a 2011 Lancet paper. The third patient is still alive but has been in intensive care since the surgery in August 2012.
The documentary also provided details about the case of one woman who died after Macchiarini operated on her in Russia, despite the fact that her trachea injury was non life-threatening and therefore did not warrant such a risky procedure.
Macchiarini was previously considered a pioneer of stem-cell medicine and something of a celebrity surgeon, claiming to have treated high-profile patients such as Pope John Paul II and the Clintons.
The Karolinska Institute has now dismantled his research group and said it would not be renewing his contract, which is due to expire later this year. The Institute has now relaunched its investigation into Macchiarini's conduct, but the Swedish Academy of Science has demanded this be transferred to the country's Central Ethical Review Board to ensure impartiality. The Academy is also seeking a retraction of the Lancet article, which omits the subsequent fate of Macchiarini's patient.
On 7 February, Urban Lendahl, secretary general of the Nobel Assembly, which is based at the Karolinska Institute, also resigned as a result of the scandal 'out of respect for the integrity of the Nobel Prize work'. Lendahl had been involved in hiring Macchiarini to the Institute in 2010.