HELSINKI (AP) — The secretary-general of the Swedish panel that awards the Nobel medicine prize has resigned because of an investigation into disputed stem-cell scientist Paolo Macchiarini.

Ann-Mari Dumanski, a spokeswoman of the Nobel Assembly at Karolinska University, confirmed Monday that Urban Lendahl's Saturday resignation took effect immediately, but gave no details. The Nobel panel said on its website that the professor resigned "out of respect for the integrity of the Nobel Prize work," and because he might become involved in the investigation.

Lendahl was one of several professors at Karolinska who in 2010 recommended hiring Macchiarini, whose work with stem cells was viewed as revolutionary. Macchiarini was part of a team that conducted the first transplant using a windpipe partly made from a patient's own stem cells in 2008, in Barcelona.

Lendahl's resignation — as secretary-general of the assembly and from the Nobel Committee — follows last week's decision by the university to investigate Macchiarini after a Swedish documentary last month raised ethical concerns about several operations performed by him, which Karolinska described as "truly alarming." A Vanity Fair article last month also suggested Macchiarini had falsified his CV.

The university announced it would commission a lawyer to lead a team to investigate issues, including whether Macchiarini broke any laws or standard scientific protocols, and said it was not renewing his contract beyond Nov. 30, expecting him to use the remaining time to dismantle his research group.

Last year, Macchiarini was cleared of misconduct charges related to his creation of windpipes made from patients' stem cells.

The Nobel Assembly has 50 voting members composed of professors in medical subjects at Karolinska. Its working body is the Nobel Committee, elected from among its members for a three-year term.