Indianapolis Colts quarterback Peyton Manning has become the newest face of stem cell therapy in a treatment decision that has elicited mixed opinions from top doctors in the field.

Buzz about Manning’s decision to fly to Europe to take advantage of an FDA-unapproved stem cell treatment for his neck exploded this weekend with a report on Fox’s NFL pre-game show by Jay Glazer.

The bulging disk in Manning’s neck has thus far defied three surgical repair attempts and months of physical therapy, and the 35-year-old QB is expected to be out of the game for two to three months, and possibly more. Manning has already missed his team’s first two games.

He has not kept his disappointment at his slow recovery a secret.

“To say I am disappointed in not being able to play is an understatement,” Manning said in a statement released by his team earlier this month. “I simply am not healthy enough to play, and I am doing everything I can to get my health back.”

According to a report in the New York Daily News, the alleged stem cell treatment did not work, resulting in the team subsequently deeming the surgery “uneventful.”

Dr. Ruth Macklin, professor of bioethics at the Albert Einstein College of Medicine in New York City, called Manning’s reported action “an act of desperation.

“We live in an era where physicians are encouraged to practice ‘evidence-based’ medicine,” she told ABCNews.com in an email. “However, a sports superstar has the money and ability to travel anywhere in the world to receive an experimental procedure that is not based on any evidence that it works for his condition.”

Indeed, Dr. Lawrence Goldstein, director of the University of California-San Diego Stem Cell Program, said he was unaware of any stem cell approach that is proven to help “any sort of spinal issue.

“There are many proposed therapies that are being tested in clinical trials, and there are more to come,” Goldstein said in an email. “But in the absence of reliable evidence, it is impossible to know whether the ‘treatment’ will make Manning better or worse or merely financially poorer.”

Goldstein also expressed concern about the message Manning might be sending to the general public with regard to unproven treatments if the report is true.

“When a highly visible celebrity athlete chooses to undergo an untested/unproven therapy, and if they happen to get better without knowing whether the therapy is what caused the improvement, they encourage many other people to ignore scientific evidence and to substitute hope and blind trust for proof,” he said. “The downside is that many people might be hurt by subjecting themselves to a risky procedure, or procedure with unknown risks, when there is no evidence of benefit to be gained.”

Macklin added that Manning could have made a more socially responsible choice by instead seeking out and enrolling in a clinical trial using this or another intervention.

“Although Manning is not engaged in an action that is clearly unethical, it sets a bad example,” she said.  ”It would, indeed, be a bad thing if injured pro athletes were to fly all over the world looking for cures when the procedure in question is unproven. It would not advance science. And there are plenty of quacks out there.”