Editor's note: (December 16) the ABC was advised by the Canterbury Bulldogs that Mr Hodkinson received treatment from Regeneus, however Regeneus say he did not. This transcript was amended to note the Regeneus press statement was released in 2014.

LEIGH SALES, PRESENTER: At the end of another gruelling season of rugby league and AFL, players from all codes will be relishing a bit of time off to rest and recover before the next season begins.

As always, some won't return to the field due to career-ending injuries.

Finding a permanent cure for athletic injuries is the Holy Grail of sports medicine and one of the most talked-about new treatments is stem cell therapy.

One Australian company is touting its stem cell treatment to football players, but the results are mixed and the alarm's being sounded by medical specialists who've had to mop up after failed treatments.

As Louise Milligan reports, it's not just athletes who are at risk.

LOUISE MILLIGAN, REPORTER: Football is a game of highs and lows. Sometimes those lows can lead not just to humiliation, but to permanent injury.

NRL Canterbury Bulldogs player Trent Hodkinson escaped that fate, playing in last night's rugby league Grand Final.

Hodkinson says a stem cell injection in 2012 saved his career.*

Some footballers are not so lucky, like former AFL player Clint Bartram.

CLINT BARTRAM, FORMER MELBOURNE DEMONS HALFBACK: I loved playing football. For me, unfortunately, I've had an injury which has stopped that.

LOUISE MILLIGAN: The beginning of the end for the Melbourne Demons halfback came in 2007.

CLINT BARTRAM: In a training incident, I went over on my knee. Heard a really loud pop and then went to stand up and I couldn't actually straighten my knee out.

LOUISE MILLIGAN: Bartram had to have most of his cartilage removed. As a result, playing became very painful. Desperate to try anything, in 2012 his club doctor suggested stem cells.

Bartram filmed on his mobile phone as a club doctor injected stem cells taken from Bartram's own fat into his knee. The treatment failed.

CLINT BARTRAM: I think it's fair to say that it didn't work for me.

LOUISE MILLIGAN: Did you ever play again?

CLINT BARTRAM: Unfortunately not, no.

LOUISE MILLIGAN: As Clint Bartram's treatment shows, stem cells are still experimental, yet Regeneus is touting what it claims is an approval by the AFL to provide stem cell procedures to players.

Regeneus' co-founder is Ben Herbert, an associate professor of regenerative science. Last year, his company raised $12 million listing on the Australian Stock Exchange.

BEN HERBERT, REGENEUS CO-FOUNDER: You might go into the hospital at six or seven o'clock in the morning and you're out by the middle of the day. So, you've been scrubbed, liposuction's been done, cells have been processed, joints have been injected and you go home.

LOUISE MILLIGAN: But in the scientific and medical community, there is much disquiet about the claims Regeneus makes about stem cells.

MARK YOUNG, SPORTS PHYSICIAN: I think we're all concerned that patients are being given treatments where there's no evidence of benefit and they're paying an awful lot of money for it.

LOUISE MILLIGAN: In August 2014*, Regeneus put out a press release aimed at investors, claiming the AFL had approved its treatment for players. It said a clinical trial found Regeneus' stem cells procedure, "reduced pain and slowed cartilage degradation". 7.30 has obtained a complaint letter to the Stock Exchange about that announcement. It's written by a group of Australia's leading stem cell scientists and it alleges Regeneus misled the market.

LETTER TO STOCK EXCHANGE (male voiceover): "... it is misleading because the control (placebo) group in that trial also achieved the same reduction in pain and slowing of cartilage degradation*." A reasonable person, ".... would draw the conclusion that the company's product had been shown to be clinically efficacious when rigorously tested. ... there are no data we are aware of that support that conclusion."

JUSTIN ROE, ORTHOPAEDIC SURGEON: So to have something saline put in the joint was just as good as having the stem cells harvested. So, in a scientific, evidence base term, it's - there was no difference between the two.

LOUISE MILLIGAN: Regeneus says its clinical trial showed some improvement inside the joints of patients given stem cells, but leading stem cell biologist Professor Martin Pera says most of the clinical evidence showed there was no real benefit from the treatment.

MARTIN PERA, STEM CELL BIOLOGY, UNI. OF MELBOURNE: The answer is not to take scientific shortcuts in the evaluation of safety and efficacy. The answer is not to mislead the public about outcomes of these therapies. Both of those are pathways that will lead to disillusionment, to failure and possibly worse. They are pathways that will be bad for the field and ultimately bad for companies that are trying to pioneer these new therapies.

LOUISE MILLIGAN: 7.30 has learned that the AFL was displeased when it found out that Regeneus had issued the press release because it felt that it was dressed up to look like an official AFL endorsement. In fact, it was based on one discussion with the AFL's Chief Medical Officer about one player from one club.

Are you aware of a complaint that's been made to the Australian Stock Exchange about some statements that you made to the stock market about the agreement that you have with the AFL?

BEN HERBERT: No.

LOUISE MILLIGAN: Ben Herbert rejects the accusation that Regeneus mislead the market.

BEN HERBERT: This statement to do with the AFL was really to say that the AFL were saying that on a case-by-case basis, cell therapy, HiQCell from Regeneus could be used to treat players, they considered that it was safe and it doesn't infringe the WADA code so it's not something that would be considered performance-enhancing.

LOUISE MILLIGAN: Surely to be absolutely accurate in that statement, you would also have to say that the placebo achieved the same results?

BEN HERBERT: There's many statements on the record from Regeneus to do with placebo and pain reduction, and like I say, pain reduction on its own is not really the only story here.

LOUISE MILLIGAN: High-profile sports physician Dr Mark Young believes stem cell companies are using footballers as a marketing tool.

MARK YOUNG: I'm sure that athletes are being exploited. Athletes are vulnerable people. They want to get better as quickly as possible, they're desperate, they're well cashed up and they're high-profile.

LOUISE MILLIGAN: Hilary Richards had a Regeneus stem cell procedure last year.

And when you came out, the doctor had said to you you'll be able to walk out. Were you able to walk out?

HILARY RICHARDS: Aha! Well I tell you what, not really. I did walk out, but it was excruciatingly painful.

LOUISE MILLIGAN: The pain continued more or less unabated for a year.

And so, you paid $10,000 for this procedure.

HILARY RICHARDS: I don't like to appear stupid. But I think I really - yes, I did.

BEN HERBERT: The patients are always told that there's this risk that there's 20 per cent of people who don't get that kind of pain relief. So, you know, it's very unfortunate that that occurred. But what's also pretty clear is that stem cells are safe and they don't cause advanced disease.

LOUISE MILLIGAN: Dr Justin Roe was Hilary Richards' orthopaedic surgeon who did her knee replacement after the Regeneus treatment didn't work. He says he's seeing three or four patients a month who've had failed Regeneus procedures, and like Hilary, need major surgery.

JUSTIN ROE: Hilary was harmed not only financially, but mentally and emotionally. The fact that this procedure didn't work, it was never going to work; it's not based on good clinical evidence, unfortunately.

LEIGH SALES: Louise Milligan reporting.