Dakota Clarke's parents say they are convinced that her vision has improved
When it comes to stem cells, mainstream scientists in the UK and America tell us their potential is both exciting and unlimited.
But, they hasten to add, treatments for most illnesses are still years away and more research needs to happen.
But that caveat is not stopping British families from raising thousands of pounds in their communities in a bid to travel to foreign clinics to seek treatments promising relief for everything from blindness to degenerative multiple sclerosis.
In Stem Cells and Miracles, the Panorama team meets the Clarke family of Newtonabbey in Northern Ireland. The Clarke's three-year-old daughter, Dakota, was born with septo-optic dysplasia, in which part of her brain and her optic nerve did not develop, leaving her almost blind and suffering with balance issues.
When given the bad news that their baby's disorder prevented signals being sent from her eyes to her brain, the Clarkes were advised to be wary of promises of cures that they find on the internet.
"You know they're trying to explain that this is a rare condition, it affects one in 50,000 in the UK, (they) advise you not to check the internet because it can scare people so of course you're straight home and you're onto the internet," Wilma Clarke tells reporter Darragh MacIntyre of the family's quest for viable treatments.
It was on the web that the Clarkes read about stem cell treatment being carried out at a clinic in Qingdao on China's north-east coast.
Stem cells are prized by scientists because they can replicate and morph into any cell in the body - be it heart, liver or nerve cells. Researchers say this ability to rebuild damaged or destroyed cells offers tremendous hope but that treatments for many illnesses are not yet proven.
The Clarkes were not put off and launched a local fundraising campaign to come up with the £20,000 plus travel costs needed to take Dakota to the Beike clinic where she received six injections of stem cells over the course of a month.
While waiting to see how the Clarkes made out, Panorama enlists the help of Linda Oatley, who was diagnosed with multiple sclerosis (MS) 10 years ago.
A degenerative illness with no known cure, MS sufferers slowly lose muscle control - a process that can be slowed by drugs.
Ms Oatley tells Darragh MacIntyre of friends who have joined the internet hunt for a miracle cure.
"I know people who are very vulnerable and have been duped by the promise of a cure," she says. "People with MS that are much worse off than I am whose only hope is a cure quickly."
Ms Oatley helps Panorama investigate the promises at another stem cell clinic, Medra, a California-based company which operates out of the Dominican Republic. Run by Dr William Rader, Medra has several video testimonials on its website offering treatment for MS, Parkinson's disease and others.
Ms Oatley agrees to travel to the clinic for a consultation and to wear a hidden camera for Panorama, although she has no plans to hand over the £20,000 or undergo treatment.
It is during this consultation that Ms Oatley experiences Dr Rader's sales tactics. Even when she asks for a bit of time to think it over, Dr Rader tries to persuade her to go through with the treatment on the spot.
Dr Rader tells Ms Oatley that his stem cells, which he gets from aborted foetuses, help repair the myelin coating around the body's nerves. It is the deterioration of that myelin that causes MS.
Professor Neil Scolding is an authority on MS and stem cells based at the University of Bristol.
"What I would love to see would be proof that the treatment that he has given has been responsible for those lesions disappearing and frankly, I would be surprised if there was such proof."
Darragh MacIntyre heads to Malibu to meet Dr Rader. The doctor, who qualified in 1968 and then specialised in psychiatry, first came to public attention in the 1970s as a television doctor.
He also set up a chain of eating disorder clinics that later went bankrupt and by 1997 he was offering stem cell treatment in the Bahamas until the government put a stop to it. He then moved to the Dominican Republic.
Dr Rader said that the reason he put pressure on Linda Oatley to go ahead was out of concern for her. He said he was attempting to reassure her that the treatment was the right choice. He said it was normal for patients to hesitate, yet all of his prospective patients go through with the treatment in the end.
"Does it ever occur to you that I care about that woman? That I believe the woman wasn't phoney, that I believed that she was real that she had all this anxiety," he said in a heated exchange with Darragh MacIntyre at his Malibu headquarters.
Dr Stephen Minger, one of Britain's leading stem cell scientists, tells Panorama that the cornerstone of scientific research is published, peer-reviewed findings - standards that are missing from Dr Rader's work.
Dakoka received millions of stem cells injected into her head
Back in China with the Clarke family, the little girl's parents say they have seen an improvement in her vision after four injections.
Panorama meets the doctors behind the treatment and the marketing man at the Beike clinic, John Hakim.
Panorama finds that, in 2005, Mr Hakim helped set up a website aimed at selling the organs of executed Chinese prisoners to wealthy westerners, although no transplants ever happened.
Dr Xiang (Sean) Hu, chairman of Beike Biotech, tells Panorama that western scientists who travel to his clinic to learn about their techniques go home impressed.
"I get many English professors and doctors coming to visit us, or American doctors after they talk to our patients they start to (say) 'Congratulations, you guys are doing something great.'"
Panorama hears from Dr Larry Tychsen of St Louis Children's Hospital, who along with colleagues, has examined patients before and after visiting the Chinese clinic to assess the results.
"None of us have seen evidence of visual improvement, of any quantitative visual improvement of any kind," he tells Panorama.
Dr Tychsen worries about media coverage of so-called 'miracle cures' and also points out what he called an "interesting dynamic".
"We have no evidence of the sight increasing temporarily - but there is a very interesting dynamic - that old saying that children can feel their parents' expectations in the next room."
The Clarkes disagreed whole-heartedly with expert results in Belfast that cannot detect any improvement in their own daughter's vision.
"My daughter's seeing things. For the first time my daughter is seeing things," says Wilma Clarke. "I know she is seeing because she is a completely different child."
The Beike clinic in China disputes the accuracy of the vision tests carried out on Dakota Clarke.
Dr Stephen Minger said if stem cell therapy, as it is being offered abroad, really worked, patients need to ask themselves why it is not on offer at home where strict regulatory and safety measures are the norm.
"If these were reputable cell therapies...why do you have to go to the Dominican Republic, why do you have to go to Russia, why do you have to go to China?" he asks. "Why can't you have those therapies here in the UK?"
If Dakota Clarke's condition is improved, doctors say she will turn accepted science on its head.
Panorama: Stem Cells and Miracles, Monday, 18 May, BBC One at 8.30 pm.