The credibility of stem cell research is at risk because of charlatans and dodgy clinics peddling unproven cures for diseases, according to a group of eminent scientists in the field.

Stem cell research, or regenerative medicine, has great potential and has already delivered some breakthroughs, but its future is threatened by poor science, unrealistic hopes, unclear funding models and unscrupulous private clinics, they say in the Lancet medical journal.

A special Lancet commission made up of leading experts has reviewed the progress to date in a field that was once thought to offer answers potentially to all forms of disease and disability. If it is ever to move from small-scale experimental treatments into mainstream medicine, “substantial rethinking of the social contract that supports such research and clinical practice in the public arena will be required,” they say.

Huge excitement about possible treatments for incurable diseases like multiple sclerosis and Parkinson’s disease, inflated by media reports, has led desperate patients and families to a proliferating number of poorly regulated clinics peddling “untested and potentially ineffective therapies”.

“The great risk of the current situation is highlighted by the case of Vannoni in Italy, in which the Stamina Foundation initially succeeded in obtaining direct authorisation from the Italian government to administer an unproven therapy to patients, thus bypassing the country’s regulatory authorities,” says the report.

In March 2015, David Vannoni was convicted of conspiracy and fraud for administering unproven stem cell therapies to patients at his Stamina Foundation. Vannoni, who was not trained as a scientist or doctor, claimed that bone marrow cells could be converted to neural cells to cure diseases such as Parkinson’s disease, muscular dystrophy and spinal muscular atrophy.

The Italian Medicines Agency tried to shut down Vannoni’s operation in Brescia hospital in 2012, but parents of sick children with devastating and terminal illnesses went to court demanding stem cell treatments and hundreds of them won. The Italian government agreed in 2013 to fund a $3.9m clinical trial of the therapy. It took years of campaigning and investigation by scientists to expose Vannoni’s claims. He was sentenced to 22 months in prison, suspended on the condition he ceased treating patients.

Is there scientific documentation of the work they are offering as a basis for therapy? If not, that is a matter for concern

“It happens all over the world, including the United States,” said cell biologist Prof Giulio Cossu from the University of Manchester, who led the commission. “It is no longer the case that you go to India or China.”

It is hard for patients and parents to know whether a stem call treatment that is being offered has any validity but, said Cossu, there are a few simple rules. “Firstly, is the website showing any publication? Is there any scientific documentation of the work they are offering as a basis for the therapy? If not, that is a matter for concern.

“Second, they should give information on the cell type. They often say ‘stem cells’ with no information if they come from a donor or the patient or a bank. And you need a specific cell type for a specific disease.

“Thirdly, is there follow-up? How are patients doing after five years? What proportion of their patients are responding?”

Unfortunately, he said, many of the websites are selling hopes, not drugs.

There have been some real successes, such as bone marrow transplants for babies born with damaged immune systems who would otherwise have died. There are two areas in which stem cell treatments work well – in diseases of the blood and the epithelia, or skin. The reason is that it is possible to remove all the diseased cells first.

“As soon as you move to diseases that affect the muscles, the brain and the heart, you can’t remove the diseased tissue. You add your healthy or cured cell to 95 that have not been cured. You can’t simply transplant the cells and hope that it will work. This has been the lesson we have learned over 20 years,” he said.

Although it is dangerous to predict the future, he says there are some important trials coming up that he thinks will work: two of them in Parkinson’s disease. Parkinson’s is not like some other neurological diseases, such as MS, because it is very localised. The other promising therapy on the horizon is for the blood disorder thalassemia.

The commission says the research is important and must continue. “To realise the potential of this diverse field and improve wellbeing for all, it is clear that we must unite to address the ethical and governance issues, while supporting multifaceted research that brings together scientists, clinicians and engineers from academia and industry,” said another of the authors, Prof David Price, vice-provost for research at University College London.