By Michelle Roberts
Health reporter, BBC News
Stem cells are already being used to prevent blindness
The UK could lose its place among the world leaders in stem cell research unless adequate funding and legislation is assured, experts warn.
The UK National Stem Cell Network says red tape and poor investment threatens the future of UK stem cell work moving from research to real life therapies.
Scientists in the field say unless the obstacles can be overcome they may be forced to take their work abroad.
UK experts are already using stem cells in patients to cure blindness.
But numerous other projects remain in the pipeline awaiting funding and regulatory go-ahead to move from early animal testing to human trials.
Part of the problem is the technology has advanced much faster than anticipated, which has left regulators to play catch-up, says the UKNSCN.
Currently there is no regulatory framework for the researchers designing the clinical trials to refer to.
Dr Julie Daniels, director of the Cells for Sight Tissue Bank at Moorfields Eye Hospital which is using stem cells to treat blinding ocular surface disorders, said it had been a five-year struggle to get the treatment from the bench into the clinic.
"It's been a very time-consuming, self-learning process.
"It was very hard to gain advice from regulatory bodies. There was no one to ask 'What do we do and how do we comply?'
"And it's been incredibly difficult to find financial support."
Much of the pioneering work in the UK relies on charitable donations and investment from abroad - largely the US and Saudi Arabia.
Professor Pete Coffey, director of the London Project to Cure Blindness at University College London, is investigating stem cell therapy for age-related macular degeneration.
His team has made a bank of stem cells that are ready to be used in humans, with the potential to treat some six million patients.
All of his funding to move the work from the lab into the hospital setting so far has come from the US.
"There's not a single penny in the project as yet from the UK. I want to take this forward as a therapy but progress is slow.
"I have kept the project in the UK for as long as possible, but unless more investment comes in from the UK then this will go to the US," he said.
He said US scientists were pushing ahead and seeking regulatory approval to start safety trials of embryonic stem cells in spinal injury patients next year.
Others are looking at using stem cells taken from adult tissue rather than embryos.
Josephine Quintaville of Comment on Reproductive Ethics, a pro-life public interest group, said there was no scientific or ethical justification for using embryonic stem cells over adult stem cells.
"When times are hard and money is short there has to be greater scrutiny of what scientists are doing.
"We should be working in collaboration across Europe. We should be pooling resources, not competing."
Dr Kieran Breen, director of research and development at the Parkinson's Disease Society, said: "Stem cell research offers hope for sufferers of a number of currently incurable diseases.
"There is clearly more research and work needed before we will know exactly what therapies will be of most benefit.
"However, we must ensure that the way ahead is clear of any unnecessary obstacles that could prevent patients from benefiting as soon as possible."
A Department of Health spokesperson said: "The Department of Health believes that stem cell research offers enormous potential to deliver new treatments for diseases and is spending more than £40m a year on all types of research.
"The Department of Health and its Gene Therapy Advisory Committee are currently working with other regulators in the field to produce a 'Regulatory Route Map' to provide further clarity on the regulatory requirements for the clinical use of stem cells."
The Medical Research Council said it was unaware of any clinical studies or trials that had been held up by regulatory procedures.