A treatment for progressive multiple sclerosis could be on the horizon after a researchers found injecting stem cells into the brains of patients could potentially stop the disease advancing.
The study said the procedure was "safe, well tolerated and has a long-lasting effect that appears to protect the brain from further damage".
MS impacts the brain and spinal cord, leading to symptoms such as vision problems, as well as issues with movement, sensation or balance.
In some cases it can lead to serious disabilities.
The early-stage clinical trial led by scientists at the University of Cambridge, along with teams from the University of Milan Bicocca and Hospital Casa Sollievo della Sofferenza in Italy, injected neural stem cells directly into the brains of 15 patients with secondary MS who were recruited from two hospitals in Italy.
The cells were collected from the brain tissue of a miscarried foetal donor.
Following the treatment, researchers followed the patients over 12 months, observing no treatment-related deaths or serious adverse effects.
Some side effects were observed, researchers said, however, they were deemed "either temporary or reversible".
These included minor infections and tremors. One patient suffered a steroid-induced psychosis one month after the injection, but went on to make a full recovery.
At the start of the trial, most of the patients required wheelchairs and showed high levels of disability, but this did not worsen in the year after the treatment.
Researchers said the findings, published in Cell Stem Cell, point to a "substantial stability of the disease, without signs of progression, though the high levels of disability at the start of the trial make this difficult to confirm".
Professor Stefano Pluchino from the University of Cambridge, who co-led the study, said: "We desperately need to develop new treatments for secondary progressive MS, and I am cautiously very excited about our findings, which are a step towards developing a cell therapy for treating MS.
"We recognise that our study has limitations - it was only a small study and there may have been confounding effects from the immunosuppressant drugs, for example - but the fact that our treatment was safe and that its effects lasted over the 12 months of the trial means that we can proceed to the next stage of clinical trials."
A subgroup of patients were assessed for changes to to brain tissue volume, and found those who had received a larger dose of stem cells had a small reduction over time.
Scientists said this could be down to the stem cells dampening inflammation in the brain.
Caitlin Astbury, research communications manager at the MS Society, said: "This is a really exciting study which builds on previous research funded by us.
"We've known for some time that this method has the potential to help protect the brain from progression in MS.
"This was a very small, early-stage study and we need further clinical trials to find out if this treatment has a beneficial effect on the condition. But this is an encouraging step towards a new way of treating some people with MS."
However, Dr Aravinthan Varatharaj, a clinical lecturer in neurology at the University of Southampton, said "We do not have any good evidence" the technique can be used to repair or regrow nerve cells in the brain.
"Whilst this study showed that patients did not experience significant disease progression after treatment, there are other possible explanations for this, and this was not a controlled trial," he said.
"Also, most patients still had evidence of disease activity on MRI scans, suggesting that this treatment did not fully suppress brain inflammation."
Australian Associated Press