In the first-ever clinical trials in humans, researchers from Europe and the U.S. have found that patients with MS injected with stem cells exhibited no increase in disability or worsening of symptoms.

The promising study, published in the journal Cell Stem Cell, is hoped to lead to further clinical trials that could provide treatment for progressive MS.

More than two million people live with MS across the globe, and whilst some treatments reduce the severity and frequency of relapses, two-thirds of patients still transition into a debilitating secondary progressive phase of the disease within 25 to 30 years of diagnosis.

An autoimmune disorder like Lupus, ALS, and Crohn’s, MS is characterised by the body’s immune system attacking and damaging myelin, the protective sheath of tissue around nerve fibres, disrupting messages sent around the brain and spinal cord.

An immune cell called a microglial can attack the central nervous system in progressive forms of MS, causing chronic inflammation and damage to nerve cells.

Recent scientific advances involving the transplantation of stem cells have raised expectations that therapies could be developed to help ameliorate this damage.

Previous experiments in mice from the Cambridge University unit of the new study team have shown that skin cells reprogrammed to be brain stem cells and transplanted into the nervous system can help to reduce inflammation, and may even be able to help repair damage caused by MS.

The research team behind the latest study, incorporating experts from the U.K., U.S., Switzerland, and Italy, completed a world-first early-stage clinical trial in which neural stem cells were injected into the brains of 15 patients with secondary MS recruited from two Italian hospitals.

Along with the Cambridge unit, teams performed the trials at the University of Milano-Bicocca, the Casa Sollievo della Sofferenza and Santa Maria Terni hospitals in Italy, the Ente Ospedaliero Cantonale hospital in Lugano, Switzerland, and the University of Colorado in the United States.

The transplant patients were followed for 12 months. No deaths or serious adverse events related to the treatment were observed throughout the year. Side effects were mild, transient, and reversible.

All patients had a high degree of disability at the start of the clinical trial (for example, they were wheelchair-bound), but during the 12-month observation period, they showed no increase in disability or worsening of symptoms. None of the patients showed symptoms that would indicate a relapse or signs of clinical progression, suggesting substantial stability of the pathology.

A subgroup of patients was also assessed for changes in the volume of brain tissue associated with disease progression, which found that the larger the dose of injected stem cells, the smaller the reduction in this brain volume over time.

The researchers speculate that this may be down to the stem cell transplant dampening inflammation.

Professor Stefano Pluchino, a co-leader of the study from the University of Cambridge, admitted that though the research had limitations, the findings were extremely promising.

“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,” he said.

“Having said that, we also 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.”

Professor Angelo Vescovi, another co-leader of the study from the University of Milano-Bicocca, added that it has taken nearly three decades to translate the discovery of brain stem cells into this experiment, which he said will “pave the way” to broader studies “soon to come.”