Immune system 'rebooted'
The treatment - known as an autologous haematopoietic stem cell transplant (HSCT) - aims to destroy the faulty immune system using chemotherapy.
It is then rebuilt with stem cells harvested from the patient's own blood. These cells are at such an early stage they've not developed the flaws that trigger MS.
Prof John Snowden, consultant haematologist at Royal Hallamshire Hospital, said: "The immune system is being reset or rebooted back to a time point before it caused MS."
About 20 MS patients have been treated in Sheffield in the past three years. Prof Snowden added: "It's clear we have made a big impact on patients' lives, which is gratifying."