Worldwide, more than 2.3 million people have MS.
Multiple sclerosis (MS) is a debilitating disease of the central nervous system (CNS). It is believed to be an autoimmune disease, in which the immune system mistakenly attacks the brain, spinal cord and optic nerves.
In detail, the immune system attacks myelin - the protective coating surrounding nerve fibers - as well as the nerve fibers themselves. Such damage impairs communication between the brain and spinal cord, producing a variety of symptoms.
Common symptoms of MS include numbness or tingling of the face and body, walking and balance difficulties, involuntary muscle spasms, pain, weakness, fatigue, dizziness and cognitive impairment. Some people with MS may also experience seizures, speech problems or tremors.
Relapsing-remitting MS (RRMS) is the most common form of the disease, accounting for around 85% of all cases. In RRMS, people experience flare-ups of symptoms, followed by periods of partial or complete recovery.
Primary-progressive MS (PPMS) accounts for around 10-15% of all cases. Rather than experiencing flare-ups of symptoms, people with PPMS experience steady worsening of symptoms.
Secondary-progressive MS (SPMS) normally follows RRMS. This occurs when symptom flare-ups cease and the disease starts to progress more steadily.
MS: a debilitating disease with no cure
According to the National Multiple Sclerosis Society, around two thirds of people with MS retain their ability to walk, though many individuals may require the assistance of a cane or crutches to get around. In severe cases, some patients may become wheelchair-bound.
One such patient was 25-year-old Holly Drewry from Sheffield, UK, who was diagnosed with RRMS at the age of 21. Following the birth of her daughter Isla, her condition worsened, confining her to a wheelchair.
"Within a couple of months I got worse and worse. I couldn't dress or wash myself; I didn't even have the strength to carry my daughter," she told BBC News.
At present, the outcome is bleak for MS patients who find themselves in Holly's position. There is currently no cure for MS, only treatments that may help modify the course of the disease or help manage symptoms.
But according to preliminary trial results, a cure for MS could be on the horizon; the treatment in question has already enabled some patients with MS - including Holly - to walk again.
Utilizing a cancer treatment for MS
The groundbreaking treatment being trialed is called autologous hematopoietic stem cell transplantation (AHSCT) - a procedure that is currently used to treat cancers of the bone and blood, such as leukemia and multiple myeloma.
AHSCT aims to "reboot" the immune system, preventing it from attacking the myelin and nerve fibers.
AHSCT "reboots" the immune system by re-infusing patients' own HSCs (pictured) into their blood.
Firstly, hematopoietic stem cells (HSCs), or hemocytoblasts, are collected from the patient's bone marrow or blood and are frozen until they are needed.
HSCs are adult stem cells that are made in bone marrow. They have the ability to renew themselves and make different cells found in the blood.
Next, the patient will undergo high-dose chemotherapy in order to destroy and clear all the harmful immune cells that are attacking the brain and spinal cord.
The patient's frozen HSCs are then thawed and re-infused into their blood, where they begin to make new red and white blood cells within 2 weeks. Because the harvested HSCs have not developed the abnormalities that damage the CNS, re-introducing them into the patient's blood effectively restarts the immune system.
"The immune system is being reset or rebooted back to a time point before it caused MS," explains Prof. John Snowden, consultant hematologist at the UK's Royal Hallamshire Hospital, where 20 clinical trial patients have received the treatment so far.
After transplantation, patients are monitored for about 3-4 weeks, during which time they receive antibiotics and transfusions to aid recovery. The immune system should be fully rebuilt within 1 month.
On the next page, we look at the amazing results AHSCT has produced so far for MS patients, as well as the risks associated with the treatment.