Stem cell therapy puts multiple sclerosis in remission.

Healthline spells out the basics of rebooting an immune system from scratch – which means a pretty dramatic step forward in medicine:

Studying 24 study volunteers who underwent stem cell transplants between 2006 and 2010, Dr. Richard A. Nash of the Colorado Blood Cancer Institute in Denver and his colleagues recently published their findings in JAMA Neurology.

Researchers found that more than 86 percent of the patients remained relapse free after three years, and nearly 91 percent showed no sign of disease progression.

The study involved patients with relapsing-remitting MS whose disease did not respond to at least one FDA-approved disease-modifying drug. Patients also had to score between 3.0 and 5.5 on the Expanded Disability Status Scale (EDSS), a set of tests to measure walking, cognition, dexterity, and quality of life in MS patients. People who fall into this range typically have mild to moderate disability.

Patients were given high-dose immunosuppressive therapy, or HDIT, to erase their native immune system. Then, researchers reintroduced blood-forming stem cells that had been harvested from the patients’ own blood.

“On average patients were hospitalized for three to four weeks,” said Nash in an interview with Healthline. That allowed enough time for the immune system to regenerate so patients could safely return home.

Improvement in the EDSS scores from baseline suggests that nerves may be remyelinating, the holy grail of MS research. Restoring myelin can repair damaged nerves, restoring their function.

According to some reasonable-sounding folks on reddit (go figure!), one of the keys here is the new ability to regenerate the thymus, which regulates the immune system. (See In other words, doctors can basically switch it off and switch it on again, like a malfunctioning computer. And then, nerve coverings start growing back, and things start working again. The same therapy could be used on other immune-related diseases, like AIDS.

Twenty-four patients is not a large sample size, but it’s a start.