India, June 24 -- A donor stem cell transplant has kept two patients with neuromyelitis optica relapse-free for 15 years without ongoing medication.

NMO is a rare autoimmune disorder in which the immune system attacks the spinal cord and optic nerve, causing vision loss, paralysis and other severe symptoms.

Researchers say the treatment may have worked by replacing the patients' immune systems and restoring immune tolerance.

Scientists remain cautious because the study involved only two patients and the procedure carries serious risks, including infections and other complications.

A stem cell transplant has kept two patients with neuromyelitis optica (NMO) - a rare, aggressive autoimmune disease - relapse-free for 15 years without the...