CSPGs are large and complex molecules composed of both proteins and sugars that accumulate as plaques at the site of myelin damage. This prevents both the migration and maturation of myelin-producing cells, called oligodendrocyte precursor cells.
These cells are present in demyelinated lesions in MS patients’ brains, even in advanced disease stages. But researchers have not yet figured out how to reactivate their maturation.
In the study “Protamine neutralizes chondroitin sulfate proteoglycan-mediated inhibition of oligodendrocyte differentiation,” a team used mice to test the effect of protamine in CSPGs.
Giving protamine intranasally to newborn mice, the researchers observed increased markers of myelination, supporting the idea that protamine might promote myelination. These mice, however, were normal with a healthy developing brain.
Would protamine have the same properties in adult mice with myelin damage, they wondered.
To find out, the team exposed mice to cuprizone — a chemical that causes demyelinating brain lesions. Ten days of intranasal protamine treatment did not improve the animals’ brain damage. But when researchers administered the compound directly into the brain for 10 days, new myelin started forming.
Moreover, they noted a decline in the number of damaged neuronal axons in these animals.