Aptamer Treatment Reverses Multiple Sclerosis in a Mouse Model

Researchers have used a nucleic acid aptamer selected for affinity to mouse myelin to demonstrate the possibility of using this type of reagent to stimulate regeneration and repair of nerve coatings in mice with a disease that mimics multiple sclerosis.

Multiple sclerosis (MS), which affects more than 200 million people worldwide, is a debilitating inflammatory disease of the central nervous system characterized by local destruction of the insulating myelin surrounding neuronal axons.

Nucleic acid aptamers are nucleic acid species that have been engineered through repeated rounds of in vitro selection to bind to various molecular targets such as small molecules, proteins, nucleic acids, and even cells, tissues, and organisms. Aptamers are useful in biotechnological and therapeutic applications as they offer molecular recognition properties that rival that of antibodies. In addition to their discriminate recognition, aptamers offer advantages over antibodies as they can be engineered completely in a test tube, are readily produced by chemical synthesis, possess desirable storage properties, and elicit little or no immunogenicity in therapeutic applications. Relative to monoclonal antibodies, DNA aptamers are small, stable, and nonimmunogenic.

Investigators at the Mayo Clinic (Rochester, MN, USA) designed a 40-nucleotide single-stranded DNA aptamer selected for affinity to mouse myelin. This aptamer was shown to bind to multiple myelin components in vitro.

Mice suffering from a neurological disease that mimics MS were treated by peritoneal injection of the aptamer. Results published in the June 27, 2012, online edition of the journal PLoS ONE revealed that the aptamer was rapidly distributed to central nervous system tissues where it promoted remyelination of lesions.

“The problem has been to find a way to encourage the nervous system to regenerate its own myelin so nerve cells can recover from an MS attack,” said senior author Dr. L. James Maher III, professor of biochemistry and molecular biology at the Mayo Clinic. “We show here that these small molecules, called aptamers, can stimulate repair in the mice we are studying.”

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