Abstract
We previously reported the in vitro selection and characterization of a DNA aptamer capable of stimulating remyelination in a mouse model of multiple sclerosis. This aptamer was selected for its ability to bind to suspensions of crude murine myelin in vitro. Our initial studies in vitro and in vivo involved a 40-nucleotide derivative (LJM-3064) of the original 100-nucleotide aptamer. LJM-3064 retained robust myelin-binding properties. Structural characterization of LJM-3064 revealed that the guanosine-rich 5′ half of the sequence forms different G-quadruplex-type structures that are variably stable in the presence of physiologically relevant ions. We hypothesized that this structured domain is sufficient for myelin binding. In this study, we confirm that a 20-nucleotide DNA, corresponding to the 5′ half of LJM-3064, retains myelin-binding properties. We then optimize this minimal myelin-binding aptamer via systematic evolution of ligands by exponential enrichment after sparse rerandomization. We report a sequence variant (LJM-5708) of the 20-nucleotide myelin-binding aptamer with enhanced myelin-binding properties and the ability to bind cultured human oligodendroglioma cells in vitro, providing the first evidence of cross-species reactivity of this myelin-binding aptamer. As our formulation of DNA aptamers for in vivo remyelination therapy involves conjugation to streptavidin, we verified that the myelin-binding properties of LJM-5708 were retained in conjugates to avidin, streptavidin, and neutravidin. DNA aptamer LJM-5708 is a lead for further preclinical development of remyelinating aptamer technologies.
Highlights
Multiple sclerosis (MS) is a central nervous system (CNS) demyelinating disease with increasing prevalence in the Western world, affecting *0.1% of the global population [1]
Inspired by reports of remyelination induced by natural human antimyelin immunoglobulin M (IgM) antibodies, we previously reported the application of systematic evolution of ligands by exponential enrichment (SELEX) using crude murine myelin as a selection target to yield a myelin-binding DNA aptamer (LJM-3064) capable of promoting remyelination in the Theiler’s Murine Encephalomyelitis Virus model of MS [18]
Biotinylated 20-nucleotide derivatives were synthesized as individual DNA oligonucleotides LJM-5705 (5¢ G-quadruplex-forming half) and LJM-5952 (3¢ unstructured half) and formulated as streptavidin conjugates using a 4:1 aptamer:streptavidin ratio
Summary
Multiple sclerosis (MS) is a central nervous system (CNS) demyelinating disease with increasing prevalence in the Western world, affecting *0.1% of the global population [1]. Disease-altering therapy for progressive forms of MS has been less effective, with only modest clinical benefit observed for ocrelizumab (anti-CD20) [10], azathioprine (immunosuppressant) [11], glucocorticoids (immunosuppressant) [12], cyclosporine (immunosuppressant) [13], and interferon beta-1b (immunosuppressant) [14]. Only 10% of patients have a diagnosis of primary progressive MS, by 25 years after diagnosis, *90% of patients with relapsing– remitting MS convert to the secondary progressive subtype. This makes the development of effective disease-altering therapies for progressive MS an important clinical priority
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
