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Dissertation
Pre-clinical evaluation of 2'-O-methyl antisense oligonucleotides as potential therapeutics for Duchenne muscular dystrophy and spinal muscular atrophy
Doctor of Philosophy (Ph.D.), Drexel University
Nov 2007
DOI:
https://doi.org/10.17918/00009188
Abstract
Antisense Oligonucleotides (AO) with 2'-O-Methyl (2OMe) modifications can circumvent dystrophin mutations via exon skipping and correct aberrant SMN2 splicing and are hopeful drugs for Duchenne Muscular Dystrophy (DMD) and Spinal Muscular Atrophy (SMA). However, the efficacy of these compounds when delivered locally or systemically in animal models for DMD is limited by their inefficient delivery to nuclei of various cell types. Furthermore, viability of 2OMe AO correction of SMN2 in a mouse model for SMA has yet to be established. In attempt to improve the delivery efficiency of 2OMe AO in skeletal muscle, we evaluated copolymers composed of cationic poly(ethylene imine) (PEI) and polyethylene glycol (PEG) by performing localized injections into hind limb muscles of a dystrophic (mdx) mouse. We found that PEGylated low MW PEI2K formulations improved transfection efficiency over naked AO as evidenced by a high number of dystrophin positive fibers widely distributed throughout the muscle. Repeated injection of AO complexed to nanogold-conjugated PEI2K-PEG copolymer increased dystrophin expression to 20%, the mark determined to be functionally relevant for improvement of dystrophic muscle. Thus, PEGylated PEI2K copolymers are efficient carriers for local delivery of 2OMe AOs and warrant further development as potential therapeutics for treatment of DMD. We subsequently evaluated correction of SMN2 splicing in a mouse model for SMA using a 2OMe AO sequence established to effectively increase Survival of Motor Neuron (SMN) protein in SMA patient fibroblasts. Injections into the cerebrospinal fluid (CSF) over the first 10 days of life increased functional SMN in brain and spinal cord to 35-55% as compared to wild-type control. 2OMe AO treated mice were significantly heavier as compared to un-injected SMA control mice suggesting this compound may extend lifespan if treatment is continued. Overall, this study shows that 2OMe AOs are effective compounds for the correction of splice defects and the production of functional protein in animal models for DMD and SMA. In addition, the delivery efficiency of 2OMe AOs in skeletal muscle of the mdx mouse is greatly increased when complexed with PEGylated PEI2K copolymers. The results from this thesis provide an important step in the preclinical development of 2OMe AOs as effective therapeutics for DMD and SMA.
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Details
- Title
- Pre-clinical evaluation of 2'-O-methyl antisense oligonucleotides as potential therapeutics for Duchenne muscular dystrophy and spinal muscular atrophy
- Creators
- Jason H. Williams
- Contributors
- Gordon J. Lutz (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xiii, 158 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Medicine; Pharmacology and Physiology; Drexel University
- Other Identifier
- 991021888952304721