Antisense oligonucleotides are small pieces of modified DNA or RNA, which offer therapeutic potential for many diseases. We report on the synthesis of 7',5'-alpha-bc-DNA phosphoramidite building... Show moreAntisense oligonucleotides are small pieces of modified DNA or RNA, which offer therapeutic potential for many diseases. We report on the synthesis of 7',5'-alpha-bc-DNA phosphoramidite building blocks, bearing the A, G, T and C-Me nucleobases. Solid-phase synthesis was performed to construct five oligodeoxyribonucleotides containing modified thymidine residues, as well as five fully modified oligonucleotides. Incorporations of the modification inside natural duplexes resulted in strong destabilizing effects. However, fully modified strands formed very stable duplexes with parallel RNA complements. In its own series, 7',5'-alpha-bc-DNA formed duplexes with a surprising high thermal stability. CD spectroscopy and extensive molecular modeling indicated the adoption by the homo-duplex of a ladder-like structure, while hetero-duplexes with DNA or RNA still form helical structure. The biological properties of this new modification were investigated in animal models for Duchenne muscular dystrophy and spinal muscular atrophy, where exon splicing modulation can restore production of functional proteins. It was found that the 7',5'-alpha-bc-DNA scaffold confers a high biostability and a good exon splicing modulation activity in vitro and in vivo. Show less
Duchenne muscular dystrophy is an X-linked, recessive muscular dystrophy in which the absence of the dystrophin protein leads to fibrosis, inflammation and oxidative stress, resulting in loss of... Show moreDuchenne muscular dystrophy is an X-linked, recessive muscular dystrophy in which the absence of the dystrophin protein leads to fibrosis, inflammation and oxidative stress, resulting in loss of muscle tissue. Drug repurposing, i.e. using drugs already approved for other disorders, is attractive as it decreases development time. Recent studies suggested that simvastatin, a cholesterol lowering drug used for cardiovascular diseases, has beneficial effects on several parameters in mdx mice. To validate properly the effectiveness of simvastatin, two independent labs tested the effects of 12-week simvastatin treatment in either young (starting at 4 weeks of age) or adult (starting at 12 weeks of age) mdx mice. In neither study were benefits of simvastatin treatment observed on muscle function, histology or expression of genes involved in fibrosis, regeneration, oxidative stress and autophagy. Unexpectedly, although the treatment protocol was similar, simvastatin plasma levels were found to be much lower than observed in a previous study. In conclusion, in two laboratories, simvastatin did not ameliorate disease pathology in mdx mice, which could either be due to the ineffectiveness of simvastatin itself or due to the low simvastatin plasma levels following oral administration via the food. Show less
Duchenne muscular dystrophy (DMD) is caused by the lack of functional dystrophin protein. Improvements in patient care and disease management have slowed down disease progression, but current... Show moreDuchenne muscular dystrophy (DMD) is caused by the lack of functional dystrophin protein. Improvements in patient care and disease management have slowed down disease progression, but current treatments cannot stop the relentless loss of muscle tissue and function, which leads to premature death. Research is ongoing to develop effective therapies for DMD. Gene-addition, exon-skipping, stop codon readthrough and genome-editing therapies can restore the expression of partially functional dystrophin protein, whereas other therapeutic approaches aim to improve muscle function and quality by targeting pathways involved in the pathogenesis of DMD. This Review outlines important developments in these research areas and specifically focuses on new therapies that are in the clinical trial phase or have already been approved. Show less
Verhaart, I.E.C.; Vijver, D. van de; Boertje-van der Meulen, J.W.; Putker, K.; Adamzek, K.; Aartsma-Rus, A.; Putten, M. van 2019
Duchenne muscular dystrophy (DMD) is caused by a lack of dystrophin protein. Next to direct effects on the muscles, this has also metabolic consequences. The influence of nutrition on disease... Show moreDuchenne muscular dystrophy (DMD) is caused by a lack of dystrophin protein. Next to direct effects on the muscles, this has also metabolic consequences. The influence of nutrition on disease progression becomes more and more recognized. Protein intake by DMD patients may be insufficient to meet the increased demand of the constantly regenerating muscle fibers. This led to the hypothesis that improving protein uptake by the muscles could have therapeutic effects. The present study examined the effects of a modified diet, which composition might stimulate muscle growth, on disease pathology in the D2-mdx mouse model. D2-mdx males were fed with either a control diet or modified diet, containing high amounts of branched-chain amino acids, vitamin D3 and ursolic acid, for six weeks. Our study indicates that the modified diet could not ameliorate the muscle pathology. No effects on bodyweight or weight of individual muscles were observed. Neither did the diet affect severity of fibrosis or calcification of the muscles. Show less
This thesis starts with a broad introduction of Duchenne muscular dystrophy (DMD) and several therapies targeting the primary underlying genetic cause or the secondary effects caused by the disease... Show moreThis thesis starts with a broad introduction of Duchenne muscular dystrophy (DMD) and several therapies targeting the primary underlying genetic cause or the secondary effects caused by the disease. DMD is caused by a genetic defect in the DMD gene encoding the dystrophin protein, which plays an important function inside muscle cells. A more detailed analysis of 2__-O-methyl phosphorothioate antisense oligonucleotide ( 2OmePS AON)-mediated exon skipping in mouse models for DMD is given. This therapy aims to correct the genetic defect at RNA level and turn the disease in a milder form. Furthermore it describes several strategies to increase the therapeutic effects of AONs by combining it with another drug. First a compound that could potentially enhance the working of the AONs itself. Secondly, two compounds that might improve the muscle quality (thereby providing more targets for the AONs) by targeting secondary effects. The results of these experiments are described and put in a broader context Show less
Putten, M. van; Pijl, E.M. van der; Hulsker, M.; Verhaart, I.E.C.; Nadarajah, V.D.; Weerd, L. van der; Aartsma-Rus, A. 2014
