P.305 - Molecular therapy in a novel translational large animal model for Duchenne muscular dystrophy

Abstract

The development of efficient and safe strategies in gene therapy for Duchenne muscular dystrophy (DMD) remains a huge challenge. Primary myoblast culture models derived from our recently developed large animal model, the exon 52-deficient DMD pig, facilitate to assess various approaches towards dystrophin restoration. The DMD pig carries the most frequent exon deletion occurring in DMD patients and is amenable to targeted exon 51 or exon 53 antisense oligonucleotide (AON)-mediated therapies. Differentiating porcine myoblasts represent a preclinical in vitro model to examine advanced splice modulation approaches including novel oligonucleotide chemistries. Dystrophin mRNA and protein expression are primary endpoints that will be qualitatively and quantitatively examined to identify the most promising candidates for in vivo applications. Dystrophin expression is only present in differentiating myogenic cells. As compared to other species, pig myoblasts differentiate very poorly in vitro. However, by systematically improving coating of cell culture dishes and differentiation medium, we even observed spontaneous twitching of pig myotubes in vitro suggesting high-level differentiation. Besides the translational potential to DMD therapy in affected patients, differentiating myogenic cell culture models are an essential prerequisite to screen novel substances in terms of efficacy and toxicity, prior to their application in vivo.