Reparative dysfunction during muscle regeneration in Duchenne muscular dystrophy: therapeutic approaches to modulating the muscle environment and muscle stem cells

2019 ◽  
Author(s):  
◽  
Michael Everette Nance
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Muscle Regeneration ◽  
Genetic Mutation ◽  
Critical Determinant ◽  
Muscle Stem Cells ◽  
Dystrophin Protein

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Duchenne muscular dystrophy (DMD) is a lethal muscular dystrophy resulting from functional loss of the dystrophin protein, a critical sub-sarcolemmal protein involved in membrane stability. While reparative dysfunction is thought to be a critical determinant of disease progression in humans, regeneration is not significantly impaired in the murine muscular dystrophy (mdx) model. Furthermore, it is not well understood if reparative dysfunction is related to inherent defects in stem cells or chronic alterations in the muscle environment due to disease related remodeling. To address these observed discrepancies, we adapted a whole muscle transplant model to study the in vivo regeneration of intact pieces of skeletal muscle from normal and dystrophic dogs (cDMD), a physiological and clinically relevant model to humans. Regeneration in cDMD muscle grafts was significantly attenuated compared to normal and predisposed to the development of skeletal muscle tumors. We used an adeno-associated virus (AAV) expressing a micro-dystrophin protein to specifically rescue the muscle environment by preventing fiber damage while retaining dystrophin-null SCs. AAV.micro-dystrophin rescued the environment by improving fibrosis, stiffness, and fiber orientation, which significantly improved early muscle regeneration but not late regeneration (2 greater than and less than 4 months post-transplant) via enhancing muscle stem cells differentiation. We next developed Cre- and CRISPR-cas9 gene editing strategies to test the ability of AAV serotype 9 to transduce and treat the genetic mutation in muscle stem cells. We observed efficient SC transduction when used as a single vector expressing Cre. Dual-vector CRISPR-cas9 SC transduction was inefficient and likely related to the requirement for two vectors, promoter usage, and mechanistic differences between Cre-recombination and CRISPR genome editing.

scholarly journals In Vivo Gene Editing of Muscle Stem Cells with Adeno-Associated Viral Vectors in a Mouse Model of Duchenne Muscular Dystrophy

2020 ◽  
Vol 19 ◽  
pp. 320-329
Author(s):  
Jennifer B. Kwon ◽  
Adarsh R. Ettyreddy ◽  
Ashish Vankara ◽  
Joel D. Bohning ◽  
Garth Devlin ◽  
...  
Keyword(s):  
Stem Cells ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mouse Model ◽  
Viral Vectors ◽  
Gene Editing ◽  
Muscle Stem Cells

scholarly journals Empowering Muscle Stem Cells for the Treatment of Duchenne Muscular Dystrophy

2021 ◽  
pp. 1-14
Author(s):  
Romina L. Filippelli ◽  
Natasha C. Chang
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Cell Function ◽  
Critical Role ◽  
Membrane Integrity ◽  
Muscle Membrane ◽  
Muscle Stem Cell ◽  
Muscle Stem Cells

Duchenne muscular dystrophy (DMD) is a devastating and debilitating muscle degenerative disease affecting 1 in every 3,500 male births worldwide. DMD is progressive and fatal; accumulated weakening of the muscle tissue leads to an inability to walk and eventual loss of life due to respiratory and cardiac failure. Importantly, there remains no effective cure for DMD. DMD is caused by defective expression of the <i>DMD</i> gene, which encodes for dystrophin, a component of the dystrophin glycoprotein complex. In muscle fibers, this protein complex plays a critical role in maintaining muscle membrane integrity. Emerging studies have shown that muscle stem cells, which are adult stem cells responsible for muscle repair, are also affected in DMD. DMD muscle stem cells do not function as healthy muscle stem cells, and their impairment contributes to disease progression. Deficiencies in muscle stem cell function include impaired establishment of cell polarity leading to defective asymmetric stem cell division, reduced myogenic commitment, impaired differentiation, altered metabolism, and enhanced entry into senescence. Altogether, these findings indicate that DMD muscle stem cells are dysfunctional and have impaired regenerative potential. Although recent advances in adeno-associated vector and antisense oligonucleotide-mediated mechanisms for gene therapy have shown clinical promise, the current therapeutic strategies for muscular dystrophy do not effectively target muscle stem cells and do not address the deficiencies in muscle stem cell function. Here, we discuss the merits of restoring endogenous muscle stem cell function in degenerating muscle as a viable regenerative medicine strategy to mitigate DMD.

scholarly journals Autophagy in the heart is enhanced and independent of disease progression in mus musculus dystrophinopathy models

2019 ◽  
Vol 8 ◽  
pp. 204800401987958
Author(s):  
HR Spaulding ◽  
C Ballmann ◽  
JC Quindry ◽  
MB Hudson ◽  
JT Selsby
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Disease Progression ◽  
Gene Mutations ◽  
Dystrophin Gene ◽  
Mdx Mice ◽  
Dystrophin Deficiency ◽  
Muscle Wasting Disease ◽  
Dystrophin Protein

Background Duchenne muscular dystrophy is a muscle wasting disease caused by dystrophin gene mutations resulting in dysfunctional dystrophin protein. Autophagy, a proteolytic process, is impaired in dystrophic skeletal muscle though little is known about the effect of dystrophin deficiency on autophagy in cardiac muscle. We hypothesized that with disease progression autophagy would become increasingly dysfunctional based upon indirect autophagic markers. Methods Markers of autophagy were measured by western blot in 7-week-old and 17-month-old control (C57) and dystrophic (mdx) hearts. Results Counter to our hypothesis, markers of autophagy were similar between groups. Given these surprising results, two independent experiments were conducted using 14-month-old mdx mice or 10-month-old mdx/Utrn± mice, a more severe model of Duchenne muscular dystrophy. Data from these animals suggest increased autophagosome degradation. Conclusion Together these data suggest that autophagy is not impaired in the dystrophic myocardium as it is in dystrophic skeletal muscle and that disease progression and related injury is independent of autophagic dysfunction.

scholarly journals Therapeutic Strategies for Duchenne Muscular Dystrophy: An Update

Genes ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 837 ◽  
Author(s):  
Chengmei Sun ◽  
Luoan Shen ◽  
Zheng Zhang ◽  
Xin Xie
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Motor Neurons ◽  
Neuromuscular Junctions ◽  
Neuromuscular Disorders ◽  
Dystrophin Gene ◽  
Current Status ◽  
Muscle Stem Cells ◽  
Cell Based Therapy ◽  
Dystrophin Protein

Neuromuscular disorders encompass a heterogeneous group of conditions that impair the function of muscles, motor neurons, peripheral nerves, and neuromuscular junctions. Being the most common and most severe type of muscular dystrophy, Duchenne muscular dystrophy (DMD), is caused by mutations in the X-linked dystrophin gene. Loss of dystrophin protein leads to recurrent myofiber damage, chronic inflammation, progressive fibrosis, and dysfunction of muscle stem cells. Over the last few years, there has been considerable development of diagnosis and therapeutics for DMD, but current treatments do not cure the disease. Here, we review the current status of DMD pathogenesis and therapy, focusing on mutational spectrum, diagnosis tools, clinical trials, and therapeutic approaches including dystrophin restoration, gene therapy, and myogenic cell transplantation. Furthermore, we present the clinical potential of advanced strategies combining gene editing, cell-based therapy with tissue engineering for the treatment of muscular dystrophy.

scholarly journals Microtubules that form the stationary lattice of muscle fibers are dynamic and nucleated at Golgi elements

2013 ◽  
Vol 203 (2) ◽  
pp. 205-213 ◽  
Author(s):  
Sarah Oddoux ◽  
Kristien J. Zaal ◽  
Victoria Tate ◽  
Aster Kenea ◽  
Shuktika A. Nandkeolyar ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Mouse Muscle ◽  
Muscle Diseases ◽  
Superresolution Microscopy ◽  
Nuclear Membranes ◽  
Organizing Center ◽  
Static Images

Skeletal muscle microtubules (MTs) form a nonclassic grid-like network, which has so far been documented in static images only. We have now observed and analyzed dynamics of GFP constructs of MT and Golgi markers in single live fibers and in the whole mouse muscle in vivo. Using confocal, intravital, and superresolution microscopy, we find that muscle MTs are dynamic, growing at the typical speed of ∼9 µm/min, and forming small bundles that build a durable network. We also show that static Golgi elements, associated with the MT-organizing center proteins γ-tubulin and pericentrin, are major sites of muscle MT nucleation, in addition to the previously identified sites (i.e., nuclear membranes). These data give us a framework for understanding how muscle MTs organize and how they contribute to the pathology of muscle diseases such as Duchenne muscular dystrophy.

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