The super-healing MRL strain promotes muscle growth in muscular dystrophy through a regenerative extracellular matrix
Joseph G. O’Brien, … , Alexis R. Demonbreun, Elizabeth M. McNally
Joseph G. O’Brien, … , Alexis R. Demonbreun, Elizabeth M. McNally
Published January 4, 2024
Citation Information: JCI Insight. 2024;9(3):e173246. https://doi.org/10.1172/jci.insight.173246.
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Research Article Muscle biology Stem cells

The super-healing MRL strain promotes muscle growth in muscular dystrophy through a regenerative extracellular matrix

Abstract

The Murphy Roths Large (MRL) mouse strain has “super-healing” properties that enhance recovery from injury. In mice, the DBA/2J strain intensifies many aspects of muscular dystrophy, so we evaluated the ability of the MRL strain to suppress muscular dystrophy in the Sgcg-null mouse model of limb girdle muscular dystrophy. A comparative analysis of Sgcg-null mice in the DBA/2J versus MRL strains showed greater myofiber regeneration, with reduced structural degradation of muscle in the MRL strain. Transcriptomic profiling of dystrophic muscle indicated strain-dependent expression of extracellular matrix (ECM) and TGF-β signaling genes. To investigate the MRL ECM, cellular components were removed from dystrophic muscle sections to generate decellularized myoscaffolds. Decellularized myoscaffolds from dystrophic mice in the protective MRL strain had significantly less deposition of collagen and matrix-bound TGF-β1 and TGF-β3 throughout the matrix. Dystrophic myoscaffolds from the MRL background, but not the DBA/2J background, were enriched in myokines like IGF-1 and IL-6. C2C12 myoblasts seeded onto decellularized matrices from Sgcg–/– MRL and Sgcg–/– DBA/2J muscles showed the MRL background induced greater myoblast differentiation compared with dystrophic DBA/2J myoscaffolds. Thus, the MRL background imparts its effect through a highly regenerative ECM, which is active even in muscular dystrophy.

Authors

Joseph G. O’Brien, Alexander B. Willis, Ashlee M. Long, Jason Kwon, GaHyun Lee, Frank W. Li, Patrick G.T. Page, Andy H. Vo, Michele Hadhazy, Melissa J. Spencer, Rachelle H. Crosbie, Alexis R. Demonbreun, Elizabeth M. McNally

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Figure 5

Decellularized myoscaffolds from Sgcg-MRL muscle promote migration and early differentiation of C2C12 myoblasts.

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Decellularized myoscaffolds from Sgcg-MRL muscle promote migration and e...
(A) C2C12 myoblasts were seeded at low density and proliferated on dECM myoscaffolds from Sgcg-MRL (top) and Sgcg-D2 (bottom) for 24 hours. Then, growth media were replaced with low-serum differentiation media for 96 hours. Slides were fixed for imaging. (B) Imaging of dECM myoscaffolds seeded with C2C12 myoblasts. The left column (scale bars: 500 μm) represents entire myoscaffolds with seeded myoblasts costained for LAMA2 (green), desmin (DES, red), and with Hoechst (blue) to stain nuclei. The yellow region of interest is magnified in the middle and right columns (scale bars: 50 μm). DES (red) staining in the right column shows myoblast morphology. (C–H) Three independent biological replicates of the Sgcg-MRL and Sgcg-D2 dECMs were analyzed (labeled as N1 = gray, N2 = black, N3 = white). For each sample, 6 images of myoblasts were captured at ×20 magnification. (C) Area of desmin positivity relative to the number of nuclei in the field (Sgcg-MRL 797.0 and Sgcg-D2 197.4 mm2). (D) Average cell size (Sgcg-MRL 319.7 and Sgcg-D2 120.8 mm2). (E) Circularity (Sgcg-MRL.549 and Sgcg-D2.681 AU). (F) Myoblast perimeter (Sgcg-MRL 100.5 and Sgcg-D2 47.8 mm). (G) Minimum Feret diameter (Sgcg-MRL 11.5 and Sgcg-D2 8.6 mm). Quadriceps were isolated from 3 biological replicates of the Sgcg-MRL and Sgcg-D2 cohorts. (H) RNA sequencing was performed and Myh4 gene expression was found to be upregulated in the MRL strain (Sgcg-MRL 40,692 and Sgcg-D2 22,915 CPM). Data are presented as mean ± SD. **P < 0.01, ****P < 0.0001 by 2-tailed Student’s t test.