Regenerative Index reveals declining muscle regeneration in paediatric patients with Duchenne muscular dystrophy

Johnathan K Smid; Charis A McPherson; Jacob G Monast; Shanti S S Rayagiri; Steven A Moore; Michael A Rudnicki

doi:10.64898/2026.01.05.697715

Back

Regenerative Index reveals declining muscle regeneration in paediatric patients with Duchenne muscular dystrophy

Preprint

Open access

Regenerative Index reveals declining muscle regeneration in paediatric patients with Duchenne muscular dystrophy

Johnathan K Smid, Charis A McPherson, Jacob G Monast, Shanti S S Rayagiri, Steven A Moore and Michael A Rudnicki

bioRxiv

Cold Spring Harbor Laboratory

01/05/2026

DOI: 10.64898/2026.01.05.697715

PMCID: PMC12803257

PMID: 41542555

Files and links (1)

url

https://doi.org/10.64898/2026.01.05.697715View

Preprint (Author's original)This preprint has not been evaluated by subject experts through peer review. Preprints may undergo extensive changes and/or become peer-reviewed journal articles. Open Access

Abstract

Duchenne muscular dystrophy (DMD) is a devastating disease manifested in skeletal muscle by repetitious myonecrosis and regeneration. Because the regenerative process is closely linked to the cumulative severity of muscle damage, which is variably distributed within and between muscle groups, accurately quantifying muscle regeneration has remained a significant challenge. Myofibers are delineated by immunostaining for laminin, and subsequent image analysis employed to generate a masked outline precisely within each myofiber boundary. Morphometric parameters including minimal Feret's diameter, cross-sectional area, and circularity were measured for each myofiber. In addition, the number of Pax7-expressing satellite cells were quantified. To evaluate regenerative activity, newly formed myofibers were identified by immunostaining for expression of embryonic myosin heavy chain (eMHC). Necrotic myofibers were enumerated by immunofluorescent detection of immunoglobulin G (IgG) infiltration. The Regenerative Index (RI) was calculated as the number of regenerating (eMHC ) myofibers divided by the number of necrotic (IgG ) myofibers. Determination of RI was performed on muscle biopsies from 10 boys with DMD and 3 non-DMD controls of similar age. A trend toward an increasing minimal Feret's diameter, cross-sectional area and circularity was observed with increasing age in DMD boys, with circularity showing the strongest trend. Furthermore, compared to DMD boys 7- to 8-years old, the boys 9- to 11-years old had significantly increased myofiber circularity. Pax7-expressing cells were significantly elevated in DMD boys compared to control boys of similar ages, without any observation of age-related changes. Notably, the Regenerative Index in DMD boys exhibited a pronounced decline between 7-11 years of age, and a significant inverse correlation between RI and age was observed. Using eMHC and IgG immunostaining to calculate RI accurately assesses regeneration despite the variation in histopathologic severity between biopsies. This methodology demonstrated a significant negative correlation between RI and age of DMD boys from 7 to 11 years of age.

Details

Title: Subtitle: Regenerative Index reveals declining muscle regeneration in paediatric patients with Duchenne muscular dystrophy
Creators: Johnathan K Smid - Systems, Applications & Products in Data Processing
Charis A McPherson - Ottawa Hospital Research Institute
Jacob G Monast - Ottawa Hospital Research Institute
Shanti S S Rayagiri - Systems, Applications & Products in Data Processing
Steven A Moore - University of Iowa
Michael A Rudnicki - University of Ottawa
Resource Type: Preprint
Publication Details: bioRxiv
DOI: 10.64898/2026.01.05.697715
PMID: 41542555
PMCID: PMC12803257
NLM abbreviation: bioRxiv
ISSN: 2692-8205
eISSN: 2692-8205
Publisher: Cold Spring Harbor Laboratory; United States
Number of pages: 34 pages
Language: English
Date posted: 01/05/2026
Academic Unit: Pathology
Record Identifier: 9985121592802771

Metrics

1 Record Views