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Abstract Volumetric muscle loss (VML) results in permanent functional deficits and remains a substantial regenerative medicine challenge. A coordinated immune response is crucial for timely myofiber regeneration, however the immune response following VML has yet to be fully characterized. Here, we leveraged dimensionality reduction and pseudo-time analysis techniques to elucidate the cellular players underlying a functional or pathological outcome as a result of subcritical injury or critical VML in the murine quadriceps, respectively. We found that critical VML resulted in a sustained presence of M2-like and CD206hiLy6Chi‘hybrid’ macrophages whereas subcritical defects resolved these populations. Notably, the retained M2-like macrophages from critical VML injuries presented with aberrant cytokine production which may contribute to fibrogenesis, as indicated by their co-localization with fibroadipogenic progenitors (FAPs) in areas of collagen deposition within the defect. Furthermore, several T cell subpopulations were significantly elevated in critical VML compared to subcritical injuries. These results demonstrate a dysregulated immune response in critical VML that is unable to fully resolve the chronic inflammatory state and transition to a pro-regenerative microenvironment within the first week after injury. These data provide important insights into potential therapeutic strategies which could reduce the immune cell burden and pro-fibrotic signaling characteristic of VML.
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This content will become publicly available on July 3, 2026
Temporal dynamics of gene and protein signatures following volumetric muscle loss
IntroductionVolumetric muscle loss (VML) is characterized by permanent tissue impairment resulting from critically-sized muscle loss. We performed time-series transcriptomic and proteomic analyses to reveal key mediators of irreversible pathological remodeling after induction of VML in mice. MethodsThe dynamics of gene and protein expression patterns were analyzed for up to 3 weeks after muscle injury. ResultsRNA Sequencing revealed transcriptional patterns that show rapid upregulation or downregulation shortly after injury, among which a subset of genes failed to return to pre-injury levels within 3 weeks after VML. Time-series analysis revealed gene clusters with sustained upregulation after 3 weeks, including those associated with extracellular matrix remodeling and inflammation, whereas the gene clusters having sustained downregulation were associated with mitochondrial function and metabolism. We further identifiedSPI1andSP1as novel molecular mediators of the pathological remodeling process. DiscussionThis work demonstrates the utility of time-series analysis to reveal dysregulated pathways in the setting of VML.
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- PAR ID:
- 10651182
- Publisher / Repository:
- Frontiers
- Date Published:
- Journal Name:
- Frontiers in Cell and Developmental Biology
- Volume:
- 13
- ISSN:
- 2296-634X
- Page Range / eLocation ID:
- 1606609
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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