Unfractionated Bulk Culture of Mouse Skeletal Muscle to Recapitulate Niche and Stem Cell Quiescence
June 2nd, 2023
Skeletal muscle comprises multiple cell types, including resident stem cells, each with a special contribution to muscle homeostasis and regeneration. Here, the 2D culture of muscle stem cells and the muscle cell niche in an ex vivo setting that preserves many of the physiological, in vivo, and environmental characteristics are described.
Our research involves the study of healthy and diseased skeletal muscle with special emphasis on the satellite cells. One of the fundamental aspects we are exploring is the identification of transcriptional enhancers that coordinate cell specific gene expression. This protocol permits us to conduct rapid tests for determining specificity.
In the field of skeletal muscle research, single cell and single nucleus RNA sequencing approaches are frequently used to study different cell populations in homeostasis, regeneration, and disease. Also, satellite cells could be isolated by fluorescence activated cell sorting, or FACS, and cultured for hypothesis testing and sequencing result validation. Studying satellite cells in vitro poses a significant challenge.
Recent studies highlighted the role of satellite cells niche in its physiology. While it's common to culture FACS isolated satellite cells, replicating the satellite cells niche in vitro is yet to be achieved. Our protocol provides an efficient and practical way of culturing whole muscle tissue, including non myogenic cells, such as endothelial cells and fibro edoprogenetic progenitors.
We showed that quiescent-like cells appear within one week of culture. This protocol could also be used to study the influence that other cells have on reestablishing this quiescent-like pool.
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Overview
This study explores the role of satellite cells in skeletal muscle homeostasis and regeneration, highlighting the challenges of replicating their niche in vitro. The authors present a protocol for culturing whole muscle tissue, which includes non-myogenic cells, allowing for the analysis of satellite cells.
Key Study Components
Research Area
- Skeletal muscle biology
- Satellite cell function and behavior
- Cellular interactions in tissue culture
Background
- Understanding the physiological role of satellite cells is crucial for muscle health.
- Satellite cells are key for muscle regeneration and homeostasis.
- Existing in vitro models fail to adequately mimic the satellite cell niche.
Methods Used
- Fluorescence activated cell sorting (FACS) for isolating satellite cells
- Ex vivo muscle tissue culture
- Single cell and single nucleus RNA sequencing for cell population analysis
Main Results
- Quiescent-like satellite cells emerge within one week of culture.
- The study demonstrates the physiological relevance of the muscle cell niche.
- Validation of protocols for future hypothesis testing and sequencing applications.
Conclusions
- This research offers a novel approach to study satellite cells in their native-like environment.
- Findings contribute to our understanding of muscle biology and potential therapeutic avenues for muscle-related diseases.
Frequently Asked Questions
Executive Industry Relevance
Recapitulating the native skeletal muscle niche ex vivo addresses a critical gap in early discovery by enabling the study of muscle stem cell quiescence in a physiologically relevant context. This capability enhances predictive confidence for target validation and mechanistic de-risking in muscle biology portfolios. The protocol supports translational continuity from discovery through preclinical research by preserving complex cell-cell interactions essential for functional assessment.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables interrogation of therapeutic hypotheses involving muscle stem cell quiescence and activation.
- Supports functional target validation by maintaining niche-dependent signaling and cell states.
- Facilitates mechanistic de-risking through preservation of physiological microenvironments.
- Improves predictive confidence for prioritizing muscle-related targets.
Screening & Assay Development
- Provides a validated multicellular system for downstream screening of modulators affecting stem cell quiescence.
- Enables reproducible immunostaining and quantitative assessment of Pax7-positive quiescent cells.
- Supports assay standardization by maintaining consistent cellular composition and niche factors.
- Prepares a platform for reliable evaluation of candidate compounds in a physiologically relevant context.
Translational & Preclinical Research
- Aligns with disease-relevant systems by modeling the native muscle microenvironment ex vivo.
- Enables continuity from discovery to preclinical validation of regenerative or disease-modifying interventions.
- Supports risk-adjusted advancement decisions by providing translationally relevant data on stem cell behavior.
- Facilitates biomarker alignment through quantifiable outputs such as Pax7 expression.
Pipeline & Workflow Integration
This protocol integrates into the discovery-to-preclinical continuum by enabling hypothesis testing, target validation, and translational assessment within a single ex vivo system.
- Discovery Biology: Supports null hypothesis testing and pathway clarification for muscle stem cell regulation.
- Screening: Delivers reproducible, quantitative outputs for compound evaluation targeting quiescence or activation.
- Analytics: Provides immunostaining and cell population measurements to compare experimental conditions.
- Translational Research: Bridges discovery and preclinical studies by modeling disease-relevant cellular interactions.
- Enterprise Reuse: Offers a reusable platform for diverse hypothesis-driven and screening applications in muscle biology.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in muscle stem cell research.
- Operational Value: Standardizes ex vivo culture conditions for reproducibility and scalability across studies.
- Strategic Value: Enables informed go/no-go decisions and capital-efficient portfolio management in muscle regeneration programs.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of muscle-targeted therapeutic candidates.
Implementation Considerations
- Requires expertise in muscle tissue processing and immunostaining techniques.
- Needs access to cell culture infrastructure and imaging platforms for quantitative analysis.
- Demands cross-team standardization of culture and analytical protocols for reproducibility.
- May require adaptation for different muscle types or disease models as supported by the protocol.
- Practical limitations include the complexity of maintaining niche integrity and cell viability ex vivo.
