Identification of Pro-Fibrotic Cellular Subpopulations in Fascia of Gluteal Muscle Contracture Using Single-Cell RNA Sequencing (PMID: 39962491)

Research Question

Which cellular subpopulations drive fibrosis in deep fascia, particularly in gluteal muscle contracture (GMC), and how do these cells contribute to pathological extracellular matrix remodeling?

This study aimed to map the cellular landscape of fibrotic fascia at single-cell resolution to understand mechanisms of fascial fibrosis.

Methods

Researchers performed a single-cell RNA sequencing (scRNA-seq) analysis on fascial tissue samples.

Samples included:

• Fibrotic deep fascia from patients with gluteal muscle contracture (GMC)

• Non-fibrotic control fascial tissue

Key analytical steps included:

• Single-cell transcriptomic profiling

• Identification of cellular subpopulations

• Comparative gene expression analysis between fibrotic and control fascia

• Focus on extracellular matrix and inflammatory signaling pathways

Key Findings

The study revealed a complex cellular ecosystem driving fibrosis in deep fascia.

Main findings included:

• Fibroblasts are central drivers of fascial fibrosis

  • Multiple fibroblast subclusters showed strong activation

  • Increased expression of collagens, proteoglycans, and ECM glycoproteins

• Macrophages play a key supportive role in fibrosis progression

  • Two pro-fibrotic macrophage subtypes were identified:

    • SPP1⁺ macrophages

    • ECM-like macrophages

• These macrophages contribute to fibrosis by:

  • Promoting fibroblast activation

  • Directly contributing to extracellular matrix production

• Significant cell–cell communication was observed between macrophages and fibroblasts, especially involving SPP1⁺ macrophage signaling

• Fibrotic fascia shows a state of active extracellular matrix overproduction and tissue remodeling

These findings highlight fibrosis as a coordinated process involving multiple interacting cell types rather than fibroblasts alone.

Why It Matters for Fascia

This study provides high-resolution molecular evidence that fascia is a biologically active, immune-influenced fibrotic tissue system.

It demonstrates that:

• Fascial fibrosis is driven by specific cellular subpopulations, not generalized tissue degeneration

• Immune cells (macrophages) actively regulate fascial remodeling

• Deep fascia behaves like other fibrotic organs with complex cell–cell signaling networks

• Targeting cellular interactions may offer new therapeutic strategies for myofascial disorders

This shifts fascial pathology toward a precision medicine model, where specific cell types and signaling pathways can be targeted.

5 Takeaways

1. Fibroblast subclusters are major drivers of fascial fibrosis.

2. Macrophages actively contribute to ECM deposition and fibroblast activation.

3. SPP1⁺ macrophages represent a key pro-fibrotic signaling population.

4. Fibrosis involves coordinated cell–cell communication within fascia.

5. Deep fascia behaves like a dynamic immune–fibrotic tissue system.