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Updated: Jan 8, 2026
Identifying Microglia and Peripheral Infiltrating Macrophages in the Injured Spinal Cords Using Flow Cytometry
Published on: June 24, 2025
Photobiomodulation Reduces Fibrous Scar Formation After Spinal Cord Injury by Downregulating CXCL3 Expression in
Zhihao Zhang1, Hongwen Gu1, Ting He2,3
1General Hospital of Northern Theater Command, Shenyang, 110000, Liaoning Province, China.
Abstract:
Although the inhibitory role of photobiomodulation (PBM) in glial scar formation after spinal cord injury (SCI) has been identified, its effects on fibrous scar formation and the underlying mechanisms remain unexplored. To assess fibrous scar deposition, Sirius Red, Masson's trichrome, and immunostaining of extracellular matrix molecules after SCI were performed. Fibroblast viability was evaluated using the CCK-8 assay, whereas migration capacity was measured using Transwell and scratch assays. RNA sequencing was performed on macrophages subjected to inflammation with and without PBM intervention. To validate the mechanism in vivo, CXCL3 and a CXCR2 inhibitor were administered to mice intraperitoneally. Findings demonstrated that PBM treatment suppressed fibrous scar formation post-SCI. Temporal profiling revealed distinct patterns of macrophage and fibroblast infiltration after injury, with fibroblast migration influenced by the macrophage-conditioned medium. RNA sequencing analysis identified CXCL3 as a key mediator of macrophage-fibroblast crosstalk under PBM modulation. More specifically, PBM downregulated CXCL3 expression in macrophages, thereby attenuating fibrous scar progression.
Insights
Photobiomodulation (PBM) therapy reduces fibrous scar formation after spinal cord injury (SCI). It works by downregulating CXCL3 in macrophages, which inhibits fibroblast activity and scar progression.
Area of Science:
- Regenerative Medicine
- Neuroscience
- Biomaterials Science
Background:
- Photobiomodulation (PBM) is known to inhibit glial scar formation post-spinal cord injury (SCI).
- The impact of PBM on fibrous scar formation and its underlying molecular mechanisms after SCI remain largely uncharacterized.
Purpose of the Study:
- To investigate the effects of PBM on fibrous scar deposition following SCI.
- To elucidate the molecular mechanisms by which PBM modulates fibrous scar formation, focusing on macrophage-fibroblast interactions.
Main Methods:
- Fibrous scar deposition was assessed using Sirius Red and Masson's trichrome staining.
- Fibroblast behavior (viability, migration) was evaluated via CCK-8, Transwell, and scratch assays.
- Macrophage gene expression was analyzed by RNA sequencing, and in vivo validation used CXCL3 and CXCR2 inhibition in mice.
Main Results:
- PBM treatment significantly suppressed fibrous scar formation after SCI.
- Macrophage-derived factors influenced fibroblast migration, with PBM modulating this crosstalk.
- RNA sequencing identified CXCL3 as a key mediator, with PBM downregulating its expression in macrophages.
Conclusions:
- PBM effectively attenuates fibrous scar progression after SCI.
- The mechanism involves PBM-induced downregulation of CXCL3 in macrophages, disrupting pro-fibrotic signaling to fibroblasts.
- This study highlights PBM as a potential therapeutic strategy for mitigating detrimental scarring post-SCI.
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