2. Academic Validation
  3. Profibrotic macrophage-derived CXCL4 promotes pericyte-to-myofibroblast transition after spinal cord injury

Profibrotic macrophage-derived CXCL4 promotes pericyte-to-myofibroblast transition after spinal cord injury

  • J Orthop Translat. 2026 Feb 11:56:101032. doi: 10.1016/j.jot.2025.101032.
Gang Li 1 2 3,  Le Wang 2 3,  Xiaoyu Wu 2 3,  Xiaolin Zeng 4,  Lingli Long 5,  Wenwu Zhang 6,  Jiewen Chen 7,  Di Zhang 2 3,  Xi Chen 8,  YiLong Deng 2 3,  XinZhi 2 3,  Yong Wan 2 3,  Xiang Li 2 3
Affiliations

Affiliations

  • 1 Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China.
  • 2 Department of Spine Surgery, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China.
  • 3 Guangdong Province Key Laboratory of Orthopaedics and Traumatology, Guangzhou, Guangdong Province, China.
  • 4 Division of Spine Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu Province, China.
  • 5 Research Center of Translational Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China.
  • 6 Department of Spine Surgery, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan Province, China.
  • 7 Department of Spine Surgery, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China.
  • 8 Faculty of Medicine, Macau University of Science and Technology, Taipa, Macao Special Administrative Region of China.
PMID: 41836554 DOI: 10.1016/j.jot.2025.101032
Abstract

Introduction: Spinal cord injury (SCI) induces fibrotic scarring that impairs axonal regeneration. Pericytes contribute to scar formation via pericyte-to-myofibroblast transition (PMT), yet the mechanisms underlying PMT in SCI remain unclear. Although CXCL4, a pleiotropic chemokine, is implicated in various fibrotic disorders, its role in driving PMT post-SCI remains unexplored.

Objectives: To investigate whether CXCL4 drives PMT after SCI, elucidate its mechanisms, and assess its therapeutic potential.

Methods: scRNA-seq characterized cell-type dynamics and profibrotic signals in injured mouse spinal cords. In vitro, primary pericytes were exposed to exogenous CXCL4 or co-cultured with Spp1+Fn1+ macrophages. PMT was evaluated by RT-qPCR, Western blot, immunofluorescence, and flow cytometry. PI3K/Akt inhibition or CXCR3 knockdown dissected signaling pathways. In vivo, intrathecal injections of a CXCL4-neutralizing antibody or PI3K Inhibitor were administered post-injury. Pericyte differentiation and fibrotic remodeling were assessed via immunostaining, Masson's trichrome staining, and gene expression profiling. Axonal regeneration and motor function were evaluated using CST tracing, serotonergic fiber labeling, Basso Mouse Scale scoring, and footprint analysis.

Results: PMT occurred post SCI, with PDGFRβ+Acta2+ pericytes acting as major contributors. Spp1+Fn1+ macrophage subpopulation was identified as the main source of CXCL4, transcriptionally regulated by MAFB. CXCL4 levels were significantly upregulated post-injury, while pericytes in the lesion expressed its receptor, CXCR3. In vitro, exogenous CXCL4 induced PMT in pericytes via PI3K/Akt signaling. Co-culture experiments confirmed that Spp1+Fn1+ macrophages promoted pericyte transition through the CXCL4/CXCR3 axis. In vivo, blocking CXCL4 or PI3K suppressed PMT, reduced fibrotic scarring, enhanced axonal regeneration, and improved locomotor function in SCI mice.

Conclusion: Profibrotic macrophage-derived CXCL4 activates CXCR3/PI3K/Akt signaling in pericytes, driving their transition into scar-forming myofibroblasts after SCI. Blocking this axis mitigates fibrosis and enhances axonal regeneration and motor recovery.

The translational potential of this article: This study indicates that targeting the CXCL4-driven pericyte-to-myofibroblast transition to reduce fibrotic scar formation may provide an effective therapeutic strategy for enhancing axonal regeneration and functional recovery after SCI.

Keywords

CXCL4; Fibrosis; Pericyte; Pericyte-myofibroblast transition (PMT); Spinal cord injury.

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