Decellularized tendon scaffold seeded with adipose-derived MSCs and supplemented with G-CSF injection promotes tendon repair in a rat model

BACKGROUND: Tendon injuries cause pain and functional limitations, posing a clinical burden due to poor healing and recurrence. Combining mesenchymal stem cells (MSCs), tissue-specific extracellular matrix (ECM) scaffolds, and bioactive factors may enhance tendon regeneration. This study investigated integrating adipose-derived MSCs (AD-MSCs) seeded on a decellularized tendon scaffold (DTS) with G-CSF injection for tendon repair. METHODS: DTS was prepared from rat Achilles tendons through freeze-thaw cycles and sodium dodecyl sulfate decellularization, preserving ECM structure. In vitro, AD-MSC viability, tenogenic gene expression, and scratch wound closure were assessed in response to G-CSF ± DTS. In vivo, a rat Achilles tendon defect model included: control (CTL), DTS, DTS with G-CSF, and DTS and AD-MSCs with G-CSF. After 6 weeks, histology, immunohistochemistry, collagen quantification, gene expression, and immunofluorescence analyses were performed. RESULTS: DTS maintained AD-MSC viability and tenogenic differentiation in vitro by upregulating SCX, COL1, and TN-C. G-CSF (1000 ng/mL) enhanced AD-MSC-mediated wound closure in the presence of DTS extract. In vivo, DTS with AD-MSCs and G-CSF showed organized collagen alignment, reduced cellularity and inflammation, increased collagen deposition, and the highest total collagen content. Furthermore, it exhibited upregulation of SCX, TN-C, COL1, THBS-4, and DCN, an improved COL1/COL3 ratio, reduced IL-6, MMP3, and MMP13, and increased IL-10, CXCR4, SDF-1, CD34, and CD31 compared with other groups. CONCLUSION: DTS combined with AD-MSCs and G-CSF injection demonstrated the most favorable histological and molecular tendon repair profile, including enhanced tenogenic marker expression, improved ECM remodeling, increased homing- and vascular-associated marker expression, and modulation of inflammatory responses.