SHED-derived exosome-mimetics promotes rotator cuff tendon-bone healing via macrophage immunomodulation through NF-κB suppression and autophagy activation

Rotator cuff tendon-bone healing is impeded by inflammation and inadequate regeneration. This study evaluates exosome-mimetics (EMs) derived from stem cells of human exfoliated deciduous teeth (SHEDs) as a therapeutic strategy to enhance repair.SHED-EMs were synthesized via serial extrusion and characterized using transmission electron microscopy, nanoparticle tracking analysis, and Western blot. In vitro experiments assessed biocompatibility, tenogenic differentiation of tendon stem/progenitor cells (TSPCs), chondrogenic differentiation of bone marrow stromal cells (BMSCs), and macrophage polarization (Raw264.7 cells). Transcriptomic sequencing of LPS-stimulated macrophages and autophagy inhibition (via 3-MA) were conducted to explore mechanisms. A rat rotator cuff tear model treated with GM@PDA&EMs hydrogel was analyzed through histology, micro-CT, and biomechanical testing.SHED-EMs exhibited uniform morphology (average 124.9 nm) and high yield (57.6 μg per T25 flask). They promoted TSPC tenogenesis (increased COL I, Tnmd, Scx) and BMSC chondrogenesis (elevated Col II, Acan, Sox9). SHED-EMs polarized macrophages toward the M2 phenotype (reduced CD86/iNOS, increased CD163), reversing M1-mediated suppression of BMSC osteogenesis (enhanced Runx2, OCN) and HUVEC angiogenesis (upregulated VEGF, CD31). In vivo, GM@PDA&EMs reduced M1 macrophage infiltration, enhanced osteocalcin and VEGF expression, and improved biomechanical strength. Transcriptomic analysis of macrophages revealed SHED-EMs suppressed NF-κB signaling, while subsequent experiments demonstrated autophagy activation (increased LC3II/I, decreased P62) and reduced inflammation (lower TNF-α/iNOS). Autophagy inhibition abolished these anti-inflammatory effects. SHED-EMs accelerates tendon-bone healing by modulating macrophage polarization, enhancing tissue regeneration, and suppressing NF-κB-mediated inflammation via autophagy activation, offering a promising therapy for rotator cuff injuries.