Bone marrow mesenchymal stem cell-derived exosomes enhance tendon regeneration and promote TDSC migration and...

To explore the role of bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exos) in promoting the motility and functional enhancement of tendon-derived stem cells (TDSCs) and assess their potential in tendon regeneration and repair.

In vitro experiments involved the isolation and characterization of BMSCs-Exos from cultured bone marrow mesenchymal stem cells. The exosomes were analyzed for their size, morphology, and protein content using nanoparticle tracking analysis (NTA) and western blotting for exosomal markers. Tendon stem cell (TDSC) migration was assessed using a scratch assay. For in vivo analysis, a rat tendon injury model was used to evaluate the therapeutic effects of BMSCs-Exos on tendon healing and tissue regeneration. Rats were injected with BMSCs-Exos at varying doses, and the healing process was monitored through histological analysis and assessment of angiogenesis and collagen deposition.

The results demonstrated successful extraction of BMSCs-Exosomes, confirmed by positive expression of exosomal markers (CD9, CD63, and ALIX) and the absence of cellular contaminants via western blot and uniform particle size (median 134.8 nm, concentration 8.7 × 10¹¹ particles/mL). Immunofluorescence showed a time-dependent uptake of purified PKH26-labeled Exosomes by TDSCs. While no significant difference in proliferation or survival was observed, Exosomes promoted scratch closure (p < 0.05) and osteogenic differentiation, as evidenced by increased ALP activity, calcium deposition (ARS), and upregulation of Runx-2/COL-1 expression. In vivo, Exosomes promoted collagen synthesis (COL-1) and angiogenesis (CD31), improving tendon structural integrity (H&E staining).

BMSCs-Exos demonstrate therapeutic potential for tendon repair by orchestrating key regenerative processes, including tendon stem cell motility and differentiation.