Articular cartilage possesses limited intrinsic self-healing capacity due to its avascular and aneural nature. Emerging cell-free regenerative therapies utilizing Mesenchymal Stem Cell (MSC) exosomes offer targeted biological repair without the complications of whole-cell transplantation.
Exosome Paracrine Signaling Mechanisms
Extracellular vesicles (30–150 nm) secreted by umbilical cord and bone marrow-derived MSCs deliver therapeutic molecular cargo directly to stressed chondrocytes:
- MicroRNAs (miR-140-5p, miR-26a-5p): Inhibit matrix-degrading enzymes ADAMTS5 and MMP-13, halting cartilage degradation.
- Transforming Growth Factor-Beta (TGF-β): Upregulates type II collagen (COL2A1) and aggrecan synthesis.
- Anti-Inflammatory Cytokines (IL-10, IL-1RA): Neutralize synovial inflammation and blunt pain nociception.