Figure 2 Schematic diagram summarizing the roles and mechanisms of polydeoxyribonucleotide (PDRN) in the treatment of tendon disorders based on preclinical investigations. PDRN inhibits inflammation by decreasing the expression of the pro-inflammatory cytokines, including TNF-α and IL-6, thereby enhancing tendon repair. PDRN suppresses cell apoptosis by reducing the expression of caspase-9/3 and Bax while increasing Bcl-2 expression, thereby promoting tendon healing. PDRN encourages type I collagen synthesis by enhancing the expression of TGF-β1, VEGF, and FGF, thereby improving tendon healing. PDRN – polydeoxyribonucleotide; ↑ – increase; ↓ – decrease; TNF-α – tumor necrosis factor alpha; IL-6 – interleukin 6; TGF-β1 – transforming growth factor-beta 1; VEGF – vascular endothelial growth factor; FGF – fibroblast growth factor. Created with Adobe Photoshop software version 26.2.