In vitro study on the effects of mechanical load on the behavior and signal pathway regulation of pediatric hip cartilage cells

Objective: To explore the effects of mechanical load on the behavior and related signaling pathways of pediatric hip cartilage cells, providing experimental evidence for optimizing cartilage regeneration and repair strategies. Methods: Human-derived pediatric hip cartilage cells were cultured in vitro and subjected to uniaxial tensile stress at a specific frequency (1 Hz) with varying strain amplitudes (0%, 2%, 5%, 10%). Cell proliferation curves were assessed using the CCK-8 assay, while qPCR was used to detect changes in the expression of COL2A1, ACAN, and genes such as ITGB1, TGF-β1, WNT3A, MAPK1, among others. Western Blot analysis was conducted to measure protein levels of Collagen II, Aggrecan, MMP-13, as well as p-ERK, p-p38, β-catenin, MAPK1, and MAPK14. The relationship between strain amplitude and cellular biological effects was also analyzed. Results: After mechanical strain application, cell proliferation significantly increased on days 5 and 7 (p < 0.05), and COL2A1 and ACAN gene expression levels were upregulated (p < 0.05). Protein levels of Collagen II and Aggrecan significantly increased, while MMP-13 levels decreased (p < 0.05). Upstream signaling molecules such as Integrin β1, TGF-β1, and WNT3A were upregulated (p < 0.05), while TGFBR2 showed no significant changes (p > 0.05). Downstream molecules p-ERK, MAPK1, and MAPK14 were significantly upregulated (p < 0.05), whereas p-p38 and β-catenin showed no significant differences (p > 0.05). ACAN and p-ERK expression levels exhibited a dose-response relationship with increasing strain amplitude (p < 0.05). Conclusion: Mechanical load promotes the proliferation and matrix synthesis of pediatric hip cartilage cells through specific regulation of upstream and downstream signaling pathway molecules, showing strain intensity-dependent molecular responses. This study lays the foundation for precision regulation strategies in cartilage development and repair.