Regulating chondrocyte senescence through substrate stiffness modulation

Chondrocytes, the resident cells of articular cartilage, play a vital role in tissue maintenance and regeneration. Recent studies have highlighted chondrocyte senescence as a key contributor to cartilage dysfunction. In this study, we investigated the influence of substrate stiffness on chondrocyte senescence using polydimethylsiloxane (PDMS) substrates with varying stiffness ratios (1:5, 1:20, and 1:60). After culturing chondrocytes on these substrates, we found that softer substrates (1:60) significantly reduced chondrocyte senescence, as evidenced by a decrease in senescence-associated β-galactosidase (SA-β-gal) activity by 33% compared with stiffer substrates (1:5). Furthermore, quantitative real-time polymerase chain reaction (PCR) analysis revealed that chondrocytes cultured on softer substrates exhibited lower expression levels of senescence-related genes (e.g., p16INK4a) and matrix-degrading enzymes (e.g., MMP13). These findings suggest that substrate stiffness plays a critical role in regulating chondrocyte senescence and could potentially inform the design of scaffolds for cartilage tissue engineering.