Surface-elastic hydrogels delay senescence via the modulation of redox homeostasis and cytoskeletal tension

The Bone marrow-derived mesenchymal stem cells (MSCs) are widely used in clinical applications owing to their therapeutic properties. However, in vitro expansion of MSCs in tissue culture dishes induces aging, which reduces their quality through an undefined mechanism. This study delineates the role of substrate stiffness as a potential modulator to delay MSC aging by elucidating the senescence progression of preconditioned and serially passaged MSCs on engineered stiffness-tunable gelatinous hydrogels. We demonstrated that mechanoactivation of MSCs increased their radical-scavenging capacity, maintained redox homeostasis, restored actin dynamics, and maintained their therapeutic properties. The hydrogels alleviated hydrogen peroxide-induced oxidative stress, linking mechanical signaling to redox balance and senescence. These hydrogels restored actin remodeling, highlighting the importance of cytoskeletal tension and dynamics in cellular senescence. We established a new culture method to maintain the stemness, proliferation, motility, and osteogenic differentiation potential of MSCs by serially passaging the cells on stepwise surface-elastic gels. Evidence points toward the complex interplay between mechanical memories and actin dynamics and their implications for autophagic activity in the delaying of senescent MSCs via hydrogels. Our findings suggest that mechanoregulation of culture substrates finely tunes the balance between cellular stress, redox homeostasis, and cytoskeletal dynamics to delay the progression of MSC senescence.