Engineered PDMS microtopography: Precision regulation of tendon stem cell behavior for tendon regeneration

Microtopography critically regulates tendon stem cell (TSC) migration for repair, yet its precise roles remain unclear. We engineered polydimethylsiloxane (PDMS) scaffolds with precisely defined micron-scale pits and columns (diameters 7-21 μm, spacings 13-47 μm) via ultraviolet lithography and etching. High-throughput screening to promote TSC viability identified six optimal topographies: three pit-based topographies (diameters/spacings: 7 μm/47 μm, 11 μm/18 μm, 21 μm/26 μm) and three column-based topographies (diameters/spacings: 8 μm/14 μm, 13 μm/13 μm, 18 μm/18 μm). Strikingly, TSCs exhibited distinct mechanoresponses: bypassing pits while wrapping around columns, with both inducing cytoskeletal alignment (40 % reduced orientation angle, 2-fold increased polarization compared to smooth substrates). Live-cell tracking revealed migration distance correlated with filopodia density, and crucially, migration rate peaked at a specific topological area proportion (AP ≈ 0.1). Critically, pits induced filopodia branching, whereas columns triggered pseudopodial wrapping and substrate deformation, revealing topology-specific mechanotransduction pathways. This study establishes microtopography as a potent designer signal for TSC mechanobiology and provides the quantitative principle for fabricating tendon-regenerative scaffolds with tailored topological gradients, offering a novel strategy to enhance repair efficiency.