Topographical screening identifies optimal micropatterns for functional rat Achilles tendon regeneration

Tendon injuries often cause disordered healing and functional impairment because current treatments fail to restore native tissue structure and function. This study evaluated the in vivo efficacy of polydimethylsiloxane scaffolds with different pit or column patterns to identify optimal surface parameters for functional Achilles tendon regeneration. Six micropatterned scaffolds were fabricated via photolithography and implanted in a rat Achilles tendon injury model. Healing outcomes were assessed at two and five weeks via histological analysis, gene expression of tendon-related markers and TGF-β1, and biomechanical testing. Pit scaffolds outperformed column scaffolds, promoting collagen deposition, reducing adhesion, and upregulating Tnmd and DCN. The pit structure with 21 μm diameter and 26 μm spacing designated P-21-26 emerged as the optimal topography. By week five, this group restored 93.7% of healthy tendon tensile strength, a recovery strongly correlated with higher collagen density and lower adhesion scores. Column scaffolds exhibited inferior matrix organization and mechanical recovery. These results demonstrate that a 21 μm pit topography optimally balances inflammation and fibrosis, leading to superior functional tendon regeneration. These findings establish a critical design parameter for scaffolds and show that optimized surface topography alone enhances functional tendon repair, offering a translatable strategy for next-generation scaffolds.