Mechanical Memory Induction by Microgrooved Hydrogels Enables Stem Cell–Driven Cartilage Repair

Mechanical memory, or when cells retain traits from their physical environment, influences stem cell fate. During cartilage repair, the extra-cellular mechanical microenvironment could direct stem cell behavior through mechanical memory. In this study, we developed a micropattern-based method to impart mechanical memory in human synovial-derived stem cells (hSSCs), through the process of mechanical dosing. Photolithography was employed to create gelatin hydrogels with grooved patterns at the micron scale (20-200 μm). Mechanical dosing was applied by culturing hSSCs on groove-patterned hydrogel substrates for 3 days to establish mechanical memory. Based on protein and gene expression analyses, 50 μm was identified as the optimal groove size for promoting chondrogenesis. Extending the mechanical dosing period to 6 days further enhanced the effect. RNA sequencing revealed that 6 days of mechanical dosing increased expression of TGF-β3, Sox9, and ACAN genes. In a mouse model of full-thickness cartilage defect, 6 day mechanically dosed hSSCs demonstrated enhanced cartilage repair. Super-resolution imaging and microindentation assays showed that mechanical dosing reconfigures load-bearing cytoskeletal structures, establishing mechanical memory that promotes chondrogenesis via TGF-β pathway activation. Together, this study demonstrates that microgroove-patterned hydrogels could induce chondrogenic mechanical memory in hSSCs, improving their cartilage repair potential. This approach offers a promising strategy for advancing tissue engineering and regenerative medicine.