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.