Magnetic hydrogel-mediated periodic stimulation enhances mesenchymal stem cell small extracellular vesicle release

Small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) are regarded as important "cell-free" therapeutic carriers due to their potential for immune regulation and tissue repair. However, their large-scale application is constrained by bottlenecks such as low secretion yields under conventional culture conditions. This study established a magnetically controlled dynamic mechanical stimulation platform to enhance MSC-sEVs production. Superparamagnetic Fe₃O₄ nanoparticles were embedded into polyacrylamide to form magnetic composite hydrogels. An variable magnetic field induced reversible deformation of the hydrogel, thereby applying periodic mechanical loading to adherent cells. Results demonstrate that, compared to conventional plastic substrates, dynamic loading on MSCs significantly increases sEVs secretion (up to approximately 5-fold) without altering typical vesicle morphology or size distribution. Mechanistic studies indicate that this stimulus induces upregulation of the mechanosensitive channel Piezo1 and the nuclear YAP signaling pathway, thereby promoting sEVs release. Inhibition of Piezo1 or YAP attenuated the enhanced production effect, supporting a dual-pathway synergistic model where "Piezo1-Ca²⁺ promotes release, while YAP promotes multivesicular bodies (MVB) generation." This platform offers an economical, simple, and promising solution for efficient and controllable sEVs production.