Spatial dimension cues derived from fibrous scaffolds trigger mechanical activation to potentiate the paracrine and regenerative functions of MSCs via the FAK-PI3K/AKT axis

Secretomes from mesenchymal stem cells (MSCs) have significant therapeutic potential and could be the basis for future MSCs treatments. Innovative design of the topology of biomaterials, which mechanically regulate cell behavior and function, can tremendously improve the efficacy of stem cell therapy. However, how spatial dimension cues derived from specific topology command cell mechanotransduction to regulate the paracrine function of MSCs remains unknown. In this study, the three-dimensional (3D) fibrous constructs with box-like pores and precise strand spacing from 150 μm down to only 40 μm were manufactured using melt electrowriting (MEW), which were used to systematically investigate the spatial dimension cues-triggered mechanotransduction of adipose-derived mesenchymal stem cells (Ad-MSCs) and their impact on the paracrine and regeneration function of Ad-MSCs. The results demonstrated that spatial instructions from the 3D fibrous constructs could influence the spatial reorganization of the cytoskeleton, resulting in cell elongation and augmented immunomodulatory and angiogenic paracrine effects of Ad-MSCs, which was most pronounced at a minimum strand spacing of 40 μm. Besides, mechanical activation of the FAK-PI3K/AKT axis significantly enhanced the paracrine function of Ad-MSCs. In vivo experiments demonstrated that the Ad-MSCs trained using well-defined 3D fibrous constructs with a strand spacing of 40 μm significantly promoted skin regeneration via paracrine signals. In conclusion, this study provides a new horizon for deciphering space dimension insights into the interactional mechanisms of mechanotransduction in regulating cell function, which has inspired innovations in biomaterials for improving tissue regeneration. STATEMENT OF SIGNIFICANCE: Designing cell-scale spatial dimension cues in engineered constructs potentiates the paracrine and regenerative functions of Ad-MSCs. FAK-PI3K/AKT signaling serves as the key mechanotransduction checkpoints for spatial dimension cues triggering mechanical activation. Paracrine signals of Ad-MSCs triggered by mechanical activation promotes skin repair and regeneration via the immunomodulation and angiogenesis.