Ultrasound-Generated Nanoscale Mechanical Stimulation to Regulate Stem Cell Differentiation.

Harnessing nanoscale mechanical cues to direct stem cell fate represents a transformative strategy in cell-engineered tissue regeneration. In this study, we demonstrate that low-frequency ultrasound (LFU) induces nanoscale vertical displacements (30-65 nm) at the cell-substrate interface, effectively promoting osteogenic differentiation of human mesenchymal stem cells (hMSCs). Remarkably, this ultrasound-driven mechanotransduction occurs on both soft and rigid matrices, highlighting the robustness of the approach. Daily 30 min LFU treatments over 7 days result in significant osteogenic commitment, as confirmed by immunofluorescence and gene expression analyses. Mechanistically, the response is mediated by RhoA-ROCK-dependent myosin IIA contractility, with pharmacological inhibition validating the pathway's role in LFU-induced osteogenesis. This noninvasive, scalable, and cost-effective LFU treatment offers an interesting alternative to traditional biochemical or scaffold-based methods, paving the way for ultrasound-based bioreactors in regenerative medicine and 3D bone tissue engineering.