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  • Short‐Duration High Frequen...
    Ambattu, Lizebona August; Gelmi, Amy; Yeo, Leslie Y.

    Small, 02/2022, Letnik: 18, Številka: 8
    Journal Article

    Stem cell fate can be directed through the application of various external physical stimuli, enabling a controlled approach to targeted differentiation. Studies involving the use of dynamic mechanical cues driven by vibrational excitation to date have, however, been limited to low frequency (Hz to kHz) forcing over extended durations (typically continuous treatment for >7 days). Contrary to previous assertions that there is little benefit in applying frequencies beyond 1 kHz, we show here that high frequency MHz‐order mechanostimulation in the form of nanoscale amplitude surface reflected bulk waves are capable of triggering differentiation of human mesenchymal stem cells from various donor sources toward an osteoblast lineage, with early, short time stimuli inducing long‐term osteogenic commitment. More specifically, rapid treatments (10 min daily over 5 days) of the high frequency (10 MHz) mechanostimulation are shown to trigger significant upregulation in early osteogenic markers (RUNX2, COL1A1) and sustained increase in late markers (osteocalcin, osteopontin) through a mechanistic pathway involving piezo channel activation and Rho‐associated protein kinase signaling. Given the miniaturizability and low cost of the devices, the possibility for upscaling the platform toward practical bioreactors, to address a pressing need for more efficient stem cell differentiation technologies in the pursuit of translatable regenerative medicine strategies, is ensivaged. Although it has previously been claimed that 1 kHz mechanostimulation is optimal for inducing osteogenic differentiation in stem cells, with little further benefit to be derived from the use of higher frequencies, it is shown and explicated here how mechanostimulation at 10 MHz not only triggers comparable levels of osteogenic differentiation, but does so much earlier, with substantially shorter treatment regimens.