Nanoindentation Characteristics of Stem Cells Towards Osteogenic Differentiation in a Nanoscale Vibratory Bioreactor

Mimicking chemical and physical cues present in the microenvironment of the original tissue not only facilitates the differentiation process of mesenchymal stem cells but also contributes to the attainment of cells with morphology and functionality closely resembling those of the native tissue. Among the types of mechanical stimuli utilized to induce osteogenic differentiation of stem cells, nanoscale vibrations were the focus of the present study. By investigating osteoblast-specific proteins following 21-day exposure to nanovibrational stimuli, our research confirms previous findings that highlight the upregulation of specific osteogenic proteins, including osteocalcin, osteopontin, and collagen type I. Here, we addressed the lack of investigation into the mechanical properties of mesenchymal stem cells subjected to nanovibration stimulation as a cellular differentiation biomarker. From a mechanical perspective, our findings revealed a remarkable elevation in Young’s modulus, which increased by approximately 100% over the nucleus, coupled with a notable 60% reduction in the viscosity of differentiated mesenchymal stem cells after 21 days of continuous 1-kHz nanovibrational stimulation. Such alterations are associated with thicker and more aligned actin bundles, indicating a robust cellular response to mechanical stimuli. Our results can be beneficial for cell-based regenerative therapy when stem cells are intended to be manipulated in vitro before transplantation.