Exploring the mechanical heterogeneity of human adipose-derived mesenchymal stem cells: A pilot study

Mesenchymal stem cells (MSCs) hold significant promise for tissue engineering and regenerative medicine thanks to their combination of accessibility and multilineage differentiation potential. Among the several factors that influence MSC function, mechanical properties are increasingly recognized as key regulators of cell fate decisions. Despite their importance, the variability of these properties across biologically relevant conditions remains poorly characterized. In this study, we used atomic force microscopy nanoindentation to quantify two mechanical parameters in human adipose tissue-derived MSCs: the Young's modulus (E) and, for the first time in this cell type, the poroelastic diffusion constant (Dp). Measurements were performed on 120 cells derived from six human subjects (three female and three male), at two passages (P4 and P7), and in two subcellular compartments (above the nucleus and above the cytoplasm). Results revealed statistically significant mechanical heterogeneity across subjects, higher values with increasing passages for both E and Dp, and a sex-based difference in E, with female-derived cells being stiffer, but no differences in Dp. These findings preliminarily reveal and quantify mechanical heterogeneity in MSCs, and underscore the need for considering biological variables when designing MSC-based therapies for regenerative medicine and tissue engineering. Our dataset, based on a relatively small sample size, is not intended to capture the full variability of these factors. Instead, it provides preliminary data collected under consistent conditions, intended to inform the estimation of optimal sample sizes for future large-scale studies investigating mechanical heterogeneity.