Nanoscale Extracellular Vesicles Carry the Mechanobiology Signatures of Breast Cancer Cells

Breast cancer cells secrete abundant nanometer-sized vesicles. Small extracellular vesicle (or sEV) cargos are known to have similar biomolecular signatures to their secreting parental breast cancer cells. However, whether malignant transformation modulates the physical and biomechanical profiles of secreted nanosized sEVs (40-120 nm) has not been established. Here, using multiparametric atomic force microscopy imaging, we directly compared the structure-mechanical properties (including topographic height, Young's modulus, and adhesion) of breast cancer cell-derived sEVs and secreting cells. Our findings reveal that sEVs show reduced Young's modulus concomitant with a decrease in cell stiffness as cells progress from nontumor to noninvasive to invasive breast cancer phenotypes across different probing forces, isolation techniques, and particle sizes. Further, single sEV structure-mechanical analysis of actual patient plasma samples showed alterations in biomechanical properties of sEVs in breast cancer patients compared to sEVs from benign healthy controls. Our study demonstrates that precise biomechanical fingerprinting of single nanoscale sEVs provides an attractive label-free, cell-free, and orthogonal approach to detect changes in parental cells, such as during malignant transformation.