Single-Cell Mechanical Properties: Label-Free Biomarkers for Cell Status Evaluation

Abstract

The mechanical behavior of biological cells is largely determined by their cytoskeletons; abnormal cellular functions can change cytoskeletons, leading to variations in cellular mechanical properties. This chapter begins with a summary of the relationships between cellular mechanical properties and various disease processes and changes in cell states: (1) changes in stiffness of red blood cells in cytoskeletal disorders, such as malaria and sickle cell anemia; (2) increased cell deformability of invasive cancer cells, compared with benign counterparts; (3) increased stiffness of leukocytes in sepsis; and (4) decreased deformability during the stem cell differentiation process. In the following section, we discuss the well-established techniques that are being used to measure the mechanical properties of single cells, including atomic force microscopy and micropipette aspiration. Finally, we describe the microfluidic approaches—including microfluidic constriction channels, microfluidic optical stretchers, and microfluidic hydrodynamic stretchers—that are being developed as next-generation, automated, and high-throughput techniques for characterization of the mechanical properties of single cells. The advantages and limitations of each technique are compared and future research opportunities are highlighted.