Biomechanical Study on Elastic and Viscoelastic Properties of Osteoblasts Using Atomic Force Microscopy

Exploration of cellular biomechanics properties has important pathophysiologic relevance since cellular response to external mechanical load play an significant role in the development of multitudinous clinical issues including cancer metastasis and diabetes. The qualification of cellular mechanical properties is of tremendous interest in biology and medicine. Atomic Force Microscopy (AFM) is widely used as a quantitative nanoscale biometric tool for the characterization of cell morphology and mechanical properties. However, extraction of cellular mechanical properties from the measurements in the nanoscale remains quite complex due to challenges to analyze data according to proper theoretical model. In this paper, the cellular elastic and viscoelastic properties were characterized using AFM on murine osteoblastic MC3T3-E1 cells as a prototypical biomechanical system. The Young's modulus at different subcellular regions labelled at nucleus, cytoplasm and edge of osteoblasts was analyzed according to Hertz model with sphere indenter. The morphology of single cell grown on fibronectin coated plastic petri dishes display a polygonal shape in cobblestone appearance with cytoskeleton arrangement along the long axis. The lowest Young's modulus is observed at the cell nucleus, followed by the cytoplasm and the edge. The time dependent cellular mechanical behavior was also investigated for strain creep at constant external forces. The viscoelastic mechanical response at nuclear region is more notable than the perinuclear region. Our findings and results provide novel perspective for the biomechanical function of osteoblast and offers similar strategy pattern for understanding the structure-function correlation across varied length-scale in other biomechanical sub-systems.