Large Deformation Finite Element Analysis of Micropipette Aspiration to Determine the Mechanical Properties of the Chondrocyte
- 482 Downloads
Chondrocytes, the cells in articular cartilage, exhibit solid-like viscoelastic behavior in response to mechanical stress. In modeling the creep response of these cells during micropipette aspiration, previous studies have attributed the viscoelastic behavior of chondrocytes to either intrinsic viscoelasticity of the cytoplasm or to biphasic effects arising from fluid–solid interactions within the cell. However, the mechanisms responsible for the viscoelastic behavior of chondrocytes are not fully understood and may involve one or both of these phenomena. In this study, the micropipette aspiration experiment was modeled using a large strain finite element simulation that incorporated contact boundary conditions. The cell was modeled using finite strain incompressible and compressible elastic models, a two-mode compressible viscoelastic model, or a biphasic elastic or viscoelastic model. Comparison of the model to the experimentally measured response of chondrocytes to a step increase in aspiration pressure showed that a two-mode compressible viscoelastic formulation accurately captured the creep response of chondrocytes during micropipette aspiration. Similarly, a biphasic two-mode viscoelastic analysis could predict all aspects of the cell’s creep response to a step aspiration. In contrast, a biphasic elastic formulation was not capable of predicting the complete creep response, suggesting that the creep response of the chondrocytes under micropipette aspiration is predominantly due to intrinsic viscoelastic phenomena and is not due to the biphasic behavior.
KeywordsCartilage Osteoarthritis Cytoskeleton Biomechanics Poroelastic Poroviscoelastic Nonlinear
Unable to display preview. Download preview PDF.
- 1.Baaijens, F. An U-ALE formulation of 3-D unsteady viscoelastic flow. Int. J. Numer. Methods Eng. 36:1115–1143, 1993.Google Scholar
- 6.Guilak, F., R. L. Sah, and L. A. Setton. Physical Regulation of Cartilage Metabolism, In: Mow VC, Hayes W. C., Editors. Basic Orthopaedic Biomechanics. 2nd ed. Philadelphia: Lippincott-Raven; 1997, p. 179–207.Google Scholar
- 10.Hung, C., K. Costa, and X. Guo. Apparent and transient mechanical properties of chondrocytes during osmotic loading using triphasic theory and afm indentation. ASME Bioeng. Conf. BED-50:625–626, 2001.Google Scholar
- 14.Mow, V., D. Sun, X. Guo, C. Hung, and W. Lai. Chondrocyte-extracellular matrix interactions during osmotic swelling. ASME Bioeng. Conf. BED42:133–134, 1999.Google Scholar
- 15.Poole, R. Imbalances of Anabolism and Catabolism of Cartilage Matrix Components in Osteoarthritis. In: Keuttner, K. E., Goldberg, V. M., eds. Osteoarthritic Disorders. AAOS Press, Rosemont, Illinois, USA, 1995, p. 247–260.Google Scholar
- 21.Trickey, W., F. Baaijens, T. Laursen, L. Alexopoulos, and F. Guilak. Determination of the Poisson’s ratio of the cell: Recovery properties of chondrocytes after release from complete micropipette aspiration. J. Biomech. (Submitted), 2004a.Google Scholar
- 23.Trickey, W., T. Vail, and F. Guilak. The role of the cytoskeleton in the viscoelastic properties of human articular chondrocytes. J. Orthop. Res. 22:131–139, 2004b.Google Scholar
- 24.Wilkes, R., and K. Athanasiou. The intrinsic incompressibility of osteoblast-like cells. Tissue Eng. 2:167–181, 1996.Google Scholar