Dynamic mechanical properties of the tissue-engineered matrix associated with individual chondrocytes

Lee, BoBae; Han, Lin; Frank, Eliot H.; Chubinskaya, Susan; Ortiz, Christine; Grodzinsky, Alan J.

doi:10.1016/j.jbiomech.2009.09.053

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Volume 43, Issue 3 , Pages 469-476, 10 February 2010

Dynamic mechanical properties of the tissue-engineered matrix associated with individual chondrocytes

BoBae Lee
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
Lin Han
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
Eliot H. Frank
- Center for Biomedical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
Susan Chubinskaya
- Department of Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA
Christine Ortiz
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
Alan J. Grodzinsky
- Center for Biomedical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Corresponding author at: Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. Tel.: +6172534969; fax: +6172585239.

Accepted 28 September 2009. published online 04 November 2009.

Abstract

The success of cell-based tissue engineering approaches in restoring biological function will be facilitated by a comprehensive fundamental knowledge of the temporal evolution of the structure and properties of the newly synthesized matrix. Here, we quantify the dynamic oscillatory mechanical behavior of the engineered matrix associated with individual chondrocytes cultured in vitro for up to 28 days in alginate scaffolds. The magnitude of the complex modulus (|E*|) and phase shift (δ) were measured in culture medium using Atomic Force Microscopy (AFM)-based nanoindentation in response to an imposed oscillatory deformation (amplitude ∼5nm) as a function of frequency (f=1–316Hz), probe tip geometry (2.5μm radius sphere and 50nm radius square pyramid), and in the absence and presence of growth factors (GF, insulin growth factor-1, IGF-1, and osteogenic protein-1, OP-1). |E*| for all conditions increased nonlinearly with frequency dependence approximately f^1/2 and ranged between ∼1 and 25kPa. This result, along with theoretical calculations of the characteristic poroelastic relaxation frequency, f_p, (∼50–90Hz) suggested that this time-dependent behavior was governed primarily by fluid flow-dependent poroelasticity, rather than flow-independent viscoelastic processes associated with the solid matrix. |E*(f)| increased, (f) decreased, and the hydraulic permeability, k, decreased with time in culture and with growth factor treatment. This trend of a more elastic-like response was thought to be associated with increased macromolecular biosynthesis, density, and a more mature matrix structure/organization.