ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

ROLE OF ANATOMICAL REPRESENTATION OF CELL
DISTRIBUTION ON THE PREDICTION OF CHONDROCYTE
MECHANICS
1. ABSTRACT
J.P. Halloran 1+ , S.C. Sibole 2+ , and A. Erdemir 3*+
Computational studies of chondrocyte mechanics have typically been performed using
single cell models embedded in an extracellular matrix (ECM) construct [1,2]. The
assumption of a single cell microstructural model may not capture inter-cellular
interactions or accurately reflect the macro-scale mechanics of cartilage with higher cell
concentrations, as may be the case in many instances [3]. Hence, the goal of this study
was to compare the overall and cell level response of single and eleven [3] cell biphasic
finite element (FE) models. Biphasic material properties were adopted from the
literature [4] and FE simulations of single and eleven cell constructs modeled. Volume
averaged chondrocyte effective strain was up to 9.5% for the single cell case and varied
depending on cell location from 9.5 to 15.5% for the 11 cell case. The cellular fluid flux
vector field also exhibited variations for the 11 cell case, meriting further quantitative
investigation. Regarding aspects of cell health and function, preliminary results
highlight that for a given point in the cartilage, neighboring cells may behave differently
as predicted by anatomically realistic representation of chondrocyte distribution.
2. INTRODUCTION
Among other factors, including genetic, environmental and soluble mediators,
mechanical loading influences articular cartilage growth, maintenance, and degradation
[5]. Within the cartilage, the mechanical environment of chondrocytes, the sole resident
cell type, has been shown to be a contributor to cell activity and presumably tissue
health. Computational simulations of chondrocyte mechanics have been developed,
which provide information complimentary to experimentation or provide an avenue to
investigate aspects infeasible to experimentally capture [1,2]. Often hypothesis driven
and at times performed in a parametric fashion, such studies have looked at cell
deformation within the context of the tissue microstructure. In particular, depth
dependent simulations including singular or combined mechanics of the collagen
fibrillar network (extracellular matrix, ECM), pericellular matrix, and chondrocytes
have been developed. Especially when the influence of the surrounding aqueous
solution is included, as accounted for through biphasic theory [6], such studies have
highlighted the potential for complex, time dependent loading on chondrocytes.
Previous computational studies of chondrocyte mechanics have typically been
performed using single cell models embedded in an ECM construct [1,2]. Deformations
predicted from a homogeneous tissue model are generally used to drive such
1 Research Associate
2 Research Engineer
3 Assistant Staff, *erdemira@ccf.org web: http://www.lerner.ccf.org/bme/erdemir/lab
+ Computational Biomodeling (CoBi) Core, Department of Biomedical Engineering, Lerner Research
Institute, Cleveland Clinic, Cleveland, OH. 44195 USA