Articular cartilage mechanical and biochemical property relations before and after in vitro growth

Abstract

The aim of this study was to design in vitro growth protocols that can comprehensively quantify articular cartilage structure-function relations via measurement of mechanical and biochemical properties. Newborn bovine patellofemoral groove articular cartilage explants were tested sequentially in confined compression (CC), unconfined compression (UCC), and torsional shear before (D0 i.e. day zero) and after (D14 i.e. day 14) unstimulated in vitro growth. The contents of collagen (COL), collagen-specific pyridinoline (PYR) crosslinks, glycosaminoglycan, and DNA significantly decreased during in vitro growth; consequently, a wide range of biochemical properties existed for investigating structure-function relations when pooling the D0 and D14 groups. All D0 mechanical properties were independent of compression strain while only Poisson's ratios were dependent on direction (i.e. anisotropic). Select D0 and D14 group mechanical properties were correlated with biochemical measures; including (but not limited to) results that CC/UCC moduli and UCC Poisson's ratios were correlated with COL and PYR. COL network weakening during in vitro growth due to reduced COL and PYR was accompanied by reduced CC/UCC moduli and increased UCC Poisson's ratios.

The Yucatan Minipig Temporomandibular Joint Disc Structure–Function Relationships Support Its Suitability for Human Comparative Studies

“…This further supports the minipig model for translational biomedical research. Contrary to the oft-reported structure-function relationship of articular cartilage that correlates GAG content with compressive properties, 36 for humans, minipigs, and FPs, the TMJ disc's compressive properties trended lower in the central regions despite higher GAG content in these regions. 12,13 Thus, components beside GAGs likely contribute to disc compressive properties; for example, the mean diameter of collagen fibril correlated with the compressive properties of the human intervertebral disc's annulus fibrosus.…”

Predicting Articular Cartilage Constituent Material Properties Following In Vitro Growth Using a Proteoglycan-Collagen Mixture Model

“…For instance, AC has been shown to have highly non-linear equilibrium tension and compression properties where the tissue has a much higher Young's modulus in tension than in compression (Soltz and Ateshian 2000;Williamson et al 2003;Huang C-Y et al 2005;Ficklin et al 2007). …”

“…While these models strive to develop PG models that are based on physically realistic continuum electromechanical interactions, they often require the determination of difficult to measure quantities such as fixed charge density, or glycosaminoglycan (GAG) molecule radius, and can result in overestimation of PG swelling stress and numerical instability in finite element analysis (FEA) (Klisch 2007;Davol et al 2008;Buschmann and Grodzinsky 1995 Studies have shown that the immature and mature AC equilibrium aggregate modulus ( ) and AC compressive modulus ( ), may initially decrease then increase with increasing compressive strains (Ficklin et al 2001;Wang et al 2003;Williams et al 2010). Therefore, it is hypothesized that under large compressive strains (>15% -45%) the COL fibers should undergo a transition from tension to compression.…”

Review on Patents for Mechanical Stimulation of Articular Cartilage Tissue Engineering

“…Computer-guided study designs can be helpful in this context, and using computers to interpret and extrapolate experimental data may turn out to be the only way to break through the trial-and-error-like approaches that are adopted nowadays. In the past few years many different theoretical models for cartilage mechanics have been developed [82][83][84][85][86][87][88][89]. These models form the basis for computer models that are dedicated for describing cartilage tissue engineering [33,72,[90][91][92][93][94][95][96][97].…”