Imaging of nuclear magnetic resonance spin-lattice relaxation activation energy in cartilage.

R J Foster,R A Damion,S W Smye,A Radjenovic,D G Mcgonagle,D A Binks,M E Ries

doi:10.1098/rsos.180221

Abstract

Samples of human and bovine cartilage have been examined using magnetic resonance imaging to determine the proton nuclear magnetic resonance spin–lattice relaxation time, T1, as a function of depth within through the cartilage tissue. T1 was measured at five to seven temperatures between 8 and 38°C. From this, it is shown that the T1 relaxation time is well described by Arrhenius-type behaviour and the activation energy of the relaxation process is quantified. The activation energy within the cartilage is approximately 11 ± 2 kJ mol−1 with this notably being less than that for both pure water (16.6 ± 0.4 kJ mol−1) and the phosphate-buffered solution in which the cartilage was immersed (14.7 ± 1.0 kJ mol−1). It is shown that this activation energy increases as a function of depth in the cartilage. It is known that cartilage composition varies with depth, and hence, these results have been interpreted in terms of the structure within the cartilage tissue and the association of the water with the macromolecular constituents of the cartilage.

Highlights

Articular cartilage is mainly composed of type II collagen, glycosaminoglycans (GAGs) and interstitial water
The organization and complex interplay of these components imbues the tissue with 2 beneficial load-bearing and lubrication properties and, because of this, cartilage and its function have been the subject of recent intense research, for example see the reviews in Binks et al [1], Mow & Huiskes [2], Vaca-González et al [3] and Wilson et al [4] and the mini-review series introduced by Pacifici [5] on cartilage biology and pathology
The cartilage surface is placed at a distance of zero, with the phosphate-buffered solution (PBS) on the left and the cartilage extending to the right

Summary

Introduction

Articular cartilage is mainly composed of type II collagen, glycosaminoglycans (GAGs) and interstitial water. The distribution of these constituents is heterogeneous and the collagen is. A major motivating factor for the study of articular cartilage is that cartilage is a key site for both the initiation and progression of osteoarthritis (OA), which is a highly prevalent age-related condition for which the treatment for the end stage of the disease is joint replacement [6]. The early stages of OA are associated with changes in the macromolecular composition of the cartilage and softening of the tissue due to increased water content, which is thought to occur prior to tissue loss

Methods

Results

Conclusion