Tendon functional extracellular matrix

Abstract

This article is one of a series, summarizing views expressed at the Orthopaedic Research Society New Frontiers in Tendon Research Conference. This particular article reviews the three workshops held under the "Functional Extracellular Matrix" stream. The workshops focused on the roles of the tendon extracellular matrix, such as performing the mechanical functions of tendon, creating the local cell environment, and providing cellular cues. Tendon is a complex network of matrix and cells, and its biological functions are influenced by widely varying extrinsic and intrinsic factors such as age, nutrition, exercise levels, and biomechanics. Consequently, tendon adapts dynamically during development, aging, and injury. The workshop discussions identified research directions associated with understanding cell-matrix interactions to be of prime importance for developing novel strategies to target tendon healing or repair.

Keywords: cell; collagen; hierarchy; mechanics; proteoglycans; structure; tendinopathy; tenocyte.

Figure 1

Schematic depicting the hierarchical structure of tendon, with inset images: Transverse sections show fibril and fascicle packing. The longitudinal histological section (H&E) shows the tendon cell populations.

Figure 2

Quasi-static and time dependent mechanical properties differ between energy storing and positional tendons. Typical data in parts a and b highlight differences in (a) the quasi-static properties and (b) the time dependent properties of the equine superficial digital flexor tendon (SDFT - energy storing tendon - solid line) and the common digital extensor tendon (CDET - positional tendon - dotted line). The table (c) provides a more comprehensive overview of data from a series of studies comparing paired equine SDFT & CDET tendons. Note the less stiff, more extensible and more fatigue resistant energy storing tendon properties^{; ; ;} .