Multiphase Biodegradable Scaffolds for Tissue Engineering a Tendon-Bone Junction

Abstract

Tendons play an important role in transferring stress between muscles and bones and in maintaining joint stability. Tendon tears are difficult to heal, and are associated with high recurrence rates. So the objective of this study was to develop a biodegradable scaffold for tendon-bone junction regeneration. Two types of polylactic acid (PLA) yarns, having fibers with round and four deep grooved cross-sections, were braided into tubular scaffolds and cultured with murine TGF-β Type II receptor (TGFBR2)-expressing joint progenitor cells. The scaffolds were designed to mimic the mechanical, immuno-chemical and biological properties of natural mouse tendon-bone junctions. Three different tubular scaffolds measuring 2 mm in diameter were braided on a Steeger 16-spindle braiding machine using these PLA yarns. The three different scaffold structures were: 1) PLA hollow tube using round fibers, 2) PLA hollow tube using grooved and round fibers, and 3) PLA multicomponent tube containing round fibers in the sheath and grooved core fibers inserted within the lumen. The dynamic tensile strength and initial Young’s modulus of the three scaffolds were monitored on an Instron mechanical tester, and cell attachment, viability, proliferation and migration were measured at different time points. The three different braided structures provided a wide range of mechanical properties that mimicked the various zones of the tendon bone junction. The biological tests confirmed that cell viability, attachment and proliferation occurred throughout all three scaffolds, indicating that they have the potential to be used as scaffolds for the regeneration of a tendon bone tissue junction.