Design and characterization of three-dimensional twist-braid scaffolds for anterior cruciate ligament regeneration

Abstract

The anterior cruciate ligament (ACL) is the most commonly injured ligament in the knee, with more than 350,000 ACL injuries reported annually in the US. Current treatments include the use of autografts and allografts, which have a number of disadvantages. Previous attempts to use synthetic materials in ligament replacement have been unsuccessful due to their inability to replicate the long-term mechanical properties of the native ligament. The focus of this study was to develop twist-braid poly(L-lactic acid) (PLLA) scaffolds for ACL regeneration. Poly(ethylene glycol) diacrylate (PEGDA) was incorporated into the twist-braid scaffolds to evaluate its impact on their mechanical behavior. The twist-braid scaffolds were also compared with braided scaffolds. Scaffold mechanical properties were evaluated based on stress-relaxation, tensile and fatigue properties of the braided-only, twist-braid, and the twist-braid scaffolds with PEGDA. All the scaffolds exhibited properties comparable to the native human ACL with the twist-braid scaffolds displaying resistance to fatigue. Scaffolds were seeded with rat patellar tendon fibroblasts. Cell viability and the amount of protein released were studied over a course of 8 weeks. The scaffolds were stained with Picrosirius red after 8 weeks to show the deposition of extracellular matrix by the cells. The results from this study showed that the twist-braid scaffolds have properties most suitable for ligament regeneration.