Printed Variable Stiffness Tissue Scaffolds For Potential Meniscus Repair

The treatment of meniscus injuries has recently been facing a paradigm shift toward the field of tissue engineering (TE), with the aim of regenerating damaged and diseased menisci. In this work, bovine meniscus was characterized, and the regionally-dependent mechanical properties analysed. It was established that both the collagen structure and glycosaminoglycans (GAG) content play a critical synergetic role in withstanding compressive loads. To produce a scaffold which mimicked this behaviour with anatomically relevant mechanical properties, 3D printing technology was employed and a polycaprolactone (PCL) meniscus scaffold was produced, allowing for the deposition of fibres mimicking the internal architecture of the native meniscus, while achieving regional and variable mechanical stiffness. The PCL scaffold was infiltrated with an extracellular matrix (ECM) like hydrogels comprising of Gelatin methacryloyl (GelMA) and GAGs such as hyaluronic acid (HA) and chondroitin sulphate (CS), and subsequently freeze dried. Human mesenchymal stem cells were seeded onto the scaffolds and the infiltrated cells were found to produce ECM components of the native meniscus. Collagen and GAG production was successfully established, and the synthesis of new matrix was found to increase the mechanical properties of the hydrogel over time. Additionally, the circumferential PCL fibres within the scaffold guided the newly synthesised matrix, by allowing replication of the structure of native tissue. These results indicate that the ECM infiltrated 3D printed PCL scaffold is a promising solution for meniscus repair.