3D-printed variable stiffness tissue scaffolds for potential meniscus repair

The treatment of meniscus injuries has recently shifted toward the field of tissue engineering (TE). In this work, bovine menisci were characterized, and the regionally-dependent mechanical properties were analyzed. Three-dimensional (3D) printing technology was employed to produce a scaffold that mimicked the mechanical properties of the meniscus. A polycaprolactone (PCL) meniscus scaffold was 3D printed, allowing for the deposition of fibers mimicking the internal architecture of the native meniscus, while achieving regional and variable mechanical stiffness, varying from 2.74 to 0.88 MPa. The PCL scaffold was infiltrated with extracellular matrix (ECM)-like hydrogels composed of gelatin methacrylate (GelMA) and glycosaminoglycans (GAGs), such as hyaluronic acid (HA) and chondroitin sulfate (CS), and subsequently freeze-dried. Human mesenchymal stem cells were seeded onto the scaffolds, and the infiltrated cells were observed to produce ECM components of the native meniscus. Collagen and GAGs production was successfully established. The synthesis of a new matrix reportedly enhances the mechanical properties of the hydrogel over time. Additionally, the circumferential PCL fibers within the scaffold guided the newly synthesized matrix, facilitating replication of the native tissue structure. These results indicate that the ECM-infiltrated 3D-printed PCL scaffold is a promising solution for meniscus repair.