Development of coaxial-printing of scaffolds for meniscus replacement

Knee meniscus lesions are a common injury that can significantly impact an individual's quality of life. Current treatments for total meniscus replacement are unavailable, and the partial replacement alternatives provide only short-term relief, increasing the risk of knee arthritis in the long run. However, advancements in knee meniscus implants and 3D printing technology have the potential to revolutionize the treatment of knee meniscus lesions. This project uses a dual coaxial printing approach which allows for the simultaneous extrusion of two or more materials through a single nozzle. The materials are extruded in a coaxial manner, meaning that they are aligned along the same axis and flow out of the nozzle together. This allows for the choice of two different materials, one to provide good mechanical properties and the other to support cell attachment. In this work, we aimed to use polycaprolactone (PCL), for the mechanical properties, and silk fibroin (SF) for the biological properties, once these materials are already approved by Food and Drug Administration (FDA) and European Medicines Agency (EMA). However, various studies have highlighted the enhanced mechanical properties of SF when in the β-sheet, which can be achieved through different treatments, like the addition of organic solvents. Having this in mind, we developed a method capable printing PCL and SF at the same time, while changing the SF conformation instantly upon contact with acetone used to dissolve PCL. This innovative approach led to the formation of scaffolds with enhanced mechanical properties while maintaining the biological properties provided by the SF.