Tissue Engineering Approaches to Recapitulate the Micro- and Macro-architecture of the Knee Meniscus

Abstract: Meniscus injuries are common, and repair can be challenging. In this review, we discuss the complex structure of the knee meniscus, and recent strategies that have been investigated to develop scaffolds that recapitulate the meniscus macro- and micro-architecture. We searched PubMed using the keywords [(meniscus) OR (knee meniscus)] and relevant studies were selected. The knee meniscus contains type I collagen fibers arranged in various orientations, including circumferentially and radially; this arrangement is crucial for the overall health and function of the meniscus and knee joint. When injuries occur, regeneration is typically inhibited by limited vascularization, making tissue engineering strategies attractive options for alternative treatments. Techniques, such as decellularization of meniscal tissue, 3D bioprinting, and electrospinning, have been used to generate tissue engineered meniscus constructs. Each technique has advantages in mimicking certain aspects of the meniscus; for example, nanofibrous scaffolds produced via electrospinning are capable of mimicking the micro-architecture of the meniscus. Convergent strategies that combine the benefits of multiple strategies while mitigating the limitations of each strategy have had more success in mimicking the complex architecture and, in turn, generate scaffolds with similar mechanical properties to the native tissue. This review will discuss current strategies to recapitulate the micro- and macro- architecture of the meniscus, as well as combined strategies that have been used to produce more complex meniscal scaffolds. Lay Summary: There have been several recent approaches investigated to develop knee meniscus tissue replacements to treat injuries. When meniscus injuries occur, the tissue structure becomes disrupted, which negatively impacts the function of the tissue. In order to restore function, meniscus scaffolds have been developed using complex techniques to mimic the tissue structure. The scaffolds that mimic the complex tissue structure have more promise in being successful tissue replacements.