Biofabrication Approaches to Tendon and Ligament Reconstruction

Tendons and ligaments are indispensable connective tissues that assist in locomotion of the body via connections between muscle to bone (tendon) and bone to bone (ligaments). There is an increasing incidence in tendon and ligament tears, due to more intensive sporting activities or age-related tissue degeneration. The achilles tendon, supraspinatus tendon, and anterior cruciate ligaments are the tissues with greatest susceptibility for rupture among the tendon and ligament family. Current solutions for tendon and ligament ruptures involve the use of suturing or allograft replacement, although the tissue mechanics are altered and there is a risk for re-rupture. Tissue engineering involving the use of cells and biomaterials has become an alternative approach that has the potential to enable natural tissue repair and allows the restoration of tissue mechanics. For this purpose, mesenchymal stromal cells, tendon stem/progenitor cells, and tenocytes have been investigated for the cellular component, while scaffolds created from either collagen, polylactic acid or polyethylene glycol have been extensively studied. Recent studies have described the use of novel 3D printing techniques to develop scaffolds with a specific architecture to enhance cellular response both in vitro and for potential clinical applications. This chapter summarizes the current status of tissue engineering approaches for tendon and ligament treatment, while also outlining the current clinical therapies for these tissues.