Ligament Regenerative Engineering: Braiding Scalable and Tunable Bioengineered Ligaments Using a Bench-Top Braiding Machine

Anterior cruciate ligament (ACL) injuries are common sports injuries that typically require surgical intervention. Autografts and allografts are used to replace damaged ligaments. The drawbacks of autografts and allografts, which include donor site morbidity and variability in quality, have spurred research in the development of bioengineered ligaments. Herein, the design and development of a cost-effective bench-top 3D braiding machine that fabricates scalable and tunable bioengineered ligaments is described. It was demonstrated that braiding angle and picks per inch can be controlled with the bench-top braiding machine. Pore sizes within the reported range needed for vascularization and bone regeneration are demonstrated. By considering a one-to-one linear relationship between cross-sectional area and peak load, the bench-top braiding machine can theoretically fabricate bioengineered ligaments with a peak load that is 9 × greater than the human ACL. This bench-top braiding machine is generalizable to all types of yarns and may be used for regenerative engineering applications. Lay Summary Worldwide, 400,000 ACL reconstructions are performed annually. Rehabilitation after ACL reconstruction can take greater than 8 months, and the recurrence of ACL rupture is 30% in young active patients. Therefore, significant efforts have been made to develop an off-the-shelf ACL that is functionally superior to current ACL grafts. This study describes the development of a bench-top braiding machine that can be used in research laboratories to investigate the fabrication of bioengineered ACLs that are much stronger than current ACL grafts. Future Work Future studies will investigate the development of bioengineered ACL matrices made of non-degradable and degradable polymers, and in vivo experiments will be conducted to determine the functionality of the bioengineered ACL matrix.