Tissue engineering approaches to regeneration of anterior cruciate ligament

Ligament tissue engineering has achieved much progress in recent years and many potential tissue-engineered ligaments used for ligament regeneration have been reported. The success of ligament regeneration procedure depends on three major factors: implant characteristics (including scaffolds, cells, and signaling molecules), surgical procedure, and postsurgery rehabilitation. The major challenges include complex mechanical stress faced by tissue-engineered anterior cruciate ligament (ACL), harsh environment, and poor blood supply after ACL ruptures. As tissue-engineered ligaments combine three dominant components, that is, scaffolds, cells, and signaling molecules, we will discuss ACL anatomy, current challenges in tissue repair, biomaterials and scaffold design, cell sources, bioreactors, and delivery of growth factors, as well as animal models in ligament tissue engineering. With greater research intensity and better understanding, a suitable substitute for ligament regeneration can be developed for clinical application.