Engineering of a Functional Tendon Using Collagen As a Natural Polymer

Reconstruction of a tendon rupture is surgically challenging as each end of the tendon retracts, leaving a substantial gap and direct repair is often not feasible. A tendon graft is required to bridge this defect and restore function. Presently, these gaps are filled with auto-, allo-, or synthetic grafts, but they all have clinical limitations. To address this issue, we developed tissue-engineered grafts by a rapid process using compressed type I collagen, which is the most dominant protein in the tendon. However, biomechanical properties were found to be unsuitable to withstand complete load-bearing in vivo. Hence, a modified suture technique was previously developed to reduce the load on the engineered collagen graft to aid integration in vivo. Using this technique, we tested engineered collagen grafts in vivo on a lapine model in three groups up to 12 weeks without immobilization. Gross observation at 3 and 12 weeks showed the bridge integrated without adhesions with a significant increase in the mechanical, structural and histological properties as compared to 1 week. Insertion of a tissue-engineered collagen graft using a novel load-bearing suture technique which partially loads in vivo showed integration, greater mechanical strength and no adhesion formation in the time period tested. This collagen graft has inherent advantages as compared to the present-day tendon grafts.