Allograft integration in a rabbit transgenic model for anterior cruciate ligament reconstruction

Background: Tissue engineering strategies include both cell-based and cell homing therapies. Ligamentous tissues are highly specialized and constitute vital components of the musculoskeletal system. Their damage causes significant morbidity and loss in function. Hypothesis: The aim of this study is to analyze tendinous graft integration, cell repopulation and ligamentization by using GFP+/- allografts in GFP+/- transgenic New Zealand white (NZW) rabbits. Material and methods: Graft implantation was designed to closely mimic anterior cruciate ligament (ACL) repair surgery. Allografts were implanted in 8 NZW rabbits and assessed at 5 days, 3 weeks and 6 weeks through: ( 1) arthroCT imaging, ( 2) morphological analysis of the transplanted allograft, ( 3) histological analysis, ( 4) collagen type I immunochemistry, and ( 5) GFP cell tracking. Collagen remodeling was appreciated at 3 and 6 weeks. Results: Graft repopulation with host cells, chondrocyte-like cells at the tendon-bone interface and graft corticalization in the bone tunnels were noticed at 3 weeks. By contrast we noticed a central necrosis aspect in the allografts intra-articularly at 6 weeks with a cell migration towards the graft edge near the synovium. Discussion: Our study has served to gain a better understanding of tendinous allograft bone integration, ligamentization and allograft repopulation. We believe that both cell-based therapies and cell homing therapies are beneficial in ligament tissue engineering. Future studies may elucidate whether cell repopulation occurs with pre-differentiated or progenitor cells. We believe that both cell-based therapies and cell homing therapies are beneficial in ligament tissue engineering. (C) 2015 Elsevier Masson SAS. All rights reserved.