Localization of growth factors in the reconstructed anterior cruciate ligament: immunohistological study in dogs

This study was designed to examine localization of the growth factors in the autogenous patellar tendon graft used to reconstruct the anterior cruciate ligament (ACL) in the canine model. Among the various growth factors, basic fibroblast growth factor, transforming growth factor-pr, and platelet-derived growth factor were selected for analysis as potential factors that regulate graft remodeling processes. In the control patellar tendon and the ACL only basic fibroblast growth factor was positively stained. In the reconstructed graft increased levels of staining for all the three factors were observed in the early postoperative period, reaching the greatest expression 3 weeks after implantation. Thereafter immunoreactivity of these growth factors decreased and returned to the preoperative levels, which were similar to that of the control ACL 12 weeks postoperatively. This rapid reduction in the level of their localization indicates that once the extrinsic cells are infiltrated to the graft and revascularization completed, these growth factors may have less significance for subsequent remodeling.