Tripeptide–copper complex GHK‐Cu (II) transiently improved healing outcome in a rat model of ACL reconstruction

After anterior cruciate ligament reconstruction (ACLR), the biological healing of the graft is a rate‐limiting step which can contribute to graft failure. The tripeptide–copper complex glycyl‐ L ‐histidyl‐ L ‐lysine‐Cu(II) (GHK‐Cu) is a well‐known activator of tissue remodeling. We investigated whether GHK‐Cu can improve graft healing following ACLR. Seventy‐two rats underwent unilateral ACLR were randomized to saline, 0.3 or 3 mg/ml GHK‐Cu groups ( n  = 24). Post‐operational intra‐articular injections were given from week 2, once a week, for 4 weeks. Gait analysis was performed pre‐injury and at harvesting time. At 6 or 12 weeks post‐operation, knee specimens were harvested for knee laxity test, graft pull‐out test, and histology. At 6 weeks post‐ACLR, GHK‐Cu groups resulted in a smaller side‐to‐side difference in knee laxity as compared to the saline group ( p  = 0.009), but there was no significant difference at 12 weeks post‐operation. The graft complex in the 0.3 mg/ml GHK‐Cu group had higher stiffness than saline group at 6 weeks post‐operation ( p  = 0.026), but there was no significant difference in ultimate load, gait parameters, and histological scores among treatment groups. All grafts failed mid‐substance during pull‐out test. Intra‐articular supplementation with a bioactive small molecule GHK‐Cu improved graft healing following ACLR in rat, but the beneficial effects could not last as treatment discontinued. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1024–1033, 2015.