The use of gold nanoparticles in improving ACL graft performance in an ovine model

Surgical repair of the anterior cruciate ligament (ACL) can involve autograft or allograft materials. Allografts are typically chosen to avoid donor site morbidity associated with autografts harvest, but they can also result in a prolonged inflammatory period and delayed graft remodeling when compared to autografts. The aim of this study was to investigate the use of gold nanoparticles (AuNPs) conjugated to allografts to determine if AuNPs can reduce inflammation and enhance graft remodeling in an ovine model. Six sheep had their ACL surgically removed and replaced with a decellularized human gracilis tendon. Three of the sheep received grafts conjugated with 20 nm gold nanoparticles, while three of the sheep received grafts without the gold nanoparticles. The sheep were sacrificed 8 weeks after ACL reconstruction. Immediately following sacrifice, joint fluid was collected for cytology. Semi-quantitative histological scoring of the bone tunnel portion and the intra-articular portion of the grafts were performed independently along with descriptive analysis of histologic changes and quantitative analysis of revascularization. The results demonstrated that AuNP experimental grafts had an overall better histological scores than the non-AuNPs graft. The AuNPs grafts exhibited decreased inflammation in the bone tunnel portion of the graft, the intra-articular portion of the graft, and in the synovial fluid cell count. Overall, the results demonstrated that the grafts conjugated with nanoparticles have the potential to be influence inflammation and overall remodeling response.