Natural Biomineralization-Inspired Magnesium Silicate Composite Coating Upregulates Osteogenesis, Enabling Strong Anterior Cruciate Ligament Graft-Bone Healing In Vivo

Artificial ligaments prepared from polyethylene terephthalate (PET) are widely accepted for clinical anterior cruciate ligament (ACL) reconstruction to recover the native function of knee joints. However, due to the chemical inertness and hydrophobicity of PET, improving its bioactivity and promoting graft-bone integration are still great challenges. Inspired by the natural biomineralization process on the surface of a historical PET stone, in this study, a bioactive organic/inorganic composite coating that is composed of poly(allylamine hydrochloride) and ligan differential,on chondroitin sulfate with magnesium silicate (MgSiO3) doping is developed for surface modification of PET (MSPC-PET). This composite coating promotes adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs) and its bioactive inorganic components (MgSiO3) could induce osteogenic differentiation of BMSCs. Furthermore, an in vivo experiment indicated that this composite coating might afford superior graft-bone integration between MSPC-PET and the host bone tunnel, and fibrous scar tissue formation was also inhibited. More importantly, a biomechanical analysis proved that there was a strong integration between the MSPC-PET graft and the bone tunnel, which will improve biomechanical properties for the restoration of ACL function. This study shows that this bioactive composite coating-modified PET graft for the ACL reconstruction can effectively achieve good integration of ACL artificial grafts and bone tunnels and prevent surgical failure.