Effect of PET graft coated with silk fibroin via EDC/NHS crosslink on graft-bone healing in ACL reconstruction

Anterior cruciate ligament (ACL) reconstruction under arthroscopy using (PET) artificial ligaments helps to return to sport earlier compared with using autografts and allografts, but defective biocompatibility of PET worries surgeons. The purpose of this study is to investigate whether silk fibroin coating on PET via EDC/NHS crosslink could promote the compatibility of PET and enhance graft-bone healing. SF was immobilized on the surface of PET ligaments via EDC/NHS crosslinking method. Changes in the surface properties were characterized by scanning electron microscope (SEM), water contact angle measurement, and Fourier transform infrared spectra (FTIR). SF coating enhanced the hydrophilia of PET. In vitro studies by culturing BMSCs demonstrated that SF coating could improve BMSCs proliferation and increase the expression level of BMP-2, OCN, collagen I. Rabbit ACL reconstruction model was applied to observe the graft-bone healing process in vivo. The histological results proved that SF coating promoted graft-bone healing. However, the histological improvement was not translated into significant amelioration in biomechanical results and micro-CT analysis. In conclusion, SF coating via EDC/NHS crosslink improved the graft-bone healing of PET ligaments within the bone tunnel, which might positively influence the outcome of ACL reconstruction.