Cross-Linking of Knitted Silk Scaffold for Effective Entheseal Chondrogenesis and Ligamentogenesis

Abstract

The ligament is a connective tissue that bridges two bones and stabilizes the joints during motor activities.Anterior Cruciate Ligament(ACL)is one of the primary ligaments present in the knee connecting notch of the femur leads back into the femoral chondyle and fixes deep within tibia of the lower limb.ACL is the most commonly injured ligament among young and active individuals.Further,like other ligaments,ACL fails to heal optimally due to its low vascularity.The core insertional strength of ligaments is provided by a specialized organ called enthesis comprising of avascular fibrocartilage.Thus,if the current method of ligament tissue engineering would be integrated with pre-installation of enthesis at the bone-ligament interface,the original insertional strength can be envisaged in the tissue engineered construct.The current research project focuses on the fabrication of a silk based multi-compartmental scaffold,reinforced with natural polymers using a series of cross-linkers that can be used for ligament tissue engineering by enhancing the biocompatibility features.Briefly,the backbone of the scaffold was made by knitted silk followed by a coating of biopolymers like chitosan and gelatin for ligament and enthesial region respectively by the simple soaking method. To increase the coating yield and the stability of biopolymers on the knitted silk scaffolds, four different cross-linkers(i.e. araldite DY-T,PEG-dimethacrylate, glutaraldehyde and tyrosinase) were used and the outcomes were compared.These cross-linkers showed improvement in surface morphology, absorption,biodegradation and mechanical studies when compared with non-crosslinked scaffolds.TGA and FTIR spectroscopy were conducted for thermal and structural behavior analysis.MG-63 cells were used for biocompatibility of the scaffold using MTT assay. For both chitosan and gelatin coated scaffolds,tyrosinase was found to be the most suitable crosslinker on account of biocompatibility.