Preparation of Silk Fibroin/Chitosan/Nano-Hydroxyapatite and Its Effect on the Repair of Cartilage Damage in Rats

Abstract

This study was aimed to prepare a silk fibroin (SF)/chitosan (CS)/nano-Hydroxyapatite (n-HAp) composite scaffold for repair of cartilage damage. A four-layer bionic scaffold SF/CS/n-HAp was constructed by cryogenic freezing and forming. Sodium Tripolyphosphate (STPP) was used as a cross-linking agent to post-process the scaffold to improve the mechanical strength of the scaffold. The various materials prepared were characterized. The SF/CS/n-HAp scaffold prepared in this study was cream-colored cylindrical and elastic. It can show variability after external force was applied, and can be restored to its original appearance after elimination of the external force. The diameter of the scaffold was 5 cm, and the total thickness was about 1 cm. The scanning electron microscope (SEM) results showed that the surface of the scaffold material was smooth, the pore size changed gradually, and the connectivity among the holes was good. The pore size distribution of the entire scaffold material was between 100 μm∼300 μm, and the pore size range was suitable for the adhesion, expansion, and migration of chondrocytes and osteoblasts. The mechanical performance test results showed that the composite scaffold had a compression modulus of 706 kPa, which can meet the mechanical performance requirements for repair of smaller articular cartilage damage. In addition, the porosity of each layer of the scaffold was more than 91%, which was conducive to the adhesion of cells on the surface of the material. The cell experiment results revealed that the composite scaffold material was beneficial to the growth and proliferation of cells. Under osteogenic and chondrogenic induction culture, bone marrow stromal cells (BMSCs) can differentiate in the direction of osteogenesis and cartilage. The results of animal experiments revealed that the SF/CS/n-HAp material group showed better effect than the blank control group in repairing rat cartilage defects, and the Wayne score and O’Driscoll score were also significantly higher than the blank control group. This suggested that the biomimetic scaffold SF/CS/n-HAp prepared in this study showed good physical properties and biocompatibility, and had certain prospects in the application of repairing cartilage damage.