Construction of acellular cartilage matrix/silk fibroin scaffold and its cartilage tissue engineering study

Abstract

Objective·To construct a bioactivity tissue engineering scaffold with double network cross-linking for cartilage tissue regeneration using an acellular cartilage matrix (ACM) with a natural silk fibroin (SF) biomaterial.Methods·The cell-associated immunogenic components were removed by nuclease digestion, and the extracellular matrix-associated glycoproteins and collagen structures were retained, The efficiency of cartilage tissue decellularization was measured by spectrophotometry by using DNA, histoglycosaminoglycan and collagen quantification kits. ACM and SF were configured into a mixed solution, and the nucleophilic cross-linking reaction with the hydroxyl and carboxyl groups contained in both was carried out by adding ethylene glycol diglycidyl ether. Then it was freeze-dried to make porous bionic scaffolds (n=5). At the same time, porous scaffolds containing only ACM or SF were prepared by the same method (n=5). The microstructure of the scaffolds was observed by scanning electron microscopy (SEM), and the mechanical strength, elastic modulus and resilience of different groups of scaffolds were evaluated by mechanical tests. The internal and external nutrient exchange capacity of the scaffolds was reacted by water absorption rate. Chondrocytes from rabbit ears were isolated, cultured, and seeded on ACM-SF scaffolds. After 1, 4, and 7 days of culture, the adhesion, distribution, and matrix secretion of the cells on the scaffolds were observed by SEM, and the viability status of the cells was determined by double-staining of live and dead cells. CCK-8 method was used to determine the cytotoxicity of the scaffolds. The cells were implanted subcutaneously in nude mice, cultured in vivo for 4 and 8 weeks, and finally removed for histological testing. Differences between groups were tested by One-Way ANOVA. Statistical significance was accepted at a value of P<0.05.Results·After enzymatic digestion, almost no cells remained in the acellular matrix, and the active components of the extracellular matrix were retained. The composite scaffold prepared by ACM-SF has interconnected microporous structure and good elasticity, and could recover its original shape after repeated compression in the wet state. The water absorption rate of ACM-SF reached nearly 20 times, which provided an effective material exchange condition for the cell adhesion environment. Histological tests showed that the ACM-SF scaffold regenerated homogeneous, typical cartilage tissue in vivo.Conclusion·ACM-SF composite porous scaffold has a good bionic microenvironment and can be applied to tissue engineering cartilage regeneration.

Keywords

• acellular cartilage matrix
• silk fibroin
• porous scaffold
• cartilage regeneration