In vitro study on silk fibroin textile structure for anterior cruciate ligament regeneration

Abstract

A novel hierarchical textile structure made of silk fibroin from Bombyx mori capable of matching the mechanical performance requirements of anterior cruciate ligament (ACL) and in vitro cell ingrowth is described. This sericin-free, Silk Fibroin Knitted Sheath with Braided Core (SF-KSBC) structure was fabricated using available textile technologies. Micro-CT analysis confirmed that the core was highly porous and had a higher degree of interconnectivity than that observed for the sheath. The in vivo cell colonization of the scaffolds is thus expected to penetrate even the internal parts of the structure. Tensile mechanical tests demonstrated a maximum load of 1212.4±56.4 N (under hydrated conditions), confirming the scaffold's suitability for ACL reconstruction. The absence of cytotoxic substances in the extracts of the SF-KSBC structure in culture medium was verified by in vitro tests with L929 fibroblasts. In terms of extracellular matrix production, Human Periodontal Ligament Fibroblasts (HPdLFs) cultured in direct contact with SF-KSBC, compared to control samples, demonstrated an increased secretion of aggrecan (PG) and fibronectin (FBN) at 3 and 7 days of culture, and no change in IL-6 and TNF-α secretion. Altogether, the outcomes of this investigation confirm the significant utility of this novel scaffold for ACL tissue regeneration.

Keywords: ACL; Cytocompatibility; Hierarchical textile structure; Micro-CT; Silk fibroin; Tensile mechanical properties.