Silk–Inorganic Nanoparticle Hybrid Hydrogel as an Injectable Bone Repairing Biomaterial

Abstract

Silk fibroin is regarded as a promising biomaterial in various areas, including bone tissue regeneration. Herein, Laponite® (LAP), which can promote osteogenic differentiation, was introduced into regenerated silk fibroin (RSF) to prepare an RSF/LAP hybrid hydrogel. This thixotropic hydrogel is injectable during the operation process, which is favorable for repairing bone defects. Our previous work demonstrated that the RSF/LAP hydrogel greatly promoted the osteogenic differentiation of osteoblasts in vitro. In the present study, the RSF/LAP hydrogel was found to have excellent biocompatibility and significantly improved new bone formation in a standard rat calvarial defect model in vivo. Additionally, the underlying biological mechanism of the RSF/LAP hydrogel in promoting osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) was extensively explored. The results indicate that the RSF/LAP hydrogels provide suitable conditions for the adhesion and proliferation of BMSCs, showing good biocompatibility in vitro. With the increase in LAP content, the alkaline phosphatase (ALP) activity and mRNA and protein expression of the osteogenic markers of BMSCs improved significantly. Protein kinase B (AKT) pathway activation was found to be responsible for the inherent osteogenic properties of the RSF/LAP hybrid hydrogel. Therefore, the results shown in this study firmly suggest such an injectable RSF/LAP hydrogel with good biocompatibility (both in vitro and in vivo) would have good application prospects in the field of bone regeneration.

Silk-Based 3D Porous Scaffolds for Tissue Engineering

“… Similarly, our research group, in collaboration with others, observed that SF/LAP hydrogels facilitated bone repair similarly and further identified that the inherent osteogenic properties of the RSF/LAP hybrid materials stemmed from the activation of the AKT pathway. This osteogenic effect was notably inhibited by an AKT pathway inhibitor, underscoring the critical role of AKT in the osteogenic capabilities of these materials …”

“…This osteogenic effect was notably inhibited by an AKT pathway inhibitor, underscoring the critical role of AKT in the osteogenic capabilities of these materials. 78 Many researchers have also simulated the natural inorganic composition of bone by artificial means. For example, polyphosphate (CPP), calcium phosphate (OCP), biphasic calcium phosphate (BCP), and β-tricalcium phosphate (β-TCP) are commonly employed in bone repair and replacement.…”

Application of Silk-Fibroin-Based Hydrogels in Tissue Engineering

“…Roohaniesfahani et al incorporated MSM-10 ceramic particles into SF hydrogels by ultrasonic cross-linking, demonstrating that magnesium, strontium, and silicon ions released from MSM-10 ceramic particles increased the gelling time and silk I: silk II ratios in the secondary protein structure of SF hydrogels while improving the in vitro osteogenic properties of hydrogels [139]. Sun et al prepared RSF/LAP hydrogels for optimized bone repair [140]. According to previous studies [104], LAP in RSF hydrogels can either increase the number of β-sheet domains that act as hydrogel crosslinkers or limit their growth.…”