Nanoclay mineral-reinforced macroporous nanocomposite scaffolds for in situ bone regeneration: In vitro and in vivo studies

Abstract

Biomimetic organic-inorganic nanocomposite scaffolds represent a tremendous opportunity to accelerate bone regeneration due to their excellent structural and biological cues. However, the tradeoffs between biodegradability, mechanical strength, porosity and pore size, and bioactivity of the tissue-engineered nanocomposites remain a challenge. To this end, we constructed a novel biodegradable nanocomposite scaffold by chemical crosslinking of hydroxyethyl cellulose (HEC)/soy protein isolate (SPI) and montmorillonite (MMT) modification. Owing to the strong interfacial interaction between nanoclay and polymer chains, the prepared nanocomposites showed enhanced mechanical and physical properties, within the ideal range for bone tissue engineering. Furthermore, sustained sequential release of Ca and Mg ions during the degradation of the nanocomposites provided essential signaling cues for guiding bone regeneration. It was verified in vitro that the engineered nanocomposites possessed satisfactory cytocompatibility, offering a highly desirable microenvironment for cellular behaviors, including adhesion, proliferation, and spreading, as well as promoting the mineralization and osteoblastic differentiation of rat bone marrow stem cells. Notably, when employed to repair critical-sized cranial defects in rat models, the nanocomposites demonstrated not only reliable biosafety but also significant osteointegration and bone-forming ability in vivo. Collectively, our results confirmed that the incorporation of inorganic MMT nanosheets into biocompatible HEC/SPI scaffolds is a viable strategy for fabricating a suitable biomaterial that enhances the regeneration of large bone defects.