Eggshell particle-reinforced hydrogels for bone tissue engineering: an orthogonal approach

Hydrogel-based biomimetic scaffolds have generated broad interest due to their tunable physical, chemical, and biological properties for bone tissue engineering applications. We fabricated eggshell microparticle (ESP) reinforced gelatin-based hydrogels to obtain mechanically stable and biologically active three-dimensional (3D) constructs that can differentiate pre-mature cells into osteoblasts. Physical properties including swelling ratio, degradation, and mechanical properties of the composite hydrogels were investigated. Pre-osteoblasts were encapsulated within the ESP-reinforced hydrogels to study their differentiation and evaluate mineral deposition by these cells. The ESP-reinforced gels were then subcutaneously implanted in a rat model to determine their biocompatibility and degradation behaviors. The composite hydrogels have shown outstanding tunability in physical and biological properties holding substantial promise for engineering mineralized tissues ( e.g. bone, cartilage, tooth, and tendon). These 3D scaffolds enabled the differentiation of pre-osteoblasts without the use of specialized osteogenic growth medium. The ESP-reinforced gels exhibited significant enhancement in mineralization by pre-osteoblasts. These behaviors are positively correlated with increasing concentrations of ESP. Findings suggest that our novel composite hydrogel exhibits superior mechanical properties and indicates a favorable in vivo response by subcutaneous implantation in a rat model. Eggshell microparticle-reinforced hydrogels have been fabricated and characterized to obtain mechanically stable and biologically active scaffolds that can direct the differentiation of cells.