Hybrid gelatin/oxidized chondroitin sulfate hydrogels incorporating bioactive glass nanoparticles with enhanced mechanical properties, mineralization, and osteogenic differentiation.

Biopolymer based hydrogels are characteristic of their biocompatibility and capability of mimicking extracellular matrix structure to support cellular behavior. However, these hydrogels suffer from low mechanical properties, uncontrolled degradation, and insufficient osteogenic activity, which limits their applications in bone regeneration. In this study, we developed hybrid gelatin (Gel)/oxidized chondroitin sulfate (OCS) hydrogels that incorporated mesoporous bioactive glass nanoparticles (MBGNs) as bioactive fillers for bone regeneration. Gel-OCS hydrogels could be self-crosslinked in situ under physiological conditions in the presence of borax. The incorporation of MBGNs enhanced the crosslinking and accelerated the gelation. The gelation time decreased with increasing the concentration of MBGNs added. Incorporation of MBGNs in the hydrogels significantly improved the mechanical properties in terms of enhanced storage modulus and compressive strength. The injectability of the hydrogels was not significantly affected by the MBGN incorporation. Also, the proliferation and osteogenic differentiation of rat bone marrow mesenchymal stem cells in vitro and rat cranial defect restoration in vivo were significantly promoted by the hydrogels in the presence of MBGNs. The hybrid Gel-OCS/MBGN hydrogels show promising potential as injectable biomaterials or scaffolds for bone regeneration/repair applications given their tunable degradation and gelation behavior as well as favorable mechanical behavior and osteogenic activities.

Bioactive glass functionalized chondroitin sulfate hydrogel with proangiogenic properties.

Blood vessels play an important role in bone defect repair and growth, and a critical challenge of bone defect repair is the promotion of blood vessel formation. Most of the current methods promote vascularization by adding specific growth factors, which are costly and easy to inactivate. In this study, we developed a covalently cross-linked aminated bioactive glass nanoparticle-chondroitin sulfate methacrylate (ABGN-CSMA) organic-inorganic composite hydrogel with angiogenic properties. The amino groups of the ABGNs form covalent bonds with the carboxyl groups on CSMA. Surface amination modification of BGNs not only improved the dispersion of BGNs in CSMA but also significantly improved the mechanical properties of the composite hydrogel. The largest storage modulus (1200 Pa), the largest loss modulus (560 Pa) and the strongest resistance to deformation of the hydrogel are seen at 10% concentration of ABGNs. Simultaneously, the local pH stability and sustained ion release of the composite hydrogel are conducive to cell adhesion, proliferation, and angiogenesis. This work provides evidence for the development of covalently cross-linked organic-inorganic composite hydrogels with angiogenic properties.