Keqing Huang

Effective bone regeneration remains a challenge for bone-tissue engineering. In this study, we propose a new strategy to accelerate bone regeneration via a sustained supply of phosphorus without providing foreign calcium. Herein, a black phosphorus nanosheet (BPN)-based hydrogel platform was developed, and the BPNs were used to stably and mildly provide phosphorus. The hydrogel was fabricated by photo-crosslinking of gelatin methacrylamide, BPNs, and cationic arginine-based unsaturated poly(ester amide)s. This platform combines the following advantages: the hydrogel scaffold would keep BPNs inside, and the encapsulated BPNs can degrade into phosphorus ions and capture calcium ions to accelerate biomineralization in a bone defect. The introduction of BPNs helped to enhance the mechanical performance of hydrogels, photoresponsively release phosphate, and accelerate mineralization in vitro. Moreover, BPN-containing hydrogels improved osteogenic differentiation of human dental pulp stem cells via the bone morphogenic protein-runt-related transcription factor 2 pathway. In vivo results from a rabbit model of bone defects revealed that the BPNs helped to accelerate bone regeneration. All these results strongly suggest that the strategy of a sustained supply of calcium-free phosphorus and this BPN-containing hydrogel platform hold promise for effective bone regeneration.

Double network (DN) hydrogels, a kind of promising soft and tough hydrogels, are produced by two unique contrasting networks with designed network entanglement burst into the field of materials science as versatile functional systems for a very broad range of applications. A part of the DN hydrogels is characterized by extraordinary mechanical properties providing efficient biocompatible and high strength for holding considerable promise in tissue engineering. Following DN hydrogels principles and consideration of biomedical applications, we provide an overall view of the present various DN hydrogels and look forward to the future of DN hydrogels for tissue engineering. In this review, the preparation methods, structure, properties, current situation, and challenges are mainly discussed for the purpose of tissue engineering. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

Bone tissue engineering uses the principles and methods of engineering and life sciences to study bone structure, function and growth mechanism for the purposes of repairing, maintaining and improving damaged bone tissue. Scaffolds not only provide structural support for stem cells in cell adhesion and proliferation and bone formation, but also serve as a microenvironment for guiding stem cell differentiation and tissue regeneration and for controlling tissue structure. This review presents the research status of the scaffold microenvironment for bone-related stem cells based on bone tissue engineering. Scaffold materials and the stem cell microenvironment are described in this review, and the existing shortcomings are also simply mentioned.

Bone regeneration remains a clinical challenge with limited bone substitutes, urging for effective alternative strategies. Nanotubes, especially carbon nanotubes and titanium dioxide nanotubes, have been widely utilized for bone regeneration; however, their further applications were limited by the composition and degradability. As naturally occurring aluminosilicate nanoclay, halloysite nanotubes (HNTs), with good biocompatibility, functionality, and nanotubular structures, may be a promising platform for promoting bone regeneration. Herein, we presented a HNTs incorporated hydrogel and explored the potential bone tissue engineering applications of HNTs. The HNTs encapsulated hydrogel was simply fabricated by using the photopolymerization method with gelatin methacrylate (GelMA) and HNTs. The incorporation of HNTs led to an enhanced mechanical performance while maintaining a good cytocompatibility in vitro. The osteogenic activities of the HNTs incorporated platform have also been studied in vitro and in vivo. Remarkably, the addition of HNTs obviously upregulated the expression of osteogenic differentiation-related genes and concomitant protein of human dental pulp stem cells (hDPSCs) and therefore facilitated subsequent bone regeneration in calvarial defects of rats. Overall, the results obtained in this study highlight the bone regeneration capacity of HNTs, which may enhance current understanding of HNTs, and present a promising alternative strategy for bone regeneration.

After a biomaterial is implanted in a bone defect area, the immune response and bacterial infection affect the success of bone regeneration. In this study, we describe the development of a promising therapeutic approach to accelerate bone regeneration via combining osteoimmunomodulatory and antibacterial activities. Herein, we fabricated a nanosilver/halloysite nanotubes/gelatin methacrylate (nAg/HNTs/GelMA) hybrid hydrogel and evaluated its osteoimmunomodulatory and antibacterial properties in vitro and in vivo. The nAg/HNTs/GelMA hybrid hydrogel had good biocompatibility with human periodontal ligament stem cells (hPDLSCs) and macrophages. Moreover, the nAg/HNTs/GelMA hybrid hydrogel modulated inflammatory cytokines secreted by macrophages and enhanced the osteogenic differentiation of hPDLSCs in an inflammatory environment. In addition, nAg/HNTs/GelMA hybrid hydrogel inhibited the growth of Gram-positive and Gram-negative bacteria in vitro and in vivo. Compared with HNTs/GelMA hydrogel, the nAg/HNTs/GelMA hybrid hydrogel better modulated the osteoimmune microenvironment and eliminated bacterial infection. Thus, this hybrid hydrogel combining osteoimmunomodulatory with antibacterial activities is a promising biomaterial for bone regeneration in defect areas.