Natural Polymer-Based Micronanostructured Scaffolds for Bone Tissue Engineering

Engineering Self-Assembling Peptide Hydrogel to Enhance the Capacity of Dendritic Cells to Activate In Vivo T-Cell Immunity

The efficacy of the dendritic cell (DC) has failed to meet expectations thus far, and crucial problems such as the immature state of DCs, low targeting efficiency, insufficient number of dendritic cells, and microenvironment are still the current focus. To address these problems, we developed two self-assembling peptides, RLDI and RQDT, that mimic extracellular matrix (ECM). These peptides can be self-assembled into highly ordered three-dimensional nanofiber scaffold structures, where RLDI can form gelation immediately. In addition, we found that RLDI and RQDT enhance the biological function of DCs, including releasing antigens sustainably, adhering to DCs, promoting the maturation of DCs, and increasing the ability of DC antigen presentation. Moreover, peptide hydrogel-based DC treatment significantly achieved prophylactic and treatment effects on colon cancer. These results have certain implications for the design of new broad-spectrum vaccines in the future.

Regulation of Immune Inflammation and Promotion of Periodontal Bone Regeneration by Irisin-Loaded Bioactive Glass Nanoparticles

Clinical solutions of bone defects caused by periodontitis involve surgical treatment and subsequent anti-infection treatment using antibiotics. Such a strategy faces a key challenge in that the excessive host immune response results in the damage of periodontal tissues. Consequently, it is of great importance to develop novel periodontitis treatment that allows the regulation of the host immune response and promotes the generation of periodontal tissues. Irisin has a good bone regeneration ability and could reduce the inflammatory reaction by regulating the differentiation of macrophages. In this study, we loaded irisin onto bioactive glass nanoparticles (BGNs) to prepare a composite, irisin-BGNs (IR-BGNs) with anti-inflammatory, bacteriostatic, and tissue regeneration functions, providing a novel idea for the design of ideal materials for repairing oral tissue defects caused by periodontitis. We also verified that the IR-BGNs had better anti-inflammatory properties on RAW264.7 cells compared to irisin and BGNs alone. Strikingly, when hPDLCs were stimulated with IR-BGNs, they exhibited increased expression of markers linked to osteogenesis, ALP activity, and mineralization ability in comparison to the negative control. Furthermore, on the basis of RNA sequencing results, we validated that the p38 pathway can contribute to the osteogenic differentiation of the IR-BGNs. This work may offer new thoughts on the design of ideal materials for repairing oral tissue defects.

NOVEL HIGH-STRENGTH POLYESTER COMPOSITE SCAFFOLDS FOR BONE REGENERATION

Repair of critical sized bone defects, particularly in load-bearing areas, is a major clinical problem that requires surgical intervention and implantation of biological or engineered grafts. For load-bearing sites, it is essential to use engineered grafts that have both sufficient mechanical strength and appropriate pore properties to support bone repair and tissue regeneration. Unfortunately, the mechanical properties of such grafts are often compromised due to the creation of pores required to facilitate tissue ingrowth following implantation. To overcome the limitations associated with porous scaffolds and their reduced mechanical strength, we have developed a methodology for creating a solid structure that retains its bulk mechanical properties while also evolving into a porous structure in a biological environment through degradation and erosion. In this study, we utilized polyesters that have been approved by the FDA, including poly (lactic acid) (PLA), poly(glycolic acid) (PGA), their copolymer PLGA (PLGA, with a ratio of 85:15 and 50:50 of PLA:PGA), and poly(caprolactone) (PCL). These polymers and their ceramic composites with tricalcium phosphate (TCP) were compression molded into solid forms, which exhibited mechanical properties with compressive modulus as high as 2745 ± 364 MPa within the range of human trabecular bone and in the lower range of human cortical bone. The use of fast-degrading PLGA (50:50) and PGA as porogens allowed the formation of pores within the solid structures due to their degradation, and the TCP acts as a buffering agent to neutralize their acidic degradation byproducts. These scaffolds facilitated the growth of new blood vessels and tissue ingrowth in a subcutaneous implantation model. In addition, in a rat critical-sized mandibular bone defects these scaffolds supported bone growth with 70% of new bone volume fraction. Furthermore, the extent of bone regeneration was found to be higher for the scaffolds with bone morphogenic proteins (BMP2), indicating their suitability for bone repair and regeneration.

Progress and challenges of graphene and its congeners for biomedical applications

Nanomaterials by virtue of their small size and enhanced surface area, present unique physicochemical properties that enjoy widespread applications in bioengineering, biomedicine, biotechnology, disease diagnosis, and therapy. In recent years, graphene and its derivatives have attracted a great deal of attention in various applications, including photovoltaics, electronics, energy storage, catalysis, sensing, and biotechnology owing to their exceptional structural, optical, thermal, mechanical, and electrical. Graphene is a two-dimensional sheet of sp2 hybridized carbon atoms of atomic thickness, which are arranged in a honeycomb crystal lattice structure. Graphene derivatives are graphene oxide (GO) and reduced graphene oxide (rGO), which are highly oxidized and less oxidized forms of graphene, respectively. Another form of graphene is graphene quantum dots (GQDs), having a size of less than 20 nm. Contemporary graphene research focuses on using graphene nanomaterials for biomedical purposes as they have a large surface area for loading biomolecules and medicine and offer the potential for the conjugation of fluorescent dyes or quantum dots for bioimaging. The present review begins with the synthesis, purification, structure, and properties of graphene nanomaterials. Then, we focussed on the biomedical application of graphene nanomaterials with special emphasis on drug delivery, bioimaging, biosensing, tissue engineering, gene delivery, and chemotherapy. The implications of graphene nanomaterials on human health and the environment have also been summarized due to their exposure to their biomedical applications. This review is anticipated to offer useful existing understanding and inspire new concepts to advance secure and effective graphene nanomaterials-based biomedical devices.