Ion release behavior of vanadium-doped mesoporous bioactive glass particles and the effect of the released ions on osteogenic differentiation of BMSCs via the FAK/MAPK signaling pathway

Vanadium and strontium co-doped hydroxyapatite enriched polycaprolactone matrices for effective bone tissue engineering: A synergistic approach

Scientific research targeted at enhancing scaffold qualities has increased significantly during the last few decades. This emphasis frequently centres on adding different functions to scaffolds in order to increase their usefulness as instruments in the field of regenerative medicine. This study aims to investigate the efficacy of a multifunctional sustainable polymer scaffold, specifically Polycaprolactone (PCL) embedded with hydroxyapatite co-doped with vanadium and strontium (HVS), for bone tissue engineering applications. Polycaprolactone was used to fabricate the scaffold, while hydroxyapatite co-doped with vanadium and strontium (HVS) served as the nanofiller. A thorough investigation of the physicochemical and biological characteristics of the HVS nanofiller was carried out using cutting-edge techniques including Dynamic Light Scattering (DLS), and X-ray Photoelectron Spectroscopy (XPS) and in vitro cell studies. A cell viability rate of more than 70 % demonstrated that the synthesised nanofiller was cytotoxic, but in an acceptable range. The mechanical, biological, and physicochemical properties of the scaffold were extensively evaluated after the nanofiller was integrated. The water absorption characteristics of scaffold were enhanced by the addition of HVS nanofillers, leading to increased swelling, porosity, and hydrophilicity. These improvements speed up the flow of nutrients and the infiltration of cells into the scaffold. The scaffold has been shown to have important properties that stimulate bone cell activity, including better biodegradability and improved mechanical strength, which increased from 5.30 ± 0.37 to 10.58 ± 0.42 MPa. Further, its considerable antimicrobial qualities, blood-compatible nature, and capacity to promote biomineralization strengthen its appropriateness for usage in biomedical applications. Mainly, enhanced Alkaline phosphatase (ALP) activity, Alizarin Red Staining (ARS) activity, and excellent cell adhesive properties, indicating the outstanding osteogenic potential observed in rat bone marrow-derived stromal cells (rBMSC). These combined attributes highlight the pivotal role of these nanocomposite scaffolds in the field of bone tissue engineering.

Engineering mesoporous bioactive glasses for emerging stimuli-responsive drug delivery and theranostic applications

Mesoporous bioactive glasses (MBGs), which belong to the category of modern porous nanomaterials, have garnered significant attention due to their impressive biological activities, appealing physicochemical properties, and desirable morphological features. They hold immense potential for utilization in diverse fields, including adsorption, separation, catalysis, bioengineering, and medicine. Despite possessing interior porous structures, excellent morphological characteristics, and superior biocompatibility, primitive MBGs face challenges related to weak encapsulation efficiency, drug loading, and mechanical strength when applied in biomedical fields. It is important to note that the advantageous attributes of MBGs can be effectively preserved by incorporating supramolecular assemblies, miscellaneous metal species, and their conjugates into the material surfaces or intrinsic mesoporous networks. The innovative advancements in these modified colloidal inorganic nanocarriers inspire researchers to explore novel applications, such as stimuli-responsive drug delivery, with exceptional in-vivo performances. In view of the above, we outline the fabrication process of calcium-silicon-phosphorus based MBGs, followed by discussions on their significant progress in various engineered strategies involving surface functionalization, nanostructures, and network modification. Furthermore, we emphasize the recent advancements in the textural and physicochemical properties of MBGs, along with their theranostic potentials in multiple cancerous and non-cancerous diseases. Lastly, we recapitulate compelling viewpoints, with specific considerations given from bench to bedside.

A Glutathione Peroxidase-Mimicking Nanozyme Precisely Alleviates Reactive Oxygen Species and Promotes Periodontal Bone Regeneration

The use of oxidoreductase nanozymes to regulate reactive oxygen species (ROS) has gradually emerged in periodontology treatments. However, current nanozymes for treating periodontitis eliminate ROS extensively and non-specifically, ignoring the physiological functions of ROS under normal conditions, which may result in uncontrolled side effects. Herein, using the MIL-47(V)-F (MVF) nanozyme, which mimics the function of glutathione peroxidase (GPx), it is proposed that ROS can be properly regulated by specifically eliminating H2 O2 , the most prominent ROS. Through H2 O2 elimination, MVF contributes to limiting inflammation, regulating immune microenvironment, and promoting periodontal regeneration. Moreover, MVF stimulates osteogenic differentiation of periodontal stem cells directly, further promoting regeneration due to the vanadium in MVF. Mechanistically, MVF regulates ROS by activating the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) pathway and promotes osteogenic differentiation directly through the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway. A promising periodontitis therapy strategy is presented using GPx-mimicking nanozymes through their triple effects of antioxidation, immunomodulation, and bone remodeling regulation, making nanozymes an excellent tool for developing precision medicine.

Bioactive VS4-based sonosensitizer for robust chemodynamic, sonodynamic and osteogenic therapy of infected bone defects

BACKGROUND

Most bone defects caused by bone disease or trauma are accompanied by infection, and there is a high risk of infection spread and defect expansion. Traditional clinical treatment plans often fail due to issues like antibiotic resistance and non-union of bones. Therefore, the treatment of infected bone defects requires a strategy that simultaneously achieves high antibacterial efficiency and promotes bone regeneration.

RESULTS

In this study, an ultrasound responsive vanadium tetrasulfide-loaded MXene (VSM) Schottky junction is constructed for rapid methicillin-resistant staphylococcus aureus (MRSA) clearance and bone regeneration. Due to the peroxidase (POD)-like activity of VS4 and the abundant Schottky junctions, VSM has high electron-hole separation efficiency and a decreased band gap, exhibiting a strong chemodynamic and sonodynamic antibacterial efficiency of 94.03%. Under the stimulation of medical dose ultrasound, the steady release of vanadium element promotes the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). The in vivo application of VSM in infected tibial plateau bone defects of rats also has a great therapeutic effect, eliminating MRSA infection, then inhibiting inflammation and improving bone regeneration.

CONCLUSION

The present work successfully develops an ultrasound responsive VS4-based versatile sonosensitizer for robust effective antibacterial and osteogenic therapy of infected bone defects.

Direct osteogenesis and immunomodulation dual function via sustained release of naringin from the polymer scaffold

Many traditional Chinese medicine monomers, such as naringin (NG), can regulate the local immune microenvironment to benefit osteogenesis. However, the rapid release of NG from scaffolds severely influences the osteogenesis-promoting effect. Herein, NG was loaded into mesoporous bioglass (MBG) to achieve sustained release through physical adsorption and the barrier role of mesoporous channels, then MBG loaded with NG was added to poly(L-lactic acid) (PLLA) to fabricate composite scaffolds by selective laser sintering (SLS) technology. The results showed that the NG-MBG/PLLA scaffolds could continuously and slowly release NG for 14 days compared with NG/PLLA scaffolds, and the cumulative release amount for the NG-MBG/PLLA scaffolds was 44.26%. In addition, the NG-MBG/PLLA scaffolds can promote the proliferation and osteogenesis differentiation of mouse bone marrow mesenchymal stem cells (mBMSCs). Meanwhile, the composite scaffolds decreased the reactive oxygen species (ROS) level of RAW264.7 under the stimulation of lipopolysaccharide (LPS) and significantly suppressed interleukin-6 (IL-6) and enhanced arginase-1 (Arg-1) protein expressions. Moreover, calcium nodule and alkaline phosphatase production of mBMSCs in a macrophage-conditioned medium for the NG-MBG/PLLA group also evidently increased compared with the PLLA and MBG/PLLA groups. These NG sustained-release composite scaffolds with osteo-immunomodulation function have great application prospects in the clinic.

Focal adhesion kinase (FAK): its structure, characteristics, and signaling in skeletal system

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase and distributes important regulatory functions in skeletal system. Mesenchymal stem cell (MSC) possesses significant migration and differentiation capacity, is an important source of distinctive bone cells production and a prominent bone development pathway. MSC has a wide range of applications in tissue bioengineering and regenerative medicine, and is frequently employed for hematopoietic support, immunological regulation, and defect repair, although current research is insufficient. FAK has been identified to cross-link with many other keys signaling pathways in bone biology and is considered as a fundamental "crossroad" on the signal transduction pathway and a "node" in the signal network to mediate MSC lineage development in skeletal system. In this review, we summarized the structure, characteristics, cellular signaling, and the interactions of FAK with other signaling pathways in the skeletal system. The discovery of FAK and its mediated molecules will lead to a new knowledge of bone development and bone construction as well as considerable potential for therapeutic use in the treatment of bone-related disorders such as osteoporosis, osteoarthritis, and osteosarcoma.

Vanadium-Doped Mesoporous Bioactive Glass Promotes Osteogenic Differentiation of rBMSCs via the WNT/β-Catenin Signaling Pathway

Pentavalent vanadium [V(V)] has been studied as bioactive ions to improve the bone defect repair; however, its osteogenic promotion mechanism is still not fully understood so far. In this study, a V-doped mesoporous bioactive glass (V-MBG) was prepared, and its effects on osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and potential signaling pathways were investigated. The physicochemical characterization revealed that the incorporation of V slightly reduced the specific surface area and increased the mesoporous pore size, and the abundant mesopores of V-MBG were beneficial to the sustained dissolution of V(V) ions as well as calcium, silicon, and phosphorus ions. Cell proliferation results indicated that the high dilution ratio (>16) V-MBG extract markedly promoted the proliferation of rBMSCs compared with the control group and the same dilution ratio MBG extract. Compared with the same dilution ratio MBG extract, diluted V-MBG extracts markedly promoted the secretion of alkaline phosphatase (ALP) and osteocalcin (OCN) protein at day 7 but insignificantly stimulated the runt-related transcription factor 2 (RUNX2) and vascular endothelial growth factor (VEGF) protein synthesis. In depth, the diluted V-MBG extracts remarkably up-regulated the expression of WNT/β-catenin pathway direct target genes, including WNT3a, β-catenin, and AXIN2 genes in contrast to the same dilution ratio MBG extracts, suggesting that the released V(V) ions might promote osteogenic differentiation of rBMSCs via the WNT/β-catenin signaling pathway.

The Effects of Graphene on the Biocompatibility of a 3D-Printed Porous Titanium Alloy

3D-printed titanium (Ti) materials have attracted much attention in the field of bone tissue repair. However, the combination strength of traditional alloy materials with bone tissue is lower, and the elastic modulus is higher than that of natural bone tissue, which makes the titanium alloy susceptible to stress shielding phenomena after implantation. Therefore, it is urgent to find better surface modification technology. In this study, the physical and chemical properties, toxicity, and proliferation of adipose stem cells of composite graphene-coated titanium alloy (Gr–Ti) were investigated using 3D-printed titanium alloy as a material model. Physical and chemical property tests confirmed that 3D printing could produce porous titanium alloy materials; the compressive strength and elastic modulus of the titanium alloy scaffolds were 91 ± 3 MPa and 3.1 ± 0.4 GPa, matching the elastic modulus of normal bone tissue. The surface characterization shows that graphene can be coated on titanium alloy by a micro-arc oxidation process, which significantly improves the surface roughness of titanium alloy. The roughness factor (Ra) of the Ti stent was 4.95 ± 1.12 μm, while the Ra of the Gr–Ti stent was 6.37 ± 0.72 μm. After the adipose stem cells were co-cultured with the scaffold for 4 h and 24 h, it was found that the Gr–Ti scaffold could better promote the early cell adhesion. CCK-8 tests showed that the number of ADSCs on the G–Ti scaffold was significantly higher than that on the Ti scaffold (p < 0.01). The relative growth rate (RGR) of ADSCs in Gr–Ti was grade 0–1 (non-toxic). In the in vivo experiment of repairing a critical bone defect of a rabbit mandible, the bone volume fraction in the Gr–Ti group increased to 49.42 ± 3.28%, which was much higher than that in the Ti group (39.76 ± 3.62%) (p < 0.05). In conclusion, the porous graphene–titanium alloy promotes the proliferation and adhesion of adipose stem cells with multidirectional differentiation potential, which has great potential for the application of bone tissue engineering in repairing bone defects in the future.