Beta1-integrin/Hedgehog-Gli1 signaling pathway fuels the diameter-dependent osteoblast differentiation on different TiO2 nanotubes: The optimal-diameter nanotubes for osteoblast differentiation

Emerging Technologies to Enhance Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells: Focus on Nanomaterials and Bioactive Compounds

Bone tissue damage and associated disorders significantly compromise the quality of life of affected patients, and existing therapeutic options remain limited. Bone marrow mesenchymal stem cells (BMSCs) play a crucial role in bone regenerative medicine, owing to their ability to differentiate into osteoblasts. Utilizing cutting-edge technologies, nanomaterials, and bioactive compounds can emulate the natural bone tissue microenvironment, offer a three-dimensional scaffold that facilitates the osteogenic differentiation of BMSCs, and modulate signals at the molecular level, thereby showing promise for applications in bone regeneration and repair. This review seeks to discuss the latest research advancements, elucidate the underlying mechanisms, and highlight the potential benefits of these technologies in augmenting the osteogenic capacity of BMSCs. Furthermore, the challenges and future directions for integrating these technologies in practical settings are discussed to pioneer new vistas in bone regenerative medicine.

Investigating the interplay between environmental conditioning and nanotopographical cueing on the response of human MG63 osteoblastic cells to titanium nanotubes

Titanium nanotubular surfaces have been extensively studied for their potential use in biomedical implants due to their ability to promote relevant phenomena associated with osseointegration, among other functions. However, despite the large body of literature on the subject, potential synergistic/antagonistic effects resulting from the combined influence of environmental variables and nanotopographical cues remain poorly investigated. Specifically, it is still unclear whether the nanotube-induced variations in cellular activity are preserved across different biochemical contexts. To bridge this gap, this study systematically evaluates the combined influence of nanotopographical cues and environmental factors on human MG63 osteoblastic cells. To this end, we capitalized on a triphasic anodization protocol to create nanostructured surfaces characterized by an average nanotube inner diameter of 25 nm (NT1) and 82 nm (NT2), as well as a two-tiered honeycomb (HC) architecture. A variable glucose content was chosen as the environmental modifier due to its well-known ability to affect specific functions of MG63 cells. Alkaline phosphatase (ALP), viability/metabolic activity and proliferation were quantified to identify the suitable preconditioning window required for dictating a change in behaviour without significantly damaging cells. Successively, a combination of immunofluorescence, colorimetric assays, live cell imaging and western blots quantified viability/metabolic activity and cell proliferation, migration and differentiation as a function of the combined effects exerted by the nanostructured substrates and the glucose content. To achieve a thorough understanding of MG63 cell adaptation and response, a comparative analysis table that includes and systematically cross-analyzes all variables from this study was used for interpretation and discussion of the results. Taken together, we have demonstrated that all surfaces mitigate the negative effects of high glucose. However, nanotubular topographies, particularly NT2, elicit a more beneficial outcome in high glucose in respect to untreated titanium. In addition, while NT1 surfaces are associated with the most stable cellular response across varying glucose levels, the NT2 and HC substrates exhibit the strongest enhancement of cell migration, viability/metabolism and differentiation. Moreover, shorter-term processes such as adhesion and proliferation are favored on untreated titanium, while anodized samples support later-term events. Lastly, the role of anodized surfaces is dominant over the effects of environmental glucose, underscoring the importance of carefully considering nanoscale surface features in the design and development of cell-instructive titanium surfaces.

Differential expression of osteoblast-like cells on self-organized titanium dioxide nanotubes

Background/purpose

Titanium dioxide nanotube (TNT) structures have been shown to enhance the early osseointegration of dental implants. Nevertheless, the optimal nanotube diameter for promoting osteogenesis remains unclear due to variations in cell types and manufacture of nanotubes. This study aimed to evaluate the differences in MC3T3-E1 and Saos-2 cells behavior on nanotubes of varying diameters.

Materials and methods

TNT structures were fabricated by anodizing titanium foil at voltages ranging from 15V to 70V and annealed at 450 °C. Surface morphology and wettability were characterized using field emission scanning electron microscopy and water contact angle measurements, respectively. MC3T3-E1 and Saos-2 cells were cultured to evaluate biocompatibility. Early cell morphology and adhesion were visualized by scanning electron microscopy. Cell proliferation was quantified using CCK-8 assays, and differentiation was assessed through alkaline phosphatase assays. Osteogenesis-related gene expression was analyzed by real-time polymerase chain reaction (PCR), measuring runt-related transcription factor 2 (Runx-2), alkaline phosphatase (ALP), collagen type 1 (COL-1), osteocalcin (OCN), and Osteopontin (OPN) gene levels.

Results

Our results found that Saos-2 cells may be more suitable for TNT-related studies compared to MC3T3-E1 cells. Notably, the 65V nanotube group, with a diameter of 135.9 ± 15.83 nm, demonstrated the most significant osteogenic effect in our assays.

Conclusion

We propose that the use and screening of multiple cell lines prior to the evaluation of biomaterials can lead to more accurate in vitro experiments, thereby enhancing the reliability of biomaterial research.

WeiNaiAn capsule attenuates intestinal mucosal injury and regulates gut microbiome in indomethacin-induced rat

Indomethacin, as a non-steroidal anti-inflammatory drugs, is widely used in the clinic. However, it can cause severe injury to the gastrointestinal tract and the incidence is increasing. It has become an essential clinical problem in preventing intestinal damage. Teprenone has been reported to have a significant positive effect on intestinal mucosal lesions, but long-term use of teprenone can elicit adverse reactions. WeiNaiAn capsule is a traditional Chinese medicine formulation used widely in the treatment of gastric and duodenal mucosal injury. However, how WeiNaiAn protects against intestinal mucosal injury and its mechanism of action are not known. In this study, WeiNaiAn capsule or Teprenone treatment improved the intestinal mucosal pathological score and antioxidant level in indomethacin-induced rats. 16 S rRNA sequence data showed WeiNaiAn capsule reverted the structure community and replenished the beneficial bacteria. Furthermore, fingerprint analysis revealed multiple components of WeiNaiAn capsule, including calycosin glucoside, ginsenoside Rg1, ginsenoside Rb1, taurocholic acid sodium, formonetin, and calycosin glucoside. The components of WeiNaiAn capsule promoted the wound healing of the epithelial cell in vitro. Moreover, the components of WeiNaiAn capsule inhibited the protein expressions of phosphoinositide 3-kinase /protein kinase B /mammalian target of rapamycin in hydrogen peroxide or lipopolysaccharides-induced cell model. In conclusion, WeiNaiAn capsule improves intestinal mucosal injury by regulating cell migration, enhancing antioxidant activity, and promoting the structure of the bacterial community homeostasis, the multiple targets provide the parameters for the treatment in the clinic.

Size-Dependent Effect of Titania Nanotubes on Endoplasmic Reticulum Stress to Re-establish Diabetic Macrophages Homeostasis

In patients with diabetes, endoplasmic reticulum stress (ERS) is a crucial disrupting factor of macrophage homeostasis surrounding implants, which remains an obstacle to oral implantation success. Notably, the ERS might be modulated by the implant surface morphology. Titania nanotubes (TNTs) may enhance diabetic osseointegration. However, a consensus has not been achieved regarding the tube-size-dependent effect and the underlying mechanism of TNTs on diabetic macrophage ERS. We manufactured TNTs with small (30 nm) and large diameters (100 nm). Next, we assessed how the different titanium surfaces affected diabetic macrophages and regulated ERS and Ca2+ homeostasis. TNTs alleviated the inflammatory response, oxidative stress, and ERS in diabetic macrophages. Furthermore, TNT30 was superior to TNT100. Inhibiting ERS abolished the positive effect of TNT30. Mechanistically, topography-induced extracellular Ca2+ influx might mitigate excessive ERS in macrophages by alleviating ER Ca2+ depletion and IP3R activation. Furthermore, TNT30 attenuated the peri-implant inflammatory response and promoted osseointegration in diabetic rats. TNTs with small nanodiameters attenuated ERS and re-established diabetic macrophage hemostasis by inhibiting IP3R-induced ER Ca2+ depletion.

Micro/nano topological modification of TiO2 nanotubes activates Thy-1 signaling to control osteogenic differentiation of stem cells

Micro/nano topological modification is critical for improving the in vivo behaviors of bone implants, regulating multiple cellular functions. Titania (TiO2) nanotubes show the capacity of promoting osteoblast-related cell differentiation and induce effective osseointegration, serving as a model material for studying the effects of micro/nano-topological modifications on cells. However, the intracellular signaling pathways by which TiO2 nanotubes regulate the osteogenic differentiation of stem cells are not fully defined. Thy-1 (CD90), a cell surface glycoprotein anchored by glycosylphosphatidylinositol, has been considered a key molecule in osteoblast differentiation in recent years. Nevertheless, whether the micro/nano topology of the implant surface leads to changes in Thy-1 is unknown, as well as whether these changes promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Here, TiO2 nanotubes of various diameters were prepared by adjusting the anodizing voltage. qPCR and immunoblot were carried out to assess the mechanism by which TiO2 nanotubes regulate Thy-1. The results revealed Ti plates harboring TiO2 nanotubes ∼100-nm diameter (TNT-100) markedly upregulated Thy-1. Subsequently, upregulated Thy-1 promoted the activation of Fyn/RhoA/MLC Ⅱ/F-actin axis, which enhanced the nuclear translocation of YAP. After Thy-1 knockdown by siRNA, the Fyn/RhoA/MLC Ⅱ/F-actin axis was significantly inhibited and TiO2 nanotubes showed decreased effects on osteogenic differentiation. Therefore, Thy-1 upregulation might be a major mechanism by which micro/nano-topological modification of TiO2 nanotubes promotes osteogenic differentiation in BMSCs. This study provides novel insights into the molecular mechanism of TiO2 nanotubes, which may help design improved bone implants for clinical application.

TiO2 nanotube topography enhances osteogenesis through filamentous actin and XB130-protein-mediated mechanotransduction

TiO2 nanotube topography, as nanomechanical stimulation, can significantly promote osteogenesis and improve the osteointegration on the interface of implants and bone tissue. However, the underlying mechanism has not been fully elucidated. XB130 is a member of the actin filament-associated protein family and is involved in the regulation of cytoskeleton and tyrosine kinase-mediated signalling as an adaptor protein. Whether XB130 is involved in TiO2 nanotubes-induced osteogenic differentiation and how it functions in mechano-biochemical signalling transduction remain to be elucidated. In this study, the role of XB130 on TiO2 nanotube-induced osteogenesis and mechanotransduction was systematically investigated. TiO2 nanotube topography was fabricated via anodic oxidation and characterized. The osteogenic effect was significantly accelerated by the TiO2 nanotube surface in vitro and vivo. XB130 was significantly upregulated during this process. Moreover, XB130 overexpression significantly promoted osteogenic differentiation, whereas its knockdown inhibited it. Filamentous actin depolymerization could change the expression and distribution of XB130, thus affecting osteogenic differentiation. Mechanistically, XB130 could interact with Src and result in the activation of the downstream PI3K/Akt/GSK-3β/β-catenin pathway, which accounts for the regulation of osteogenesis. This study for the first time showed that the enhanced osteogenic effect of TiO2 nanotubes could be partly due to the filamentous actin and XB130 mediated mechano-biochemical signalling transduction, which might provide a reference for guiding the design and modification of prostheses to promote bone regeneration and osseointegration. STATEMENT OF SIGNIFICANCE: TiO2 nanotubes topography can regulate cytoskeletal rearrangement and thus promote osteogenic differentiation of BMSCs. However, how filamentous actin converts mechanical stimulus into biochemical activity remains unclear. XB130 is a member of actin filament-associated protein family and involves in the regulation of tyrosine kinase-mediated signalling. Therefore, we hypothesised that XB130 might bridge the mechano-biochemical signalling transduction during TiO2 nanotubes-induced osteogenic differentiation. For the first time, this study shows that TiO2 nanotubes enhance osteogenesis through filamentous actin and XB130 mediated mechanotransduction, which provides new theoretical basis for guiding the design and modification of prostheses to promote bone regeneration and osseointegration.

Surface-modified titanium and titanium-based alloys for improved osteogenesis: A critical review

As implantable materials, titanium, and its alloys have garnered enormous interest from researchers for dental and orthopedic procedures. Despite their success in wide clinical applications, titanium, and its alloys fail to stimulate osteogenesis, resulting in poor bonding strength with surrounding bone tissue. Optimizing the surface topology and altered compositions of titanium and titanium-based alloys substantially promotes peri-implant bone regeneration. This review summarizes the utilization and importance of various osteogenesis components loaded onto titanium and its alloys. Further, different surface-modification methods and the release efficacy of loaded substances are emphasized. Finally, we summarize the article with prospects. We believe that further investigation studies must focus on identifying novel loading components, exploring various innovative, optimized surface-modification methods, and developing a sustained-release system on implant surfaces to improve peri-implant bone formation.

Towards modular engineering of cell signalling: Topographically-textured microparticles induce osteogenesis via activation of canonical hedgehog signalling

Polymer microparticles possess great potential as functional building blocks for advanced bottom-up engineering of complex tissues. Tailoring the three-dimensional architectural features of culture substrates has been shown to induce osteogenesis in mesenchymal stem cells in vitro, but the molecular mechanisms underpinning this remain unclear. This study proposes a mechanism linking the activation of Hedgehog signalling to the osteoinductive effect of surface-engineered, topographically-textured polymeric microparticles. In this study, mesenchymal progenitor C3H10T1/2 cells were cultured on smooth and dimpled poly(D,l-lactide) microparticles to assess differences in viability, cellular morphology, proliferation, and expression of a range of Hedgehog signalling components and osteogenesis-related genes. Dimpled microparticles induced osteogenesis and activated the Hedgehog signalling pathway relative to smooth microparticles and 2D-cultured controls without the addition of exogenous biochemical factors. We observed upregulation of the osteogenesis markers Runt-related transcription factor2 (Runx2) and bone gamma-carboxyglutamate protein 2 (Bglap2), as well as the Hedgehog signalling components, glioma associated oncogene homolog 1 (Gli1), Patched1 (Ptch1), and Smoothened (Smo). Treatment with the Smo antagonist KAAD-cyclopamine confirmed the involvement of Smo in Gli1 target gene activation, with a significant reduction in the expression of Gli1, Runx2 and Bglap2 (p ≤ 0.001) following KAAD-cyclopamine treatment. Overall, our study demonstrates the role of the topographical microenvironment in the modulation of Hedgehog signalling, highlighting the potential for tailoring substrate topographical design to offer cell-instructive 3D microenvironments. Topographically-textured microparticles allow the modulation of Hedgehog signalling in vitro without adding exogenous biochemical agonists, thereby eliminating potential confounding artefacts in high-throughput drug screening applications.

Effects of Puerarin-Loaded Tetrahedral Framework Nucleic Acids on Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is recognized as a common refractory orthopedic disease that causes severe pain and poor quality of life in patients. Puerarin (Pue), a natural isoflavone glycoside, can promote osteogenesis and inhibit apoptosis of bone mesenchymal stem cells (BMSCs), demonstrating its great potential in the treatment of osteonecrosis. However, its low aqueous solubility, fast degradation in vivo, and inadequate bioavailability, limit its clinical application and therapeutic efficacy. Tetrahedral framework nucleic acids (tFNAs) are promising novel DNA nanomaterials in drug delivery. In this study, tFNAs as Pue carriers is used and synthesized a tFNA/Pue complex (TPC) that exhibited better stability, biocompatibility, and tissue utilization than free Pue. A dexamethasone (DEX)-treated BMSC model in vitro and a methylprednisolone (MPS)-induced ONFH model in vivo is also established, to explore the regulatory effects of TPC on osteogenesis and apoptosis of BMSCs. This findings showed that TPC can restore osteogenesis dysfunction and attenuated BMSC apoptosis induced by high-dose glucocorticoids (GCs) through the hedgehog and Akt/Bcl-2 pathways, contributing to the prevention of GC-induced ONFH in rats. Thus, TPC is a promising drug for the treatment of ONFH and other osteogenesis-related diseases.

Response of mesenchymal stem cells to surface topography of scaffolds and the underlying mechanisms

Mesenchymal stem/stromal cells (MSCs) serve as essential components of regenerative medicine. Their destiny is influenced by the interaction of the cells with the external environment. In addition to the biochemical cues in a microenvironment, physical cues of the topography of the surrounding materials such as the extracellular matrix emerge as a crucial regulator of stem cell destiny and function. With recent advances in technologies of materials production and surface modification, surfaces with micro/nanotopographical characteristics can be fabricated to mimic the micro/nanoscale mechanical stimuli of the extracellular matrix environment and regulate the biological behavior of cells. Understanding the interaction of cells with the topography of a surface is conducive to the control of stem cell fate for application in regenerative medicine. However, the mechanisms by which topography affects the biological behavior of stem cells have not been fully elucidated. This review will present the effects of surface topography at the nano/micrometer scale on stem cell adhesion, morphology, proliferation, migration, and differentiation. It also focuses on discussing current theories about the sensing and recognition of surface topology cues, the transduction of the extracellular cues into plasma, and the final activation of related signaling pathways and downstream gene expression in MSCs. These insights will provide a theoretical basis for the future design of biomaterial scaffolds for application in regenerative medicine and tissue engineering.

Effects of Modulation of the Hedgehog and Notch Signaling Pathways on Osteoblast Differentiation Induced by Titanium with Nanotopography

BACKGROUND

The events of bone formation and osteoblast/titanium (Ti) interactions may be affected by Hedgehog and Notch signalling pathways. Herein, we investigated the effects of modulation of these signalling pathways on osteoblast differentiation caused by the nanostructured Ti (Ti-Nano) generated by H₂SO₄/H₂O₂.

METHODS

Osteoblasts from newborn rat calvariae were cultured on Ti-Control and Ti-Nano in the presence of the Hedgehog agonist purmorphamine or antagonist cyclopamine and of the Notch antagonist N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) or agonist bexarotene. Osteoblast differentiation was evaluated by alkaline phosphatase activity and mineralization, and the expression of Hedgehog and Notch receptors was also evaluated.

RESULTS

In general, purmorphamine and DAPT increased while cyclopamine and bexarotene decreased osteoblast differentiation and regulated the receptor expression on both Ti surfaces, with more prominent effects on Ti-Nano. The purmorphamine and DAPT combination exhibited synergistic effects on osteoblast differentiation that was more intense on Ti-Nano.

CONCLUSION

Our results indicated that the Hedgehog and Notch signalling pathways drive osteoblast/Ti interactions more intensely on nanotopography. We also demonstrated that combining Hedgehog activation with Notch inhibition exhibits synergistic effects on osteoblast differentiation, especially on Ti-Nano. The uncovering of these cellular mechanisms contributes to create strategies to control the process of osseointegration based on the development of nanostructured surfaces.

Titania-Nanotube-Coated Titanium Substrates Promote Osteogenesis and Suppress Osteoclastogenesis via Integrin ανβ3

The balance of bone turnover mediated by osteoclastogenesis and osteogenesis implants that could suppress osteoclastogenesis and promote osteogenesis is an appropriate treatment strategy for osteoporosis patients. Titanium is one of the most applied materials in implants. In this study, titania nanotubes (Ti-NTs) were produced by anodization at 10, 40, and 60 V. We found that Ti-NTs were nontoxic to bone marrow mesenchymal stem cells (BMSCs). Ti-NTs suppressed osteoclast formation and function in a diameter dependent manner in vitro. Furthermore, Ti-NTs enhanced the activity of osteogenesis, expressions of osteogenesis-related marker genes were increased and β-Catenin pathway was active. Alkaline phosphatase (ALP) activity and matrix mineralization were also promoted in vitro. To explore the possible mechanisms, we performed a series of experiments to indicate the effects of Ti-NTs on cytoskeletal organization and integrin ανβ3 expression of osteoclasts and osteoblasts. The results demonstrated that 90-nm-diameter Ti-NTs could suppress the expression of integrin ανβ3 in osteoclast precursor cells. Interestingly, it revealed an opposite effect on BMSCs. Moreover, 90 nm-diameter Ti-NTs prevented ovariectomy (OVX)-induced bone loss. These findings indicated that Ti-NTs could inhibit osteoclastogenesis and enhance osteogenesis; it was mediated via regulation of integrin ανβ3─90 nm-diameter Ti-NT revealed a good biological ability especially suited for osteoporosis treatment.

From mesenchymal niches to engineered in vitro model systems: Exploring and exploiting biomechanical regulation of vertebrate hedgehog signalling

Tissue patterning is the result of complex interactions between transcriptional programs and various mechanical cues that modulate cell behaviour and drive morphogenesis. Vertebrate Hedgehog signalling plays key roles in embryogenesis and adult tissue homeostasis, and is central to skeletal development and the osteogenic differentiation of mesenchymal stem cells. The expression of several components of the Hedgehog signalling pathway have been reported to be mechanically regulated in mesodermal tissue patterning and osteogenic differentiation in response to external stimulation. Since a number of bone developmental defects and skeletal diseases, such as osteoporosis, are directly linked to aberrant Hedgehog signalling, a better knowledge of the regulation of Hedgehog signalling in the mechanosensitive bone marrow-residing mesenchymal stromal cells will present novel avenues for modelling these diseases and uncover novel opportunities for extracellular matrix-targeted therapies. In this review, we present a brief overview of the key molecular players involved in Hedgehog signalling and the basic concepts of mechanobiology, with a focus on bone development and regeneration. We also highlight the correlation between the activation of the Hedgehog signalling pathway in response to mechanical cues and osteogenesis in bone marrow-derived mesenchymal stromal cells. Finally, we propose different tissue engineering strategies to apply the expanding knowledge of 3D material-cell interactions in the modulation of Hedgehog signalling in vitro for fundamental and translational research applications.

GSK-3β suppression upregulates Gli1 to alleviate osteogenesis inhibition in titanium nanoparticle-induced osteolysis

Wear particle-induced periprosthetic osteolysis (PPO) have become a major reason of joint arthroplasty failure and secondary surgery following joint arthroplasty and thus pose a severe threat to global public health. Therefore, determining how to effectively suppress particle-induced PPO has become an urgent problem. The pathological mechanism involved in the PPO signaling cascade is still unclear. Recently, the interaction between osteogenic inhibition and wear particles at the implant biological interface, which has received increasing attention, has been revealed as an important factor in pathological process. Additionally, Hedgehog (Hh)-Gli1 is a crucial signaling cascade which was regulated by multiple factors in numerous physiological and pathological process. It was revealed to exert a crucial part during embryonic bone development and metabolism. However, whether Hh-Gli1 is involved in wear particle-induced osteogenic inhibition in PPO remains unknown. Our present study explored the mechanism by which the Hh-Gli1 signaling cascade regulates titanium (Ti) nanoparticle-induced osteolysis. We found that Hh-Gli1 signaling was dramatically downregulated upon Ti particle treatment. Mechanistically, glycogen synthesis kinase 3β (GSK-3β) activation was significantly increased in Ti particle-induced osteogenic inhibition via changes in GSK-3β phosphorylation level and was found to participate in the posttranslational modification and degradation of the key transcription factor Gli1, thus decreasing the accumulation of Gli1 and its translocation from the cytoplasm to the nucleus. Collectively, these findings suggest that the Hh-Gli1 signaling cascade utilizes a GSK3β-mediated mechanism and may serve as a rational new therapeutic target against nanoparticle-induced PPO.

Enhancement of Biofunctionalization by Loading Manuka Oil on TiO2 Nanotubes

Metallic implants (mesh) for guided bone regeneration can result in foreign body reactions with surrounding tissues, infection, and inflammatory reactions caused by micro-organisms in the oral cavity after implantation. This study aimed to reduce the possibility of surgical failure caused by microbial infection by loading antibacterial manuka oil in a biocompatible nanostructure surface on Ti and to induce stable bone regeneration in the bone defect. The manuka oil from New Zealand consisted of a rich β-triketone chemotype, leptospermone, which showed strong inhibitory effects against several bacteria, even at very low oil concentrations. The TiO₂ nanotubular layer formed by anodization effectively enhanced the surface hydrophilicity, bioactivity, and fast initial bone regeneration. A concentration of manuka oil in the range of 0.02% to less than 1% can have a synergistic effect on antibacterial activity and excellent biocompatibility. A manuka oil coating (especially with a concentration of 0.5%) on the TiO₂ nanotube layer can be expected not only to prevent stenosis of the connective tissue around the mesh and inflammation by microbial infection but also to be effective in stable and rapid bone regeneration.