Nodule formation and mineralisation of human primary osteoblasts cultured on a porous bioactive glass scaffold

Gallium-containing mesoporous nanoparticles influence in-vitro osteogenic and osteoclastic activity

Mesoporous silica nanoparticles were synthesized using a microemulsion-assisted sol-gel method, and calcium, gallium or a combination of both, were used as dopants. The influence of these metallic ions on the physicochemical properties of the nanoparticles was investigated by scanning and transmission electron microscopy, as well as N2 adsorption-desorption methods. The presence of calcium had a significant impact on the morphology and textural features of the nanoparticles. The addition of calcium increased the average diameter of the nanoparticles from 80 nm to 150 nm, while decreasing their specific surface area from 972 m2/g to 344 m2/g. The nanoparticles of all compositions were spheroidal, with a disordered mesoporous structure. An ion release study in cell culture medium demonstrated that gallium was released from the nanoparticles in a sustained manner. In direct contact with concentrations of up to 100 μg/mL of the nanoparticles, gallium-containing nanoparticles did not exhibit cytotoxicity towards pre-osteoblast MC3T3-E1 cells. Moreover, in vitro cell culture tests revealed that the addition of gallium to the nanoparticles enhanced osteogenic activity. Simultaneously, the nanoparticles disrupted the osteoclast differentiation of RAW 264.7 macrophage cells. These findings suggest that gallium-containing nanoparticles possess favorable physicochemical properties and biological characteristics, making them promising candidates for applications in bone tissue regeneration, particularly for unphysiological or pathological conditions such as osteoporosis.

Osteogenic Differentiation and Proliferation of Apical Papilla Stem Cells Using Chitosan-Coated Nanohydroxyapatite and Bioactive Glass Nanoparticles

OBJECTIVE

 The aim of this study was to evaluate the osteogenic differentiation ability and proliferation of apical papilla stem cells (SCAPs) using chitosan-coated nanohydroxyapatite and bioactive glass nanoparticles.

MATERIALS AND METHODS

 Hydroxyapatite, chitosan-coated nanohydroxyapatite, and bioactive glass 45S5 nanoparticles were prepared and characterized using a transmission electron microscope and X-ray diffraction. SCAPs were harvested from freshly extracted impacted wisdom teeth, cultured, and characterized using flow cytometric analysis. Tested nanomaterials were mixed and samples were classified into five equal groups as follows: negative control group: SCAP with Dulbecco's modified eagle's medium, positive control group: SCAP with inductive media, first experimental group: nanohydroxyapatite with SCAP, second experimental group: chitosan-coated nanohydroxyapatite with SCAP, third experimental group: bioactive glass nanoparticles with SCAP. Osteoblastic differentiation was assessed using an alkaline phosphatase (ALP) assay. Receptor activator of nuclear factor kappa beta ligand (RANKL) expression was evaluated using specific polyclonal antibodies by fluorescence microscope. The proliferation of SCAP was assessed using cell count and viability of trypan blue in addition to an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

RESULTS

 Isolated SCAP showed a nonhematopoietic origin. Chitosan-coated nanohydroxyapatite showed the highest ALP concentration followed by nanobioactive glass, nanohydroxyapatite, and negative control. Chitosan-coated nanohydroxyapatite showed the highest H score followed by nanobioactive glass, nanohydroxyapatite, and negative control in RANKL expression. Chitosan-coated nanohydroxyapatite showed the highest viable cell count.

CONCLUSION

 SCAP isolation is achievable from extracted fully impacted immature third molars. All tested biomaterials have the ability to induce osteogenic differentiation and proliferation of SCAP. Composite nanoparticle materials show better osteogenic differentiation and proliferation of SCAP than single nanoparticles.

A comparative in vitro and in vivo analysis of the impact of copper substitution on the cytocompatibility, osteogenic, and angiogenic properties of a borosilicate bioactive glass

The 0106-B1-bioactive glass (BG) composition (in wt %: 37.5 SiO2, 22.6 CaO, 5.9 Na2O, 4.0 P2O5, 12.0 K2O, 5.5 MgO, and 12.5 B2O3) has demonstrated favorable processing properties and promising bone regeneration potential. The present study aimed to evaluate the biological effects of the incorporation of highly pro-angiogenic copper (Cu) in 0106-B1-BG in vitro using human bone marrow-derived mesenchymal stromal cells (BMSCs) as well as its in vivo potential for bone regeneration. CuO was added to 0106-B1-BG in exchange for CaO, resulting in Cu-doped BG compositions containing 1.0, 2.5 and 5.0 wt % CuO (composition in wt %: 37.5 SiO2, 21.6/ 20.1/17.6 CaO, 5.9 Na2O, 4.0 P2O5, 12.0 K2O, 5.5 MgO, 12.5 B2O3, and 1.0/ 2.5/ 5.0 CuO). In vitro, the BGs' impact on the viability, proliferation, and growth patterns of BMSCs was evaluated. Analyses of protein secretion, matrix formation, and gene expression were used for the assessment of the BGs' influence on BMSCs regarding osteogenic differentiation and angiogenic stimulation. The presence of Cu improved cytocompatibility, osteogenic differentiation, and angiogenic response when compared with unmodified 0106-B1-BG in vitro. In vivo, a critical-size femoral defect in rats was filled with scaffolds made from BGs. Bone regeneration was evaluated by micro-computed tomography. Histological analysis was performed to assess bone maturation and angiogenesis. In vivo effects regarding defect closure, presence of osteoclastic cells or vascular structures in the defect were not significantly changed by the addition of Cu compared with undoped 0106-B1-BG scaffolds. Hence, while the in vitro properties of the 0106-B1-BG were significantly improved by the incorporation of Cu, further evaluation of the BG composition is necessary to transfer these effects to an in vivo setting.

Versatile Bioactive Glass/Zeolitic Imidazolate Framework-8-Based Skin Scaffolds toward High-Performance Wound Healing

Designing a novel biomaterial for wound healing is based on biocompatibility and excellent mechanical strength. In this study, bioactive glass (BG) and zeolitic imidazolate framework-8 (ZIF-8) have been incorporated into poly(ε-caprolactone)/poly(vinyl alcohol) (PCL/PVA) composite skin scaffolds via microfluidic electrospinning. Interestingly, the addition of ZIF-8 further strengthens the BG stability and demonstrates better antibacterial effects. Utilizing the slow release of Zn, Ca, and Si ions, it also significantly promotes growth factor expression and skin regeneration. In addition, it is further demonstrated by in vitro and in vivo studies that the prepared composite skin scaffolds possess excellent biocompatibility, antibacterial capabilities, and mechanical properties. The prepared BG/ZIF-8-loaded scaffold possesses high tensile strength (26 MPa) and excellent antibacterial properties (achieves 89.64 and 78.8% inhibition of E. coli and S. aureus, respectively), and cell viability increased by 51.2%. More importantly, the wound shrinkage of the BG/ZIF-8-loaded scaffold is better than that of an unloaded scaffold, and the shrinkage rates of PCL/PVA@BG/ZIF-8(1 wt %) group is 95% with 2.2 mm granulation growth thickness within 12 days. Thus, the composite skin scaffold loaded with BG/ZIF-8 prepared by microfluidic electrospinning provides a new perspective for accelerating wound healing and is a potential novel therapeutic strategy for efficient wound healing.

Osteogenic differentiation and proliferation of apical papilla stem cells using nanoparticles of Neo MTA and bioactive glass

Objective

The aim of this study was to evaluate the osteogenic differentiation ability and proliferation of apical papilla stem cells using nanoparticles of Neo MTA and bioactive glass.

Methods

Neo MTA and bioactive glass 45S5 nanoparticles were prepared and characterized using a transmission electron microscope and X-ray diffraction. Apical papilla stem cells were harvested from freshly-extracted fully-impacted wisdom teeth, cultured, and characterized using flow cytometric analysis. Tested nanomaterials were mixed and samples were classified into four equal groups as follows; Negative control group: SCAP with Dulbecco's modified eagle's medium, Positive control group: SCAP with inductive media, First experimental group: Neo MTA nanoparticles with SCAP, Second experimental group: Bioactive glass nanoparticles with SCAP. Osteoblastic differentiation was assessed using an alkaline phosphatase assay and RANKL expression using specific polyclonal antibodies by fluorescence microscope. The proliferation of SCAP was assessed using cell count and viability of Trypan Blue in addition to an MTT assay.

Results

Isolated SCAP showed a non-hematopoietic origin. Neo MTA showed the highest ALP concentration followed by bioactive glass nanoparticles, and negative control. Bioactive glass nanoparticles showed the highest H score for RANKL protein expression followed by Neo MTA, and negative control. Bioactive glass nanoparticles showed the highest viable cell count.

Conclusions

SCAP isolation is achievable from extracted fully impacted immature third molars. Both tested nanobiomaterials have the ability to induce osteogenic differentiation and proliferation of SCAP.

In vitro immunomodulatory effect of solid versus porous phosphate-based glass microspheres using macrophages

This study aimed to investigate the immunomodulatory effect of two different forms of phosphate-based glass microspheres (solid and porous), on human macrophages. Human THP-1 monocytes were converted to M0 macrophages after being treated with 100 ng/mL phorbol 12-myristate 13-acetate for 48 h. The differentiated cells were analysed for the CD14 marker using flow cytometry. The adhesion, spreading, and viability of M0 macrophages grown directly or indirectly (extracts) at varying concentrations of solid and porous glass microspheres (GMs) were analysed via phase contrast microscopy, confocal microscopy, and XTT assay. The expression of IL-8, IL-1β, IL-6, IL-10, TNF-α, and IL-12p70 cytokines was investigated using flow cytometry. The conversion to M0 macrophages was confirmed by their adherent nature, increased granularity, and CD14 expression. The results showed that both solid and porous GMs or extracts favored the attachment, spreading, and proliferation of macrophages in a comparable manner to cells grown in a normal tissue culture medium. Only the higher concentration of porous GMs (10 mg/mL) changed the morphology of M0 macrophages and increased the expression of IL-1β and IL-8 pro-inflammatory cytokines; this could be related to the fast degradation nature of porous GMs. Of the six cytokines analysed, M0 macrophages grown directly or indirectly with GMs only expressed IL-1β, IL-10, and IL-8. Accordingly, solid microspheres may have advantages as regenerative agents due to their controlled degradation.

Elucidating osseointegration in vivo in 3D printed scaffolds eliciting different foreign body responses

Osseointegration between biomaterial and bone is critical for the clinical success of many orthopaedic and dental implants. However, the mechanisms of in vivo interfacial bonding formation and the role of immune cells in this process remain unclear. In this study, we investigated the bone-scaffold material interfaces in two different 3D printed porous scaffolds (polymer/hydroxyapatite and sintered hydroxyapatite) that elicited different levels of foreign body response (FBR). The polymer/hydroxyapatite composite scaffolds elicited more intensive FBR, which was evidenced by more FBR components, such as macrophages/foreign body giant cells and fibrous tissue, surrounding the material surface. Sintered hydroxyapatite scaffolds showed less intensive FBR compared to the composite scaffolds. The interfacial bonding appeared to form via new bone first forming within the pores of the scaffolds followed by growing towards strut surfaces. In contrast, it was previously thought that bone regeneration starts at biomaterial surfaces via osteogenic stem/progenitor cells first attaching to them. The material-bone interface of the less immunogenic hydroxyapatite scaffolds was heterogenous across all samples, evidenced by the coexistence of osseointegration and FBR components. The presence of FBR components appeared to inhibit osseointegration. Where FBR components were present there was no osseointegration. Our results offer new insight on the in vivo formation of bone-material interface, which highlights the importance of minimizing FBR to facilitate osseointegration for the development of better orthopaedic and dental biomaterials.

The Impact of the Molecular Weight of Degradation Products with Silicon from Porous Chitosan-Siloxane Hybrids on Neuronal Cell Behavior

Silicon (Si) is an essential trace element in the human body and it exists in connective tissue as aqueous orthosilicic acid. Porous chitosan-3-glycidoxypropyltrimethoxysilane (GPTMS) hybrids can regenerate nerve tissue and recover sensor and motor functions. However, the structures and roles of the degradation products with Si extracted from the hybrids in nerve regeneration are not clear. In this study, we prepared porous chitosan-GPTMS hybrids with different amounts of GPTMS to amino groups of chitosan (chitosan:GPTMS = 1:0.5 and 1:1 molar ratios). The structures of the degradation products with Si from the hybrids were examined using time-of-flight mass spectrometry, and biological assessments were conducted in order to evaluate their potential use in the preparation of devices for nerve repair. Glial and motor cell lines and ex vivo explants of dorsal root ganglia were used in this study for evaluating their behavior in the presence of the different degradation products with Si. The structure of the degradation products with Si depended on the starting composition. The results showed that glial cell proliferation was lower in the medium with the higher-molecular-weight degradation products with Si. Moreover, motor cell line differentiation and the neurite outgrowth of dorsal root ganglion explants were improved with the lower-molecular-weight degradation products with Si. The results obtained could be useful for designing a new nerve regeneration scaffold including silicon components.

3D-plotted zinc silicate/β-tricalcium phosphate ceramic scaffolds enable fast osteogenesis by activating the p38 signaling pathway

Biomaterials in combination with multiple bioactive ions could create a favorable microenvironment for bone remolding. Herein, zinc silicate/β-tricalcium phosphate (ZS/β-TCP) composite ceramic scaffolds with different amounts of ZS (5, 10, and 15 wt%) were constructed using a three-dimensional fiber deposition (3DF) technique. The physicochemical, osteogenic and angiogenic properties of these interconnected macroporous scaffolds were investigated systematically. Simultaneously, GeneChip, alkaline phosphatase (ALP), western blot (WB) and polymerase chain reaction (PCR) were utilized to elucidate the underlying mechanism of the enhancement in osteogenic differentiation. The results showed that the incorporation of ZS significantly improved the mechanical performance by more than 5 fold in comparison with the β-TCP ceramic scaffold (4.79 ± 0.99 MPa). The ZS modified β-TCP scaffolds greatly supported the cytoactivity, adhesion, proliferation of mouse bone marrow mesenchymal stem cells (mBMSCs) and human umbilical vein endothelial cells (HUVECs). The expression levels of osteogenic genes and proteins as well as angiogenic genes were markedly upregulated by the sustained release of bioactive ions (mainly Si and Zn) from the composite scaffolds. The 10ZS/β-TCP demonstrated the best overall performance in vitro. Moreover, the 10ZS/β-TCP displayed a high bone volume fraction, bone maturity and angiogenesis after implantation in the rat skull defects for 6 weeks. It was further verified that ZS/β-TCP scaffolds stimulated the osteogenic differentiation of mBMSCs by activating the p38 signaling pathway directly. The 10ZS/β-TCP ceramic scaffold holds great potential for the fast repair of bone defects, and deep understanding of the mechanism will facilitate the formulation of new strategies for bone repair.

Influence of Copper-Strontium Co-Doping on Bioactivity, Cytotoxicity and Antibacterial Activity of Mesoporous Bioactive Glass

Mesoporous bioactive glass (MBG) is an extensively studied biomaterial used for the healing of bone defects. Its biological applications can be tailored by introducing metallic ions, such as strontium (Sr) and copper (Cu), which can enhance its functionalities, including osteogenetic, angiogenetic and antibacterial functionalities. In this study, Cu and Sr ions were co-doped (ratio 1:1) with x = 0.5, 1 and 2 mol% each in glass with an intended nominal composition of 80SiO2-(15-2x)CaO-5P2O5-xCuO-xSrO and synthesized with an evaporation-induced self-assembly (EISA)-based sol-gel technique. XRD confirmed the amorphous nature of the glass, while compositional analysis using ICP-OES confirmed the presence of dopant ions with the required amounts. A TEM study of the MBG powders showed fringes that corresponded to the formation of a highly ordered mesoporous structure. The Cu-Sr-doped MBG showed a positive effect on apatite formation when immersed in SBF, although the release of Cu and Sr ions was relatively slow for 1 mol% of each co-dopant, which signified a stable network structure in the glass. The impact of the Cu and Sr ions on the osteoblast-like cell line MG-63 was assessed. At the particle concentrations of 1 wt./vol.% or lower, the cell viability was above 50%. An antibacterial test was conducted against Gram-negative E. coli and Gram-positive S. aureus bacteria. With a sequential increase in the co-doped ion content in the glass, the zone of inhibition for bacteria increased. The results suggest that the doping of MBG with Cu and Sr ions at up to 2 mol% can result in tailored sustained release of ions to enhance the applicability of the studied glass as a functional biomaterial for bone regeneration applications.

Periodontal Therapy Using Bioactive Glasses: A Review

This paper reviews the use of bioactive glasses as materials for periodontal repair. Periodontal disease causes bone loss, resulting in tooth loosening and eventual tooth loss. However, it can be reversed using bioactive glass, typically the original 45S5 formulation (Bioglass®) at the defect site. This is done either by plcing bioactive glass granules or a bioactive glass putty at the defect. This stimulates bone repair and causes the defect to disappear. Another use of bioactive glass in periodontics is to repair so-called furcation defects, i.e., bone loss due to infection at the intersection of the roots in multi-rooted teeth. This treatment also gives good clinical outcomes. Finally, bioactive glass has been used to improve outcomes with metallic implants. This involves either placing bioactive glass granules into the defect prior to inserting the metal implant, or coating the implant with bioactive glass to improve the likelihood of osseointegration. This needs the glass to be formulated so that it does not crack or debond from the metal. This approach has been very successful, and bioactive glass coatings perform better than those made from hydroxyapatite.

In vitro evaluation of porous poly(hydroxybutyrate-co-hydroxyvalerate)/akermanite composite scaffolds manufactured using selective laser sintering

Incorporation of a bioactive mineral filler in a biodegradable polyester scaffold is a promising strategy for scaffold assisted bone tissue engineering (TE). The current study evaluates the in vitro behavior of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)/Akermanite (AKM) composite scaffolds manufactured using selective laser sintering (SLS). Exposure of the mineral filler on the surface of the scaffold skeleton was evident from in vitro mineralization in PBS. PHBV scaffolds and solvent cast films served as control samples and all materials showed preferential adsorption of fibronectin compared to serum albumin as well as non-cytotoxic response in human osteoblasts (hOB) at 24 h. hOB culture for up to 21 days revealed that the metabolic activity in PHBV films and scaffolds was significantly higher than that of PHBV/AKM scaffolds within the first two weeks of incubation. Afterwards, the metabolic activity in PHBV/AKM scaffolds exceeded that of the control samples. Confocal imaging showed cell penetration into the porous scaffolds. Significantly higher ALP activity was observed in PHBV/AKM scaffolds at all time points in both basal and osteogenic media. Mineralization during cell culture was observed on all samples with PHBV/AKM scaffolds exhibiting distinctly different mineral morphology. This study has demonstrated that the bioactivity of PHBV SLS scaffolds can be enhanced by incorporating AKM, making this an attractive candidate for bone TE application.

The Effect of Heat Treatment of β-Tricalcium Phosphate-Containing Silica-Based Bioactive Aerogels on the Cellular Metabolism and Proliferation of MG63 Cells

β-Tricalcium phosphate was combined with silica aerogel in composites prepared using the sol–gel technique and supercritical drying. The materials were used in this study to check their biological activity and bone regeneration potential with MG63 cell experiments. The composites were sintered in 100 °C steps in the range of 500–1000 °C. Their mechanical properties, porosities, and solubility were determined as a function of sintering temperature. Dissolution studies revealed that the released Ca-/P molar ratios appeared to be in the optimal range to support bone tissue induction. Cell viability, ALP activity, and type I collagen gene expression results all suggested that the sintering of the compound at approximately 700–800 °C as a scaffold could be more powerful in vivo to facilitate bone formation within a bone defect, compared to that documented previously by our research team. We did not observe any detrimental effect on cell viability. Both the alkaline phosphatase enzyme activity and the type I collagen gene expression were significantly higher compared with the control and the other aerogels heat-treated at different temperatures. The mesoporous silica-based aerogel composites containing β-tricalcium phosphate particles treated at temperatures lower than 1000 °C produced a positive effect on the osteoblastic activity of MG63 cells. An in vivo 6 month-long follow-up study of the mechanically strongest 1000 °C sample in rat calvaria experiments provided proof of a complete remodeling of the bone.

A novel bioactive glass-based root canal sealer in endodontics

Background/purpose

Bioactive glass (BG), one type of bioceramics, shows similar or better characteristics to calcium silicate which has been regarded as a promising root filling material in endodontics. This study aimed to develop a novel BG-based root canal sealer for endodontics.

Materials and methods

The novel BG-based root canal sealer was composed of phytic acid derived bioactive calcium phosphosilicate glass named PSC mixed with zirconium oxide (ZrO₂) as powder, and phosphate solution (PS) dissolved with sodium alginate (SA) named PS-SA as liquid. Moreover, the physicochemical properties, mineralization, sealing ability and biocompatibility of the novel BG-based root canal sealer were evaluated.

Results

This study developed a novel BG-based sealer named BGS-SA-Zr which contained the powder of PSC and ZrO₂ and the liquid of PS-SA. Results indicated that the flow, film thickness and radiopacity of BGS-SA-Zr conformed to ISO 6876:2012. The setting time and solubility of BGS-SA-Zr were 53.7 ± 1.5 min and 21.46 ± 0.54%, respectively. The pH value of the simulated body fluid (SBF) immersed with BGS-SA-Zr raised slightly up to 7.70. The CCK-8 assay indicated that BGS-SA-Zr had no cytotoxic effects on MG-63 cells. After immersion in SBF for 4 weeks, dense hydroxyapatite crystals were observed on the surface of BGS-SA-Zr. Furthermore, there was no difference in the sealing ability between BGS-SA-Zr and the bioceramic sealer iRoot SP whether setting at 1 day or immersed in SBF for 4 weeks (P > 0.05).

Conclusion

Our results suggest that the novel BG-based sealer may be a promising sealer for endodontic treatment.

Titanium-Containing Silicate-Based Sol-Gel Bioactive Glass: Development, Characterization, and Applications

Bioactive glasses are surface-reactive glasses that, when placed in physiological fluid, undergo a transformation from glass to hydroxyapatite. Doping the bioactive glass with metallic ions can impart desirable and unique properties that are not inherent to natural hydroxyapatite. Once such ion is titanium. Titanium exists in trace amounts in native dental enamel, and its presence has been correlated with increased tooth hardness and brightness, both desirable clinical properties. Synthetic titanium-substituted hydroxyapatite exhibits better mechanical and antibacterial properties and demonstrates potential for an improved cellular response when compared to unmodified hydroxyapatite with applications in the broader field of bone tissue engineering. In this work, we use the sol-gel method to synthesize a titanium-containing silicate-based bioactive glass aimed at generating titanium-substituted hydroxyapatite on the glass surface upon immersion in body fluid. Titanium is homogeneously distributed throughout our glass, which keeps its amorphous nature. After 14 days of immersion in simulated body fluid, the glass forms a titanium-substituted hydroxyapatite on its surface. Enamel surfaces treated with the titanium-containing glass show significantly increased microhardness compared to enamel surfaces treated with a control glass, confirming the potential for the proposed glass in enamel remineralization. We also show that the presence of titanium in the glass promotes cell differentiation toward bone formation, suggesting further applications for this material in the broader field of bone tissue engineering.

Bioactive Ceramic Scaffolds for Bone Tissue Engineering by Powder Bed Selective Laser Processing: A Review

The implementation of a powder bed selective laser processing (PBSLP) technique for bioactive ceramics, including selective laser sintering and melting (SLM/SLS), a laser powder bed fusion (L-PBF) approach is far more challenging when compared to its metallic and polymeric counterparts for the fabrication of biomedical materials. Direct PBSLP can offer binder-free fabrication of bioactive scaffolds without involving postprocessing techniques. This review explicitly focuses on the PBSLP technique for bioactive ceramics and encompasses a detailed overview of the PBSLP process and the general requirements and properties of the bioactive scaffolds for bone tissue growth. The bioactive ceramics enclosing calcium phosphate (CaP) and calcium silicates (CS) and their respective composite scaffolds processed through PBSLP are also extensively discussed. This review paper also categorizes the bone regeneration strategies of the bioactive scaffolds processed through PBSLP with the various modes of functionalization through the incorporation of drugs, stem cells, and growth factors to ameliorate critical-sized bone defects based on the fracture site length for personalized medicine.

Silver, silicon co-substituted hydroxyapatite modulates bacteria-cell competition for enhanced osteogenic function

Combating bacteria while promoting tissue regeneration is an aim of highest priority for employing biomaterials in orthopedics that often embroiled with pre-operative contamination. Through simulating a surgical site infection environment and an infected implant site, we showcase the ability of a functionally modified hydroxyapatite, Ag,Si-HA that permits preferential adhesion of human bone marrow derived mesenchymal stem cells (BMSCs) over co-cultured bacterial pathogen,Pseudomonas aeruginosa, by displaying immediate suppression and killing of the bacteria present with minimum cytotoxicity for 28 d. And, at the same time, Ag,Si-HA stimulates BMSCs towards osteogenic differentiation despite being within the contaminated milieu. These findings provide well-defined requirements for incorporating antibacterial properties to biomaterials in managing pre-operative contamination. In addition, it highlights the dual positive attributes of Ag,Si-HA as an effective antibacterial biomaterial and at the same time, promotes bone tissue regeneration.

Zeolite Socony Mobil-Five Coating on Ti-24 Nb-4 Zr-7.9 Sn Promotes Biocompatibility and Osteogenesis In Vitro and In Vivo

The aim of this study was to evaluate the biocompatibility and osteogenic potential of a Zeolite Socony Mobil-5 (ZSM-5) coating on a Ti-24 Nb-4 Zr-7.9 Sn (Ti-2448) surface. ZSM-5-modified Ti-2448 (ZSM-5/Ti-2448) and Ti-2448 (control) groups were employed. The physical and chemical properties of the two types of samples were evaluated by scanning electron microscopy, Fourier-transform infrared spectroscopy, nitrogen adsorption/desorption, and contact angle methods. The surface of the ZSM-5/Ti-2448 was rougher than that of the original Ti-2448, while the contact angle of the ZSM-5/Ti-2448 was smaller than that of Ti-2448. In addition, the ZSM-5/Ti-2448 largely increased the specific surface area and introduced silanol groups. A bone-like apatite layer could be formed on the surface of ZSM-5/Ti-2448 after 14 days of incubation in a simulated body fluid. ZSM-5/Ti-2448 was not cytotoxic. The number and alkaline phosphatase (ALP) activity of osteoblasts on ZSM-5/Ti-2448 were significantly higher than those on Ti-2448 surfaces, obtained in vitro using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide and ALP activity assays. Few inflammatory cells were observed around ZSM-5/Ti-2448 after insertion into the femurs of Japanese white rabbits after 4, 12, and 26 weeks through hematoxylin-eosin staining. The average gray scale of transforming growth factor-β1 (TGF-β1) on ZSM-5/Ti-2448 peaked earlier than that on Ti-2448, according to immunohistochemical staining. These results indicate that ZSM-5/Ti-2448 has a good biocompatibility and improved early osteogenic potential compared to a noncoated Ti-2448.

Improvement of the mechanical and biological properties of bioactive glasses by the addition of zirconium oxide (ZrO2 ) as a synthetic bone graft substitute

In this study, mechanical properties of bioactive glass (BAG) synthetic bone graft substitute was improved by containing ZrO2 (ZrO2 -BAG), while maintaining advantageous biological properties of BAG such as osteoinductive and osteoconductive properties. The ZrO2 -BAG was produced by adding ZrO2 in the following proportions to replace Na2 O in 45S5 BAG: 1% (Zr1-BAG), 3% (Zr3-BAG), 6% (Zr6-BAG), and 12% (Zr12-BAG). Properties including XRD, XPS, SEM, DSC, fracture toughness, and Vickers microhardness were evaluated. To assess the biological properties, Ca/P apatite formation, ion release, degradation rate, cell proliferation, ALP activity (ALP), and alizarin red S staining assay (ARS) were evaluated. Also, expression of osteogenic differentiation markers, Osteopontin (OPN), confirmed by immunofluorescence staining. Finally, an in vivo test was carried out to by implanting ZrO2 -BAG into the subcutaneous tissue of rats. The results of each test were statistically analyzed with one-way ANOVA followed by Tukey's post hoc statistical test. Amorphous ZrO2 -BAG was successfully produced with increased mechanical properties as the ZrO2 content was increased. Additionally, ZrO2 -BAG exhibited a slower ion release and degradation rate compare to BAG without ZrO2 . Bioactivity of ZrO2 -BAG was confirmed with apatite layer formed on the surface, significantly higher proliferation rate and significantly enhanced ALP and the degree of ARS of the cells compare to respective controls. The tissue reactions observed in the in vivo study showed neo-formed vessels after implantation of ZrO2 -BAG.

Regeneration of pulp-dentine complex-like tissue in a rat experimental model under an inflammatory microenvironment using high phosphorous-containing bioactive glasses

AIM

To investigate the effects of a bioactive glass with a high proportion of phosphorus (BG-hP) on the repair and regeneration of dental pulps in rats under an inflammatory microenvironment.

METHODOLOGY

Human dental pulp cells (hDPCs) stimulated with 1 μg mL^-1 lipopolysaccharide (LPS) were co-cultured with 0.1 mg mL^-1 BG-hP. Cell proliferation was detected by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assays. The expression of inflammation-related genes and odontogenic differentiation-related genes was determined by real-time PCR. Alizarin red staining was used to detect the formation of mineralized nodules. Coronal pulp tissues of rat molars were stimulated with 10 mg mL^-1 LPS and then treated with BG-hP. The expression of inflammation-related genes in pulp tissue was determined by real-time PCR. Haematoxylin-eosin staining and Masson staining were performed to observe the inflammatory response and mineralized matrix formation, after subcutaneous implantation in nude mice, at 3 days and 4 weeks, respectively. Analysis of variance was performed to measure statistical significance (P < 0.05).

RESULTS

BG-hP significantly reduced expression of interleukin-6 (IL-6) and IL-8 and significantly upregulated the expression of IL-10, IL-4 and transforming growth factor-β1 of the LPS-stimulated hDPCs (P < 0.05). BG-hP significantly inhibited the initial cell number (P < 0.05), but the hDPCs stimulated by LPS and co-cultured with BG-hP maintained the same proliferation rate as the untreated hDPCs. BG-hP significantly promoted the expression of dentine matrix protein-1 and dentine sialophosphoprotein and the mineralization capacity of the LPS-stimulated hDPCs (P < 0.05). Furthermore, BG-hP significantly downregulated the expression of Il-6 and reduced the inflammatory response of the LPS-stimulated pulp tissue 3 days after subcutaneous implantation (P < 0.05). Four weeks after subcutaneous implantation, BG-hP induced the formation of a continuous layer of dentine-like structure with dentinal tubules and polarizing odontoblast-like cells aligned along it in the LPS-stimulated pulp tissue.

CONCLUSION

The present preliminarily results demonstrated that the bioactive glass with a high proportion of phosphorus inhibited the inflammatory response and promoted the formation of a pulp-dentine complex in a rat experimental model. This study provides a foundation for the construction of materials with the dual functions of exerting anti-inflammatory effects and promoting tissue regeneration to meet the needs of dental pulp repair and regeneration.

Mechanical Biocompatibility, Osteogenic Activity, and Antibacterial Efficacy of Calcium Silicate-Zirconia Biocomposites

Zirconia ceramics with high mechanical properties have been used as a load-bearing implant in the dental and orthopedic surgery. However, poor bone bonding properties and high elastic modulus remain a challenge. Calcium silicate (CaSi)-based ceramic can foster osteoblast adhesion, growth, and differentiation and facilitate bone ingrowth. This study was to prepare CaSi-ZrO₂ composites and evaluate their mechanical properties, long-term stability, in vitro osteogenic activity, and antibacterial ability. The Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria and human mesenchymal stem cells (hMSCs) were used to evaluate the antibacterial and osteogenic activities of implants in vitro, respectively. Results indicated that the three-point bending strength of ZrO₂ was 486 MPa and Young's modulus was 128 GPa, which were much higher than those of the cortical bone. In contrast, the bending strength and modulus of 20% (201 MPa and 48 GPa, respectively) and 30% CaSi (126 MPa and 20 GPa, respectively) composites were close to the reported strength and modulus of the cortical bone. As expected, higher CaSi content implants significantly enhanced cell growth, differentiation, and mineralization of hMSCs. It is interesting to note the induction ability of CaSi in osteogenic differentiation of hMSCs even when cultured in the absence of an osteogenic differentiation medium. The composite with the higher CaSi contents exhibited the greater bacteriostatic effect against E. coli and S. aureus. In conclusion, the addition of 20 wt % CaSi can effectively improve the mechanical biocompatibility, osteogenesis, and antibacterial activity of ZrO₂ ceramics, which may be a potential choice for load-bearing applications.

Biodegradable intramedullary nail (BIN) with high-strength bioceramics for bone fracture

About 10 million fractures occur worldwide each year, of which more than 60% are long bone fractures. It is generally agreed that intramedullary nails have significant advantages in rigid fracture fixation. Metal intramedullary nails (INs) can provide strong support but a stress shielding effect can occur that results in nonunion healing in clinic. Nondegradable metals also need to be removed by a second operation. Could INs be biodegradable and used to overcome this issue? As current degradable biomaterials always suffer from low strength and cannot be used in Ins, herein, we report a novel device consisting of biodegradable IN (BIN) made for the first time with bioceramics. These BINs have an extremely high bending strength and stable internal and external structure. Experiments show that the BINs could not only fix and support the tibial fracture model, but also promote osteogenesis and affect the microenvironment of the bone marrow cavity. Therefore, they could be expected to replace traditional metal IN and become a more effective treatment option for tibial fractures.

Preventive Effects of Chrysanthemum coronarium L. Extract on Bone Metabolism In Vitro and In Vivo

Osteoporosis is characterized by decreased bone mass and bone microarchitectural failure, leading to an enhanced risk of bone fractures. Chrysanthemum coronarium L. (CC) is a natural plant with powerful antioxidant activity. This study investigated the antiosteoporotic effects of CC extracts in in vitro cell cultures and in vivo bone loss animal models. CC stimulated osteoblast differentiation and mineralized bone formation by osteoblasts by increasing the expression of bone formation markers (alkaline phosphatase, osteoprotegerin, and osteoprotegerin/receptor activator nuclear factor-κB ligand ratio) in the murine preosteoblastic cell line MC3T3-E1. Additionally, CC was found to inhibit osteoclast differentiation by downregulating bone resorption markers (tartrate-resistant acid phosphatase, cathepsin K, dendritic cell-specific transmembrane protein, and calcitonin receptor) in the murine macrophage-like cell line RAW264.7. CC prevented ovariectomy-induced bone loss, preserved trabecular microarchitecture, and improved serum bone turnover markers in an osteoporotic mouse model. These findings suggest that CC extract may be considered as a natural therapeutic or preventive agent for osteoporotic bone loss.

Scopolin Attenuates Osteoporotic Bone Loss in Ovariectomized Mice

Bone remodeling is a renewal process regulated by bone synthesis (osteoblasts) and bone destruction (osteoclasts). A previous study demonstrated that Lycii radicis cortex (LRC) extract inhibited ovariectomized (OVX)-induced bone loss in mice. This study investigated the anti-osteoporotic effects of bioactive constituent(s) from the LRC extract. The effective compound(s) were screened, and a single compound, scopolin, which acts as a phytoalexin, was chosen as a candidate component. Scopolin treatment enhanced alkaline phosphatase activity and increased mineralized nodule formation in MC3T3-E1 pre-osteoblastic cells. However, osteoclast differentiation in primary-cultured monocytes was reduced by treatment with scopolin. Consistently, scopolin treatment increased osteoblast differentiation in the co-culture of monocytes (osteoclasts) and MC3T3-E1 (osteoblast) cells. Scopolin treatment prevented bone mineral density loss in OVX-induced osteoporotic mice. These results suggest that scopolin could be a therapeutic bioactive constituent for the treatment and prevention of osteoporosis.

Fabrication, Mechanical Properties and In-Vitro Behavior of Akermanite Bioceramic

Pure nanocrystalline akermanite (Ca₂MgSi₂O₇) powder was synthesized by mechanical activation with subsequent annealing of talc, calcium carbonate, and silicate powders as the initial materials. Powder samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) techniques. The results showed that pure nanocrystalline akermanite with a crystalline size of 35 nm was synthesized after ball milling the initial powders for 20 h with subsequent annealing at 900 °C for 1 h. Mechanical properties of bulk akermanite samples were studied as well. The results showed that the produced akermanite tablets sintered at 1200 °C for 5 h had a Young's modulus of 3800 MPa, an ultimate compressive strength of 24.7 MPa, and a density of 2.489 g/cm³. The in-vitro behavior of the produced akermanite was evaluated by soaking the samples in an SBF solution. The results showed that the produced akermanite had the apatite formation ability on its surface and can be a good candidate for bone tissue engineering applications.

An improved process for the fabrication and surface treatment of custom-made titanium cranioplasty implants informed by surface analysis

Cranioplasty implants are routinely fabricated from commercially pure titanium plates by maxillofacial prosthetists. The differing fabrication protocols adopted by prosthetists working at different hospital sites gives rise to considerable variations in surface topography and composition of cranioplasty implants, with residues from the fabrication processes having been found to become incorporated into the surface of the implant. There is a growing recognition among maxillofacial prosthetists of the need to standardise these protocols to ensure quality and consistency of practice within the profession. In an effort to identify and eliminate the source of the inclusions associated with one such fabrication protocol, the present study examined the surfaces of samples subjected to each of the manufacturing steps involved. Surface and elemental analysis techniques identified the main constituent of the surface inclusions to be silicon from the glass beads used to texture the surface of the implant during fabrication. Subsequent analysis of samples prepared according to a revised protocol resulted in a more homogeneous titanium dioxide surface as evidenced by the reduction in area occupied by surface inclusions (from 8.51% ± 2.60% to 0.93% ± 0.62%). These findings may inform the development of improved protocols for the fabrication of titanium cranioplasty plates.

MagnetOs, Vitoss, and Novabone in a Multi-endpoint Study of Posterolateral Fusion: A True Fusion or Not?

STUDY DESIGN

This study was a multi-endpoint analysis of bone graft substitutes implanted as a standalone graft in a clinically relevant Ovine model of instrumented posterolateral spinal fusion (PLF).

OBJECTIVE

The objective of this study was to obtain high-quality evidence on the efficacy of commercial bone graft substitutes compared with autograft in instrumented PLF using a state-of-the-art model with a complete range of assessment techniques.

SUMMARY OF BACKGROUND DATA

Preclinical and clinical data on the quality of spinal fusions obtained with bone graft substitutes are often limited. Calcium phosphates with submicron topography have shown promising results in PLF, as these are able to induce bone formation in tissues distant from the host bone, which facilitates bony union.

METHODS

Nine female, skeletally mature sheep (4-5 y) underwent posterior pedicle screw/rods instrumented PLF at L2-L3 and L4-L5 using the following bone graft materials as a standalone graft per spinal segment: (1) biphasic calcium phosphate with submicron topography (BCP<µm), (2) 45S5 Bioglass (BG), and (3) collagen-β-tricalcium phosphate with a 45S5 Bioglass adjunct (TCP/BG). Autograft bone (AB) was used as a positive control treatment. Twelve weeks after implantation, the spinal segments were evaluated by fusion assessment (manual palpation, x-ray, micro-computed tomography, and histology), fusion mass volume quantification (micro-computed tomography), range of motion (ROM) testing, histologic evaluation, and histomorphometry.

RESULTS

Fusion assessment revealed equivalence between AB and BCP<µm by all fusion assessment methods, whereas BG and TCP/BG led to significantly inferior results. Fusion mass volume was highest for BCP<µm, followed by AB, BG, and TCP/BG. ROM testing determined equivalence for spinal levels treated with AB and BCP<µm, while BG and TCP/BG exhibited higher ROM. Histologic evaluation revealed substantial bone formation in the intertransverse regions for AB and BCP<µm, whereas BG and TCP/BG grafts contained fibrous tissue and minimal bone formation. Histologic observations were supported by the histomorphometry data.

CONCLUSIONS

This study reveals clear differences in efficacy between commercially available bone graft substitutes, emphasizing the importance of clinically relevant animal models with multiendpoint analyses for the evaluation of bone graft materials. The results corroborate the efficacy of calcium phosphate with submicron topography, as this was the only material that showed equivalent performance to autograft in achieving spinal fusion.

Robust and nanostructured chitosan-silica hybrids for bone repair application

In this study, chitosan-silica hybrids (CSHs) with superior mechanical strength and homogeneous dispersion of nano-sized silica particles were synthesized via a facile sol-gel method aiming for bone regeneration. The effects of varied acidic conditions of sol-gel reaction and inorganic/organic ratios on the performance of the hybrid were investigated. CSHs synthesized under weak acidic conditions (acetic acid, pH 4.0) showed a homogeneous nanostructure and robust strength (maximum compressive strength: 42.6 ± 3.3 MPa and 271 ± 31 MPa in wet and dry forms, respectively). However, those developed under the strong acidic condition (HCl, pH 4.0) and the strong acid condition plus lower pH (HCl, pH 2.8) tended to aggregate and exhibited inferior mechanical properties (compressive strength: 6.3 ± 0.3 MPa in wet form at pH 2.8). Under the latter conditions, the interactions between silica and chitosan were weak. Moreover, the mechanical properties of the CSHs could be tuned in a wide range by conveniently varying the inorganic/organic composition ratio between 50% and 70%. In vitro cytocompatibility study indicated that CSHs were non-cytotoxic. These results suggested that the weak acidic sol-gel process were essential for fabricating chitosan-silica hybrids with high mechanical strength, which had potential to be applied as a bone substitute.

Review on calcium- and magnesium-based silicates for bone tissue engineering applications

Bone is a self-engineered structural component of the human body with multifaceted mechanical strength, which provides indomitable support to the effective functioning of the human body. It is indispensable to find a suitable biomaterial for substituting the bone as the bone substitute material requirement is very high due to the rate of bone fracture and infection lead to osteoporosis in human beings increases rapidly. It is not an easy task to design a material with good apatite deposition ability, a faster rate of dissolution, superior resorbability, high mechanical strength, and significant bactericidal activity. Since the synthetic hydroxyapatite was not able to achieve the dahlite phase of hydroxyapatite (natural bone mineral phase), silicates emerged as an alternate biomaterial to meet the need for bone graft substitutes. All silicates do not exhibit the properties required for bone graft substitutes, as their composition and methodology adopted for the synthesis are different. Calcium, magnesium, and silicon play a major role in the formation of bone mineral and their metabolism during bone formation. In this review, the relationship between composition and activity of calcium, magnesium-based silicates have been discussed along with the future scope of these materials for hard tissue engineering applications.

Recent advances and future perspectives of sol–gel derived porous bioactive glasses: a review

Sol–gel derived bioactive glasses have been extensively explored as a promising and highly porous scaffold materials for bone tissue regeneration applications owing to their exceptional osteoconductivity, osteostimulation and degradation rates.

Fabrication and multiscale characterization of 3D silver containing bioactive glass-ceramic scaffolds

In this work, we fabricated and characterized bioactive 3D glass-ceramic scaffolds with inherent antibacterial properties. The sol-gel (solution-gelation) technique and the sacrificial template method were applied for the fabrication of 3D highly porous scaffolds in the 58.6SiO2 - 24.9CaO - 7.2P2O5 - 4.2Al2O3 - 1.5Na2O -1.5K2O - 2.1Ag2O system (Ag-BG). This system is known for its advanced bioactive and antibacterial properties. The fabrication of 3D scaffolds has potential applications that impact tissue engineering. The study of the developed scaffolds from macro-characteristics to nano-, revealed a strong correlation between the macroscale properties such as antibacterial action, bioactivity with the microstructural characteristics such as elemental analysis, crystallinity. Elemental homogeneity, morphological, and microstructural characteristics of the scaffolds were studied by scanning electron microscopy associated with energy dispersive spectroscopy (SEM-EDS), transmittance electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopy methods. The compressive strength of the 3D scaffolds was measured within the range of values for glass-ceramic scaffolds with similar compositions, porosity, and pore size. The capability of the scaffolds to form an apatite-like phase was tested by immersing the scaffolds in simulated body fluid (SBF) and the antibacterial response against methicillin-resistant Staphylococcus aureus (MRSA) was studied. The formation of an apatite phase was observed after two weeks of immersion in SBF and the anti-MRSA effect occurs after both direct and indirect exposure.

Anti-Osteoporotic Effects of Combined Extract of Lycii Radicis Cortex and Achyranthes japonica in Osteoblast and Osteoclast Cells and Ovariectomized Mice

Osteoporosis is characterized by low bone density and quality with high risk of bone fracture. Here, we investigated anti-osteoporotic effects of natural plants (Lycii Radicis Cortex (LRC) and Achyranthes japonica (AJ)) in osteoblast and osteoclast cells in vitro and ovariectomized mice in vivo. Combined LRC and AJ enhanced osteoblast differentiation and mineralized bone-forming osteoblasts by the up-regulation of bone metabolic markers (Alpl, Runx2 and Bglap) in the osteoblastic cell line MC3T3-E1. However, LRC and AJ inhibited osteoclast differentiation of monocytes isolated from mouse bone marrow. In vivo experiments showed that treatment of LRC+AJ extract prevented OVX-induced trabecular bone loss and osteoclastogenesis in an osteoporotic animal model. These results suggest that LRC+AJ extract may be a good therapeutic agent for the treatment and prevention of osteoporotic bone loss.

Favorable angiogenic properties of the borosilicate bioactive glass 0106-B1 result in enhanced in vivo osteoid formation compared to 45S5 Bioglass

The 45S5-bioactive glass (BG) composition is the most commonly investigated amongst BG-based bone substitutes. By changing BG compositions and by addition of therapeutically active ions such as boron, the biological features of BGs can be tailored towards specific needs and possible drawbacks can be overcome. The borosilicate glass 0106-B1 (composition in wt%: 37.5 SiO₂, 22.6 CaO, 5.9 Na₂O, 4.0 P₂O₅, 12.0 K₂O, 5.5 MgO, 12.5 B₂O₃) has demonstrated pro-angiogenic properties. However, the osteogenic performance of the 0106-B1-BG and its influence on cell viability and proliferation in vitro as well as its osteogenic and angiogenic properties in vivo have not been investigated. Therefore, in this study, the impact of 0106-B1-BG and 45S5-BG on osteogenic differentiation, viability and proliferation on human mesenchymal stromal cells (MSCs) was assessed in vitro. Furthermore, MSC-seeded scaffolds made from both BG types were implanted subcutaneously in immunodeficient mice for 10 weeks. Osteoid formation was quantified by histomorphometry, vascularization was visualized by immunohistological staining. Additionally, the in vivo expression patterns of genes correlating with osteogenesis and angiogenesis were analyzed. In vitro, the impact of 45S5-BG and 0106-B1-BG on the proliferation, viability and osteogenic differentiation of MSCs was comparable. In vivo, scaffolds made from 0106-B1-BG significantly outperformed the 45S5-BG-based scaffolds regarding the amount and maturation of the osteoid. Furthermore, 0106-B1-BG-based scaffolds showed significantly increased angiogenic gene expression patterns. In conclusion, the beneficial angiogenic properties of 0106-B1-BG result in improved osteogenic properties in vivo, making the 0106-B1-BG a promising candidate for further investigation, e.g. in a bone defect model.

Cost-Effectiveness Study of One-Stage Treatment of Chronic Osteomyelitis with Bioactive Glass S53P4

This study was set up to evaluate the costs of a one-stage treatment of chronic osteomyelitis using bioactive glass S53P4 versus a two-stage treatment using gentamicin-loaded PMMA beads. Furthermore, a cost-effectiveness analysis was performed from a hospital’s perspective together with the evaluation of clinical outcome. A treatment group (n = 25) receiving one-stage surgery with bioactive glass was retrospectively compared with a two-stage control group (n = 25). An assessment was made of all costs included from first outpatient visit until one year after treatment. Bootstrap simulation and sensitivity analyses were performed. The primary endpoint was cost-effectiveness with clinical outcome as the secondary endpoint. The base case analyses shows dominance of the one-stage treatment with bioactive glass S53P4 due to lower costs and a better clinical outcome. Sensitivity analyses confirm these findings. This study is the first in its kind to show one-stage treatment of chronic osteomyelitis with bioactive glass S53P4 to be cost-effective.

The influence of polycaporolacton fumarate coating on mechanical properties and in vitro behavior of porous diopside-hardystonite nano-composite scaffold

One of the significant challenges in bone tissue engineering is the fabrication of highly porous scaffolds with interconnected pores and appropriate mechanical properties. Artificial scaffolds which used in the field of medicine are usually made of single phase of polymer or ceramic. However, composition of these materials can produce the scaffolds with improve mechanical and biological properties.The aim of this study is to synthesize three-dimensional hardystonite-diopside (HT-Dio) porous scaffolds modified by polycaporolacton fumarate coating for low-load-bearing bone tissue engineering applications. The results showed that hardystonite scaffolds with 15 wt. % diopside and 6 w/v % polymer polycaporolacton fumarate (PCLF) had a significant bioactivity. The cell culture and cell attachment assay results revealed the well spreading of BMS cells on the surface of modified scaffolds which indicates the high biocompatibility of this scaffold. The modified scaffolds had a mean pore size, porosity, compressive strength, modules and toughness of 293.47 ± 5.51 μm, 74% ± 1.01, 3.37 ± 0.6 MPa, 151 ± 1.1 MPa and 31.3 ± 0.32 kJ/m³, respectively, which are in the appropriate range for spongy bone and hence can be a good candidate for bone tissue engineering applications.

Tuning of ion-release capability from bio-ceramic-polymer composites for enhancing cellular activity

In our previous study, we investigated the synergetic effects of inorganic ions, such as silicate, Mg2+ and Ca2+ ions on the osteoblast-like cell behaviour. Mg2+ ions play an important role in cell adhesion. In the present study, we designed a new composite that releases a high concentration of Mg2+ ions during the early stage of the bone-forming process, and silicate and Ca2+ ions continuously throughout this process. Here, 40SiO2-40MgO-20Na2O glass (G) with high solubility and vaterite-based calcium carbonate (V) were selected as the source of silicate and Mg2+ and Ca2+ ions, respectively. These particles were mixed with poly(lactic-co-glycolic acid) (PLGA) using a kneading method at 110°C to prepare the composite (G-V/PLGA, G/V/PLGA = 4/56/40 (in weight ratio)). Most of the Mg2+ ions were released within 3 days of immersion at an important stage for cell adhesion, and silicate and Ca2+ ions were released continuously at rates of 70-80 and 180 ppm d-1, respectively, throughout the experiment (until day 7). Mouse-derived osteoblast-like MC3T3-E1 proliferated more vigorously on G-V/PLGA in comparison with V-containing PLGA without G particles; it is possible to control the ion-release behaviour by incorporating a small amount of glass particles.

Supplementation with 45S5 Bioactive Glass Reduces In Vivo Resorption of the β-Tricalcium-Phosphate-Based Bone Substitute Material Vitoss

Compared to other materials such as 45S5 bioactive glass (BG), β-tricalcium phosphate (β-TCP)-based bone substitutes such as Vitoss show limited material-driven stimulation of osteogenesis and/or angiogenesis. The unfavorable degradation kinetics of β-TCP-based bone substitutes may result in an imbalance between resorption and osseous regeneration. Composite materials like Vitoss BA (Vitoss supplemented with 20 wt % 45S5-BG particles) might help to overcome these limitations. However, the influence of BG particles in Vitoss BA compared to unsupplemented Vitoss on osteogenesis, resorption behavior, and angiogenesis is not yet described. In this study, Vitoss and Vitoss BA scaffolds were seeded with human mesenchymal stromal cells before subcutaneous implantation in immunodeficient mice for 10 weeks. Scaffold resorption was monitored by micro-computed tomography, while osteoid formation and vascularization were assessed by histomorphometry and gene expression analysis. Whilst slightly more osteoid and improved angiogenesis were found in Vitoss BA, maturation of the osteoid was more advanced in Vitoss scaffolds. The volume of Vitoss implants decreased significantly, combined with a significantly increased presence of resorbing cells, whilst the volume remained stable in Vitoss BA scaffolds. Future studies should evaluate the interaction of 45S5-BG with resorbing cells and bone precursor cells in greater detail to improve the understanding and application of β-TCP/45S5-BG composite bone substitute materials.

Cerium- and Iron-Oxide-Based Nanozymes in Tissue Engineering and Regenerative Medicine

Nanoparticulate materials displaying enzyme-like properties, so-called nanozymes, are explored as substitutes for natural enzymes in several industrial, energy-related, and biomedical applications. Outstanding high stability, enhanced catalytic activities, low cost, and availability at industrial scale are some of the fascinating features of nanozymes. Furthermore, nanozymes can also be equipped with the unique attributes of nanomaterials such as magnetic or optical properties. Due to the impressive development of nanozymes during the last decade, their potential in the context of tissue engineering and regenerative medicine also started to be explored. To highlight the progress, in this review, we discuss the two most representative nanozymes, namely, cerium- and iron-oxide nanomaterials, since they are the most widely studied. Special focus is placed on their applications ranging from cardioprotection to therapeutic angiogenesis, bone tissue engineering, and wound healing. Finally, current challenges and future directions are discussed.

Anti-Osteoporotic Effects of Kukoamine B Isolated from Lycii Radicis Cortex Extract on Osteoblast and Osteoclast Cells and Ovariectomized Osteoporosis Model Mice

Osteoporosis is an abnormal bone remodeling condition characterized by decreased bone density, which leads to high risks of fracture. Previous study has demonstrated that Lycii Radicis Cortex (LRC) extract inhibits bone loss in ovariectomized (OVX) mice by enhancing osteoblast differentiation. A bioactive compound, kukoamine B (KB), was identified from fractionation of an LRC extract as a candidate component responsible for an anti-osteoporotic effect. This study investigated the anti-osteoporotic effects of KB using in vitro and in vivo osteoporosis models. KB treatment significantly increased the osteoblastic differentiation and mineralized nodule formation of osteoblastic MC3T3-E1 cells, while it significantly decreased the osteoclast differentiation of primary-cultured monocytes derived from mouse bone marrow. The effects of KB on osteoblastic and osteoclastic differentiations under more physiological conditions were also examined. In the co-culture of MC3T3-E1 cells and monocytes, KB promoted osteoblast differentiation but did not affect osteoclast differentiation. In vivo experiments revealed that KB significantly inhibited OVX-induced bone mineral density loss and restored the impaired bone structural properties in osteoporosis model mice. These results suggest that KB may be a potential therapeutic candidate for the treatment of osteoporosis.

Assessing behaviour of osteoblastic cells in dynamic culture conditions using titanium-doped phosphate glass microcarriers

Tissue engineering is a promising approach for bone regeneration; yet challenges remain that limit successful translation to patients. It is necessary to understand how real-world manufacturing processes will affect the constituent cells and biomaterials that are needed to create engineered bone. Bioactive phosphate glasses processed into microspheres are an attractive platform for expanding bone-forming cells and also for driving their osteogenic differentiation and maturation. The aim of this study was to assess whether Ti-doped phosphate glass microspheres could support osteoblastic cell responses in dynamic cell culture environments. Dynamic culture conditions were achieved using microwell studies under orbital agitation. Dimensionless parameters such as the Froude number were used to inform the choice of agitation speeds, and the impact on cell proliferation and microunit formation was quantified. We found that phosphate glass microspheres doped with titanium dioxide at both 5 and 7 mol% provided a suitable biomaterial platform for effective culture of MG63 osteoblastic cells and was not cytotoxic. Dynamic culture conditions supported expansion of MG63 cells and both 150 and 300 rpm orbital shake resulted in higher cell yield than static cultures at the end of the culture (day 13). The Froude number analysis provided insight into how the microunit size could be manipulated to enable an appropriate agitation speed to be used, while ensuring buoyancy of the microunits. These small-scale experiments and analyses provide understanding of the impact of fluid flow on cell expansion that will have increasing importance when scaling up to process technologies that can deliver clinical quantities of cell-microsphere units. Such knowledge will enable future engineering of living bone-like material using processing systems such as bioreactors that use mixing and agitation for nutrient transfer, therefore introducing cells to dynamic culture conditions.

Nanostructured akermanite glass-ceramic coating on Ti6Al4V for orthopedic applications

Glass ceramics are widely used to enhance the functionality of inert metallic materials typically used for hard-tissue engineering. Biofunctionality of glass ceramics can in turn be significantly boosted with the addition of trace element dopants. Herein, we synthesized a nanostructured glass ceramic and used magnesium (Mg), which is known to promote osteoblast adhesion and proliferation, for further functionalization. The nanostructured akermanite glass ceramic (Ca₂MgSi₂O₇) was used to coat Ti6Al4V substrates by the sol-gel method. Scanning and transmission electron microscopy as well as X-ray diffraction were used to assess the structural morphology and phase composition of the coating, respectively. The micrographs showed a uniform and crack-free coating structure. Atomic force microscopy observation revealed a disordered surface roughness for coated samples. In vitro cytocompatibility tests revealed that Saos-2 cells cultured on bare samples adopted a rounded morphology, whereas cells cultured on the coated samples represented a more spread out configuration and also increased proliferation. The characterizing tests confirmed the efficiency of the synthesis method and the in vitro biocompatibility of the synthesized coating, indicating its suitability to be used for bone implants.