Magnesium Modified β-Tricalcium Phosphate Induces Cell Osteogenic Differentiation In Vitro and Bone Regeneration In Vivo

Magnesium-enhanced porcine particles using hydrothermal technique improve the osteogenic differentiation of cells

Background: Guided bone regeneration (GBR) uses bone grafts and barrier membranes to block soft tissue invasion and eventually create a new bone. Some studies indicate that a porcine bone graft demonstrates excellent biocompatibility and holds promise as a xenograft for GBR. However, only a few studies have investigated the effectiveness of this biomaterial after magnesium coating in improving osteoblast performance. Aim: This study aimed to prove that the hydrothermal method can be used to coat magnesium oxide (MgO) on the surface of a porcine graft and enhance the biomaterial's property for better osteogenic differentiation of osteoblasts in vitro. Materials and Method: A porcine bone graft was produced, and the hydrothermal method was used to coat 2 mM and 5 mM of MgO on the graft. Material physiochemistry and biocompatibility analyses were performed at days 1, 3, and 5. Results: pH value assay results suggested that MgO slightly increased the alkalinity of the graft. SEM images showed that MgO with some surface roughness was coated on the porcine bone surface, and EDX indicated that the Mg and O element percentages increased by about 5% and 9%, respectively. The porcine graft coated with MgO was rougher than an uncoated porcine graft. FTIR analysis of the porcine graft implied that its chemical structure did not change due to MgO hydrothermal processing. Cell viability assay illustrated the highest cell proliferation with the porcine graft with 5 mM MgO (P < 0.001), and good cell attachment was observed on the graft with immunofluorescence using confocal laser scanning microscopy. Cell differentiation assay results revealed that the porcine graft with 5 mM MgO had the highest alkaline phosphate activity (P < 0.0001) among the uncoated porcine graft and the porcine graft with 2 mM MgO. Relative quantitative polymerase chain reaction (qPCR) at days 1 and 5 revealed upregulated osteoblast gene expression with a statistically significant difference. Conclusion: The porcine graft hydrothermally coated with 5 mM MgO was more biocompatible and enhanced osteoblast differentiation. Thus, the findings of this study indicate that a porcine graft with 5 mM MgO has great potential as a bio-bone graft for guided bone regeneration.

MgO-enhanced β-TCP promotes osteogenesis in both in vitro and in vivo rat models

Allogeneic bone grafts are used to treat bone defects in orthopedic surgery, but the osteogenic potential of artificial bones remains a challenge. In this study, we developed a β-tricalcium phosphate (β-TCP) formulation containing MgO, ZnO, SrO, and SiO2 and compared its bone-forming ability with that of β-TCP without biological elements. We prepared β-TCP discs with 60% porosity containing 1.0 wt% of these biological elements. β-TCP scaffolds were loaded with bone marrow-derived mesenchymal stem cells (BMSC) from 7-week-old male rats and cultured for 2 weeks. ALP activity and mRNA expression of osteogenic markers were evaluated. In addition, scaffolds were implanted subcutaneously in rats and analyzed after 7 weeks. In vitro, the MgO group showed lower Ca concentrations and higher osteogenic marker expression compared to controls. In vivo, the MgO group showed higher ALP activity compared to controls, and RT-qPCR analysis showed significant expression of BMP2 and VEGF. Histopathology, fluorescent immunostaining, and micro-CT also showed relatively better bone formation in the MgO group. β-TCP with MgO may enhance bone morphology in vitro and in vivo and improve the prognosis of patients with substantial and refractory bone defects.

3D-bioprinted alginate-based bioink scaffolds with β-tricalcium phosphate for bone regeneration applications

Background/purpose

3D-printed bone tissue engineering is becoming recognized as a key approach in dentistry for creating customized bone regeneration treatments fitting patients bone defects requirements. 3D bioprinting offers an innovative method to fabricate detailed 3D structures, closely emulating the native bone micro-environment and better bone regeneration. This study aimed to develop an 3D-bioprintable scaffold using a combination of alginate and β-tricalcium phosphate (β-TCP) with the Cellink® BioX printer, aiming to advance the field of tissue engineering.

Materials and methods

The physical and biological properties of the resulting 3D-printed scaffolds were evaluated at 10 %, 12 %, and 15 % alginate combined with 10 % β-TCP. The scaffolds were characterized through printability, swelling behavior, degradability, and element analysis. The biological assessment included cell viability, alkaline phosphatase (ALP) activity.

Results

10 % alginate/β-TCP 3D printed at 25 °C scaffold demonstrated the optimal condition for printability, swelling capability, and degradability of cell growth and nutrient diffusion. Addition of β-TCP particles significantly improved the 3D printed material viscosity over only alginate (P < 0.05). 10 % alginate/β-TCP enhanced MG-63 cell's proliferation (P < 0.05) and alkaline phosphatase activity (P < 0.001).

Conclusion

This study demonstrated in vitro that 10 % alginate/β-TCP bioink characteristic for fabricating 3D acellular bioprinted scaffolds was the best approach. 10 % alginate/β-TCP bioink 3D-printed scaffold exhibited superior physical properties and promoted enhanced cell viability and alkaline phosphatase activity, showing great potential for personalized bone regeneration treatments.

Evaluation of Physiochemical and Biological Properties of Biofunctionalized Mg-Based Implants Obtained via Large-Scale PEO Process for Dentistry Applications

An increasing number of tooth replacement procedures ending with implant failure generates a great need for the delivery of novel biomedical solutions with appropriate mechanical characteristics that would mimic natural tissue and undergo biodegradation. This phenomenon constitutes a significant difficulty for scientists, since currently applied biomaterials dedicated for this purpose are based on stainless steel, Ti, and Ti and CoCr alloys. One of the most promising raw materials is magnesium, which has been proven to promote bone regeneration and accelerate the tissue healing process. Nevertheless, its high reactivity with body fluid components is associated with fast and difficult-to-control biocorrosion, which strongly limits the application of Mg implants as medical devices. The achievement of appropriate functionality, both physiochemical and biological, to enable the commercial use of Mg biomaterials is possible only after their superficial modification. Therefore, the obtainment of uniform, reproducible coatings increasing resistance to the aqueous environment of the human body combined with a nanostructured surface that enhances implant-cell behaviors is an extremely important issue. Herein, we present a successful strategy for the modification of Mg implants via the PEO process, resulting in the obtainment of biomaterials with lower corrosion rates and superior biological properties, such as the promotion of extracellular matrix formation and a positive impact on the proliferation of MG-63 cells. The implants were investigated regarding their chemical composition using the FT-IR and XRD methods, which revealed that MgO layer formation, as well as the incorporation of electrolyte components such as fluorine and silica, were responsible for the increased microhardness of the samples. An extensive study of the biomaterials' morphology confirmed that successful surface modification led to a microporous structure suitable for the attachment and proliferation of cells. The three-layer nature of the newly-formed coatings, typical for PEO modification, was confirmed via cross-section analysis. A biocorrosion and biodegradation study proved that applied modification increased their resistance to body fluids. The cell culture study performed herein confirmed that the correct adjustment of modification parameters results in a lack of cytotoxicity of the magnesium implants, cell proliferation enhancement, and improvement in extracellular matrix formation.

Review of Physical, Mechanical, and Biological Characteristics of 3D-Printed Bioceramic Scaffolds for Bone Tissue Engineering Applications

This review focuses on the advancements in additive manufacturing techniques that are utilized for fabricating bioceramic scaffolds and their characterizations leading to bone tissue regeneration. Bioscaffolds are made by mimicking the human bone structure, material composition, and properties. Calcium phosphate apatite materials are the most commonly used scaffold materials as they closely resemble live bone in their inorganic composition. The functionally graded scaffolds are fabricated by utilizing the right choice of the 3D printing method and material combinations to achieve the requirement of the bioscaffold. To tailor the physical, mechanical, and biological properties of the scaffold, certain materials are reinforced, doped, or coated to incorporate the functionality. The biomechanical loading conditions that involve flexion, torsion, and tension exerted on the implanted scaffold are discussed. The finite element analysis (FEA) technique is used to investigate the mechanical property of the scaffold before fabrication. This helps in reducing the actual number of samples used for testing. The FEA simulated results and the experimental result are compared. This review also highlights some of the challenges associated while processing the scaffold such as shrinkage, mechanical instability, cytotoxicity, and printability. In the end, the new materials that are evolved for tissue engineering applications are compiled and discussed.

Deferoxamine/magnesium modified β-tricalcium phosphate promotes the bone regeneration in osteoporotic rats

Recently, Deferoxamine (DFO) and magnesium (Mg) have been identified as critical factors for angiogenesis and bone formation. However, in current research studies, there is a lack of focus on whether DFO plus Mg can affect the regeneration of β-tricalcium phosphate (β-TCP) in osteoporosis and through what biological mechanisms. Therefore, the present work was aimed to preparation and evaluate the effect of Deferoxamine/magnesium modified β-tricalcium phosphate promotes (DFO/Mg-TCP) in ovariectomized rats model and preliminary exploration of possible mechanisms. The MC3T3-E1 cells were co-cultured with the exudate of DFO/Mg-TCP and induced to osteogenesis, and the cell viability, osteogenic activity were observed by Cell Counting Kit-8(CCK-8), Alkaline Phosphatase (ALP) staining, Alizarin Red Staining (RES) and Western Blot. In vitro experiments, CCK-8, ALP and ARS staining results show that the mineralization and osteogenic activity of MC3T3-E1increased significantly after intervention by DFO/Mg-TCP, as well as a higher levels of protein expressions including VEGF, OC, Runx-2 and HIF-1α. In vivo experiment, Micro-CT and Histological analysis evaluation show that DFO/Mg-TCP treatment presented the stronger effect on bone regeneration, bone mineralization and biomaterial degradation, when compared with OVX+Mg-TCP group and OVX+TCP group, as well as a higher VEGF, OC, Runx-2 and HIF-1α gene expression. The present study indicates that treatment with DFO/Mg-TCP was associated with increased regeneration by enhancing the function of osteoblasts in an OVX rat.

Improvement of the mechanical properties and osteogenic activity of 3D-printed polylactic acid porous scaffolds by nano-hydroxyapatite and nano-magnesium oxide

Porous bone scaffolds based on high-precision 3D printing technology gave recently been developed for use in bone defect repair. However, conventional scaffold materials have poor mechanical properties and low osteogenic activity, limiting their clinical use. In this study, a porous composite tissue-engineered bone scaffold was prepared using polylactic acid, nano-hydroxyapatite, and nano-magnesium oxide as raw materials for high-precision 3D printing. The composite scaffold takes full advantage of the personalized manufacturing features of 3D printers and can be used to repair complex bone defects in clinical settings. The composite scaffold combines the advantages of nano-hydroxyapatite, which improves the formability of scaffold printing, and of nano-magnesium oxide, which regulates pH during degradation and provide a good environment for cell growth. Additionally, nano-magnesium oxide and nano-hydroxyapatite have a bidirectional effect on promoting the compressive strength and osteogenic activity of the scaffolds. The prepared composite porous scaffolds based on 3D printing technology show promise for bone defect repair.