Bone response of Mg ion-implanted clinical implants with the plasma source ion implantation method

Challenges and Pitfalls of Research Designs Involving Magnesium-Based Biomaterials: An Overview

Magnesium-based biomaterials hold remarkable promise for various clinical applications, offering advantages such as reduced stress-shielding and enhanced bone strengthening and vascular remodeling compared to traditional materials. However, ensuring the quality of preclinical research is crucial for the development of these implants. To achieve implant success, an understanding of the cellular responses post-implantation, proper model selection, and good study design are crucial. There are several challenges to reaching a safe and effective translation of laboratory findings into clinical practice. The utilization of Mg-based biomedical devices eliminates the need for biomaterial removal surgery post-healing and mitigates adverse effects associated with permanent biomaterial implantation. However, the high corrosion rate of Mg-based implants poses challenges such as unexpected degradation, structural failure, hydrogen evolution, alkalization, and cytotoxicity. The biocompatibility and degradability of materials based on magnesium have been studied by many researchers in vitro; however, evaluations addressing the impact of the material in vivo still need to be improved. Several animal models, including rats, rabbits, dogs, and pigs, have been explored to assess the potential of magnesium-based materials. Moreover, strategies such as alloying and coating have been identified to enhance the degradation rate of magnesium-based materials in vivo to transform these challenges into opportunities. This review aims to explore the utilization of Mg implants across various biomedical applications within cellular (in vitro) and animal (in vivo) models.

Applications of Biodegradable Magnesium-Based Materials in Reconstructive Oral and Maxillofacial Surgery: A Review

Reconstruction of defects in the maxillofacial region following traumatic injuries, craniofacial deformities, defects from tumor removal, or infections in the maxillofacial area represents a major challenge for surgeons. Various materials have been studied for the reconstruction of defects in the maxillofacial area. Biodegradable metals have been widely researched due to their excellent biological properties. Magnesium (Mg) and Mg-based materials have been extensively studied for tissue regeneration procedures due to biodegradability, mechanical characteristics, osteogenic capacity, biocompatibility, and antibacterial properties. The aim of this review was to analyze and discuss the applications of Mg and Mg-based materials in reconstructive oral and maxillofacial surgery in the fields of guided bone regeneration, dental implantology, fixation of facial bone fractures and soft tissue regeneration.

Research status of biodegradable metals designed for oral and maxillofacial applications: A review

The oral and maxillofacial regions have complex anatomical structures and different tissue types, which have vital health and aesthetic functions. Biodegradable metals (BMs) is a promising bioactive materials to treat oral and maxillofacial diseases. This review summarizes the research status and future research directions of BMs for oral and maxillofacial applications. Mg-based BMs and Zn-based BMs for bone fracture fixation systems, and guided bone regeneration (GBR) membranes, are discussed in detail. Zn-based BMs with a moderate degradation rate and superior mechanical properties for GBR membranes show great potential for clinical translation. Fe-based BMs have a relatively low degradation rate and insoluble degradation products, which greatly limit their application and clinical translation. Furthermore, we proposed potential future research directions for BMs in the oral and maxillofacial regions, including 3D printed BM bone scaffolds, surface modification for BMs GBR membranes, and BMs containing hydrogels for cartilage regeneration, soft tissue regeneration, and nerve regeneration. Taken together, the progress made in the development of BMs in oral and maxillofacial regions has laid a foundation for further clinical translation.

A Magnesium-Incorporated Nanoporous Titanium Coating for Rapid Osseointegration

Purpose

Micro-arc oxidation (MAO) is a fast and effective method to prepare nanoporous coatings with high biological activity and bonding strength. Simple micro/nano-coatings cannot fully meet the requirements of osteogenesis. To further improve the biological activity of a titanium surface, we successfully added biological magnesium (Mg²⁺) to a coating by micro-arc oxidation and evaluated the optimal magnesium concentration in the electrolyte, biocompatibility, cell adhesion, proliferation, and osteogenesis in vitro.

Methods

Nanoporous titanium coatings with different concentrations of magnesium were prepared by micro-arc oxidation and characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The Mg²⁺ release ability of the magnesium-incorporated nanoporous titanium coatings was determined by inductively coupled plasma emission spectrometry (ICP-OES). The cytotoxicity of the magnesium-incorporated nanoporous titanium coatings was detected with live/dead double-staining tests. A CCK-8 assay was employed to evaluate cell proliferation, and FITC-phalloidin was used to determine the structure of the cytoskeleton by staining β-actin. Alkaline phosphatase (ALP) activity was evaluated by alizarin red S (ARS) staining to determine the effect of the coatings on osteogenic differentiation in vitro. The mRNA expression of osteogenic differentiation-related markers was measured using qRT-PCR.

Results

EDS analyses revealed the successful addition of magnesium to the microporous coatings. The best magnesium concentration of the electrolyte for preparing the new coating was determined. The results showed that the nano-coatings prepared using the electrolyte with 2 g/L magnesium acetate best promoted the adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs).

Conclusion

These results suggest that the new titanium metal coating with a dual effect of promoting bone morphology and supplying the biological ion Mg²⁺ can be beneficial for rapid osseointegration.

Effect of magnesium ion on human osteoblast activity

Magnesium, a promising biodegradable metal, has been reported in several studies to increase bone formation. Although there is some information regarding the concentrations of magnesium ions that affect bone remodeling at a cellular level, little is known about the effect of magnesium ions on cell gap junctions. Therefore, this study aimed to systematically investigate the effects of different concentrations of magnesium on bone cells, and further evaluate its effect on gap junctions of osteoblasts. Cultures of normal human osteoblasts were treated with magnesium ions at concentrations of 1, 2 and 3 mM, for 24, 48 and 72 h. The effects of magnesium ions on viability and function of normal human osteoblasts and on gap junction intercellular communication (GJIC) in osteoblasts were investigated. Magnesium ions induced significant (P<0.05) increases in cell viability, alkaline phosphate activity and osteocalcin levels of human osteoblasts. These stimulatory actions were positively associated with the concentration of magnesium and the time of exposure. Furthermore, the GJIC of osteoblasts was significantly promoted by magnesium ions. In conclusion, this study demonstrated that magnesium ions induced the activity of osteoblasts by enhancing GJIC between cells, and influenced bone formation. These findings may contribute to a better understanding of the influence of magnesium on bone remodeling and to the advance of its application in clinical practice.

Cellular Response of Human Bone Marrow Derived Mesenchymal Stem Cells to Titanium Surfaces Implanted with Calcium and Magnesium Ions

Surface characteristics and cellular response to titanium surfaces that had been implanted with calcium and magnesium ions using plasma immersion ion implantation and deposition (PIIID) were evaluated. Three different titanium surfaces were analyzed: a resorbable blast media (RBM) surface (blasted with hydroxyapatite grit), a calcium ion-implanted surface, and a magnesium ion-implanted surface. The surface characteristics were investigated by scanning electron microscopy (SEM), surface roughness testing, X-ray diffraction (XRD), and Auger electron spectroscopy (AES). Human bone marrow derived mesenchymal stem cells were cultured on the 3 different surfaces. Initial cell attachment was evaluated by SEM, and cell proliferation was determined using MTT assay. Real-time polymerase chain reaction (PCR) was used to quantify osteoblastic gene expression (i.e., genes encoding RUNX2, type I collagen, alkaline phosphatase, and osteocalcin). Surface analysis did not reveal any changes in surface topography after ion implantation. AES revealed that magnesium ions were present in deeper layers than calcium ions. The calcium ion- and magnesium ion-implanted surfaces showed greater initial cell attachment. Investigation of cell proliferation revealed no significant difference among the groups. After 6 days of cultivation, the expression of RUNX2 was higher in the magnesium ion-implanted surface and the expression of osteocalcin was lower in the calcium ion-implanted surface. In conclusion, ion implantation using the PIIID technique changed the surface chemistry without changing the topography. Calcium ion- and magnesium ion-implanted surfaces showed greater initial cellular attachment.

Osseointegration of magnesium-incorporated sand-blasted acid-etched implant in the dog mandible: Resonance frequency measurements and histomorphometric analysis

The aim of this pilot study was to investigate the bone responses of novel magnesium (Mg)-incorporated sand-blasted and acid-etched (SLA) titanium (Ti) implant in an experimental animal model. Novel Mg-incorporated SLA Ti implant was obtained via vacuum arc source ion implantation method and Mg-ions were implanted into the SLA implant surface. Control group consisted of two commercial implants; resorbable blasting media (RBM) and SLA. Twelve implants from each group were placed into the mandibles of 6 mongrel dogs. Experimental animals were divided into 2 groups of 3 animals, with 4 weeks and 8 weeks healing time points. Resonance frequency analysis was performed at the time of fixture installation, 1, 2, 4, and 8 weeks after installation. Bone to implant contact (BIC) measurements were assessed at the 4 and 8 weeks healing time points. The overall implant survival rate was 97.2%. The Mg-incorporated SLA Ti implants showed more rapid osseointegration than control group implants at follow-up periods of 4 weeks. Histomorphometric analysis showed a tendency for BIC% values of Mg-incorporated SLA Ti implant to be higher than that of other the implant groups. The results of this study suggest that Mg-incorporated SLA Ti implant may be effective in enhancing the bone responses by rapid osseointegration in early healing periods.

Bioactive coatings for orthopaedic implants-recent trends in development of implant coatings

Joint replacement is a major orthopaedic procedure used to treat joint osteoarthritis. Aseptic loosening and infection are the two most significant causes of prosthetic implant failure. The ideal implant should be able to promote osteointegration, deter bacterial adhesion and minimize prosthetic infection. Recent developments in material science and cell biology have seen the development of new orthopaedic implant coatings to address these issues. Coatings consisting of bioceramics, extracellular matrix proteins, biological peptides or growth factors impart bioactivity and biocompatibility to the metallic surface of conventional orthopaedic prosthesis that promote bone ingrowth and differentiation of stem cells into osteoblasts leading to enhanced osteointegration of the implant. Furthermore, coatings such as silver, nitric oxide, antibiotics, antiseptics and antimicrobial peptides with anti-microbial properties have also been developed, which show promise in reducing bacterial adhesion and prosthetic infections. This review summarizes some of the recent developments in coatings for orthopaedic implants.

Magnesium vs. machined surfaced titanium - osteoblast and osteoclast differentiation

PURPOSE

This study focused on in vitro cell differentiation and surface characteristics in a magnesium coated titanium surface implanted on using a plasma ion source.

MATERIALS AND METHODS

40 commercially made pure titanium discs were prepared to produce Ti oxide machined surface (M) and Mg-incorporated Ti oxide machined surface (MM). Surface properties were analyzed using a scanning electron microscopy (SEM). On each surface, alkaline phosphatase (ALP) activity, alizarin red S staining for mineralization of MC3T3-E1 cells, and quantitative analysis of osteoblastic gene expression, were evaluated. Actin ring formation assay and gene expression analysis of TRAP and GAPDH performing RT-PCR were performed to characterize osteoclast differentiation on mouse bone marrow-derived macrophages (BMMs).

RESULTS

MM showed similar surface morphology and surface roughness with M, but was slightly smoother after ion implantation at the micron scale. M was more hydrophobic than MM. No significant difference between surfaces on ALP activity at 7 and 14 days were observed. Real-time PCR analyses showed similar levels of mRNA expression of the osteoblast phenotype genes; osteopontin (OPN), osteocalcin (OCN), bone sialoprotein (BSP), and collagen 1 (Col 1) in cell grown on MM at 7, 14 and 21 days. Alizarin red S staining at 21 days showed no significant difference. BMMs differentiation increased in M and MM. Actin ring formation assay and gene expression analysis of TRAP showed osteoclast differentiation to be more active on MM.

CONCLUSION

Both M and MM have a good effect on osteoblastic cell differentiation, but MM may speed the bone remodeling process by activating on osteoclast differentiation.

Magnesium ion implantation on a micro/nanostructured titanium surface promotes its bioactivity and osteogenic differentiation function

As one of the important ions associated with bone osseointegration, magnesium was incorporated into a micro/nanostructured titanium surface using a magnesium plasma immersion ion-implantation method. Hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 30 minutes (Mg30) and hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 60 minutes (Mg60) were used as test groups. The surface morphology, chemical properties, and amount of magnesium ions released were evaluated by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, field-emission transmission electron microscopy, and inductively coupled plasma-optical emission spectrometry. Rat bone marrow mesenchymal stem cells (rBMMSCs) were used to evaluate cell responses, including proliferation, spreading, and osteogenic differentiation on the surface of the material or in their medium extraction. Greater increases in the spreading and proliferation ability of rBMMSCs were observed on the surfaces of magnesium-implanted micro/nanostructures compared with the control plates. Furthermore, the osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) genes were upregulated on both surfaces and in their medium extractions. The enhanced cell responses were correlated with increasing concentrations of magnesium ions, indicating that the osteoblastic differentiation of rBMMSCs was stimulated through the magnesium ion function. The magnesium ion-implanted micro/nanostructured titanium surfaces could enhance the proliferation, spreading, and osteogenic differentiation activity of rBMMSCs, suggesting they have potential application in improving bone-titanium integration.

Bone regeneration by stem cell and tissue engineering in oral and maxillofacial region

Clinical imperatives for the reconstruction of jaw bone defects or resorbed alveolar ridge require new therapies or procedures instead of autologous/allogeneic bone grafts. Regenerative medicine, based on stem cell science and tissue engineering technology, is considered as an ideal alternative strategy for bone regeneration. In this paper, we review the current choices of cell source and strategies on directing the osteogenic differentiation of stem cells. The preclinical animal models for bone regeneration and the key translational points to clinical success in oral and maxillofacial region are also discussed. We propose comprehensive strategies based on stem cell and tissue engineering researches, allowing for clinical application in oral and maxillofacial region.