In vivoassessment of a new multifunctional coating architecture for improved Mg alloy biocompatibility

Abstract

Magnesium alloys are regarded as potential biodegradable load-bearing biomaterials for orthopedic applications due to their physico-chemical and biomechanical properties. However, their clinical applicability is restricted by their high degradation rate, which limits the physiological reconstruction of the neighbouring tissues. In this work, a multifunctional coating architecture was developed on an AZ31 alloy by conjoining an anodization process with the deposition of a polymeric-based layer consisting of polyether imine reinforced with hydroxyapatite nanoparticles, aiming at improved control of the corrosion activity and biological performance of the Mg substrate. Anodization and coating protocols were evaluated either independently or combined for corrosion resistance and biological behaviour, i.e. the irritation potential and angiogenic capability within a chicken chorioallantoic membrane assay, and bone tissue response following tibia implantation within a rabbit model. Electrochemical impedance spectroscopy (EIS) analysis showed that coated Mg constructs, particularly anodized plus coated with AZ31, exhibited excellent stability compared to the anodized alloy and, particularly, to the bare AZ31. Microtomographic evaluation of the implanted samples correlated with these degradation results. Mg constructs displayed a non-irritating behaviour, and were associated with high levels of vascular ingrowth. Bone ingrowth neighbouring the implanted constructs was observed for all samples, with coated and anodized plus coated samples presenting the highest bone formation. Gene expression analysis suggested that the enhanced bone tissue formation was associated with the boost in osteogenic activity through Runx2 upregulation, following the activation of PGC-1α/ERRα signaling. Overall, the developed multifunctional coatings appear to be a promising strategy to obtain safe and bioactive biodegradable Mg-based implants with potential applications within bone tissue.

NIPA2 regulates osteoblast function by modulating mitophagy in type 2 diabetes osteoporosis

“…Yoshizawa et al found enhanced PGC-1α expression in the presence of Mg 2+ in bone marrow stromal cells 40 . An in vivo experiment also confirmed the positive effect of Mg 2+ on the expression of PGC-1α 41 . Consequently, our existing data demonstrate the specific molecular mechanism regulated by intracellular Mg 2+ .…”

Degradation, Bone Regeneration and Tissue Response of an Innovative Volume Stable Magnesium-Supported GBR/GTR Barrier Membrane

“…Closer examination of inflammatory relationships (e.g., the involvement of different cell types and the alignment of macrophages) could also be of interest for further development of this material class [19]. Finally, the direct comparison or amplification of other surface modifications such as duplex-(MgF 2 /PCL) [50], nanocomposite- [73] and composite-coatings [51,74] as well as the extension of other magnesium alloys [47][48][49][50][51][75][76][77][78][79][80][81] should be investigated and might promise new results in the future. Overall, especially in comparison with other studies, there is further need for simplification and standardization of in vitro and in vivo studies of magnesium-based materials.…”

The chick embryo chorioallantoic membrane assay as a model for the study of angiogenesis

“…Finally, we also identified that 193 (7.9%) of articles used CAM method to test inorganic compounds and 89 (3,9%) used it to test nanoparticles (Fig 3). The main goal of these articles was to evaluate if the tested compound could be used in implants (GOMES et al, 2016); or to verify if the sample tested was toxic (AHMAD et al, 2016); or if the compound could promote tumor angiogenesis (KAMBLE et al, 2016). Then, our data indicate that CAM assay is widely used, but seems to be more often seen in articles aiming to investigate biological questions linked to cancer research.…”