Biosafety and biodegradation studies of AZ31B magnesium alloy carotid artery stent in vitro and in vivo

Abstract

Biosafety of AZ31B magnesium (Mg) alloy and the effect of its degradation products on tissues, organs, and whole systems are highly needed to be evaluated before clinical application. This study serves a wide variety of safety evaluations of biodegradable AZ31B alloy on nerve cells. As a result of this in vitro study, the maximum aluminum (Al) ion and Mg ion concentrations in the medium were estimated to be 22 μmol/L and 2.75 mmol/L, respectively, during degradation. In addition, the corresponding cell mortality was observed to be 36% and lower than 5% according to the resistance curves of the cell to Mg and Al ions. Furthermore, the maximum Al ion and Mg ion concentrations in serum and cerebrospinal fluid were detected to be 26.1 μmol/L and 1.2 mmol/L, respectively, for 5 months implantation. Combining the result of in vivo dialysis with the result of ion tolerance assay experiments, the actual death rate of nerve cells is estimated between 4 and 10% in vivo, which is lower than the result of in vitro cytotoxicity evaluation. Moreover, no psychomotor disability during clinical studies is observed. Consequently, stent made of AZ31B alloy with surface treatment is feasible for carotid artery stenosis, and it is safe in terms of cell viability on the nervous system.

The Flow-Induced Degradation and Vascular Cellular Response Study of Magnesium-Based Materials

“…In particular, the vascular cellular responses of AZ31 indicated a potential application for stents. Moreover, Erişen et al reported that the dissolved Al ions during the degradation of AZ31B alloy did not cause a danger for the viability of the nerve cells in the in vitro and in vivo studies ( Erişen et al, 2022 ). This, once again, shows that biodegradable AZ31B magnesium alloy stent has a prospect of application.…”

“…Generally, Mg alloys contain aluminum (Al) or the rare earth elements (REEs) ( Li et al, 2008 ). Alloying with Al and REEs enhances the corrosion resistance of Mg ( Li et al, 2016 ; Erişen et al, 2022 ). Mg-based materials, currently under investigation as implant materials, mostly contain pure Mg, Mg–Al alloys, Mg–rare earth alloys, and so on ( Wu et al, 2012 ; Liu et al, 2015 ; Törne et al, 2017 ; Han et al, 2019 ).…”

Progress in bioactive surface coatings on biodegradable Mg alloys: A critical review towards clinical translation

“…Mg alloys are prone to micro-galvanic corrosion due to the highly electronegative electrode potential of −2.37 V, which further accelerates the degradation phenomena in the presence of physiological media [ 13 ]. Secondly, Mg suffers from an abnormal phenomenon of negative difference effect (NDE) where corrosion rate and hydrogen evolution increase rapidly with an increase in corrosion potential, which may lead to blockage of blood paths and cause tissue necrosis by H 2 accumulation [ 14 ]. Thus, wound healing after prosthetic surgery becomes a major challenge.…”

A Novel PLLA/MgF2 Coating on Mg Alloy by Ultrasonic Atomization Spraying for Controlling Degradation and Improving Biocompatibility

“…Among them, fluorine conversion treating on Mg alloy has proved to be an effective method for corrosion resistance with the occurrence of MgF 2 . MgF 2 has been proved to slow down the degradation rates of Mg alloys [ 20 , 21 ], thus preventing hydrogen accumulation in tissues and fluid [ 22 ]. Moreover, numerous studies showed MgF 2 had no cytotoxicity [ 23 ].…”