Initial organ distribution and biological safety of Mg ²⁺ released from a Mg alloy implant

Abstract

Magnesium (Mg) alloys are considered promising materials for biodegradable medical devices; however, the initial effects and distribution of released Mg ions following implantation are unclear. This is addressed in the present study, using two types of Mg alloys implanted into rats. An in vitro immersion test was first carried out to quantify Mg ions released from the alloys at early stages. Based on these data, we performed an in vivo experiment in which large amounts of alloys were subcutaneously implanted into the backs of rats for 1, 5, 10, and 25 h. Mg accumulation in organs was measured by inductively coupled plasma mass spectrometry. In vivo, blood and urine Mg concentrations were higher in rats receiving the implants than in controls after 1 h; however, the levels were within clinically accepted guidelines. The Mg concentration in bone was significantly higher in the 25 h implanted group than in the other groups. Our results suggest that homeostasis is maintained by urinary excretion and bone accumulation of released Mg ions in response to sudden changes in Mg ion concentration in the body fluid in a large number of Mg alloy implants at the early stages.

Biodegradation behaviors of magnesium(Mg)-based alloy nails in autologous bone grafts: In vivo study in rabbit skulls

“…30 However, this Mg alloy is small and degrades slowly, maintaining Mg homeostasis. 22 Histopathology showed the formation of a thick fibrous capsule and slight inflammatory cell infiltration around the Mg alloys, indicating that Mg alloys are likely safe in vivo. 31 No postoperative complications or weight loss was observed the current study.…”

“…A total of 12 rabbits were randomized into four groups (n = 3 per group). According to preliminary experiments and previous reports, [20][21][22] the skull experimental areas were resected and analyzed at 1, 4, 12, and 24 weeks postoperatively (three rabbits/week). The animals were sacrificed by injecting approximately 800 mg of pentobarbital into the ear vein.…”

Influence of Spin Coating and Dip Coating with Gelatin/Hydroxyapatite for Bioresorbable Mg Alloy Orthopedic Implants: In Vitro and In Vivo Studies

“…The test results showed that the amount of Mg 2+ ions in the blood serum of the uncoated group was lower than that of the coated group, which suggested that a large amount of Mg 2+ ions in the uncoated group was quickly absorbed into the subcutaneous tissues surrounding the implant and rapidly excreted to urine causing the decrease of the magnesium ion concentration after 21 days of implantation. 33 Meanwhile, the coating groups with an active protective layer made the Mg ion release more harmonious and stable; therefore, the Mg ion content remained relatively stable across the test points.…”

“…The Mg 2+ ions in the blood serum were detected by inductively coupled plasma optical emission spectroscopy (Thermo Scientific iCAP 7000 series ICP-OES). 33 The ion concentration analyses were performed using the parameters listed in Table 1. Each sample test was repeated 3 times to calculate the mean and standard deviation.…”

Mg Biodegradation Mechanism Deduced from the Local Surface Environment under Simulated Physiological Conditions

“…Mg‐based materials [ 1–3 ] are the current leading‐edge biodegradable metals for bone remodeling. However, despite the introduction of some Mg‐based implants for bone fixation (MAGNEZIX and Resomet) and atherosclerosis treatments (Magmaris), some questions remain unclear from a fundamental point of view, and that hinders their introduction for new applications: i) a current mismatch between mechanical properties for high‐load applications and acceptable degradation rates, ii) the unclear physiological paths of released Mg 2+ on the complex bone remodeling process [ 4 ] and the response of other dissolution products including its possible physiological accumulation (e.g., alloying elements and H 2 ) in the tissue healing process, [ 5 ] iii) the complex and not the well‐defined physiological environment of different implantation sites hinders the possibility of direct laboratory mimicking of the in vivo conditions [ 6,7 ] and difficult to understand the degradation mechanism.…”