In vivo urinary compatibility of Mg-Sr-Ag alloy in swine model

Abstract

A biodegradable metallic ureteral stent with suitable mechanical properties and antibacterial activity remains a challenge. Here we reveal the scientific significance of a biodegradable Mg-Sr-Ag alloy with a favorable combination of balanced mechanical properties, adjustable indwelling time in urinary tract and evident antibacterial activity via in vivo experiments in a swine model. Attributed to the rheo-solidification process, equiaxial microstructure and significantly refined grains (average grain size: 27.1 μm) were achieved. Mg 17 Sr 2 and Mg 4 Ag were found as the primary precipitates in the matrix, due to which the alloy obtained ca. 111% increase in ultimate tensile strength in comparison to pure magnesium. Both the in vitro and in vivo results demonstrated the satisfactory biocompatibility of the alloy. Histological evaluation and bioindicators analysis suggested that there was no tissue damage, inflammation and lesions in the urinary system caused by the degradation process. The stent also improved the post-operative bladder functions viewed from the urodynamic results. Our findings highlight the potential of this alloy as antibacterial biodegradable urinary implant material.

Degradation Adaptability Assessment of Semisolid Powder Molded Mg–Zn–Mn Alloys for Orthopedic Applications

“…Comprehensively considering the cell growth and osteogenic differentiation, the Mn-containing Mg–6Zn alloy is more suitable than the Mn-free alloy as a bone implant. In addition to being used as a bone implant, there are also studies on the use of biodegradable magnesium alloys as ureteral stents …”

Recent development and future application of biodegradable ureteral stents

“…In 2021, Tie et al innovatively developed the Mg-Sr-Ag alloy, combining the exceptional mechanical properties of the Mg-Sr alloy with the pronounced antimicrobial activity of silver (Ag). They validated its biocompatibility and impact on the urological system ( Tie et al, 2022 ). Previously, they had preliminarily confirmed the applicability of the Mg-Sr alloy for the manufacture of biodegradable bone fixation devices and demonstrated the pronounced antibacterial activity of magnesium alloys containing silver in an in vitro setting ( Tie et al, 2013 ; Tie et al, 2016 ).…”

“…In 2022, Tie et al fabricated Mg-1.0Sr-0.5Ag (wt.%) alloy (JQ alloy) through semi-solid rheo-extrusion ( Tie et al, 2022 ). Their experimental results demonstrated a 111% increase in ultimate tensile strength for JQ alloy (223.7 MPa) compared to pure magnesium (105.9 MPa).…”

Advances in ureteral stent technology

“…Tie et al examined biocompatibility of an antibacterial biodegradable metallic ureteral stent (magnesium-strontium-silver alloy) that showed a significant reduction in colony forming units in the urine compared to magnesium stents at 6 and 12 weeks in a swine model [24]. Although complete degradation was not achieved at the end of the 12-week study period [24]. An ideal biodegradable stent needs to maintain patency and stability for the first 1–2 weeks with subsequent quick and reliable degradation time.…”

“…Most recent animal model studies have demonstrated limited success of biodegradable stents with variable degradation time (either degrading too fast or too slow), increased biofilm formation and bacteriuria [22,23]. Tie et al examined biocompatibility of an antibacterial biodegradable metallic ureteral stent (magnesiumstrontium-silver alloy) that showed a significant reduction in colony forming units in the urine compared to magnesium stents at 6 and 12 weeks in a swine model [24]. Although complete degradation was not achieved at the end of the 12-week study period [24].…”