Lukas Weber Lukas Weber Jelena Horky Jelena Horky Christopher Riedmüller Christopher Riedmüller Carina Kampleitner Carina Kampleitner Eylem Acar Eylem Acar Mariangela Fedel Mariangela Fedel Claudia Höchsmann (Centre of Pathobiology, Department of Biological Sciences and Pathobiology, Departments, University of Veterinary Medicine Vienna) Claudia Höchsmann Magdalena Eskinja Magdalena Eskinja Stefan Mitsche Stefan Mitsche Bernhard Mingler Bernhard Mingler Laszlo Sajti Laszlo Sajti Gregor Mori Gregor Mori Manfred Bammer Manfred Bammer Ingrid Walter (Centre of Pathobiology, Department of Biological Sciences and Pathobiology, Departments, University of Veterinary Medicine Vienna) Ingrid Walter Stefan Tangl Stefan Tangl Helga Bergmeister Helga Bergmeister Bruno K. Podesser Bruno K. Podesser Marjan Enayati Marjan Enayati Elsevier 2026 Bioresorbable magnesium (Mg) alloys are promising alternatives to permanent implants in cardiovascular and orthopedic applications. Alloying with rare earth elements (REEs) can enhance corrosion resistance and mechanical strength, though their long-term biological behavior and biosafety are still being clarified. Herein, we compared the widely used REE-containing alloy WE43 with a previously self-designed REE-free alloy, ZX00 (Mg–0.6Zn–0.5Ca), focusing on biocompatibility, toxicity, degradation, and mechanical performance in vitro and in vivo. ZX00 demonstrated significantly higher fibroblast viability than WE43 in vitro (100.00% ± 9.30% vs. 43.00% ± 6.88%; p < 0.0001) and did not elicit inflammatory responses in primary human macrophages, while both alloys showed comparable hemocompatibility. After 5 months of subcutaneous implantation in rats, ZX00 and WE43 exhibited similar overall biocompatibility, with mild gas formation observed in X-ray imaging and histology. Although ZX00 degraded faster than WE43 according to micro-computed tomography and histological analyses, it retained markedly superior ductility after 5 months of implantation, due to uniform, non-localized corrosion. No systemic toxicity was detected for either alloy through histopathological assessment of multiple organs and hematological analyses. This study shows that the REE-free ZX00 alloy possesses the biological and mechanical requirements for demanding biomedical environments, positioning it as a promising candidate for cardiovascular applications and marking a first step toward a bioabsorbable material specifically designed for cardiac annuloplasty devices. PDFDocument eng 2026-10-16T07:53:39.782302771Z 2026 Magnesium alloy Biocompatibility Inflammatory response Biodegradability Mechanical performance 17639909 b application/pdf http://creativecommons.org/licenses/by/4.0/