Elsevier 2026 isPartOf:https://phaidra.vetmeduni.ac.at/o:605 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. Magnesium alloy Biocompatibility Inflammatory response Biodegradability Mechanical performance doi:10.1016/j.mtbio.2026.103225 https://phaidra.vetmeduni.ac.at/o:5604 Text Wissenschaftlicher Artikel Materials Today Bio © 2026 The Authors open access A high-toughness, rare-earth-free magnesium alloy with excellent biocompatibility profile: Integrated in vitro and in vivo characterization Open Access Documento PDF Articolo scientifico application/pdf eng issn:2590-0064 Text journal article http://creativecommons.org/licenses/by/4.0/ Lukas Weber Jelena Horky Christopher Riedmüller Carina Kampleitner Eylem Acar Mariangela Fedel Claudia Höchsmann (Centre of Pathobiology, Department of Biological Sciences and Pathobiology, Departments, University of Veterinary Medicine Vienna) Magdalena Eskinja Stefan Mitsche Bernhard Mingler Laszlo Sajti Gregor Mori Manfred Bammer Ingrid Walter (Centre of Pathobiology, Department of Biological Sciences and Pathobiology, Departments, University of Veterinary Medicine Vienna) Stefan Tangl Helga Bergmeister Bruno K. Podesser Marjan Enayati