Medizinische Universität Graz - Research portal
Selected Publication:
Okutan, B.
In vivo characterization of designated magnesium materials by microCT and fluorescence imaging in rats
PhD-Studium (Doctor of Philosophy); Humanmedizin; [ Dissertation ] Medizinische Universität Graz; 2023. pp.
- Authors Med Uni Graz:
- Advisor:
- Schindl Rainer
- Sommer Nicole
- Weinberg Annelie-Martina
- Altmetrics:
- Abstract:
- Conventional permanent metals (i.e. stainless steel, cobalt-chromium alloys, titanium) are used as orthopedic implants that i) can induce stress shielding; ii) have long-term toxicological risk; iii) increase the patients’ burden and risk in the case of secondary implant removal surgery, especially for paediatric cases. Therefore, implants with suitable biological and mechanical properties are required in the field of orthopedics and traumatology. Recently, magnesium (Mg)-based materials have attracted significant attention as promising metallic implants because of their biocompatibil-ity, biodegradability, and suitable mechanical properties that replicate the biomechanical proper-ties of the host bones. The high corrosion rate and excessive hydrogen gas formation of pure Mg implants can be minimized with added ions alloyed with Mg or reducing the impurities of pure Mg i.e. the amount of iron ions. While released Mg2+ ions from degrading Mg-based implants exhibit osteoconductive properties and promote new bone tissue formation, the effect of degrad-ing Mg-based implants on bone tissue and its intracellular regulation and signal transduction are still unclear. Hence, it is important to understand the local and systemic effects of their degrada-tion products. Here I demonstrate i) in vivo degradation behaviour of two Mg-based implants, Mg-Zn-Ca (ZX00) and extra high-purity Mg (XHP-Mg), ii) the potential underlying molecular mechanisms, and iii) the local and systemic effects of ZX00 and XHP-Mg in comparison to state-of-the-art non-degradable Ti and control groups in a healthy juvenile growing-rat model. The rats were di-vided into two groups: short-term (days 3, 14, 42) and mid-term (weeks 6 and 24) evaluation groups. Degradation performance of both Mg-based materials were investigated using micro-computed tomography. Histology, histomorphometry, real-time PCR analysis, and live cell imag-ing were performed to evaluate the potential differences in bone formation and in-growth (local effects), whereas biochemical analysis, histopathological examinations, immunohistochemistry, and metabolomics were performed to investigate the systemic effects of both Mg-based implant groups and compared with control groups. Taken together, these results suggest that both Mg-based alloys showed good osseointegration and promote osteogenesis in the medullary cavity. In terms of in vivo degradation, I observed a moderate gas accumulation and slower degradation rate of the ZX00 alloy, indicating that ZX00 implants are more favorable compared to XHP-Mg. These results provide evidence that both alloy types are superior to Ti pins and promising candidates for orthopedic interventions.