It is well-known that nanoparticles could cause toxic effects in cells. Alloy nanoparticles with yet unknown health risk may be released from cardiovascular implants made of Nickel–Titanium or Cobalt–Chromium due to abrasion or production failure. We show the bio-response of human primary endothelial and smooth muscle cells exposed to different concentrations of metal and alloy nanoparticles. Nanoparticles having primary particle sizes in the range of 5–250 nm were generated using laser ablation in three different solutions avoiding artificial chemical additives, and giving access to formulations containing nanoparticles only stabilized by biological ligands. Endothelial cells are found to be more sensitive to nanoparticle exposure than smooth muscle cells. Cobalt and Nickel nanoparticles caused the highest cytotoxicity. In contrast, Titanium, Nickel–Iron, and Nickel–Titanium nanoparticles had almost no influence on cells below a nanoparticle concentration of 10 μM. Nanoparticles in cysteine dissolved almost completely, whereas less ions are released when nanoparticles were stabilized in water or citrate solution. Nanoparticles stabilized by cysteine caused less inhibitory effects on cells suggesting cysteine to form metal complexes with bioactive ions in media.

The first degradable implant made of a magnesium alloy, a compression screw, was launched to the clinical market in March 2013. Many different complex considerations are required for the marketing authorization of degradable implant materials. This review gives an overview of existing and proposed standards for implant testing for marketing approval. Furthermore, different common in vitro and in vivo testing methods are discussed. In some cases, animal tests are inevitable to investigate the biological safety of a novel medical material. The choice of an appropriate animal model is as important as subsequent histological examination. Furthermore, this review focuses on the results of various mechanical tests to investigate the stability of implants for temporary use. All the above aspects are examined in the context of development and testing of magnesium-based biomaterials and their progress them from bench to bedside. A brief history of the first market launch of a magnesium-based degradable implant is given. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 329-347, 2017.

Medical devices made of polymers are often protected against infection-relevant biofilm formation by embedding nanoparticles as a source of bioactive metal ion release. Safe application of such nanocomposites requires finding the optimal ion dose and identifying the cross-effects caused by material mixtures. This study investigated the safety and antimicrobial efficacy of thermoplastic polyurethane (TPU), which is widely used for medical devices, e.g., catheters containing zinc, silver, copper and magnesium nanoparticles, respectively, and combinations thereof. Nanoparticles were generated by using pulsed laser ablation in polymer solution. We found that the composites embedded with nanosilver were noncytotoxic to cells but toxic to bacteria, with an optimal effect at 0.5 wt%. In contrast, zinc, copper, and magnesium nanoparticle composites did not inhibit bacteria growth. Interestingly, by combining the antibacterial metals (Ag, Cu) with nanoparticles made of elements required in biological systems (Zn, Mg), we observed an altered ion release and corresponding changes to their antibacterial efficacy and biocompatibility. The combination of silver with magnesium in the nanocomposites did increase both the amount and rate of silver ion release, and resulted in an increased antimicrobial effect of this Ag-Mg-TPU composite material. The therapeutic window of silver could not be changed quantitatively by the Ag-Mg combination, but less wt% silver was required for achieving antimicrobial efficacy because of faster ion release in the clinically relevant, critical initial phase of immersion. According to our observations, the mechanism of Mg increasing the mass-specific bio-effectivity of silver is possibly nonelectrochemical but volumetric. A fine-tuning of the Mg to Ag ratio and the overall load would be required to test whether a larger therapeutic window compared with Ag composites can be gained by the mixed Mg-Ag nanocomposites. Overall, the addition of Mg to Ag reduces the lag phase of bioactivity by increasing the Ag ion release in the critical first days after application of the medical device.

Summary: Permanent metallic stent implants are the most frequently applied treatment option in angioplastic interventions. Here we report in vitro and in vivo characteristics of the newly developed absorbable metal stent (AMS), consisting of magnesium (Mg) with yttrium and rare earth additives, in comparison to the clinically applied steel stent (316L). Viability and proliferation of smooth muscle cells (SMC) and endothelial cells (EC) exposed to various Mg‐alloys were analyzed. AMS and 316L were implanted into coronary arteries of Göttingen minipigs (n = 17) and explanted after 28 and 56 days. Stented arterial segments were analyzed prior to explantation by angiography and ex vivo by micro‐computer tomography (micro‐CT), by histology, and by immunohistochemistry. Exposure to the alloy in vitro resulted in reduced viability and proliferation of smooth muscle cells. Consistently, larger luminal diameter and less neointimal formation were found in AMS both 28 and 56 days after implantation. Histological analysis revealed no significant differences in the number of macrophages and Ki‐67 positive cells, yet a significantly higher number of proliferating cells around 316L struts at the earlier time point. The reduction in neointima formation and a larger vessel lumen indicates the superiority of the recently developed AMS over commercial available steel stents. Furthermore, AMS is absorbable, and thus will not cause stress to the stented vessel for the lifetime of the recipient.

We identified 100% of the CFTR gene mutations, including three novel mutations, in 126 unrelated cystic fibrosis chromosomes from Tyrol, Austria. The frequency of the major mutation ΔF508 (74.6%) was not significantly different in Tyrolian CF‐patients than in patients from Bavaria (71.0%) and Middle‐and Northern Germany (71.9%), but was significantly higher than in patients from Styria (58.1%) or Northern Italy (47.6%). Interestingly, the distribution of the next most frequent mutations, R1162X (8.7%) 2183AA→G, 2789 +5G→A and G542X (2.4% each), was more similar to the distribution of these mutations among CF‐patients from Northern Italy than to those from Styria, Bavaria or Middle‐and Northern Germany. Nine further mutations occurred once or twice. One of these, the missense mutation M1101K, is rare worldwide but very frequent in the Hutterite brethren, a small founder population which came from Southern Austria to Northern America. Three other different mutations (ΔL453, 1874insT and 4108delT) were present in single Tyrolian families and have not been described before. The identification of 100% of CFTR gene mutations in a particular CF population demonstrates the power of genetic analysis for the diagnosis and counselling of CF families in this restricted geographical area of Austria. Our study provides evidence for a closer genetic relation between CF patients from Tyrol and those from Bavaria or Middle‐and Northern Germany as well as Northern Italy, than between CF patients from the two Austrian states Tyrol and Styria.

Amphiphysins interact directly with clathrin and have a function in clathrin-mediated synaptic vesicle recycling and clathrin-mediated endocytosis. The neuronal isoform amphiphysin-1 is a serine/threonine phosphoprotein that is dephosphorylated upon stimulation of synaptic vesicle endocytosis. Rephosphorylation was stimulated by nerve growth factor. We analysed the regulation of amphiphysin-clathrin interactions by phosphorylation. The N-terminal domain of clathrin bound to unphosphorylated amphiphysin-1, but not to the phosphorylated protein. A search for possible phosphorylation sites revealed two casein kinase 2 consensus motifs in close proximity to the clathrin binding sites in amphiphysin-1 and -2. We mutagenized these residues (T350 and T387) to glutamate, mimicking a constitutive phosphorylation. The double mutant showed a strong reduction in clathrin binding. The assumption that casein kinase 2 phosphorylates amphiphysin-1 at T350 and T387 was corroborated by experiments showing that: (i) casein kinase 2 phosphorylated these residues directly in vitro, (ii) when expressed in HeLa cells, the glutamate mutant showed reduced phosphorylation, and (iii) casein kinase 2 inhibitors blocked nerve growth factor-induced phosphorylation of endogenous amphiphysin-1 in PC12 cells. These observations are consistent with the hypothesis that, upon activation by nerve growth factor, casein kinase 2 phosphorylates amphiphysin-1 and thereby regulates the endocytosis of clathrin-coated vesicles via the interaction between clathrin and amphiphysin.

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