Ni and TiO2 nanoparticles cause adhesion and cytoskeletal changes in human osteoblasts

Titanium-based alloys have established a crucial role in implantology. As material deteriorates overtime, nanoparticles of TiO₂ and Ni are released. This study is focused on the impact of TiO₂ and Ni nanoparticles with size of 100 nm on cytoskeletal and adhesive changes in human physiological and osteoarthritic osteoblasts. The impact of nanoparticles with concentration of 1.5 ng/mL on actin and tubulin expression and gene expression of FAK and ICAM-1 was studied. The cell size and actin expression of physiological osteoblasts decreased in presence of Ni nanoparticles, while TiO₂ nanoparticles caused increase in cell size and actin expression. Both cell lines expressed more FAK as a response to TiO₂ nanoparticles. ICAM-1 gene was overexpressed in both cell lines as a reaction to both types of nanoparticles. The presented study shows a crucial role of Ni and TiO₂ nanoparticles in human osteoblast cytoskeletal and adhesive changes, especially connected with the osteoarthritic cells. Graphical abstract.

Effect of Ni ion release on the cells in contact with NiTi alloys

Nickel-titanium alloys have been used in medical applications for several years; however, biocompatibility of the material remains controversial. In the present study, the human umbilical vein endothelial cells (HUVEC) were cultured in contact with the nitinol used in two different heat treatment  surface modifications-helium and hydrogen. The amount of Ni ions released from these alloys in contact with HUVEC was measured in media and in the cells by ICP-MS. An increased release of Ni ions was detected in He alloy compared with H₂ alloy modification with an elevation with the metal exposition duration (24 h vs. 72 h). The cells contained the Ni ions in both selected alloy modifications with the lower levels in H₂ alloys. To evaluate the potential of multiple metal applications, similar values were observed in media and in cell suspension for all surface modification combinations. The model analysis of effect of metal ion release on distant cells in the body showed that the concentration is interestingly similar to concentrations in cells in direct contact with the metal alloy. The cells are able to regulate the concentration of Ni ions within the cell. According to our best knowledge, the study for the first time describes the presence of Ni ions released from nitinol directly in the cells. In the case of the H₂ modification, the lowest levels of Ni ions were detected both in medium and in the cells, which likely increases the biocompatibility of the nitinol alloy.

Interaction of primary human trabecular meshwork cells with metal alloy candidates for microinvasive glaucoma surgery

BACKGROUND

Microinvasive glaucoma surgery (MIGS) is a relatively new addition to the glaucoma treatment paradigm. Small metallic stents are inserted into the trabecular meshwork in order to increase aqueous humour drainage. MIGS procedures are rapidly being adopted owing to a more favourable side effect profile when compared with traditional surgery. Remarkably, this rapid rate of utilization has occurred without any published studies on the effect of metal alloys used in these stents on human trabecular meshwork cells (HTMCs). Therefore, this study aimed to determine the effect of candidate metal alloys for MIGS on HTMC morphology, viability and function.

METHODS

Human trabecular meshwork cells were cultured on the surfaces of titanium (polished and sandblasted), a titanium-nickel (nitinol) alloy and glass (as control substratum). Fluorescence imaging was used to assess cell morphology and spreading. A lactate dehydrogenase cytotoxicity assay, cell death detection ELISA, MTT cell viability assay, BrdU cell proliferation assay and fibronectin ELISA were also conducted.

RESULTS

Cells cultured on sandblasted titanium exhibited significantly greater spreading than cells cultured on other substrata. In comparison, HTMCs cultured on nitinol displayed poor spreading. Significantly more cell death, by both necrosis and apoptosis, occurred on nitinol than on titanium and glass. Also, cell viability and proliferation were suppressed on nitinol compared with titanium or glass. Finally, HTMCs on both titanium and nitinol produced greater amounts of fibronectin than cells grown on glass.

CONCLUSIONS

Substratum topography and metal alloy composition were found to impact morphology, viability and function of primary HTMC cultures.

Elevated circulating levels of copper and nickel are found in elderly subjects with left ventricular hypertrophy

Identified risk factors for left ventricular hypertrophy (LVH) are hypertension, diabetes and obesity. However, since these risk factors only explain a part of the variation in left ventricular mass, we investigated if trace and heavy metals might also play a role in LVH. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, left ventricular mass index (LVMI) and relative wall thickness (RWT) were determined by echocardiography together with eleven different trace and heavy metals in 993 subjects aged 70 years. Only copper levels were significantly related to LVMI following adjustment for sex, blood pressure, antihypertensive treatment, diabetes and body mass index (BMI) (p<0.0001). However, both copper (Cu) and nickel (Ni) were related to RWT following adjustment (p<0.0001). When divided into four geometric groups, both Cu and Ni were elevated in subjects with concentric remodelling and concentric LVH, but not in those with eccentric hypertrophy, when compared to subjects with a normal left ventricle. No relationships were found for zinc, aluminium, manganese, molybdenum, mercury, lead, cadmium, cobalt or chromium. Elevated levels of copper and nickel are found in elderly subjects with LVH, especially of the concentric type, following adjustment for known risk factors for LVH.