Mapping differential cellular protein response of mouse alveolar epithelial cells to multi-walled carbon nanotubes as a function of atomic layer deposition coating

A tantalum-containing zirconium-based metallic glass with superior endosseous implant relevant properties

Zirconium-based metallic glasses (Zr-MGs) are demonstrated to exhibit high mechanical strength, low elastic modulus and excellent biocompatibility, making them promising materials for endosseous implants. Meanwhile, tantalum (Ta) is also well known for its ideal corrosion resistance and biological effects. However, the metal has an elastic modulus as high as 186 GPa which is not comparable to the natural bone (10-30 GPa), and it also has a relative high cost. Here, to fully exploit the advantages of Ta as endosseous implants, a small amount of Ta (as low as 3 at. %) was successfully added into a Zr-MG to generate an advanced functional endosseous implant, Zr58Cu25Al14Ta3 MG, with superior comprehensive properties. Upon carefully dissecting the atomic structure and surface chemistry, the results show that amorphization of Ta enables the uniform distribution in material surface, leading to a significantly improved chemical stability and extensive material-cell contact regulation. Systematical analyses on the immunological, angiogenesis and osteogenesis capability of the material are carried out utilizing the next-generation sequencing, revealing that Zr58Cu25Al14Ta3 MG can regulate angiogenesis through VEGF signaling pathway and osteogenesis via BMP signaling pathway. Animal experiment further confirms a sound osseointegration of Zr58Cu25Al14Ta3 MG in achieving better bone-implant-contact and inducing faster peri-implant bone formation.

Osteopontin mRNA expression by rat mesothelial cells exposed to multi-walled carbon nanotubes as a potential biomarker of chronic neoplastic transformation in vitro

Mesothelioma is a cancer of the lung pleura primarily associated with inhalation of asbestos fibers. Multi-walled carbon nanotubes (MWCNTs) are engineered nanomaterials that pose a potential risk for mesothelioma due to properties that are similar to asbestos. Inhaled MWCNTs migrate to the pleura in rodents and some types cause mesothelioma. Like asbestos, there is a diversity of MWCNT types. We investigated the neoplastic potential of tangled (tMWCNT) versus rigid (rMWCNT) after chronic exposure using serial passages of rat mesothelial cells in vitro. Normal rat mesothelial (NRM2) cells were exposed to tMWCNTs or rMWCNTs for 45 weeks over 85 passages to determine if exposure resulted in transformation to a neoplastic phenotype. Rat mesothelioma (ME1) cells were used as a positive control. Osteopontin (OPN) mRNA was assayed as a biomarker of transformation by real time quantitative polymerase chain reaction (qPCR) and transformation was determined by a cell invasion assay. Exposure to rMWCNTs, but not tMWCNTs, resulted in transformation of NRM2 cells into an invasive phenotype that was similar to ME1 cells. Moreover, exposure of NRM2 cells to rMWCNTs increased OPN mRNA that correlated with cellular transformation. These data suggest that OPN is a potential biomarker that should be further investigated to screen the carcinogenicity of MWCNTs in vitro.

Role of p53 in the chronic pulmonary immune response to tangled or rod-like multi-walled carbon nanotubes

The fiber-like shape of multi-walled carbon nanotubes (MWCNTs) is reminiscent of asbestos, suggesting they pose similar health hazards when inhaled, including pulmonary fibrosis and mesothelioma. Mice deficient in the tumor suppressor p53 are susceptible to carcinogenesis. However, the chronic pathologic effect of MWCNTs delivered to the lungs of p53 heterozygous (p53^+/-) mice has not been investigated. We hypothesized that p53^+/- mice would be susceptible to lung tumor development after exposure to either tangled (t-) or rod-like (r-) MWCNTs. Wild-type (p53^+/+) or p53^+/- mice were exposed to MWCNTs (1 mg/kg) via oropharyngeal aspiration weekly over four consecutive weeks and evaluated for cellular and pathologic outcomes 11-months post-initial exposure. No lung or pleural tumors were observed in p53^+/+ or p53^+/- mice exposed to either t- or rMWCNTs. In comparison to tMWCNTs, the rMWCNTs induced the formation of larger granulomas, a greater number of lymphoid aggregates and greater epithelial cell hyperplasia in terminal bronchioles in both p53^+/- and p53^+/+ mice. A constitutively larger area of CD45R⁺/CD3⁺ lymphoid tissue was observed in p53^+/- mice compared to p53^+/+ mice. Importantly, p53^+/- mice had larger granulomas induced by rMWCNTs as compared to p53^+/+ mice. These findings indicate that a combination of p53 deficiency and physicochemical characteristics including nanotube geometry are factors in susceptibility to MWCNT-induced lymphoid infiltration and granuloma formation.

Characterization of the proteome and lipidome profiles of human lung cells after low dose and chronic exposure to multiwalled carbon nanotubes

The effects of long-term chronic exposure of human lung cells to multi-walled carbon nanotubes (MWCNT) and their impact upon cellular proteins and lipids were investigated. Since the lung is the major target organ, an in vitro normal bronchial epithelial cell line model was used. Additionally, to better mimic exposure to manufactured nanomaterials at occupational settings, cells were continuously exposed to two non-toxic and low doses of a MWCNT for 13-weeks. MWCNT-treatment increased ROS levels in cells without increasing oxidative DNA damage and resulted in differential expression of multiple anti- and pro-apoptotic proteins. The proteomic analysis of the MWCNT-exposed cells showed that among more than 5000 identified proteins; more than 200 were differentially expressed in the treated cells. Functional analyses revealed association of these differentially regulated proteins to cellular processes such as cell death and survival, cellular assembly, and organization. Similarly, shotgun lipidomic profiling revealed accumulation of multiple lipid classes. Our results indicate that long-term MWCNT-exposure of human normal lung cells at occupationally relevant low-doses may alter both the proteome and the lipidome profiles of the target epithelial cells in the lung.