Evaluation of cytotoxic concentration–time response in A549 cells exposed to respirable α‐quartz

Abstract

A causal pathway between quartz, silicosis and lung cancer has been postulated. The aim of our study was to assess cytotoxic effects induced in a human lung epithelial cell line (A549) by exposure to alpha-quartz. Cells were exposed to respirable alpha-quartz (SRM1878a, NIST) at 25, 50 or 100 microg ml(-1 )for 24 h and at 50 or 100 microg ml(-1) for 48 h. Cytotoxic effects were analyzed by scanning electron microscopy (SEM), apoptotic morphology analysis with Hoechst staining and lactate dehydrogenase (LDH) release assay. In cells exposed to alpha-quartz for 24 h, a concentration-dependent bleb development and in particular the localization of blebs at the cell edge at higher concentrations were observed. The blebbing phenomenon was more evident after 48 h of exposure to 50 or to 100 microg ml(-1) of alpha-quartz and large blebs were localized at the cell edge. At the same concentrations surface smoothing was also observed. Moreover the presence of holes and tears was detected at the highest concentration both at 24 and 48 h. Results of morphological analysis with Hoechst stain evidenced an increase concentration-time dependent of apoptotic cell percentage that was more marked after 48 h exposure to 100 microg ml(-1) and a prevalence of late apoptosis stage with the increase of exposure time and concentration. Cells exposed to 50 or 100 microg ml(-1) of alpha-quartz for 24 and 48 h produced a significant increase in LDH release. The concentration-time-dependent bleb induction evidenced by SEM correlates with the increase of apoptotic cells and LDH activity release, demonstrating the onset of cytotoxic effects in human lung cells exposed to alpha-quartz.

Activation of Egr-1 in Human Lung Epithelial Cells Exposed to Silica through MAPKs Signaling Pathways

“…But whether elevated TGFβ is also a potent inducer for Egr-1 in this process, in other word whether there is an Egr-1 /TGFβ positive feedback loop need to be further explored. Many studies found silica induced cell apoptosis [38,39], and recent studies [40,41] demonstrated that Egr-1 took part in regulating cell apoptosis, but whether activated Egr-1 plays an important role in silicosis by affecting cell apoptosis need further study to elucidate.…”

Comparative study of hydrophilic and hydrophobic ionic liquids for observing cultured human cells by scanning electron microscopy

“…SEM and TEM photographs of these cells were taken using ordinary methods, and various cell protrusions or microvilli were reported (Fanizza et al, 2009;Gualtieri et al, 2005;Ishigaki et al, 2011a;Wang et al, 2009). Rose Wrap, a food film wrap (C.I.…”

Ionic liquid enables simple and rapid sample preparation of human culturing cells for scanning electron microscope analysis

“…Such features were also observed in cultured cells by SEM and atomic microforce microscopy (Braet et al, 1998; Kim et al, 2008; Solmi et al, 2008). Although other researchers have previously observed microvilli in A549 cells (Fanizza et al, 2009; Gualtieri et al, 2005; Wang et al, 2009), to our knowledge, this is the first observation of cell‐to‐cell connections among A549 cells under an electron microscope.…”

“…SEM and transmission electron microscopy (TEM) micrographs of A549 cells have been reported by other researchers (Fanizza et al, 2009; Gualtieri et al, 2005; Wang et al, 2009). Similar to those images, SEM images of the platinum‐coated A549 cells taken in this study also showed flat shapes adhering to the polymer sheet.…”