Assessing the in vitro toxicity of the lunar dust environment using respiratory cells exposed to Al2O3 or SiO2 fine dust particles

Abstract

Prior chemical and physical analysis of lunar soil suggests a composition of dust particles that may contribute to the development of acute and chronic respiratory disorders. In this study, fine Al(2)O(3) (0.7 μm) and fine SiO(2) (mean 1.6 μm) were used to assess the cellular uptake and cellular toxicity of lunar dust particle analogs. Respiratory cells, murine alveolar macrophages (RAW 264.7) and human type II epithelial (A549), were cultured as the in vitro model system. The phagocytic activity of both cell types using ultrafine (0.1 μm) and fine (0.5 μm) fluorescent polystyrene beads was determined. Following a 6-h exposure, RAW 264.7 cells had extended pseudopods with beads localized in the cytoplasmic region of cells. After 24 h, the macrophage cells were rounded and clumped and lacked pseudopods, which suggest impairment of phagocytosis. A549 cells did not contain beads, and after 24 h, the majority of the beads appeared to primarily coat the surface of the cells. Next, we investigated the cellular response to fine SiO(2) and Al(2)O(3) (up to 5 mg/ml). RAW 264.7 cells exposed to 1.0 mg/ml of fine SiO(2) for 6 h demonstrated pseudopods, cellular damage, apoptosis, and necrosis. A549 cells showed slight toxicity when exposed to fine SiO(2) for the same time and dose. A549 cells had particles clustered on the surface of the cells. Only a higher dose (5.0 mg/ml) of fine SiO(2) resulted in a significant cytotoxicity to A549 cells. Most importantly, both cell types showed minimal cytotoxicity following exposure to fine Al(2)O(3). Overall, this study suggests differential cellular toxicity associated with exposure to fine mineral dust particles.

Lunar soil simulants alter macrophage survival and function

“…Our results reveal that although macrophages ingest lunar simulants and alter pro‐ and anti‐inflammatory gene and protein expression, the simulants also induce some degree of cell death. Our results are in agreement with other studies that have reported that exposure to quartz and JSC‐1 (a previously employed simulant similar in chemical and physical properties to JSC‐1A) (Ray et al, ) lead to apoptosis in macrophages (Jordan et al, ; Latch et al, ). Cell death caused by exposure to these simulants could possibly be due to ROS triggered by the simulants (Kaur et al, ), as it is established that ROS cause oxidative stress and apoptosis (Devasagayam et al, ).…”

“…Owing to limited availability of soil samples from the Moon's surface, previous studies have used lunar simulants derived from Earth as substitutes for lunar regolith (Caston, Luc, Hendrix, Hurowitz, & Demple, ; Harrington et al, ; Hendrix, Port, Hurowitz, & Schoonen, ; Jordan, Verhoff, Morgan, & Fischer, ; Kaur, Rickman, & Schoonen, ; Latch et al, ; Loftus et al, ). Here, we focus on seven simulants: quartz (SiO 2 ), JSC‐1A, agglutinated JSC‐1A, CSMCL‐F, NU‐LHT‐2M, agglutinated NU‐LHT‐2M and anatase (TiO 2 ).…”

Free-Radical Chemistry as a Means to Evaluate Lunar Dust Health Hazard in View of Future Missions to the Moon

“…The potential toxicity of lunar dust has been investigated in vitro and in vivo by using a sample of real lunar dust from an Apollo mission and several lunar dust simulants made of terrestrial rocks (Latch et al, 2008;Jordan et al, 2009;Cain, 2010;Loftus et al, 2010;Krisanova et al, 2013;Lam et al, 2013). The mineral composition of lunar dust, which is mainly formed by vitreous and agglutinated particles, does not explain per se the detrimental effects observed on Apollo's crew.…”

Size-dependent and shape-dependent algal toxicity of Aluminum oxide nanoparticles

“…Jacqueline et al (2009) have used 0.7 μm Al 2 O 3 and 1.6 μm SiO 2 to assess the cellular uptake and cellular toxicity of lunar dust particle analogs. According to the results, two type of cells showed minimal cytotoxicity exposure to Al 2 O 3 [3] . Wang et al (2009) characterized the toxicity and behavior of nanoparticles and bulk metal oxide ZnO, Al 2 O 3 and TiO 2 to C.elegans in an aqueous medium.…”