In Vivo Exposure to Inorganic Arsenic Alters Differentiation-Specific Gene Expression of Adipose-Derived Mesenchymal Stem/Stromal Cells in C57BL/6J Mouse Model

Abstract

The number of mesenchymal stem cell (MSC) therapeutic modalities has grown in recent years. Adipose-derived mesenchymal stem/stromal cells (ASCs) can be isolated and expanded relatively easily as compared with their bonemarrow counterparts, making them a particularly promising source of MSCs. And although the biological mechanisms surrounding ASCs are actively being investigated, little is known about the effects that in vivo environmental exposures might have on their ability to properly differentiate. Therefore, we hypothesized that ASCs isolated from mice exposed to inorganic arsenic (iAs) would have an altered response towards adipogenic, osteogenic, and/or chondrogenic differentiation. To test this hypothesis, C57BL/6J male mice were provided drinking water containing 0, 300, or 1000 ppb iAs. ASCs were then isolated and differentiated, which was assessed by immunocytochemistry and real-time quantitative PCR (RT-qPCR). Our results showed that total urinary arsenic equilibrated within 1 week of exposure to iAs and was maintained throughout the study. ASCs isolated from each exposure group maintained differentiation capabilities for each lineage. The magnitude of differentiation-specific gene expression, however, appeared to be concentration dependent. For osteogenesis and chondrogenesis, differentiation-specific gene expression decreased, whereas adipogenesis showed a biphasic response with an initial decrease followed by an increase in adipogenic-related gene expression following iAs exposure. These results suggest that the level in which differentiation-specific genes are induced within these stromal cells might be sensitive to environmental contaminants. These findings highlight the need to take into account potential environmental exposures prior to selecting stromal cell donors, so ASCs can achieve optimal efficiency in regenerative therapy applications.

Adipotropic effects of heavy metals and their potential role in obesity

“…It is proposed that the effects of heavy metal exposure on adipose tissue is biphasic ( Figure 1 ), varying from increased adipogenesis at low-dose exposure to inhibition of adipose tissue differentiation at higher doses, as demonstrated for Hg 21 , 22 , Cd 55 , 56 , 58 , 59 , and As 41 . However, direct dose-response analysis was performed only for the latter 41 . Similar patterns of biological action were shown to underlie the hermetic effect of chemical substances, including heavy metals and metal nanoparticles 60 .…”

“…Of interest, an inverse association between As dose and adipogenic response was reported by Shearer et al . (2017) 41 . Particularly, oral exposure to 300 ppb inorganic As in male C57BL/6J mice resulted in a significant decrease in the expression of adipocyte-specific genes in isolated adipose-derived mesenchymal stem/stromal cells (ASCs), whereas ASCs obtained from mice exposed to a higher dose (1000 ppb) were characterized by a significant increase in adiponectin, leptin, and FABP4 expression, indicative of a biphasic response of adipogenesis to inorganic As exposure 41 .…”

Effects of environmental stressors on stem cells

“…In embryonic mouse SCs, As inhibited differentiation into neurons and myotubes[14]. Differentiation, specifically osteogenesis and chondrogenesis, was also decreased in murine adipose-derived MSCs (AD-MSCs) after exposure to inorganic As[15]. In human induced pluripotent SCs, As exposure was shown to create a dose-dependent sequence of morphology changes, a decrease in viability, and induced genotoxicity[16].…”