Naphthenic Acid Mixtures from Oil Sands Process-Affected Water Enhance Differentiation of Mouse Embryonic Stem Cells and Affect Development of the Heart

Extraction of petrochemicals from the surface mining of oil sand deposits results in generation of large volumes of oil sands process-affected water (OSPW). Naphthenic acids (NA) are generally considered to be among the most toxic components of OSPW. Previous studies have shown that NAs are toxic to aquatic organisms, however knowledge of their effects on mammalian health and development is limited. In the present study, we evaluated the developmental effects of an NA extract prepared from fresh OSPW on differentiating mouse embryonic stem cells (ESC). We found that treatment of differentiating cells with the NA extract at noncytotoxic concentrations alters expression of various lineage specification markers and development of the heart. Notably, expression of cardiac specific markers such as Nkx2.5, Gata4, and Mef2c were significantly up-regulated. Moreover, exposure to the NA extract enhanced differentiation of embryoid bodies and resulted in the early appearance of spontaneously beating clusters. Interestingly, exposure of undifferentiated mouse ESCs to the NA extract did not change the expression level of pluripotency markers (i.e., Oct4, Nanog, and Sox2). Altogether, these data identify some of the molecular pathways affected by components within this NA extract during differentiation of mammalian cells.