Assessment of the impact of direct in vitro PFAS treatment on mouse spermatozoa

Poly- and perfluoroalkyl substances (PFAS) are synthetic environmentally persistent chemicals. Despite the phase out of specific PFAS, their inherent stability has resulted in persistent and ubiquitous environmental contamination. PFAS bioaccumulation has been reported globally with omnipresence in most populations wherein they have been associated with a range of negative health effects; with some PFAS chemicals exhibiting strong associations with increased instances of testicular cancer and reductions in overall semen quality. To elucidate the biological basis of such effects, we employed an acute in vitro exposure model in which the spermatozoa of adult male mice were exposed to a cocktail of PFAS chemicals at environmentally relevant concentrations. We hypothesized that direct PFAS treatment of spermatozoa would induce ROS generation and compromise the functional profile and DNA integrity of exposed cells. Despite this, post-exposure functional testing revealed that short-term PFAS exposure (3 hours) did not elicit a cytotoxic effect, nor did it overtly influence the functional profile, capacitation rate or the in vitro fertilization ability of spermatozoa. PFAS treatment of spermatozoa did, however, result in a significant delay in the developmental progression of the day 4 pre-implantation embryos they sired in vitro. This developmental delay could not be attributed to a loss of sperm DNA integrity, DNA damage, or elevated levels of intracellular reactive oxygen species. When considered together, the results presented here raise the intriguing prospect that spermatozoa exposed to a short term PFAS exposure period potentially harbor an alternate stress signal that is delivered to the embryo upon fertilization.