Assessing reproductive toxicity of two environmental toxicants with a novel in vitro human spermatogenic model

Abstract

Environmental influences and insults by reproductive toxicant exposure can lead to impaired spermatogenesis or infertility. Understanding how toxicants disrupt spermatogenesis is critical for determining how environmental factors contribute to impaired fertility. While current animal models are available, understanding of the reproductive toxic effects on human fertility requires a more robust model system. We recently demonstrated that human pluripotent stem cells can differentiate into spermatogonial stem cells/spermatogonia, primary and secondary spermatocytes, and haploid spermatids; a model that mimics many aspects of human spermatogenesis. Here, using this model system, we examine the effects of 2-bromopropane (2-BP) and 1–2, Dibromo-3-chloropropane (DBCP) on in vitro human spermatogenesis. 2-BP and DBCP are non-endocrine disrupting toxicants that are known to impact male fertility. We show that acute treatment with either 2-BP or DBCP induces a reduction in germ cell viability through apoptosis. 2-BP and DBCP affect viability of different cell populations as 2-BP primarily reduces spermatocyte viability whereas DBCP exerts a much greater effect on spermatogonia. Acute treatment with 2-BP or DBCP also reduces the percentage of haploid spermatids. Both 2-BP and DBCP induce reactive oxygen species (ROS) formation leading to an oxidized cellular environment. Taken together, these results suggest that acute exposure with 2-BP or DBCP causes human germ cell death in vitro by inducing ROS formation. This system represents a unique platform for assessing human reproductive toxicity potential of various environmental toxicants in a rapid, efficient, and unbiased format.

RETRACTED ARTICLE: In vitro derivation of mammalian germ cells from stem cells and their potential therapeutic application

“…We have demonstrated that bovine testicular iPSCs are useful for screening the toxicity of environmental disruptors, such as phthalate esters by examining their effects on the maintenance of stemness and pluripotency, and for identifying signaling pathways that might be affected by disruptors [ 36 , 37 ]. Modeling spermatogenesis in vitro has been employed to examine the effects of environmental toxicants on the differentiation process to spermatozoa [ 38 ]. This represents a unique platform for assessing the toxicity of various environmental disruptors on human reproductive functions in a rather straightforward manner.…”

Transgenerational Genetic Effect of Trichloroethane (TCE) on Phenotypic Variation of Acrosomal Proteolytic Enzyme and Male Infertility Risk

“…Numerous environmental toxicants (e.g. cadmium, mercury, bisphenol A (BPA) and dioxin) have been reported to adversely affect spermatogenesis in rodents and humans, which can lead to low sperm count, abnormal sperm morphology and poor semen quality (9)(10)(11).…”

Reproductive toxic agents in work environments and related cases in Korea

“…It has been known to cause reproductive toxicity and developmental disorders in animals, causing oligospermia and testicular atrophy. Male workers exposed to DBCP during the chemical manufacturing process similarly showed testicular toxicity in proportion to the exposure dose [45,46]. Workers exposed to high doses of DBCP had damage to spermatogonia and irreversible azoospermia [47].…”