An in vitro approach to determine the human relevance of anti-spermatogenic effects of 4-methylmorpholine 4-oxide, monohydrate (NMMO) in rat reproductive toxicity studies.

Reduced sperm counts have been observed in male rats in an extended one generation reproductive toxicity study (EOGRTS, OECD 443) following repeated administration of 300 mg/kg/day N-Methylmorpholine N-oxide (NMMO). However, no adverse effects on reproductive organs have been reported in studies conducted with NMMO, and the mode of action (MOA) for the effects of NMMO on spermatogenesis is unknown, which complicates the interpretation of these data for human risk assessment. Here, a New Approach Method (NAM) strategy was used to evaluate NMMO MOA and compare interspecies susceptibility for anti-spermatogenic effects using organotypic in vitro assays combined with in vitro metabolism and in vitro to in vivo extrapolation (IVIVE) biokinetic modeling to compare predicted oral equivalent doses (OEDs) in human and rat.

Blastocyst development after fertilization with in vitro spermatids derived from nonhuman primate embryonic stem cells.

Objective: To demonstrate that functional spermatids can be derived in vitro from nonhuman primate pluripotent stem cells.

Design: Green fluorescent protein-labeled, rhesus macaque nonhuman primate embryonic stem cells (nhpESCs) were differentiated into advanced male germ cell lineages using a modified serum-free spermatogonial stem cell culture medium. In vitro-derived round spermatid-like cells (rSLCs) from differentiated nhpESCs were assessed for their ability to fertilize rhesus oocytes by intracytoplasmic sperm(atid) injection.