PhD student at the University of Siena University of Siena Siena, Toscana, Italy
Abstract: Environmental pollutants, like PFOS, interfere with endocrine and developmental processes, posing significant risks to reproductive health. During early embryogenesis, primordial germ cells, the precursors of sperm and eggs, are specified from epiblast cells, a tightly regulated process essential for gametogenesis. In vitro, pluripotent stem cells can be directed into human primordial germ cell-like cells (hPGCLCs), providing an invaluable model to study early germline development. Although PFOS exposure has been associated with reproductive toxicity, its specific impact on early human germline remains unclear. Addressing this knowledge gap, we evaluated the dose-dependent effects of PFOS (7–700 nM; relevant exposure doses for humans) on the specification of hPGCLCs and embryoid body (EB) development, leveraging two human induced pluripotent stem cells (hiPSCs) lines (CTRL14, female; KICO, male) over a nine-day differentiation protocol. Maintenance and growth of both female and male hiPSC lines were not affected by PFOS exposure when compared with controls. However, a significant reduction in development was observed in EBs generated from the CTRL14 hiPSC line and exposed to PFOS. In contrast, the KICO hiPSC line originated EBs with stable development regardless of PFOS exposure. Moreover, FACS analysis showed an increase in the percentage of hPGCLCs following PFOS treatment in both lines. This increase was more pronounced in the CTRL14 line compared to KICO. Immunofluorescence staining revealed co-expression of hPGCLC markers SOX17, TFAP2C and OCT4, thus validating the specification process. These findings indicate that PFOS exposure alters normal EB development and increases hPGCLC specification, suggesting disruptions in the tightly regulated processes governing early germline formation. Ongoing transcriptomic analyses via bulk RNA sequencing will elucidate the molecular mechanisms underlying these phenotypes, focusing on the transcriptome of the early germline. By demonstrating PFOS's disruptive effects on early germline specification, this study highlights critical reproductive health risks associated with environmental toxicants and emphasizes the urgent need for stricter environmental regulations to mitigate the impact of persistent pollutants on future generations.
Funding Source: This study was supported by the Swedish Research Council, the Birgitta and Carl-Axel Rydbeck Foundation and the Department of Molecular and Developmental Medicine from the University of Siena.
