Endocrine disruptions induced by environmental toxicants have placed an immense burden on society to properly diagnose, treat and attempt to alleviate symptoms and disease. Environmental exposures during critical periods of development can permanently reprogram normal physiological responses, thereby increasing susceptibility to disease later in life - a process known as developmental reprogramming. During development, organogenesis and tissue differentiation occur through a continuous series of tightly-regulated and precisely-timed molecular, biochemical and cellular events. Humans may encounter endocrine disrupting chemicals (EDCs) daily and during all stages of life, from conception and fetal development through adulthood and senescence. Though puberty and perimenopausal periods may be affected by endocrine disruption due to hormonal effects, prenatal and early postnatal windows are most critical for proper development due to rapid changes in system growth. Developmental reprogramming is shown to be caused by alterations in the epigenome. Development is the time when epigenetic programs are ‘installed’ on the genome by ‘writers’, such as histone methyltransferases (HMTs) and DNA methyltransferases (DNMTs), which add methyl groups to lysine and arginine residues on histone tails and to CpG sites in DNA, respectively. A number of environmental compounds, referred to as estrogenic endocrine disruptors (EEDs), are able to bind to estrogen receptors (ERs) and interfere with the normal cellular development in target tissues including the prostate and uterus. These EEDs, including diethylstilbestrol (DES), bisphenol A (BPA), and genistein (a phytoestrogen derived from soybeans), have been implicated in the malformation of reproductive organs and later development of disease. Due to the lack of fully understanding the underlying mechanisms of how environmental toxicants and their level of exposure affect the human genome, it can be challenging to create clear clinical guidance to address the potential health effects of lower-level exposures commonly experienced within the general population. In addition, human studies concerning environmental exposures are limited in feasibility by ethical concerns for human safety. Therefore, studies in animal models provide great opportunities to reveal links between early-life exposure to EDCs and related diseases. It has been shown that developmental exposure to EDCs, such as diethylstilbestrol (DES) and genistein, during reproductive tract development increases the incidence, multiplicity and overall size of uterine fibroids in the Eker rat model, concomitantly reprogramming estrogen-responsive gene expression. Importantly, EDC exposure represses enhancer of zeste 2 (EZH2) and reduces levels of the histone 3 lysine 27 trimethylation (H3K27me3) repressive mark through Estrogen receptor / Phosphatidylinositide 3-kinases / Protein kinase B non-genomic signaling in the developing uterus. More recent research identified a developmental reprogramming target, Scbg2a1 gene, whose epigen...

Regulation of myometrial functions during pregnancy has been considered the result of the integration of endocrine and mechanical signals. Nevertheless, uterine regeneration is poorly understood, and the cellular source within the gravid uterus is largely unexplored.In this study, we isolated and quantified the myometrial stem cells (MSC) population from pregnant female Eker rat uteri, by using Stro1/CD44 surface markers. We demonstrated that prior parity significantly increased the percentage of Stro1+/CD44+ MSC because of injured tissue response. Interestingly, we established that Stro1+/CD44+ MSC respond efficiently to physiological cues when they were treated in vitro under different dose-dependent pregnant rat serum.Previous studies reveal strong regulatory links between O2 availability and stem cell function. Based on these premises, cell proliferation assays showed that isolated Stro1+/CD44+ MSC possess a higher proliferative rate under hypoxic versus normoxic conditions. We also detected a total of 37 upregulated and 44 downregulated hypoxia-related genes, which were differentially expressed in Stro1+/CD44+ MSC, providing an alternative approach to infer into complex molecular mechanisms such as energy metabolism, inflammatory response, uterine expansion, and/or remodeling.Since these cells preferentially grow under low oxygen conditions, we propose that the increase of the rat uterus during pregnancy involves myometrial oxygen consumption, thereby enhancing MSC proliferation. Moreover, pregnancy-induced mechanical stretching results in hypoxic conditions, ultimately creating an environment that promotes stem cell proliferation and further uterine enlargement, which is essential for a successful pregnancy. In summary, all of these data support that rat Stro1+/CD44+ MSC contribute to uterine enlargement during pregnancy.

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OBJECTIVE: To investigate uterine expression pattern and functional regulation of FoxO1 during peri-implantation period and to assess embryo implantation dynamics when FoxO1 is functionally blocked in mice.DESIGN: Experimental mouse models including; i) natural pregnancy, ii) pseudopregnancy, iii) artificial decidualization, and iv) pre-implantation stage bioneutralization (blockage) of the uterine FoxO1.MATERIALS AND METHODS: Uterine tissues of estrous phase and pregnancy (1-8 days) were obtained from 6 weeks old BALB/C female mice. Expression of FoxO1 was determined by immunohistochemistry (n¼6 in each group) and western blotting (n¼3) during peri-implantation period. Implantation sites and embryo morphology were evaluated after functional blockage of FoxO1 (n¼5). Group comparisons for H-Score and western blot analyses were done by one-way ANOVA followed by the Tukey test employing GraphPad Prism 6 software. P values < 0.05 among different groups were considered significant.RESULTS: FoxO1 expression was observed in a spatiotemporal manner in peri-implantation uterus in mice. Its expression in luminal and glandular epithelium increased significantly at the time of implantation (p<0.001). Number of embryo implantation sites decreased significantly after bioneutralization of uterine FoxO1 at pre-implantation stage (p< 0.0001). Evaluation of FoxO1 expression in pseudopregnancy and artificial decidualization groups revealed that its expression appeared to be dependent on steroid hormones but independent from the presence of the blastocyst.CONCLUSIONS: FoxO1 signaling seems to be important for uterine receptivity and implantation in mice. Moreover, studies are ongoing in human regarding the evaluation of expression patterns of FoxO1 in pre-receptive and receptive endometrium in our laboratory. A better understanding of the molecular basis governing both early pregnancy and uterine receptivity will help to improve the outcome of natural pregnancy and pregnancy conceived via assisted reproductive techniques.

A defined, feeder-free, serum-free system to generate in vitro hematopoietic progenitors and differentiated blood cells from hESCs and hiPSCs. PLoS One. 2011;6(3):e17829. 16. Dorn I, Klich K, Arauzo-Bravo MJ, et al. Erythroid differentiation of human induced pluripotent stem cells is independent of donor cell type of origin. Haematologica. 2015;100(1):32-41. 17. Kim K, Zhao R, Doi A, et al. Donor cell type can influence the epigenome and differentiation potential of human induced pluripotent stem cells.