Reproductive and developmental toxicity screening of bisphenol F by oral gavage in rats.

Bisphenol F (BPF, 4,4'-methylenediphenol) has recently been selected as an alternative to bisphenol A (BPA), which is used in the manufacturing of polycarbonates and epoxy resins. This study aimed to investigate the general, and reproductive/developmental effects of BPF. Therefore, BPF at dose levels of 0, 1, 5, 20, and 100 mg/kg/day was administered daily by oral gavage to Sprague-Dawley rats during the pre-mating, mating, gestation, and early lactation periods, and reproductive and developmental toxicities including general systemic toxicities were investigated. A decrease in body weight and food consumption was observed in the female rats treated with BPF at 20 and 100 mg/kg/day during the pre-mating and gestation periods. Additionally, gamma glutamyl transpeptidase levels were increased in the female rats administered 100 mg/kg/day. At 100 mg/kg/day, ovarian weight decreased and vaginal mucification increased according to a necropsy and histopathological examination, respectively. Moreover, the number of implantation sites and litter size decreased at 100 mg/kg/day. However, no significant BPF-related changes were observed in the male rats. Based on the results of this study, the no-observed-adverse-effect levels (NOAELs) of BPF for general systemic and reproductive effects were 5 and 20 mg/kg/day, respectively.

Functional Characterization of Endothelial Cells Differentiated from Porcine Epiblast Stem Cells.

Endothelial cells (ECs), lining blood vessels' lumen, play an essential role in regulating vascular functions. As multifunctional components of vascular structures, pluripotent stem cells (PSCs) are the promising source for potential therapeutic applications in various vascular diseases. Our laboratory has previously established an approach for differentiating porcine epiblast stem cells (pEpiSCs) into ECs, representing an alternative and potentially superior cell source. However, the condition of pEpiSCs-derived ECs growth has yet to be determined, and whether pEpiSCs differentiate into functional ECs remained unclear. Changes in morphology, proliferation and functional endothelial marker were assessed in pEpiSCs-derived ECs in vitro. pEpiSCs-derived ECs were subjected to magnetic-activated cell sorting (MACS) to collect CD-31+ of ECs. We found that sorted ECs showed the highest proliferation rate in differentiation media in primary culture and M199 media in the subculture. Next, sorted ECs were examined for their ability to act as typical vascular ECs through capillary-like structure formation assay, Dil-acetylated low-density lipoprotein (Dil-Ac-LDL) uptake, and three-dimensional spheroid sprouting. Consequently, pEpiSCs-derived ECs function as typical vascular ECs, indicating that pEpiSC-derived ECs might be used to develop cell therapeutics for vascular disease.

Bis-diamine administration during pregnancy induces developmental and reproductive toxicities in rats.

BACKGROUND: Bis-diamine was developed as amebicidal and male contraceptive agents; however, it is also reported to induce characteristic congenital heart defects especially in the cardiac conotruncal area of rats. Because of its characteristic congenital heart defects, bis-diamine-induced animal models can be used for studying congenital heart defects. However, comprehensive toxicological information regarding bis-diamine-induced congenital heart defects in this animal model is not available. METHODS: In this study, we investigated and characterized an animal model for bis-diamine-induced congenital heart defects. A single dose of 200-mg bis-diamine was administered by oral gavage to pregnant rats on gestation day 10, and then observed the representative toxicological endpoints for general systemic health of pregnant rats, embryo-fetal development, and parturition. RESULTS: Characteristic congenital heart defects and other birth defects similar to DiGeorge syndrome were observed in bis-diamine-administered pregnant rats. In addition, developmental and reproductive toxicity findings, including increased postimplantation loss, decreased fetal weight, increased perinatal death, and increased gestation period, were observed in bis-diamine-administered pregnant rats. In particular, these developmental and reproductive toxicities were observed without maternal toxicity findings. CONCLUSION: These results will be useful to use this animal model for further studies in congenital heart defects, cardiovascular defects, and understanding their mechanisms.

Prenatal developmental toxicity study of 2,4-dichlorobenzyl alcohol in rats.

Sore throat lozenges, which are over-the-counter drugs, contain 2,4-dichlorobenzyl alcohol (DCBA) as the primary ingredient. However, comprehensive data on the prenatal developmental toxicity of DCBA is limited. Therefore, this study was conducted to determine the effects of DCBA on pregnant rats and prenatal development. Sprague-Dawley rats were administered different doses of DCBA (0, 25, 100, 400, and 800 mg/kg/day) daily via an oral gavage from gestation day (GD) 6-19. Thereafter, all the live dams were sacrificed on GD 20, and caesarean sections were conducted. Live fetuses and their placenta were weighed and then examined for external, visceral, and skeletal malformations and variations. Based on the results obtained, dams at 800 mg/kg/day showed systemic toxicities, including a decrease in body weight and food consumption, and liver changes. Additionally, this treatment induced decreases in fetal and placental weights, as well as the increased incidence of retarded ossifications and full supernumery rib, and the decreased number of ossification centers. Therefore, based on these findings, the no-observed-adverse-effect level of DCBA was determined to be 400 mg/kg/day for dams and prenatal development.

Adverse postnatal developmental effects in offspring from humidifier disinfectant biocide inhaled pregnant rats.

Inhalation exposure to polyhexamethylene guanidine phosphate (PHMG-P), one of the primary biocides used in humidifier disinfectants, caused a fatal pulmonary disease in Korea. Pregnant women were also exposed to PHMG-P, and subsequent studies showed that PHMG-P inhalation during pregnancy adversely affects their health and embryo-fetal development. However, the postnatal developmental effects after birth on prenatally PHMG-P-exposed offspring have not yet been investigated. Therefore, in this study, we aimed to examine the postnatal development of prenatally PHMG-P-exposed offspring. Pregnant rats (22 or 24 females per group) were exposed to PHMG-P during pregnancy in a whole-body inhalation chamber at the target concentrations of 0, 0.14, 1.60, and 3.20 mg/m3. After parturition, the prenatally exposed offspring were transferred to non-exposed surrogate mothers to minimize the secondary effects of severe maternal toxicities. Postnatal development of offspring was then examined with a modified extended one-generation reproductive toxicity study design. At 3.20 mg/m3 PHMG-P, increased perinatal death rates and decreased viability index (postnatal survival of offspring between birth and postnatal day 4) were observed. In addition, F1 offspring had lower body weight at birth that persisted throughout the study. PHMG-P-exposed pregnant rats also had severe systemic toxicities and increased gestation period. At 1.60 mg/m3 PHMG-P, a decreased viability index was also observed with systemic toxicities of PHMG-P-exposed pregnant rats. These results indicate that prenatal PHMG-P exposure adversely affects the offspring's future health and could be used for human risk assessment.

The Presence or Absence of Alkaline Phosphatase Activity to Discriminate Pluripotency Characteristics in Porcine Epiblast Stem Cell-Like Cells.

Porcine embryonic stem cells (pESCs) would provide potentials for agricultural- and biotechnological-related applications. However, authentic pESCs have not been established yet because standards for porcine stem cell-specific markers and culture conditions are not clear. Therefore, the present study reports attempts to derive pluripotent epiblast stem cells either from in vitro or in vivo derived porcine embryos. Nine epiblast cell lines (seven lines from Berkshire and two lines from Duroc) could only be isolated from day 9- to 9.5-old in vivo derived early conceptuses. Pluripotency features were analyzed in relation to the presence or absence of alkaline phosphatase (AP) activity. Interestingly, the mRNA expression of several marker genes for pluripotency or epiblast was different between putative epiblast stem cells of the two groups [AP-positive (+) pEpiSC-like cell 2 line and AP-negative (-) pEpiSC-like cell 8 line]. For example, expressions of OCT-3/4, NANOG, SOX2, c-MYC, FGF2, and NODAL in AP-negative (-) porcine epiblast stem cell (pEpiSC)-like cells were higher than those in AP-positive (+) pEpiSC-like cells. Expression of surface markers differed between the two groups to some extent. SSEA-1 was strongly expressed only in AP-negative (-) pEpiSC-like cells, whereas AP-positive (+) pEpiSC-like cells did not express. In addition, we report to have some differences in the in vitro differentiation capacity between AP-positive (+) and AP-negative (-) epiblast cell lines. Primary embryonic germ layer markers (cardiac actin, nestin, and GATA 6) and primordial germ cell markers (Dazl and Vasa) were strongly expressed in embryoid bodies (EBs) aggregated from AP-negative (-) pEpiSC-like cells, whereas EBs aggregated from AP-positive (+) pEpiSCs did not show expression of primary embryonic germ layers and primordial germ cell markers except GATA 6. These results indicate that pEpiSC-like cells display different pluripotency characteristics in relation to AP activity.

Serial blood sampling effects in rat embryo-fetal development studies for toxicokinetics.

Serial blood sampling for toxicokinetics is generally conducted in regulatory embryo-fetal development (EFD) studies in rats. EFD studies are designed to detect the potential adverse effects of pharmaceuticals on pregnant females and their fetuses; this information is useful for understanding the relationships between systemic exposure levels and toxicity profiles. However, additional satellite pregnant females are needed for toxicokinetics because comprehensive information regarding the potential impact of serial blood sampling on pregnant females is scarce. Here, in this study, we investigated the potential impact of serial blood sampling in pregnant female rats using a typical EFD study design. Additionally, we investigated the additional endpoints (clinical pathology, organ weights, and histopathology) that were deemed likely to be sensitive to blood sampling. Results indicated that serial blood sampling in pregnant females induced physiological adaptive changes and did not affect the general endpoints in EFD studies. Nevertheless, inclusion of satellite groups in EFD studies may be a more prudent approach considering the physiological changes in pregnant females and potential off-target effects of candidate pharmaceuticals. These results provide background information on the impact of serial blood sampling in pregnant females and will be useful to design the regulatory EFD studies.

Endothelial Cells Differentiated from Porcine Epiblast Stem Cells.

Pluripotent stem cells (PSCs) have the ability of self-renewal that can retain the characteristics of the mother cell, and of pluripotency that can differentiate into several body types. PSCs typically include embryonic stem cells (ESCs) derived from the inner cell mass of the preimplantation embryo, and epiblast stem cells (EpiSCs) derived from the epiblast of postimplantation embryo. Although PSCs are able to be used by differentiation into endothelial cells as a potential treatment for vascular diseases, human ESCs and induced PSCs (iPSCs) are followed by ethical and safety issues. Pigs are anatomically and physiologically similar to humans. Therefore, the goal of this study was to establish an efficient protocol that differentiates porcine EpiSCs (pEpiSCs) into the endothelial cells for applying the treatment of human vascular diseases. As a result, alkaline phosphatase (AP)-negative (-) pEpiSCs cultured in endothelial cell growth basal medium-2 (EBM-2) differentiation medium in association with 50 ng/mL of vascular endothelial growth factor (VEGF) for 8 days were changed morphologically like the feature of endothelial cells, and expression of pluripotency-associated markers (OCT-3/4, NANOG, SOX2, and C-MYC) in porcine differentiated cells was significantly decreased (p < 0.05). Additionally, when pEpiSCs were cultured in EBM-2 + 50 ng/mL of VEGF, porcine differentiated cells represented a common endothelial cell marker positive (CD31+) but monocytes and lymphocytes marker negative (CD45-). Therefore, these results indicated that pEpiSCs cultured in EBM-2 + 50 ng/mL of VEGF culture condition were efficiently differentiated into endothelial cells for the treatment of blood vessel diseases.

A Rho-Associated Coiled-Coil Containing Kinase Inhibitor, Y-27632, Improves Viability of Dissociated Single Cells, Efficiency of Colony Formation, and Cryopreservation in Porcine Pluripotent Stem Cells.

The establishment of porcine epiblast stem cells (pEpiSCs) and induced pluripotent stem cells (piPSCs) derived from diametrical derivations is of great importance in developing biomedical models. However, pEpiSCs and piPSCs have been technically much harder to culture than mouse embryonic stem cells, showing problematic properties such as spontaneous differentiation and apoptosis after cryopreservation. Therefore, we demonstrated that Y-27632 as a Rho-associated coiled-coil containing kinase inhibitor could prevent dissociated pEpiSCs and piPSCs from undesirable differentiation and apoptosis in cryopreservation protocols. pEpiSC 2, 8 lines, Sendai virus-induced pluripotent stem cells (Sev-iPSCs), and lentivirus-induced pluripotent stem cells were cultured with 10 µM Y-27632 before collecting dissociated cells retrieved from colonies using various enzymes. Dissociated single cells were transferred into freezing mediums (open pulled straw vitrification, STEM-CELLBANKER® (SCB), 10% dimethylsulfoxide in serum) for cryopreservation. The rates of viability and colony formation obtained from dissociated porcine stem cells after freezing/thawing were examined in the presence of Y-27632. The characteristics of pluripotency and in vitro differentiation were also examined in these stem cells treated with Y-27632 after cryopreservation. As a result, the viability and efficiency of colony formation of dissociated pEpiSCs (2, 8 lines) and Sev-iPSCs treated with 10 µM Y-27632 using the SCB cryopreservation protocol were significantly increased when compared with those of nontreated Y-27632 (p < 0.05). Pluripotency genes (OCT-3/4, NANOG, and SOX2) were positively expressed in Y-27632-treated porcine pluripotent stem cells. Also, in vitro differentiation of these stem cells was successfully induced in the presence of 10 µM Y-27632. These results indicated that treatment of Y-27632 for single-cell dissociation and the SCB cryopreservation protocol could facilitate handling porcine pluripotent stem cells and provide the widespread use of these stem cells.

Activation-Induced Cytidine Deaminase Induces DNA Demethylation of Pluripotency Genes in Bovine Differentiated Cells.

Activation-induced cytidine deaminase (AID) is the only enzyme that has been suggested as a putative DNA demethylase in mammals. However, very little is known about AID function as DNA demethylase of bovine differentiated cells toward pluripotent state. To investigate the effect of AID on DNA demethylation, bovine AID complementary DNAs were transfected into bovine differentiated cells, which were mostly methylated in the promoter regions of pluripotency genes. As a result, AID-transfected bovine cells started to transform into colonies at day 19 of transfection. The colonies derived from the transfected cells showed positive alkaline phosphatase (AP) staining and expression of pluripotency genes (OCT-3/4, NANOG, SOX2) and pluripotency-related antigens (SSEA-4, TRA1-60, TRA1-81), which have been widely used to characterize human embryonic stem cells. In particular, the levels of OCT-3/4 and NANOG expression were significantly increased in the AID-transfected cells when compared with the control and empty vector-transfected cells (p < 0.05). Finally, DNA demethylation in the promoter regions of pluripotency genes (OCT-3/4, NANOG) was significantly increased compared with the control (p < 0.05). These results demonstrate that the induction of the AID gene into bovine differentiated cells improves DNA demethylation and expression of pluripotency genes.

Siberian Sturgeon Oocyte Extract Induces Epigenetic Modifications of Porcine Somatic Cells and Improves Developmental Competence of SCNT Embryos.

Somatic cell nuclear transfer (SCNT) has generally demonstrated that a differentiated cell can convert into a undifferentiated or pluripotent state. In the SCNT experiment, nuclear reprogramming is induced by exposure of introduced donor nuclei to the recipient cytoplasm of matured oocytes. However, because the efficiency of SCNT still remains low, a combination of SCNT technique with the ex-ovo method may improve the normal development of SCNT embryos. Here we hypothesized that treatment of somatic cells with extracts prepared from the germinal vesicle (GV) stage Siberian sturgeon oocytes prior to their use as nuclear donor for SCNT would improve in vitro development. A reversible permeability protocol with 4 µg/mL of digitonin for 2 min at 4°C in order to deliver Siberian sturgeon oocyte extract (SOE) to porcine fetal fibroblasts (PFFs) was carried out. As results, the intensity of H3K9ac staining in PFFs following treatment of SOE for 7 h at 18°C was significantly increased but the intensity of H3K9me3 staining in PFFs was significantly decreased as compared with the control (p<0.05). Additionally, the level of histone acetylation in SCNT embryos at the zygote stage was significantly increased when reconstructed using SOE-treated cells (p<0.05), similar to that of IVF embryos at the zygote stage. The number of apoptotic cells was significantly decreased and pluripotency markers (Nanog, Oct4 and Sox2) were highly expressed in the blastocyst stage of SCNT embryos reconstructed using SOE-treated cells as nuclear donor (p<0.05). And there was observed a better development to the blastocyst stage in the SOE-treated group (p<0.05). Our results suggested that pre-treatment of cells with SOE could improve epigenetic reprogramming and the quality of porcine SCNT embryos.