Understanding the regulatory networks for germ cell fate specification is necessary to developing strategies for improving the efficiency of germ cell production in vitro. In this study, we developed a coupled screening strategy that took advantage of an arrayed bi-molecular fluorescence complementation (BiFC) platform for protein-protein interaction screens and epiblast-like cell (EpiLC)-induction assays using reporter mouse embryonic stem cells (mESCs). Investigation of candidate interaction partners of core human pluripotent factors OCT4, NANOG, KLF4 and SOX2 in EpiLC differentiation assays identified novel primordial germ cell (PGC)-inducing factors including BEN-domain (BEND/Bend) family members. Through RNA-seq, ChIP-seq, and ATAC-seq analyses, we showed that Bend5 worked together with Bend4 and helped mark chromatin boundaries to promote EpiLC induction in vitro. Our findings suggest that BEND/Bend proteins represent a new family of transcriptional modulators and chromatin boundary factors that participate in gene expression regulation during early germline development.
Animals ; Cell Differentiation/genetics* ; Chromatin/metabolism* ; Embryonic Stem Cells ; Germ Cells/metabolism* ; Germ Layers/metabolism* ; Mice

Embryonic stem cells are derived from inner cell mass of the preimplanted blastocyst or from primordial germ cells of the early embryos, with the capacity of unlimited growth and differentiation potential. Embryonic stem cells(ES cells) can differentiate into all kinds of cells and organs under proper condition. Due to this characteristics ES cells have the attractive prospect in basic research, transplantation and gene therapy.
Blastocyst ; cytology ; Cell Differentiation ; Embryonic Stem Cells ; cytology ; Germ Cells ; cytology ; Humans ; Research ; trends

It is not fully clear why there is a higher contribution of pluripotent stem cells (PSCs) to the chimera produced by injection of PSCs into 4-cell or 8-cell stage embryos compared with blastocyst injection. Here, we show that not only embryonic stem cells (ESCs) but also induced pluripotent stem cells (iPSCs) can generate F0 nearly 100% donor cell-derived mice by 4-cell stage embryo injection, and the approach has a "dose effect". Through an analysis of the PSC-secreted proteins, Activin A was found to impede epiblast (EPI) lineage development while promoting trophectoderm (TE) differentiation, resulting in replacement of the EPI lineage of host embryos with PSCs. Interestingly, the injection of ESCs into blastocysts cultured with Activin A (cultured from 4-cell stage to early blastocyst at E3.5) could increase the contribution of ESCs to the chimera. The results indicated that PSCs secrete protein Activin A to improve their EPI competency after injection into recipient embryos through influencing the development of mouse early embryos. This result is useful for optimizing the chimera production system and for a deep understanding of PSCs effects on early embryo development.
Activins ; metabolism ; Animals ; Cells, Cultured ; Embryonic Development ; Germ Layers ; metabolism ; Mice ; Pluripotent Stem Cells ; cytology ; metabolism

Researches on manipulating pluripotent stem cells derived from blastocysts or primordial germ cells (PGCs) have a great advantage for developing innovative technologies in various fields of life science including medicine, pharmaceutics, and biotechnology. Since their first isolation in the mouse embryos(1), stem cells or stem cell-like colonies have been continuously established in the mouse of different strains(21), cattle(2, 3), pig(4, 5), rabbit(6, 7), and human(9). However, full-term development originated from established pluripotent cells, which is an absolute criterion for proving cell pluripotency and differentiation, has only been reported in the mouse(22). Due to technical difficulties, no further progress has been made in the establishment of animal embryonic stem (ES) cell line. Alternatively, the use of embryonic germ (EG) cells was selected to establish an animal stem cell line. EG cells also have pluripotent characteristics, which were proven by morphological assay, intracellular alkaline phosphatase activity, and reactions with cell surface-specific markers. The finding of Labosky et al.(23) on germline chimera development after transfer to embryos clearly proved the pluripotency of EG cells and their similar characteristics with ES cells. Avian transgenesis has an unlimited value in biotechnology industry, since its applicability as a bioreactor has proven to be greater than that of mammalian species(24). In the chicken, EG cells can be extensively utilized instead of ES cells for efficiently inducing transgenesis mediated by germline transmission. Recently, PGCs collected from the embryonic gonad were suggested to be useful in establishing avian stem cells. Technical feasibility and applicability of gonadal PGCs (gPGCs) to germline chimera production were also confirmed(25) and a gPGC culture system to establish EG cells was subsequently developed(15).
Alkaline Phosphatase ; Animals* ; Biological Science Disciplines ; Bioreactors ; Biotechnology ; Blastocyst ; Cell Line ; Chickens ; Chimera ; Embryonic Germ Cells ; Embryonic Stem Cells ; Embryonic Structures ; Gene Transfer Techniques ; Germ Cells ; Gonads ; Mice ; Pluripotent Stem Cells ; Stem Cell Research* ; Stem Cells*

Embryonic stem cells (ESCs) are an emerging source for cell-based therapies aimed at repairing damaged organ tissues; however, the efficiency of directed differentiation is low and refinement of differentiation protocols is hampered by incomplete understanding of the mechanisms involved in this process. To find new compounds which can improve the efficiency of directed differentiation of ESCs to cardiomyocytes, we screened several thousand chemical compounds and identified a promising group. All of the compounds found have a common structure of 1H-pyrrole,2,2'-(phenylmethylene)bis. Here we report the potential mechanism of action for 31002 which showed the strongest activity among the compounds selected. In the presence of 31002, 15 times more cardiomyocytes differentiated from ESCs, i.e., 3.5% to 52% of total differentiated cells. Moreover, the cardiomyocytes showed functional characteristics including rhythmic beating and marker gene expression. 31002 inhibited the down-regulation of genes related to the three germ layers in the late stage of ESCs differentiation, implying that 31002 supports a continuous fate commitment of undifferentiated ESCs to the cardiac lineage by prolonging the three germ layer stages. Therefore, compounds in this group, including 31002, might be useful as directed cardiomyogenic differentiation-inducers to produce cells for use in cell therapy aimed at restoring damaged heart tissue.
Down-Regulation ; Embryonic Stem Cells ; Gene Expression ; Germ Layers ; Heart ; Myocytes, Cardiac ; Tissue Therapy

DNA methylation is one of many epigenetic mechanisms that regulate gene expression in the human body. From the view of epigenetics, there are two phases of development, one for germ cell development and another for embryo development. This review will discuss the basic mechanism of methylation, its role in gene expression, and the role of methylation in embryonic reprogramming. Methylation of genes is very critical to embryo development and should be explored further in order to increase our understanding of development.
DNA ; DNA Methylation ; Embryonic Development ; Epigenomics ; Female ; Gene Expression ; Germ Cells ; Human Body ; Methylation ; Pregnancy

Embryonic stem (ES) cells have potential for use in evaluation of developmental toxicity because they are generated in large numbers and differentiate into three germ layers following formation of embryoid bodies (EBs). In earlier study, embryonic stem cell test (EST) was established for assessment of the embryotoxic potential of compounds. Using EBs indicating the onset of differentiation of mouse ES cells, many toxicologists have refined the developmental toxicity of a variety of compounds. However, due to some limitation of the EST method resulting from species-specific differences between humans and mouse, it is an incomplete approach. In this regard, we examined the effects of several developmental toxic chemicals on formation of EBs using human ES cells. Although human ES cells are fastidious in culture and differentiation, we concluded that the relevancy of our experimental method is more accurate than that of EST using mouse ES cells. These types of studies could extend our understanding of how human ES cells could be used for monitoring developmental toxicity and its relevance in relation to its differentiation progress. In addition, this concept will be used as a model system for screening for developmental toxicity of various chemicals. This article might update new information about the usage of embryonic stem cells in the context of their possible ability in the toxicological fields.
Animals ; Embryoid Bodies ; Embryonic Stem Cells* ; Germ Layers ; Humans* ; Mass Screening ; Mice

Strong proliferative capacity and the ability to differentiate into the derivative cell types of three embryonic germ layers are the two important characteristics of embryonic stem cells. To study whether the mesenchymal stem cells from human fetal bone marrow (hfBM-MSCs) possess these embryonic stem cell-like biological characteristics, hfBM-MSCs were isolated from bone barrows and further purified according to the different adherence of different kinds of cells to the wall of culture flask. The cell cycle of hfBM-MSCs and MSC-specific surface markers such as CD29, CD44, etc were identified using flow cytometry. The expressions of human telomerase reverse transcriptase (hTERT), the embryonic stem cell-specific antigens, such as Oct4 and SSEA-4 were detected with immunocytochemistry at the protein level and were also tested by RT-PCR at the mRNA level. Then, hfBM-MSCs were induced to differentiate toward neuron cells, adipose cells, and islet B cells under certain conditions. It was found that 92.3% passage-4 hfBM-MSCs and 96.1% passage-5 hfBM-MSCs were at G(0)/G(1) phase respectively. hfBM-MSCs expressed CD44, CD106 and adhesion molecule CD29, but not antigens of hematopoietic cells CD34 and CD45, and almost not antigens related to graft-versus-host disease (GVHD), such as HLA-DR, CD40 and CD80. hfBM-MSCs expressed the embryonic stem cell-specific antigens such as Oct4, SSEA-4, and also hTERT. Exposure of these cells to various inductive agents resulted in morphological changes towards neuron-like cells, adipose-like cells, and islet B-like cells and they were tested to be positive for related characteristic markers. These results suggest that there are plenty of MSCs in human fetal bone marrow, and hfBM-MSCs possess the embryonic stem cell-like biological characteristics, moreover, they have a lower immunogenic nature. Thus, hfBM-MSCs provide an ideal source for tissue engineering and cellular therapeutics.
Bone Marrow Cells ; cytology ; Cell Proliferation ; Embryonic Stem Cells ; cytology ; Fetus ; Germ Layers ; cytology ; Humans ; Mesenchymal Stromal Cells ; cytology

Infertility has become a serious disease since it affects 10%-15% of couples worldwide, and male infertility contributes to about 50% of the cases. Notably, a significant decrease occurs in the newborn population by 7.82 million in 2020 compared to 2016 in China. As such, it is essential to explore the effective methods of obtaining functional male gametes for restoring male fertility. Stem cells, including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), spermatogonial stem cells (SSCs), and mesenchymal stem cells (MSCs), possess the abilities of both self-renewal and differentiation into germ cells. Significantly, much progress has recently been achieved in the generation of male germ cells in vitro from various kinds of stem cells under the specified conditions, e.g., the coculturing with Sertoli cells, three-dimensional culture system, the addition of growth factors and cytokines, and/or the overexpression of germ cell-related genes. In this review, we address the current advance in the derivation of male germ cells in vitro from stem cells based on the studies of the peers and us, and we highlight the perspectives and potential application of stem cell-derived male gametes in reproductive medicine.
Humans ; Infant, Newborn ; Male ; Germ Cells ; Embryonic Stem Cells ; Cell Differentiation ; Infertility, Male ; Induced Pluripotent Stem Cells

BACKGROUND: Telomeres are repetitive DNA fragments at the termini of chromosomes functioning as stabilizing elements of the DNA. A ribonucleoprotein polymerase, called telomerase, is responsible for the synthesis of such telomeric repeats in embryo and germ cells. During ontogenesis of most normal human somatic cells, there exists a physiological telomerase repressing mechanism. In contrast, malignant cells are characterized by an unlimited progressive potential. Certain physiological agents, such as all-trans retinoic acid (ATRA), 13-cis retinoic acid (13-cisRA), 1alpha-25 dihydroxy vitamin D3 (VD3) and cytosine arabinoside (Ara-C), promote further differentiation of leukemic cells into mature granulocytes and monocytes and subsequently undergo apoptosis. METHODS: To determine if a potential linkage is present between telomerase regulation and the differentiation of malignant hematopoietic cells, the changes in telomerase activity during the maturation of HL-60 cells induced by ATRA, 13-cisRA, VD3 and Ara-C were investigated. RESULTS: Differentiating agents induce HL-60 cells to differentiate into CD11b+ granulocytes and monocyte/macrophages, respectively. Approximately 98% of HL-60 cells acquired the expression of CD11b+ antigen after ATRA, 13-cisRA or Ara-C treatment for 5 days. After 1 day treatment with differentiating agents, no significant difference in telomerase activity was shown between untreated and treated HL-60 cells. A dramatic inhibition of telomerase activity occurred at 3 days treatment of ATRA compared to untreated HL-60 cells. Longer treatment for 5 days with differentiating agents resulted in further decrease of telomerase activity. However, telomerase activity in HL-60 cells was decreased slightly by the VD3 or Ara-C treatment, even though for 5 days. No evidence of differentiation and slight decrease of telomerase activity were observed in ATRA-treated K-562 cells for 5 days. These decrease of telomerase activity were dependent on the incubation time and dose. CONCLUSION: These data clearly show the role of telomerase activity during the differentiation of HL-60 cells. This in vitro model can be useful for studies of the mechanisms controlling telomerase activity and in the search for physiological telomerase modulators.
Apoptosis ; Cholecalciferol ; Cytarabine ; DNA ; Embryonic Structures ; Germ Cells ; Granulocytes ; HL-60 Cells* ; Humans ; Monocytes ; Ribonucleoproteins ; Telomerase* ; Telomere ; Tretinoin