Low-molecular-weight estrogenic phytoprotein suppresses osteoporosis development through positive modulation of skeletal estrogen receptors.

Age-related osteoporosis is a metabolic skeletal disorder caused by estrogen deficiency in postmenopausal women. Prolonged use of anti-osteoporotic drugs such as bisphosphonates and FDA-approved anti-resorptive selective estrogen receptor modulators (SERMs) has been associated with various clinical drawbacks. We recently discovered a low-molecular-weight biocompatible and osteoanabolic phytoprotein, called HKUOT-S2 protein (32 kDa), from Dioscorea opposita Thunb that can accelerate bone defect healing. Here, we demonstrated that the HKUOT-S2 protein treatment can enhance osteoblasts-induced ossification and suppress osteoporosis development by upregulating skeletal estrogen receptors (ERs) ERα, ERß, and GPR30 expressions in vivo. Also, HKUOT-S2 protein estrogenic activities promoted hMSCs-osteoblasts differentiation and functions by increasing osteogenic markers, ALP, and RUNX2 expressions, ALP activity, and osteoblast biomineralization in vitro. Fulvestrant treatment impaired the HKUOT-S2 protein-induced ERs expressions, osteoblasts differentiation, and functions. Finally, we demonstrated that the HKUOT-S2 protein could bind to ERs to exert osteogenic and osteoanabolic properties. Our results showed that the biocompatible HKUOT-S2 protein can exert estrogenic and osteoanabolic properties by positively modulating skeletal estrogen receptor signaling to promote ossification and suppress osteoporosis. Currently, there is no or limited data if any, on osteoanabolic SERMs. The HKUOT-S2 protein can be applied as a new osteoanabolic SERM for osteoporosis treatment.

Uncovering the role of TET2-mediated ENPEP activation in trophoblast cell fate determination.

Early trophoblast differentiation is crucial for embryo implantation, placentation and fetal development. Dynamic changes in DNA methylation occur during preimplantation development and are critical for cell fate determination. However, the underlying regulatory mechanism remains unclear. Recently, we derived morula-like expanded potential stem cells from human preimplantation embryos (hEPSC-em), providing a valuable tool for studying early trophoblast differentiation. Data analysis on published datasets showed differential expressions of DNA methylation enzymes during early trophoblast differentiation in human embryos and hEPSC-em derived trophoblastic spheroids. We demonstrated downregulation of DNA methyltransferase 3 members (DNMT3s) and upregulation of ten-eleven translocation methylcytosine dioxygenases (TETs) during trophoblast differentiation. While DNMT inhibitor promoted trophoblast differentiation, TET inhibitor hindered the process and reduced implantation potential of trophoblastic spheroids. Further integrative analysis identified that glutamyl aminopeptidase (ENPEP), a trophectoderm progenitor marker, was hypomethylated and highly expressed in trophoblast lineages. Concordantly, progressive loss of DNA methylation in ENPEP promoter and increased ENPEP expression were detected in trophoblast differentiation. Knockout of ENPEP in hEPSC-em compromised trophoblast differentiation potency, reduced adhesion and invasion of trophoblastic spheroids, and impeded trophoblastic stem cell (TSC) derivation. Importantly, TET2 was involved in the loss of DNA methylation and activation of ENPEP expression during trophoblast differentiation. TET2-null hEPSC-em failed to produce TSC properly. Collectively, our results illustrated the crucial roles of ENPEP and TET2 in trophoblast fate commitments and the unprecedented TET2-mediated loss of DNA methylation in ENPEP promoter.

Endometrial stromal cells from women with repeated implantation failure display impaired invasion towards trophoblastic spheroids.

In brief: Implantation failure can occur even after the transfer of good-quality embryos. This study showed that the migration of human endometrial stromal cells towards embryonic trophoblasts is higher in women with live births in the first in vitro fertilization cycle than those with repeated implantation failure, suggesting that the chemotactic response of stroma cells is associated with successful pregnancy. Abstract: The success rate of in vitro fertilization (IVF) remains limited in some women despite transfers of good-quality embryos in repeated attempts. There is no reliable tool for assessing endometrial receptivity. This study aimed to assess the interaction between decidualized human primary endometrial stromal cells (1°-EnSC) and human embryonic stem cell-derived trophoblastic spheroids (BAP-EB) and to compare the invasion ability of decidualized 1°-EnSC towards BAP-EB between women attaining live birth in the first IVF cycle and those with repeated implantation failure (RIF). The invasion of the decidualized human endometrial cell line (T-HESC) and 1°-EnSC towards BAP-EB was studied. Real-time quantitative PCR and immunocytochemistry were employed to determine the expression of decidualization markers at mRNA and protein levels, respectively. Trophoblast-like BAP-EB-96h, instead of early trophectoderm (TE)-like BAP-EB-48h, facilitated the invasion ability of decidualized T-HESC and decidualized 1°-EnSC. Human chorionic gonadotropin at supra-physiological levels promoted the invasiveness of decidualized 1°-EnSC. The extent of BAP-EB-96h-induced invasion was significantly stronger in decidualized 1°-EnSC from women who had a live birth in the first IVF cycle when compared to those with RIF. While no difference was found in the expression of decidualization markers, PRL and IGFBP1 among two groups of women, significantly lower HLA-B was detected in the non-decidualized and decidualized 1°-EnSC from women with RIF. Collectively, the findings suggested that the invasion of decidualized 1°-EnSC towards trophoblast-like BAP-EB-96h was higher in women who had a live birth in the first IVF cycle than those with RIF.

DNA Damage Response and Cell Cycle Regulation in Pluripotent Stem Cells.

Pluripotent stem cells (PSCs) hold great promise in cell-based therapy because of their pluripotent property and the ability to proliferate indefinitely. Embryonic stem cells (ESCs) derived from inner cell mass (ICM) possess unique cell cycle control with shortened G1 phase. In addition, ESCs have high expression of homologous recombination (HR)-related proteins, which repair double-strand breaks (DSBs) through HR or the non-homologous end joining (NHEJ) pathway. On the other hand, the generation of induced pluripotent stem cells (iPSCs) by forced expression of transcription factors (Oct4, Sox2, Klf4, c-Myc) is accompanied by oxidative stress and DNA damage. The DNA repair mechanism of DSBs is therefore critical in determining the genomic stability and efficiency of iPSCs generation. Maintaining genomic stability in PSCs plays a pivotal role in the proliferation and pluripotency of PSCs. In terms of therapeutic application, genomic stability is the key to reducing the risks of cancer development due to abnormal cell replication. Over the years, we and other groups have identified important regulators of DNA damage response in PSCs, including FOXM1, SIRT1 and PUMA. They function through transcription regulation of downstream targets (P53, CDK1) that are involved in cell cycle regulations. Here, we review the fundamental links between the PSC-specific HR process and DNA damage response, with a focus on the roles of FOXM1 and SIRT1 on maintaining genomic integrity.

Human embryonic stem cell-derived blastocyst-like spheroids resemble human trophectoderm during early implantation process.

OBJECTIVE: To study the use of human embryonic stem cell-derived trophoblastic spheroids (BAP-EB) as human blastocyst surrogates for studying early implantation and trophoblast development. DESIGN: Laboratory study. SETTING: University research laboratory. PATIENT(S): Infertile in vitro fertilization patients donating endometrial aspirates and human embryonic stem cells (hESCs: VAL3 and H9/WA09). INTERVENTION(S): In BAP-EB derived from hESC, transcriptomes analyzed by next-generation RNA sequencing, effects of Hippo signaling pathway studied by a YAP inhibitor, comparison of attachment of BAP-EB onto primary endometrial epithelial cells (EEC) collected at prereceptive and receptive phases, and antibody blocking assay used to study the molecule(s) involved in BAP-EB attachment. MAIN OUTCOME MEASURE(S): Gene expression profiles and endometrial cell attachment rates. RESULT(S): The BAP-EB differentiation protocol for VAL3 could be used to induce trophoblast differentiation in another hESC line, H9. Transcriptomic analysis showed that the epiblast signature gene expression was reduced while that of the trophoblast was induced during BAP-EB differentiation. Specifically, trophectoderm signature genes were induced in BAP-EB at 48 hours and 72 hours after induction of differentiation. The Hippo signaling pathway was one of the pathways induced during BAP-EB differentiation, and YAP1 inhibitor statistically significantly reduced attachment, outgrowth, and trophoblast gene expressions of BAP-EB. A statistically significantly higher number of BAP-EB derived from both VAL3 and H9 attached onto receptive EEC than prereceptive EEC. The antibody blocking assay demonstrated that endometrial E-cadherin might be critical in early implantation. CONCLUSION(S): The data suggest that BAP-EB possesses a trophectoderm-like signature, which supports the use of BAP-EB as a blastocyst surrogate for the study of trophoblast development and endometrial receptivity.