All roads lead to Rome: the many ways to pluripotency

Use of Epigenetic Cues and Mechanical Stimuli to Generate Blastocyst-Like Structures from Mammalian Skin Dermal Fibroblasts

Mammalian embryogenesis is characterized by complex interactions between embryonic and extra-embryonic tissues that coordinate morphogenesis, coupling bio-mechanical and bio-chemical cues, to regulate gene expression and influence cell fate. Deciphering such mechanisms is essential to understand early embryogenesis, as well as to harness differentiation disorders. Currently, several early developmental events remain unclear, mainly due to ethical and technical limitations related to the use of natural embryos.Here, we describe a three-step approach to generate 3D spherical structures, arbitrarily defined "epiBlastoids," whose phenotype is remarkably similar to natural embryos. In the first step, adult dermal fibroblasts are converted into trophoblast-like cells, combining the use of 5-azacytidine, to erase the original cell phenotype, with an ad hoc induction protocol, to drive erased cells into the trophoblast lineage. In the second step, once again epigenetic erasing is applied, in combination with mechanosensing-related cues, to generate inner cell mass (ICM)-like spheroids. More specifically, erased cells are encapsulated in micro-bioreactors to promote 3D cell rearrangement and boost pluripotency. In the third step, chemically induced trophoblast-like cells and ICM-like spheroids are co-cultured in the same micro-bioreactors. The newly generated embryoids are then transferred to microwells, to encourage further differentiation and favor epiBlastoid formation. The procedure here described is a novel strategy for in vitro generation of 3D spherical structures, phenotypically similar to natural embryos. The use of easily accessible dermal fibroblasts and the lack of retroviral gene transfection make this protocol a promising strategy to study early embryogenesis as well as embryo disorders.

Micro-vibration results in vitro-derived bovine blastocysts with greater cryotolerance, epigenetic abnormalities, and a massive transcriptional change

Much effort has been employed to improve the quality of embryos obtained by in vitro production (IVP) given the relevance of this technology to current livestock systems. In this context, dynamic IVP systems have proved beneficial to the embryo once they mimic fluid flows and mechanical forces resulting from the movement of ciliated cells and muscle contraction in the reproductive tract. In the present study, we sought to confirm these initial findings as well as assess potential molecular consequences to the embryo by applying micro-vibration (45 Hz for 5 s once per 60 min) during both oocyte maturation and embryo culture in cattle. As a result, micro-vibration led to lower incidence of apoptosis in blastocysts following vitrification-thawing. Further analyses revealed epigenetic and transcriptional changes in blastocysts derived from the micro-vibration treatment, with a total of 502 differentially expressed genes. Enrichment analyses linked differentially expressed genes to 'Oxidative phosphorylation', 'Cytokine-cytokine receptor interaction', and 'Signaling pathways regulating pluripotency of stem cells'. Yet, a meta-analysis indicated that the transcriptional changes induced by micro-vibration were not toward that of in vivo-derived embryos. In conclusion, micro-vibration increases the cryoresistance of bovine embryos, but caution should be taken given the unclear consequences of epigenetic and transcriptional abnormalities induced by the treatment.

Single-cell transcriptome profiling reveals molecular heterogeneity in human umbilical cord tissue and culture-expanded mesenchymal stem cells

Human umbilical cord-derived mesenchymal stem/stromal cells (UMSCs) demonstrate great therapeutic potential in regenerative medicine. The use of UMSCs for clinical applications requires high quantity and good quality of cells usually by in vitro expansion. However, the heterogeneity and the characteristics of cultured UMSCs and the cognate human umbilical cord tissue at single-cell resolution remain poorly defined. In this study, we created a single-cell transcriptome profile of human umbilical cord tissue and the cognate culture-expanded UMSCs. Based on the inferred characteristics of cell clusters and trajectory analysis, we identified three subgroups in culture-expanded UMSCs and putative novel transcription factors (TFs) in regulating UMSC state transition. Further, putative ligand-receptor interaction analysis demonstrated that cellular interactions most frequently occurred in epithelial-like cells with other cell groups in umbilical cord tissue. Moreover, we dissected the transcriptomic differences of in vitro and in vivo subgroups and inferred the telomere-related molecules and pathways that might be activated in UMSCs for cell expansion in vitro. Our study provides a comprehensive and integrative study of the transcriptomics of human umbilical cord tissue and their cognate-cultured counterparts, which paves the way for a deeper understanding of cellular heterogeneity and offers fundamental biological insight of UMSCs-based cell therapy.

"Biomechanical Signaling in Oocytes and Parthenogenetic Cells"

Oocyte-specific competence remains one of the major targets of current research in the field of reproduction. Several mechanisms are involved in meiotic maturation and the molecular signature of an oocyte is considered to reflect its quality and to predict its subsequent developmental and functional capabilities. In the present minireview, we focus on the possible role of mechanotransduction and mechanosensor signaling pathways, namely the Hippo and the RhoGTPase, in the maturing oocyte. Due to the limited access to female gametes, we propose the use of cells isolated from parthenogenetic embryos as a promising model to characterize and dissect the oocyte distinctive molecular signatures, given their exclusive maternal origin. The brief overview here reported suggests a role of the mechanosensing related pathways in oocyte quality and developmental competence and supports the use of uniparental cells as a useful tool for oocyte molecular signature characterization.

Identification by Comprehensive Bioinformatics Analysis of KIF15 as a Candidate Risk Gene for Triple-Negative Breast Cancer

Background

Previous studies have shown that kinesin family proteins (KIFs) play an indispensable roles in several types of cancer. However, the expression and clinical significance of KIFs in triple-negative breast cancer remain unclear.

Methods

In this study, the role of KIF15, including gene expression analysis, methylation characteristic, CNV characteristic, and miRNA target regulation, was evaluated using multiple bioinformatic tools based on TCGA database. Quantitative real-time PCR and Western blot were used to determine the expression level of KIF15 in triple-negative breast cancer cell lines. Then, functional experiments were employed to explore the effects of KIF15 on tumor growth and metastasis in triple-negative breast cancer.

Results

Our data showed that KIF15 was significantly upregulated in triple-negative breast cancer (TNBC). Functionally, downregulation of KIF15 significantly facilitated apoptosis and G2/M phase arrest, and inhibited the migration and invasion of TNBC cells. The mechanism of action of KIF15 was closely related to DNA replication checkpoint and cell cycle regulation in TNBC based on GSEA. In addition, bioinformatics analysis demonstrated that high expression of KIF15 in TNBC was correlated with copy number aberration and DNA methylation levels.

Conclusion

Our findings suggest that KIF15 is a novel oncogene in TNBC and provide us a strong evidence that it might be served as a potential clinical target and biomarker in triple-negative breast cancer.

The Epigenetic Progenitor Origin of Cancer Reassessed: DNA Methylation Brings Balance to the Stem Force

Cancer initiation and progression toward malignant stages occur as the results of accumulating genetic alterations and epigenetic dysregulation. During the last decade, the development of next generation sequencing (NGS) technologies and the increasing pan-genomic knowledge have revolutionized how we consider the evolving epigenetic landscapes during homeostasis and tumor progression. DNA methylation represents the best studied mark and is considered as a common mechanism of epigenetic regulation in normal homeostasis and cancer. A remarkable amount of work has recently started clarifying the central role played by DNA methylation dynamics on the maintenance of cell identity and on cell fate decisions during the different steps of normal development and tumor evolution. Importantly, a growing number of studies show that DNA methylation is key in the maintenance of adult stemness and in orchestrating commitment in multiple ways. Perturbations of the normal DNA methylation patterns impair the homeostatic balance and can lead to tumor initiation. Therefore, DNA methylation represents an interesting therapeutic target to recover homeostasis in tumor stem cells.