Functional primordial germ cell-like cells from pluripotent stem cells in rats
Ontology highlight
ABSTRACT: In vitro generation of germ cells from pluripotent stem cells (PSCs) can crucially impact future reproductive medicine and animal breeding. A decade ago, in vitro gametogenesis was established in the mouse. However, induction of primordial germ cell-like cells (PGCLCs) to produce fertile gametes has not been achieved in any other species. Here, we demonstrate the induction of functional PGCLCs from rat PSCs. We show that epiblast-like cells in floating aggregates form rat PGCLCs. The gonadal somatic cells support maturation and epigenetic reprogramming of the PGCLCs. Notably, rat PGCLCs transplanted into the seminiferous tubules of germline-less rats produce spermatids, leading to the birth of viable offspring. Insights from our rat model will elucidate conserved and divergent mechanisms essential for the broad applicability of in vitro gametogenesis.
Project description:In mammals, pluripotent cells transit through a continuum of distinct molecular and functional states en route to initiating lineage specification. Capturing pluripotent stem cells (PSCs) mirroring in vivo pluripotent states provides accessible in vitro models to study the pluripotency program and mechanisms underlying lineage restriction. Here, we develop optimal culture conditions to derive and propagate post-implantation epiblast-derived PSCs (EpiSCs) in rats, a valuable model for biomedical research. We show that rat EpiSCs can be reset toward the naïve pluripotent state with exogenous Klf4, albeit not with the other five candidate genes (Nanog, Klf2, Esrrb, Tfcp2l1, and Tbx3) effective in mice. Finally, we demonstrate that rat EpiSCs retain competency to produce authentic primordial germ cell-like cells that contribute to functional gametogenesis leading to the birth of viable offspring. Our findings in the rat model uncover conserved principles underpinning pluripotency and germline competency across species.
Project description:The induction of the primordial germ-like cells (PGCLCs) from primate pluripotent stem cells (PSCs)provides a powerful system to study the cellular and molecular mechanism underlying germline specification, which are difficult to study in vivo. However a comprehensive single cell RNA sequencing(scRNA-seq) analysis of the developmental trajectory of PGCLCs differentiation that also dissects the required niche has not been achieved. Here, we applied the embryoid body (EB) differentiation system to induce PGCLCs specification from male and female monkey naïve-state PSCs and then performed high throughput scRNA-seq analysis of approximately 40000 of naïve cells and cells within EBs. We found that EBs provided a niche for PGCLCs differentiation by secreting growth factors critical for PGCLCs specification, such as BPM2, BMP4 and WNT3. Moreover, the developmental trajectory of PGCLCs was reconstituted and gene expression dynamics were revealed. Our study outlines the roadmap of PGCLCs specification from PSCs and provides insights that will improve the differentiation efficiency of PGCLCs from PSCs.
Project description:The pluripotent stem cell (PSC)-derived human primordial germ cell-like cells (PGCLCs) are a cell culture-derived surrogate model of embryonic primordial germ cells. Upon differentiation of PSCs to PGCLCs, multiple loci of HML-2, the hominoid-specific human endogenous retrovirus (HERV), are strongly activated, which is necessary for PSC differentiation to PGCLCs. In PSCs, strongly ac-tivated loci of HERV-H family HERVs create chromatin contacts, which are required for the plu-ripotency. Chromatin contacts in the genome of human PSCs and PGCLCs were determined by Hi-C sequencing, and their locations were compared with those of HML-2 loci strongly activated in PGCLCs but silenced in the precursor naïve iPSCs. In both iPSCs and PGCLCs, the size of chromatin contacts were found to be around one megabase, which corresponds to the Topologically Associ-ated Domains in the human genome but is slightly larger in PGCLCs than iPSCs. The number of small-sized chromatin contacts diminished while numbers of larger-sized contacts increased. The distances between chromatin contacts newly formed in PGCLCs and the degrees of activation of the closest HML-2 loci showed significant inverse correlation. Our study provides evidence that strong activation of HML-2 provirus loci may be associated with newly formed chromatin contacts in their vicinity, potentially contributing to PSC differentiation to the germ cell lineage.
Project description:The DND microRNA-mediated repression inhibitor 1 (DND1) is a conserved RNA binding protein (RBP) and plays an important role in survival and maintenance of primordial germ cells (PGCs) and the development of the male germline in zebrafish and mice. It was shown to be expressed in human pluripotent stem cells (PSCs), PGCs, and spermatogonia, but little is known about its specific role in pluripotency and human germline development. Here we use CRISPR/Cas mediated knockout and PGC-like cell (PGCLC) differentiation in human iPSCs to analyse if DND1 (1) plays a role in maintaining pluripotency and (2) in specification of PGCLCs. We generated several clonal lines with biallelic loss of function mutations and analysed their potential to differentiate towards PGCLCs and their gene expression on RNA and protein level via bulk RNA sequencing and mass spectrometry. The generated knockout iPSCs showed no differences in pluripotency gene expression, proliferation nor trilineage differentiation potential, but yielded reduced numbers o PGCLCs compared to their parental iPSCs. RNAseq analysis in PGCLCs showed significantly reduced expression of genes associated with cellular developmental processes and cell differentiation in knockout cells, including known markers for PGCs (NANOS3, SOX17, PRDM1, EPCAM) and naïve pluripotency (TFCP2L, DNMT3L).
Project description:The in vitro derivation and propagation of spermatogonial stem cells (SSCs) from pluripotent stem cells (PSCs) is a key goal in reproductive science. We show here that when aggregated with embryonic testicular somatic cells (reconstituted testes), primordial germ cell-like cells (PGCLCs) induced from mouse embryonic stem cells differentiate into spermatogonia-like cells in vitro and are expandable as cells that resemble germline stem cells (GSCs), a primary cell line with SSC activity. Remarkably, GSC-like cells (GSCLCs), but not PGCLCs, colonize adult testes and, albeit less effectively than GSCs, contribute to spermatogenesis and fertile offspring. Whole-genome analyses reveal that GSCLCs exhibit aberrant methylation at vulnerable regulatory elements, including those critical for spermatogenesis, which may restrain their spermatogenic potential. Our study establishes a strategy for the in vitro derivation of SSC activity from PSCs, which, we propose, relies on faithful epigenomic regulation.
Project description:The in vitro derivation and propagation of spermatogonial stem cells (SSCs) from pluripotent stem cells (PSCs) is a key goal in reproductive science. We show here that when aggregated with embryonic testicular somatic cells (reconstituted testes), primordial germ cell-like cells (PGCLCs) induced from mouse embryonic stem cells differentiate into spermatogonia-like cells in vitro and are expandable as cells that resemble germline stem cells (GSCs), a primary cell line with SSC activity. Remarkably, GSC-like cells (GSCLCs), but not PGCLCs, colonize adult testes and, albeit less effectively than GSCs, contribute to spermatogenesis and fertile offspring. Whole-genome analyses reveal that GSCLCs exhibit aberrant methylation at vulnerable regulatory elements, including those critical for spermatogenesis, which may restrain their spermatogenic potential. Our study establishes a strategy for the in vitro derivation of SSC activity from PSCs, which, we propose, relies on faithful epigenomic regulation.
Project description:The generation of properly functioning gametes in vitro, a key goal in developmental/reproductive biology, requires multi-step reconstitutions of complex germ cell development. Based on the logic of primordial germ cell (PGC)-specification, we demonstrate here the generation of PGC-like cells (PGCLCs) in mice with robust capacity for spermatogenesis from embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) through epiblast-like cells (EpiLCs), a cellular state highly similar to pre-gastrulating epiblasts, but distinct from epiblast stem cells (EpiSCs). The global transcription profiles, epigenetic reprogramming, and cellular dynamics during PGCLC induction from EpiLCs are a meticulous capture of those associated with PGC specification from the epiblasts. Furthermore, we identify Integrin-beta 3 and SSEA1 as markers that purify PGCLCs with spermatogenic capacity free from tumorigenic undifferentiated cells. With the reconstitution of PGC specification pathway from the naive inner cell mass state, our study defines a paradigm for the essential step of in vitro gametogenesis. We performed this analysis to reveal the characters of the cells that we created in this study, epiblast-like cells (EpiLCs) and primordial germ cells-like cells (PGCLCs). Because EpiLCs were induced from embryonic stem cells (ESCs), and equivalent to pre-gastrulating epiblast (embryonic day [E] 5.5-6.0) in vivo (embryo), ESCs and epiblast were included in this analysis. Epiblast stem cells (EpiSCs) are a culture cell type derived from epiblast, and were also included. PGCLCs were supposed to be equivalent to E9.5 PGCs based on reporter fluorescent transgene expressions and epigenetic properties, and therefore E9.5 PGCs were also inckuded in this analysis. Because epiblast and E9.5 PGCs are of a small number of cells in embryos (a few hundred to thousand cells), cDNAs were amplified with a quantitative global PCR method (Kurimoto et al., 2006, Nucleic Acids Research) for microarray analyses. We took two biological replicate for each cell type.
Project description:In vitro gametogenesis, the process of generating gametes from pluripotent cells in culture, is a powerful tool for improving our understanding of germ cell development as well as an alternative source of gametes.(1) Conservation of the northern white rhinoceros (NWR), a species for which only two females remain, would be a compelling application of in vitro gametogenesis as a gametes source. Here, we established a culture system that induces a robust number of primordial germ cell-like cells (PGCLCs) from pluripotent stem cells of the NWR and southern white rhinoceros (SWR), the closest species to the NWR. PGCLC differentiation from SWR embryonic stem cells is highly reliant on BMP and WNT signals, as observed in mice and humans, though the timing and duration of these signals need to be optimized for each species. Genetic analysis revealed that SOX17 is essential for SWR-PGCLC induction, as it is in humans. Under the defined condition, NWR induced pluripotent stem cells differentiated into PGCLCs whose transcriptome was highly similar to that of SWR-PGCLCs. We also identified cell surface markers, CD9 and ITGA6, that enabled us to isolate PGCLCs without genetic alteration in pluripotent stem cells. This study provides a first step toward production of NWR gametes in culture and understanding of the basic mechanism of PGC specification in a large animal.
Project description:The germ cell lineage ensures the continuity of life through the generation of male and female gametes, which unite to form a totipotent zygote. We have established a culture system that recapitulates the mouse germ-cell specification pathway: Using cytokines, embryonic stem cells (ESCs)/induced pluripotent stem cells (iPSCs) are induced into epiblast-like cells (EpiLCs) and then into primordial germ cell-like cells (PGCLCs) with capacity both for spermatogenesis and oogenesis, creating an opportunity for understanding and regulating mammalian germ cell development in both sexes in vitro. Here we show that, without cytokines, simultaneous over-expression of three transcription factors (TFs), Blimp1 (also known as Prdm1), Prdm14 and Tfap2c (also known as AP2γ), directs EpiLCs, but not ESCs, swiftly and highly efficiently into a PGC state with endogenous transcription circuitry. The induction of the PGC state on EpiLCs minimally requires Prdm14 but not Blimp1 or Tfap2c. The TF-induced PGC state reconstitutes key transcriptome and epigenetic reprogramming in PGCs, but bypasses a mesodermal program that accompanies PGC specification in vivo and in vitro by cytokines including BMP4. Importantly, the TF-induced PGC-like cells robustly contribute to spermatogenesis and fertile offspring. Our findings provide not only a novel insight into the transcriptional logic that creates a germ cell state, but also a foundation for the TF-based reconstitution and regulation of mammalian gametogenesis. Aim of this analysis is characterization of transcription factor-induced primordial germ cells (TF-PGCLCs) compared with cytokine-induced primordial germ cells (Ck-PGCLCs) (Hayashi et al., 2011, Cell), epiblast-like cells (EpiLCs) (Hayashi et al., 2011, Cell), and embryonic stem cells (ESCs) and identification of genes differentially expressed among them. TF-PGCLCs induced by multiple combinations of TFs (Blimp1 (B), Prdm14 (P14), and Tfap2c (A) (BP14A), BP14, P14A, P14) on day 2 and 4 (for BP14A cells) of the induction were also compared. Parental clone without exogenous TFs cultured with doxycycline, are also included as a negative control. Ck-PGCLCs day 2 and day 4 samples, which are previously unreported, EpiLCs and ESCs used in this study were also included. Overexpression of exogenous three TFs in ESCs yields stella-ECFP (SC) positive cells, which were sorted and included in the analysis. cDNA samples, prepared from approximately 20,000 cells, were amplified with a quantitative global PCR method (Kurimoto et al., 2006, Nucleic Acids Research). Two biological duplicates for each cell type were analyzed. Samples from GSE30056 were also included and reanalysed (GSM1070855-GSM1070864).
Project description:In vitro reconstitution of germ-cell development from pluripotent stem cells (PSCs) has created key opportunities to explore the fundamental mechanisms underlying germ-cell development, particularly in mice and humans. Importantly, such investigations have clarified critical species differences in the mechanisms regulating mouse and human germ-cell development, highlighting the necessity of establishing an in vitro germ-cell development system in other mammals, such as non-human primates. Here, we show that multiple lines of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) in cynomolgus monkeys (Macaca fascicularis; cy) can be maintained stably in an undifferentiated state under a defined condition with an inhibitor for WNT signaling, and such PSCs are induced efficiently into primordial germ cell-like cells (PGCLCs) bearing a transcriptome similar to early cyPGCs. Interestingly, the induction kinetics of cyPGCLCs from cyPSCs is faster than that of human (h) PGCLCs from hPSCs, and while the transcriptome dynamics during cyPGCLC induction is relatively similar to that during hPGCLC induction, it is substantially divergent from that during mouse (m) PGCLC induction. Our findings delineate common as well as species-specific traits for PGC specification, creating a foundation for parallel investigations into the mechanism for germ-cell development in mice, monkeys and humans.