The use of signalling pathway inhibitors and chromatin modifiers for enhancing pluripotency

Effect of supplemetation of Zebularine and Scriptaid on efficiency of in vitro developmental competence of ovine somatic cell nuclear transferred embryos

Somatic cell nuclear transfer (SCNT) technology has been applied in the construction of disease model, production of transgenic animals, therapeutic cloning, and other fields. However, the cloning efficiency remains limited. In our study, to improve SCNT efficiency, brilliant cresyl blue (BCB) staining were chosen to select recipient oocytes. In addition, DNA methyltransferase inhibitor Zebularine (5 nmol/L) and histone deacetylase inhibitor Scriptaid (0.2 μmol/L) were jointly used to treat sheep donor cumulus cells and reconstructed embryo. Moreover, the expression levels of embryonic development-related genes (OCT4, SOX2, H19, IGF2 and Dnmt1) of reconstructed embryo were also detected. Using BCB + oocytes as recipient cell, donor cumulus cells and reconstructed embryos were treated with 5 nmol/L Zebularine and 0.2 μmol/L Scriptaid, the blastocyst rate in Zeb + SCR-SCNT group (28.25%) was significantly higher than SCNT (21.16%) (p < 0.05). Furthermore, results showed that expression levels of OCT4, SOX2, H19, IGF2 and Dnmt1 genes in Zeb + SCR-SCNT embryos were more similar to IVF embryos. Our study proved that 5 nmol/L Zebularine and 0.2 μmol/L Scriptaid treating with sheep donor cumulus cells and reconstructed embryos improved SCNT blastocyst rate and relieve the abnormal expression of embryonic developmental related genes.

Inhibition of JAK-STAT ERK/MAPK and Glycogen Synthase Kinase-3 Induces a Change in Gene Expression Profile of Bovine Induced Pluripotent Stem Cells

Pluripotent stem cells (PSCs) fall in two states, one highly undifferentiated, the naïve state, and the primed state, characterized by the inability to contribute to germinal lineage. Several reports have demonstrated that these states can be modified by changes to the cell culture conditions. With the advent of nuclear reprogramming, bovine induced pluripotent stem cells (biPSCs) have been generated. These cells represent examples of a transient-intermediate state of pluripotency with remarkable characteristics and biotechnological potential. Herein, we generated and characterized biPSC. Next, we evaluated different culture conditions for the ability to affect the expression of the set of core pluripotent transcription factors in biPSC. It was found that the use of 6-bromoindirubin-3-oxime and Sc1 inhibitors alone or in combination with 5-AzaC induced significantly higher levels of expression of endogenous REX1, OCT4, NANOG, and SOX2. Furthermore, LIF increased the levels of expression of OCT4 and REX1, compared with those cultured with LIF + bFGF. By contrast, bFGF decreased the levels of expression for both REX1 and OCT4. These results demonstrate that the biPSC gene expression profile is malleable by modification of the cell culture conditions well after nuclear reprogramming, and the culture conditions may determine their differentiation potential.

Effects of DNMT1 and HDAC inhibitors on gene-specific methylation reprogramming during porcine somatic cell nuclear transfer

Somatic cell nuclear transfer (SCNT) in mammalian cloning currently remains inefficient. Incomplete or erroneous epigenetic reprogramming of specialized donor somatic nuclear and resulting aberrant gene expression during development of cloned embryos is commonly believed as the main reason that causes the low efficiency of SCNT. Use of small molecular reprogramming modifiers to assist the somatic nucleus to mimic naturally occurring DNA methylation and chromatin remodeling in nucleus of fertilization-derived zygotes, has been widely attempted to improve cloning efficiency. However, impacts of these small modifiers on gene-specific methylation dynamics and their potential effects on methylation of imprinted gene have rarely been traced. Here, we attempted two relatively novel DNMT1 inhibitor (DNMTi) and histone deacetylase inhibitor (HDACi), scriptaid and RG108, and demonstrated their effects on dynamics of gene-specific DNA methylation and transcription of porcine SCNT embryos. We found that scriptaid and RG108 had synergetic effects on rescuing the disrupted methylation imprint of H19 during SCNT at least partially by repression over-expressed MBD3 in eight-cell cloned embryos. Furthermore, we firstly identified a differential methylation regions (DMRs) at 5′ flanking regions of XIST gene and found that scriptaid alone and its combination with RG108 modify the dynamics of both transcription and DNA methylation levels in cloned embryos, by different manners. Additionally, we found that scriptaid alone and its combination with RG108 can significantly promote the transcription of NANOG in cloned embryos and enhance their pre-implantation developmental capacity. Our results would contribute to uncovering the epigenetic reprogramming mechanisms underlying the effects of assisted small molecules on improvement of mammalian cloning efficiency.

The state of the art for pluripotent stem cells derivation in domestic ungulates

Since the successful isolation, characterization and long-term culture of embryonic stem cells (ESCs) from mice in the early 1980s and from humans a decade later, considerable effort has been made to establish ESCs lines from livestock. The derivation of validated ESCs lines is a necessary step if the generation of economically relevant transgenic animals is to be achieved. However, this is still elusive, as the isolation of true ESCs lines for livestock has not been accomplished to date. It has been demonstrated that by forced expression of a defined set of transcription factors, it is possible to reprogram somatic cells to cells that closely resemble an ES-like state. These cells were termed induced pluripotent stem cells (iPSCs). We introduce the basic concepts relating to stem cell biology and give an overview of the various attempts to isolate and generate pluripotent stem cells (PSCs) from species relevant to livestock production. Further, we point out the issues to be addressed and hurdles to be overcome to realize the promise of stem cells in agriculture.

Embryonic stem cells and iPS cells: sources and characteristics

The field of regenerative medicine research is rapidly expanding. One area of interest to equine researchers is the possibility of isolating or generating pluripotent cells, capable of producing differentiated cell types derived from all 3 primary germ layers. Reports of equine embryonic stem-like (ES) cell isolation can be found in the literature. Other groups are working to produce equine-induced pluripotent stem (iPS) cells. This article summarizes the essential features needed to characterize a cell type as pluripotent, specific challenges in using the horse as a model organism for pluripotent cell generation, and current and upcoming clinical trials using ES/iPS cells.

Simple and efficient derivation of mouse embryonic stem cell lines using differentiation inhibitors or proliferation stimulators

The inhibition of endogenous differentiation-inducing signaling or the enhancement of growth capacity and viability of preimplantation embryos, via 2i (PD0325901 and CHIR99021), dramatically improves the establishment of mouse embryonic stem cells (mESCs). Using adrenocorticotropic hormone fragments 1-24 (ACTH 1-24), which enhances survival and/or proliferation of mESCs, also increases the derivation of mESCs from single blastomeres significantly. The CHIR99021 pathway and the proposed ACTH pathway are likely different. Therefore, this study aimed to assess the synergetic effects of 2i and ACTH 1-24 on derivation of mESCs. Results in the present study demonstrate that germline-transmitted mESCs could be efficiently derived from ICR and C57BL/6J at 0.5-4.5 days postcoitum denuded zygotes to blastocysts or isolated blastomeres of 2-8-cell embryos and cultured in 10 μL droplets with human foreskin fibroblast (Hs68) or STO (a mouse embryonic fibroblast line) feeders and in knockout serum replacement (KSR) ESC medium containing 2i or ACTH 1-24. The overall success rates for C57BL/6J and ICR were 56.2% when cultured in 2i+ACTH 1-24, 26.6% in 2i, 6.7% in ACTH 1-24, and 4.8% in KSR ESC medium. These results imply that CHIR99021 and ACTH 1-24 are synergistically enhancing the establishment of mESCs. The proposed protocol also demonstrates a highly efficient and reproducible method, has a simple layout, is easy to apply, and could be used as an alternative method for routinely establishing mESC lines.