PCI-24781 can improve in vitro and in vivo developmental capacity of pig somatic cell nuclear transfer embryos

Human and Pig Pluripotent Stem Cells: From Cellular Products to Organogenesis and Beyond

Pluripotent stem cells (PSCs) are important for studying development and hold great promise in regenerative medicine due to their ability to differentiate into various cell types. In this review, we comprehensively discuss the potential applications of both human and pig PSCs and provide an overview of the current progress and challenges in this field. In addition to exploring the therapeutic uses of PSC-derived cellular products, we also shed light on their significance in the study of interspecies chimeras, which has led to the creation of transplantable human or humanized pig organs. Moreover, we emphasize the importance of pig PSCs as an ideal cell source for genetic engineering, facilitating the development of genetically modified pigs for pig-to-human xenotransplantation. Despite the achievements that have been made, further investigations and refinement of PSC technologies are necessary to unlock their full potential in regenerative medicine and effectively address critical healthcare challenges.

The Relative Abundances of Human Leukocyte Antigen-E, α-Galactosidase A and α-Gal Antigenic Determinants Are Biased by Trichostatin A-Dependent Epigenetic Transformation of Triple-Transgenic Pig-Derived Dermal Fibroblast Cells

The present study sought to establish the mitotically stable adult cutaneous fibroblast cell (ACFC) lines stemming from hFUT2×hGLA×HLA-E triple-transgenic pigs followed by trichostatin A (TSA)-assisted epigenetically modulating the reprogrammability of the transgenes permanently incorporated into the host genome and subsequent comprehensive analysis of molecular signatures related to proteomically profiling the generated ACFC lines. The results of Western blot and immunofluorescence analyses have proved that the profiles of relative abundance (RA) noticed for both recombinant human α-galactosidase A (rhα-Gal A) and human leukocyte antigen-E (HLA-E) underwent significant upregulations in tri-transgenic (3×TG) ACFCs subjected to TSA-mediated epigenetic transformation as compared to not only their TSA-unexposed counterparts but also TSA-treated and untreated non-transgenic (nTG) cells. The RT-qPCR-based analysis of porcine tri-genetically engineered ACFCs revealed stable expression of mRNA fractions transcribed from hFUT2, hGLA and HLA-E transgenes as compared to a lack of such transcriptional activities in non-transgenic ACFC variants. Furthermore, although TSA-based epigenomic modulation has given rise to a remarkable increase in the expression levels of Galα1→3Gal (α-Gal) epitopes that have been determined by lectin blotting analysis, their semi-quantitative profiles have dwindled profoundly in both TSA-exposed and unexposed 3×TG ACFCs as compared to their nTG counterparts. In conclusion, thoroughly exploring proteomic signatures in such epigenetically modulated ex vivo models devised on hFUT2×hGLA×HLA-E triple-transgenic ACFCs that display augmented reprogrammability of translational activities of two mRNA transcripts coding for rhα-Gal A and HLA-E proteins might provide a completely novel and powerful research tool for the panel of further studies. The objective of these future studies should be to multiply the tri-transgenic pigs with the aid of somatic cell nuclear transfer (SCNT)-based cloning for the purposes of both xenografting the porcine cutaneous bioprostheses and dermoplasty-mediated surgical treatments in human patients.

Enhancement of Chromatin and Epigenetic Reprogramming in Porcine SCNT Embryos—Progresses and Perspectives

Over the last 25 years, cloned animals have been produced by transferring somatic cell nuclei into enucleated oocytes (SCNT) in more than 20 mammalian species. Among domestic animals, pigs are likely the leading species in the number of clones produced by SCNT. The greater interest in pig cloning has two main reasons, its relevance for food production and as its use as a suitable model in biomedical applications. Recognized progress in animal cloning has been attained over time, but the overall efficiency of SCNT in pigs remains very low, based on the rate of healthy, live born piglets following embryo transfer. Accumulating evidence from studies in mice and other species indicate that new strategies for promoting chromatin and epigenetic reprogramming may represent the beginning of a new era for pig cloning.

Strategies to Improve the Efficiency of Somatic Cell Nuclear Transfer

Mammalian oocytes can reprogram differentiated somatic cells into a totipotent state through somatic cell nuclear transfer (SCNT), which is known as cloning. Although many mammalian species have been successfully cloned, the majority of cloned embryos failed to develop to term, resulting in the overall cloning efficiency being still low. There are many factors contributing to the cloning success. Aberrant epigenetic reprogramming is a major cause for the developmental failure of cloned embryos and abnormalities in the cloned offspring. Numerous research groups attempted multiple strategies to technically improve each step of the SCNT procedure and rescue abnormal epigenetic reprogramming by modulating DNA methylation and histone modifications, overexpression or repression of embryonic-related genes, etc. Here, we review the recent approaches for technical SCNT improvement and ameliorating epigenetic modifications in donor cells, oocytes, and cloned embryos in order to enhance cloning efficiency.

Pig Cloning Using Somatic Cell Nuclear Transfer

Porcine cloning technology can be used to produce progenies genetically identical to the donor cells from high-quality breeding pigs. In addition, genetically modified pigs have been produced by somatic cell nuclear transfer using genetically modified porcine fetal fibroblasts. The method of preparing genetically modified pigs is critical for establishing pig models for human diseases, and for generating donor animals for future xenotransplantation. This chapter describes detailed procedures for generating cloned pigs using fetal fibroblasts as nuclear donors.

Dynamic alterations in H4K12 acetylation during meiotic maturation and after parthenogenetic activation of mouse oocytes

The aim of the study was to investigate the continuous changing pattern of H4K12 acetylation, and the expression levels of histone acetyltransferases (HATs) and histone deacetyltransferases (HDACs) in mouse oocytes during meiosis and after parthenogenetic activation (PA). The immunofluorescence results showed hyperacetylation of lysine-12 on histone H4 (H4K12) in the germinal vesicle (GV) oocytes that then decreased during germinal vesicle breakdown (GVBD), and disappeared in metaphase II (MII). However, it reappeared in the early 1-cell embryos derived after 4 h of PA. The expression levels of some selected HATs and HDACs also validated the changing pattern of H4K12 acetylation during meiosis and PA. In conclusion, H4K12 is deacetylated in GVBD and MII, and re-hyperacetylated after PA.

Expression of pluripotency-related genes is highly dependent on trichostatin A-assisted epigenomic modulation of porcine mesenchymal stem cells analysed for apoptosis and subsequently used for generating cloned embryos

The present study sought to examine whether trichostatin A (TSA)-assisted epigenetic transformation of porcine bone marrow (BM)-derived mesenchymal stem cells (BM-MSCs) affects the transcriptional activities of pluripotency-related genes (Oct4, Nanog, c-Myc, Sox2 and Rex1), multipotent stemness-related gene (Nestin) and anti-apoptotic/anti-senescence-related gene (Survivin). Epigenetically transformed or non-transformed BM-MSCs that had been transcriptionally profiled by qRT-PCR and had been analysed for different stages of apoptosis progression provided a source of nuclear donor cells for the in vitro production of cloned pig embryos. TSA-mediated epigenomic modulation has been found to enhance the multipotency extent, stemness and intracellular anti-ageing properties of porcine BM-MSCs. This has been confirmed by the relative abundances for Nanog, c-Myc Rex1, Sox2 and Survivin mRNAs in TSA-exposed BM-MSCs that turned out to be significantly higher than those of TSA-unexposed BM-MSCs. Additionally, TSA-assisted epigenomic modulation of BM-MSCs did not impact the caspase-8 activity, Bax protein expression and the incidence of TUNEL-positive cells. In conclusion, the considerably elevated quantitative profiles of Sox2, Rex1, c-Myc, Nanog and Survivin mRNA transcripts seem to trigger improved reprogrammability of TSA-treated BM-MSC nuclei in cloned pig embryos that thereby displayed remarkably increased blastocyst formation rates as compared to those noticed for embryos derived from TSA-untreated BM-MSCs.

Glycine treatment enhances developmental potential of porcine oocytes and early embryos by inhibiting apoptosis

Glycine, a component of glutathione (GSH), plays an important role in protection from reactive oxygen species (ROS) and inhibition of apoptosis. The aim of this study was to determine the effect of glycine on in vitro maturation (IVM) of porcine oocytes and their developmental competence after parthenogenetic activation (PA). We examined nuclear maturation, ROS levels, apoptosis, mitochondrial membrane potential (ΔΨm), and ATP concentration, as well as the expression of several genes related to oocyte maturation and development. Our studies found that treatment with glycine in IVM culture medium increased nuclear maturation rate, but varying the concentrations of glycine (0.6, 6, or 12 mM) had no significant effect. Furthermore, 6 mM glycine supported greater blastocyst formation rates and lesser apoptosis after PA than the other concentrations (P < 0.05). All the glycine treatment groups had decreased levels of ROS in both matured oocytes and at the 2-cell stage (P < 0.05). At the 2-cell stage, the 6 mM glycine group had ROS levels that were lesser than the other 2 glycine treatment groups (0.6 and 12 mM). From this, we deemed 6 mM to be the optimal condition, and we then investigated the effects of 6 mM glycine on gene expression. The expression of both FGFR2 and Hsf1 were greater than the control group in mature oocytes. The glycine treatment group had greater levels of expression of an antiapoptotic gene (Bcl2) in mature oocytes and cumulus cells and lesser levels of expression of a proapoptotic gene (Bax) in PA blastocysts (P < 0.05). In addition, mitochondrial ΔΨm and ATP concentration were increased in 6 mM glycine group compared with the control group. In conclusion, our results suggest that glycine plays an important role in oocyte maturation and later development by reducing ROS levels and increasing mitochondrial function to reduce apoptosis.

The Histone Deacetylase Inhibitor, CI994, Improves Nuclear Reprogramming and In Vitro Developmental Potential of Cloned Pig Embryos

Epigenetic reprogramming and somatic cell nuclear transfer (SCNT) cloning efficiency were recently enhanced using histone deacetylase inhibitors (HDACis). In this study, we investigated the time effect of CI994, an HDACi, on the blastocyst formation rate, acetylation levels of H3K9 and H4K12, DNA methylation levels of anti-5-methylcytosine (5mC), and some mRNA expression of pluripotency-related genes in pig SCNT embryos. Treatment with 10 μM CI994 for 24 hours significantly improved the blastocyst formation rate of SCNT embryos in comparison with the untreated group (p < 0.05). Moreover, average fluorescence intensities of H3K9 and H4K12 in CI994-treated embryos were remarkably increased at the pseudo-pronuclear stage, but not at the blastocyst stage. The intensity of POU5F1 was higher in CI994-treated blastocysts than in control blastocysts, whereas that of 5mC did not differ between the two groups. The percentage of apoptotic cells in blastocysts was significantly higher in the untreated group than in the CI994-treated group. mRNA levels of POU5F1 and SOX2 were significantly increased in the CI994-treated group. These observations suggest that optimum exposure (10 μM for 24 hours) to CI994 after activation elevates the level of histone acetylation and subsequently improves the in vitro development of pig SCNT embryos.

The cyclin-dependent kinase inhibitor, JNJ-7706621, improves in vitro developmental competence of porcine parthenogenetic activation and somatic cell nuclear transfer embryos

In this study we examined the effects of JNJ-7706621, a cyclin-dependent kinase inhibitor, on the in vitro growth of pig embryos that had been produced either by parthenogenetic activation (PA) or somatic cell nuclear transfer (SCNT). A significantly higher percentage of PA embryos reached the blastocyst stage by Day 7 after exposure to 10 µM JNJ-7706621 for 4 h compared with embryos exposed to 5 µg mL−1 cytochalasin B for 4 h (P < 0.05). Similarly, the rate of Tyr15 phosphorylation of the complex of cyclin and p34cdc2 (CDK1) was significantly elevated in the JNJ-7706621-treated embryos compared with embryos exposed to cytochalasin B or non-treated controls (P < 0.05). In contrast, Thr161 phosphorylation of CDK1 was significantly lower in the JNJ-7706621-treated group compared with the cytochalasin B-treated as well as the non-treated group (P < 0.05). Similarly, the level of M-phase-promoting factor (MPF) in embryos was significantly lower in the JNJ-7706621-treated group compared with the cytochalasin B-treated and non-treated groups (P < 0.05). In addition, more SCNT embryos reached the blastocyst stage after treatment with JNJ-7706621 than following exposure to cytochalasin B (P < 0.05). In conclusion, these results reveal that exposure to 10 µM JNJ-7706621 for 4 h improves early development of PA and SCNT porcine embryos by suppressing the activity of CDK1 and a concomitant reduction in the level of MPF.

Quisinostat treatment improves histone acetylation and developmental competence of porcine somatic cell nuclear transfer embryos

Abnormal epigenetic modifications are considered a main contributing factor to low cloning efficiency. In the present study, we explored the effects of quisinostat, a novel histone deacetylase inhibitor, on blastocyst formation rate in porcine somatic-cell nuclear transfer (SCNT) embryos, on acetylation of histone H3 lysine 9 (AcH3K9), and on expression of POU5F1 protein and apoptosis-related genes BAX and BCL2. Our results showed that treatment with 10 nM quisinostat for 24 hr significantly improved the development of reconstructed embryos compared to the untreated group (19.0 ± 1.6% vs. 10.2 ± 0.9%; p < 0.05). Quisinostat-treated SCNT embryos also possessed significantly increased AcH3K9 at the pseudo-pronuclear stage (p < 0.05), as well as improved immunostaining intensity for POU5F1 at the blastocyst stage (p < 0.05). While no statistical difference in BAX expression was observed, BCL2 transcript abundance was significantly different in the quisinostat-treated compared to the untreated control group. Of the 457 quisinostat-treated cloned embryos transferred into three surrogates, six fetuses developed from the one sow that became pregnant. These findings suggested that quisinostat can regulate gene expression and epigenetic modification, facilitating nuclear reprogramming, and subsequently improving the developmental competence of pig SCNT embryos and blastocyst quality.