Media switching at different time periods affects the reprogramming efficiency of buffalo fetal fibroblasts.

Many contrasting reports are available on generation of bovine induced pluripotent stem cells (iPSCs) employing different timelines and culture conditions which signifies reprogramming process varies between species and cell types. The present study determines an optimum time period required to re-initiate reprogramming events in buffalo fibroblasts after introduction of exogenous genes (OCT4, SOX2, KLF4 and c-MYC) by lentiviral vector. The reprogramming efficiency is cumulative result of many factors including culture conditions and addition of growth factors in culture media. In our study, we observed when stem cell culture conditions were provided Day 5 post-transduction, it results in maximum reprogramming efficiency in comparison when same conditions were provided too early or on later days. The putative iPSCs were expanded on feeder layer for 15 passages and found positive for alkaline phosphatase and pluripotency markers (OCT4, SOX2, KLF4, c-MYC, UTF, TELOMERASE, FOXD3, REX1, STAT3, NUCLEOSTAMIN and TRA1-81). Also, they produced embryoid bodies showing expression for ectodermal (NF68, MOBP), mesodermal (ASA, BMP4) and endodermal (GATA4, AFP) markers to confirm their pluripotent nature. Our results suggest that reprogramming is accompanied by time dependent events and providing stem cell culture conditions at definite time during reprogramming can help in generation of iPSCs with greater efficiency.

RNA sequencing and transcriptome analysis of buffalo (Bubalus bubalis) blastocysts produced by somatic cell nuclear transfer and in vitro fertilization.

Across farm animal species, the live birth rate obtained with somatic cell nuclear transfer (SCNT) embryos is only <2% compared with >40% obtained with in vitro fertilization (IVF) embryos, primarily due to incomplete nuclear reprogramming which results in aberrant embryonic gene expression. We used RNA sequencing to compare the global transcriptome profile of SCNT and IVF buffalo blastocysts. SCNT blastocysts expressed 17,061 transcripts, of which 941 were unique whereas, IVF blastocysts expressed 17,303 transcripts, of which 1,183 were unique. At ≥2-folds change (p < .05), 331 transcripts were differentially expressed in the two groups among which, 19 were unique, 188 were downregulated and 143 were upregulated in SCNT compared with IVF blastocysts. Many genes affecting pluripotency, trophectoderm development, developmental regulation, and epigenetic modifications were upregulated in SCNT compared with IVF blastocysts. Among the four functional categories analyzed, epigenetic regulators were the most affected. Most of the WNT signaling pathway genes were upregulated whereas, the inhibitors of this pathway, such as DKK1, were downregulated in SCNT blastocysts, suggesting that this pathway is overexpressed in SCNT embryos. Gene Ontology analysis revealed that 25 biological processes, 20 molecular functions, and 24 cellular compartment categories were enriched in SCNT blastocysts. This data can help identify reprogramming errors for improving cloning efficiency.

Buffalo SCNT embryos exhibit abnormal gene expression of ERK/MAPK pathway and DNA methylation.

Inhibition of ERK/MAPK pathway has been shown to decrease DNA methylation via down-regulation of DNA methyltransferases (DNMTs) in several studies suggesting that this pathway plays an important role in regulation of DNA methylation. We examined the relative expression level of seven important genes related to ERK/MAPK pathway and DNMTs (DNMT1, DNMT3a and DNMT3b) by quantitative real-time PCR in buffalo blastocysts produced by Hand-made cloning and compared it with that in blastocyst-stage embryos produced by in vitro fertilization (IVF). The expression level of six of seven genes related to ERK/MAPK pathway examined i.e., p21RAS, RAF1, AKT1, ERK2, PIK3R2 and c-Myc was significantly higher (p < 0.05) in cloned than in IVF embryos. However, the expression level of FOS was lower (p < 0.005) in cloned than in IVF embryos. The relative expression level of DNMT3a and DNMT3b but not that of DNMT1 was significantly higher (p < 0.05) in cloned than in IVF embryos. These results indicate that the cloned embryos exhibit an abnormal expression of several important genes related to ERK/MAPK pathway and DNMTs. Although a direct link between ERK/MAPK pathway and DNMTs was not examined in the present study, it can be speculated that ERK/MAPK pathway may have a role in regulating the expression of DNMTs in embryos, as also observed in other tissues.

Cumulus cell-conditioned medium supports embryonic stem cell differentiation to germ cell-like cells.

Cumulus cells provide cellular interactions and growth factors required for oogenesis. In vitro studies of oogenesis are limited primarily because of the paucity of their source, first trimester fetal gonads, and the small number of germ lineage precursor cells present within these tissues. In order to understand this obscure but vitally important process, the present study was designed to direct differentiation of embryonic stem (ES) cells into germ lineage cells. For this purpose, buffalo ES cells were differentiated, as embryoid bodies (EBs) and monolayer adherent cultures, in the presence of different concentrations of cumulus-conditioned medium (CCM; 10%, 20% and 40%) for different periods of culture (4, 8 and 14 days) to identify the optimum differentiation-inducing concentration and time. Quantitative polymerase chain reaction analysis revealed that 20%-40% CCM induced the highest expression of primordial germ cell-specific (deleted in Azoospermia- like (Dazl), dead (Asp-Glu-Ala-Asp) box polypeptide 4 (Vasa also known as DDX4) and promyelocytic leukemia zinc finger protein (Plzf)); meiotic (synaptonemal complex protein 3 (Sycp3), mutl homolog I (Mlh1), transition protein 1/2 (Tnp1/2) and protamine 2 (Prm2); spermatocyte-specific boule-like RNA binding protein (Boule) and tektin 1 (Tekt1)) and oocyte-specific growth differentiation factor 9 (Gdf9) and zona pellucida 2 /3 (Zp2/3)) genes over 8-14 days in culture. Immunocytochemical analysis revealed expression of primordial germ cell (c-KIT, DAZL and VASA), meiotic (SYCP3, MLH1 and PROTAMINE 1), spermatocyte (ACROSIN and HAPRIN) and oocyte (GDF9 and ZP4) markers in both EBs and monolayer differentiation cultures. Western blotting revealed germ lineage-specific protein expression in Day 14 EBs. The significantly lower (P<0.05) concentration of 5-methyl-2-deoxycytidine in differentiated EBs compared to undifferentiated EBs suggests that methylation erasure may have occurred. Oocyte-like structures obtained in monolayer differentiation stained positive for ZONA PELLUCIDA protein 4 and progressed through various embryo-like developmental stages in extended cultures.

WNT3A signalling pathway in buffalo (Bubalus bubalis) embryonic stem cells.

The aim of this study was to investigate the transcriptional profile and role of WNT3A signalling in maintaining buffalo embryonic stem (ES) cells in a pluripotent state and in the induction of their differentiation. ES cells were derived from embryos produced by in vitro fertilisation (iESC), parthenogenesis (pESC) and hand-made cloning (cESC). The expression of WNT3A, its receptors and intermediate signalling pathways were found to be conserved in ES cells derived from the three different sources. WNT3A was expressed in ES cells but not in embryoid bodies derived from iESC or in buffalo fetal fibroblast cells. It was revealed by real-time polymerase chain reaction analysis that following supplementation of culture medium with WNT3A (100, 200 or 400ngmL(-1)) a significant increase (P<0.05) was observed in the expression level of ß-CATENIN, which indicated the activation of the canonical WNT pathway. WNT3A, in combination with exogenous fibroblast growth factor-2 and leukaemia inhibitory factor, induced proliferation of undifferentiated ES cells. Differentiation studies showed that WNT3A caused formation of scaffold-like structures and inhibition of differentiation into neuron-like cells. In conclusion, the WNT3A signalling pathway is necessary both for maintaining undifferentiated buffalo ES cells as well as for directing their differentiation.

Production of Transgenic Handmade Cloned Goat (Capra hircus) Embryos by Targeted Integration into Rosa 26 Locus Using Transcription Activator-like Effector Nucleases.

Transgenic goats are ideal bioreactors for the production of therapeutic proteins in their mammary glands. However, random integration of the transgene within-host genome often culminates in unstable expression and unpredictable phenotypes. Targeting desired genes to a safe locus in the goat genome using advanced targeted genome-editing tools, such as transcription activator-like effector nucleases (TALENs) might assist in overcoming these hurdles. We identified Rosa 26 locus, a safe harbor for transgene integration, on chromosome 22 in the goat genome for the first time. We further demonstrate that TALEN-mediated targeting of GFP gene cassette at Rosa 26 locus exhibited stable and ubiquitous expression of GFP gene in goat fetal fibroblasts (GFFs) and after that, transgenic cloned embryos generated by handmade cloning (HMC). The transfection of GFFs by the TALEN pair resulted in 13.30% indel frequency at the target site. Upon cotransfection with TALEN and donor vectors, four correctly targeted cell colonies were obtained and all of them showed monoallelic gene insertions. The blastocyst rate for transgenic cloned embryos (3.92% ± 1.12%) was significantly (p < 0.05) lower than cloned embryos (7.84% ± 0.68%) used as control. Concomitantly, 2 out of 15 embryos of morulae and blastocyst stage (13.30%) exhibited site-specific integration. In conclusion, the present study demonstrates TALEN-mediated transgene integration at Rosa 26 locus in caprine fetal fibroblasts and the generation of transgenic cloned embryos using HMC.

Establishment, Growth, Proliferation, and Gene Expression of Buffalo (Bubalus bubalis) Transgenic Fetal Fibroblasts Containing Human Insulin Gene, and Production of Embryos by Handmade Cloning Using These Cells.

The aim of the present study was to compare transgenic cells, containing human insulin gene kept under the control of mammary gland-specific buffalo beta-lactoglobulin promoter, and their counterparts, that is, nontransgenic cells, for examining their potential for the production of embryos following somatic cell nuclear transfer (SCNT). The gene construct was delivered into buffalo fetal fibroblasts (BFF) by nucleofection following which, the transfected cells were selected by culture in the presence of G418 for 3 weeks. Transgene integration into BFF genome was confirmed by polymerase chain reaction (PCR) and reverse transcriptase PCR. At passage 8-10, the growth rate, cell proliferation rate, and quantitative expression of certain genes were compared between transgenic and nontransgenic cells. The growth rate and cell proliferation rate was significantly lower (p < 0.05) for transgenic than for nontransgenic cells. Using quantitative real-time PCR it was found that the expression level of CASPASE 3, CASPASE 9, BAX, and P53 was significantly higher (p < 0.05) and that of HDAC1 and IGF-1R was significantly lower (p < 0.05) in transgenic compared with nontransgenic cells. The differences in the relative expression level of BCL-XL, MCL-1, DNMT1, DNMT3a, GDF9, FGF2, and G6PD between the two groups were not significant. Furthermore, when the two cell types were used as donor cells for production of embryos by handmade cloning, the blastocyst rate was significantly lower (p < 0.05) with transgenic (35.69% ± 1.78%) than with nontransgenic cells (48.75% ± 2.38%). In conclusion, these results indicate that differences were present between transgenic and nontransgenic cells, which may affect the efficiency of SCNT when used as donor cells.

Epigenetic Alteration of Donor Cells with Histone Deacetylase Inhibitor m-Carboxycinnamic Acid Bishydroxymide Improves the In Vitro Developmental Competence of Buffalo (Bubalus bubalis) Cloned Embryos.

Epigenetic reprogramming is an indispensable process during the course of mammalian development, but aberrant in cloned embryos. The aim of this study was to examine the effect of donor cell treatment with histone deacetylase (HDAC) inhibitor m-carboxycinnamic acid bishydroxymide (CBHA) on cloned embryo development and establish its optimal concentration. Different concentrations of CBHA (2.5, 5.0, 10.0, and 20.0 µM) were used to treat buffalo adult fibroblast cells for 24 hours and effect on cell proliferation, gene expression, and histone modifications was analyzed. Based on these experiments, the best concentration was chosen to determine the effect of enhanced gene activation mark on developmental rates. Among the different concentrations, CBHA at higher concentration (20 µM) shows the sign of apoptosis and stress as indicated by proliferation rate and gene expression data. CBHA treatment significantly decreased the activity of HDACs and increased the level of gene activation mark H3K9ac and H3K4me3, but could not alter the level of H3K27ac. Based on these experiments, 5 µM CBHA was chosen for treatment of donor cells used for the production of cloned embryos. There was no significant difference in cleavage rate between the control and CBHA treatment group (98.5% ± 1.5% vs. 99.0% ± 1.0%), whereas, blastocyst rate markedly improved (46.65% ± 1.94% vs. 57.18% ± 2.68%). The level of H3K9ac and H3K27me3 did not differ significantly in cloned blastocyst produced from either control or CBHA-treated cells. Altogether, these results suggested that donor cell treatment with CBHA supports the reprogramming process and improves the cloned preimplantation development.

Retinoic acid induces differentiation of buffalo (Bubalus bubalis) embryonic stem cells into germ cells.

Development of precise and reproducible culture system for in vitro differentiation of embryonic stem (ES) cells into germ cells counts as a major leap forward for understanding not only the remarkable process of gametogenesis, otherwise obscured by limited availability of precursor primordial germ cells (PGCs), but in finally treating the catastrophic infertility. Taking into account the significant role of retinoic acid (RA) during in vivo gametogenesis, we designed the present study to investigate the effects of its stimulation on directing the differentiation of ES cells into germ cells. The effects of RA were analyzed across dose-and-time upon various stages of gametogenesis like PGC induction, meiosis initiation and completion, haploid cell formation and development of the final gamete (oocyte and spermatozoa). Out of the series of RA doses (2, 4, 8, 16, 20 and 30µM), 16µM RA for 8day culture interval was found to induce highest expression of PGC- and meiosis-associated genes like DAZL, VASA, SYCP3, MLH1, TNP1/2 and PRM2, while mature germ cell genes like BOULE and TEKT1 (Spermatocyte markers), GDF9 and ZP2 (Oocyte markers) showed higher expression at 2µM RA dose, suggesting functional concentration-gradient of RA activity. Immunocytochemistry revealed expression of germ lineage-specific markers like: c-KIT, DAZL and VASA (PGC-markers); SYCP3, MLH1 and PROTAMINE1 (Meiotic-markers); ACROSIN and HAPRIN (Spermatocyte-markers); and GDF9 and ZP4 (Oocyte-markers) in optimally differentiated embryoid bodies (EBs) and adherent cultures. We observed significantly reduced (p<0.05) concentration of 5-methyl-2-deoxycytidine in RA-differentiated EBs which is suggestive of the occurrence of methylation erasure. FACS analysis of optimally differentiated cultures detected 3.07% haploid cell population, indicating completion of meiosis. Oocyte-like structures (OLS) were obtained in adherent differentiated cultures. They had a big nucleus and a zona pellucida (ZP4) coat. They showed progression through 2-cell, 4-cell, 8-cell, morula and blastocyst-like structures upon extended culture beyond 14days.

Retinoic acid induces differentiation of buffalo (Bubalus bubalis) embryonic stem cells into germ cells.

Development of precise and reproducible culture system for in vitro differentiation of embryonic stem (ES) cells into germ cells counts as a major leap forward for understanding not only the remarkable process of gametogenesis, otherwise obscured by limited availability of precursor primordial germ cells (PGCs), but in finally treating the catastrophic infertility. Taking into account the significant role of retinoic acid (RA) during in vivo gametogenesis, we designed the present study to investigate the effects of its stimulation on directing the differentiation of ES cells into germ cells. The effects of RA were analyzed across dose-and-time upon various stages of gametogenesis like PGC induction, meiosis initiation and completion, haploid cell formation and development of the final gamete (oocyte and spermatozoa). Out of the series of RA doses (2, 4, 8, 16, 20 and 30µM), 16µM RA for 8day culture interval was found to induce highest expression of PGC- and meiosis-associated genes like DAZL, VASA, SYCP3, MLH1, TNP1/2 and PRM2, while mature germ cell genes like BOULE and TEKT1 (Spermatocyte markers), GDF9 and ZP2 (Oocyte markers) showed higher expression at 2µM RA dose, suggesting functional concentration-gradient of RA activity. Immunocytochemistry revealed expression of germ lineage-specific markers like: c-KIT, DAZL and VASA (PGC-markers); SYCP3, MLH1 and PROTAMINE1 (Meiotic-markers); ACROSIN and HAPRIN (Spermatocyte-markers); and GDF9 and ZP4 (Oocyte-markers) in optimally differentiated embryoid bodies (EBs) and adherent cultures. We observed significantly reduced (p<0.05) concentration of 5-methyl-2-deoxycytidine in RA-differentiated EBs which is suggestive of the occurrence of methylation erasure. FACS analysis of optimally differentiated cultures detected 3.07% haploid cell population, indicating completion of meiosis. Oocyte-like structures (OLS) were obtained in adherent differentiated cultures. They had a big nucleus and a zona pellucida (ZP4) coat. They showed progression through 2-cell, 4-cell, 8-cell, morula and blastocyst-like structures upon extended culture beyond 14days.

RETRACTED: Bone morphogenetic protein 4 (BMP4) induces buffalo (Bubalus bubalis) embryonic stem cell differentiation into germ cells.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Problems related to images published in this paper in Figure 12 were brought to the authors' attention. Unfortunately this figure contains duplicate images for ESC controls for VASA, GDF9, and ZP4, which display identical patterns superimposed on varying intensities of background. Therefore, the authors retract the paper with the agreement of the editors and deeply regret this situation and apologize for any inconvenience to the editors and readers of Biochimie.

Development, Characterization, and Pluripotency Analysis of Buffalo (Bubalus bubalis) Embryonic Stem Cell Lines Derived from In Vitro-Fertilized, Hand-Guided Cloned, and Parthenogenetic Embryos.

We present the derivation, characterization, and pluripotency analysis of three buffalo embryonic stem cell (buESC) lines, from in vitro-fertilized, somatic cell nuclear-transferred, and parthenogenetic blastocysts. These cell lines were developed for later differentiation into germ lineage cells and elucidation of the signaling pathways involved. The cell lines were established from inner cell masses (ICMs) that were isolated manually from the in vitro-produced blastocysts. Most of the ICMs (45-55%) resulted in formation of primary colonies that were subcultured after 8-10 days, leading subsequently to the formation of three buESC lines, one from each blastocyst type. All the cell lines expressed stem cell markers, such as Alkaline Phosphatase, OCT4, NANOG, SSEA1, SSEA4, TRA-1-60, TRA-1-81, SOX2, REX1, CD-90, STAT3, and TELOMERASE. They differentiated into all three germ layers as determined by ectodermal, mesodermal, and endodermal RNA and protein markers. All of the cell lines showed equal expression of pluripotency markers as well as equivalent differentiation potential into all the three germ layers. The static suspension culture-derived embryoid bodies (EBs) showed greater expression of all the three germ layer markers as compared to hanging drop culture-derived EBs. When analyzed for germ layer marker expression, EBs derived from 15% fetal bovine serum (FBS)-based spontaneous differentiation medium showed greater differentiation across all the three germ layers as compared to those derived from Knock-Out Serum Replacement (KoSR)-based differentiation medium.

Optimization of culture conditions to support long-term self-renewal of buffalo (Bubalus bubalis) embryonic stem cell-like cells.

A culture system capable of sustaining self-renewal of buffalo embryonic stem (ES) cell-like cells in an undifferentiated state over a long period of time was developed. Inner cell masses were seeded on KO-DMEM+15% KO-serum replacer on buffalo fetal fibroblast feeder layer. Supplementation of culture medium with 5 ng/mL FGF-2 and 1000 IU/mL mLIF gave the highest (p<0.05) rate of primary colony formation. The ES cell-like cells' colony survival rate and increase in colony size were highest (p<0.05) following supplementation with FGF-2 and LIF compared to other groups examined. FGF-2 supplementation affected the quantitative expression of NANOG, SOX-2, ACTIVIN A, BMP 4, and TGFß1, but not OCT4 and GREMLIN. Supplementation with SU5402, an FGFR inhibitor (≥20 µM) increased (p<0.05) the percentage of colonies that differentiated. FGFR1-3 and ERK1, K-RAS, E-RAS, and SHP-2, key signaling intermediates of FGF signaling, were detected in ES cell-like cells. Under culture conditions described, three ES cell lines were derived that, to date, have been maintained for 135, 95, and 85 passages for over 27, 19, and 17 months, respectively, whereas under other conditions examined, ES cell-like cells did not survive beyond passage 10. The ES cell-like cells were regularly monitored for expression of pluripotency markers and their potency to form embryoid bodies.