Sequence characterization and comparative expression profile of buffalo WNT10B gene in adult and fetal tissues.

In this study, Wingless-type MMTV (mouse mammary tumor virus) integration site family member (WNT10B) gene was sequence characterized in the Indian water buffalo. Sequence analysis revealed an open reading frame of 1176 nucleotides in buffalo, encoding 391 amino acids long protein. Nineteen nucleotide variations were observed between cattle and buffalo resulting in six amino acid changes. Phylogenetic analysis showed the clustering of ruminant species together. Real-time expression analysis of WNT10B in tissues collected from different organs of fetal and adult buffalo, revealed, the gene being abundantly expressed in the rumen and liver of the fetus. The fetal ovary, heart, kidney, lung, testis and mammary gland showed moderate expression, while in adult tissues, expression was high in the ovary, testis, brain, kidney, small intestine and liver, whereas lower expression was observed in the adult rumen. Significant differences in WNT10B expression levels were found for the brain, small intestine, testes, kidney, heart, rumen, and ovary when adult and fetal tissues were compared. A moderate level of genetic variation was found between cattle and buffalo WNT10B and expression patterns in a variety of tissues in adult buffalo implies that in addition to possible roles in adipogenesis and hematopoiesis, the WNT10B gene might be playing a significant role in other regulatory pathways as well.

Propagation of porcine spermatogonial stem cells in serum-free culture conditions using knockout serum replacement.

In vitro culture and expansion of spermatogonial stem cells (SSCs) is an essential prerequisite to enhancing livestock productivity through SSC transplantation. Most of the culture media have been observed to be supplemented with serum. However, the use of serum in culture media may exert detrimental effects on SSC maintenance in vitro. An attempt was made to culture SSCs by replacing serum with 5% 'Knockout Serum Replacement (KSR)' in Doom pig (Sus domesticus), one of the valued indigenous germplasm of North-East India. Testes from 7 to 15 days old piglets were used for isolation, enrichment and in vitro culture of putative SSCs using serum-based and serum-free culture media. The cells were characterized for SSC-specific pluripotent markers expression by immunofluorescence staining and quantitative real-time PCR. The diameter and number of SSC colonies were recorded on days 9, 20 and 30 of culture. Similar morphologies of the SSC colonies were observed in both serum-based and serum-free culture conditions. Colony diameter and colony number were non-significantly higher in serum-free than serum-based media. The cells from both the culture conditions showed high alkaline phosphatase activity. The expression of SSC-specific pluripotent markers was observed in immunofluorescence and quantitative real-time PCR study. The present study revealed that SSCs from porcine species could be maintained in vitro for up to 30 days in serum-free culture using 5% KSR, which is believed to be a promising protein source for improving livestock production, and health care along with their conservation.

Exposure to Pulsed Electromagnetic Fields Improves the Developmental Competence and Quality of Somatic Cell Nuclear Transfer Buffalo (Bubalus bubalis) Embryos Produced Using Fibroblast Cells and Alters Their Epigenetic Status and Gene Expression.

We examined the effects of treatment with pulsed electromagnetic fields (PEMFs) on cumulus cells and buffalo somatic cell nuclear transfer (SCNT) embryos. PEMF treatment (30 µT for 3 hours) of cumulus cells increased (p < 0.05) the relative cell viability and cell proliferation and the expression level of OCT4, NANOG, SOX2, P53, CCNB1, and GPX, but decreased (p < 0.05) that of DNMT1, DNMT3a, GSK3b, and BAX, whereas the expression level of DNMT3b, GLUT1, BCL2, CASPASE3, SOD1, and CATALASE was not affected. PEMF treatment of SCNT embryos at the beginning of in vitro culture increased (p < 0.05) the blastocyst rate (51.4% ± 1.36% vs. 42.8% ± 1.29%) and decreased (p < 0.01) the apoptotic index to the level in in vitro fertilization blastocysts, but did not significantly alter the total cell number and the inner cell mass:trophectoderm cell number ratio of blastocysts compared to the controls. PEMF treatment increased the expression level of NANOG, SOX2, CDX2, GLUT1, P53, and BCL2 and decreased that of BAX, CASPASE3, GSK3b, and HSP70, but not OCT4, DNMT1, DNMT3a, DNMT3b, HDAC1, and CCNB1 in blastocysts. It increased (p < 0.001) the global level of H3K27me3 but not H3K18ac. These results suggest that PEMF treatment of SCNT embryos improves their developmental competence, reduces the level of apoptosis, and alters the expression level of several important genes related to pluripotency, apoptosis, metabolism, and stress.

Low oxygen tension potentiates proliferation and stemness but not multilineage differentiation of caprine male germline stem cells.

The milieu of male germline stem cells (mGSCs) is characterized as a low-oxygen (O2) environment, whereas, their in-vitro expansion is typically performed under normoxia (20-21% O2). The comparative information about the effects of low and normal O2 levels on the growth and differentiation of caprine mGSCs (cmGSCs) is lacking. Thus, we aimed to investigate the functional and multilineage differentiation characteristics of enriched cmGSCs, when grown under hypoxia and normoxia. After enrichment of cmGSCs through multiple methods (differential platting and Percoll-density gradient centrifugation), the growth characteristics of cells [population-doubling time (PDT), viability, proliferation, and senescence], and expression of key-markers of adhesion (ß-integrin and E-Cadherin) and stemness (OCT-4, THY-1 and UCHL-1) were evaluated under hypoxia (5% O2) and normoxia (21% O2). Furthermore, the extent of multilineage differentiation (neurogenic, adipogenic, and chondrogenic differentiation) under different culture conditions was assessed. The survival, viability, and proliferation were significantly (p < 0.05) improved, thus, yielding a significantly (p < 0.05) higher number of viable cells with larger colonies under hypoxia. Furthermore, the expression of stemness and adhesion markers were distinctly upregulated under lowered O2 conditions. Conversely, the differentiated regions and expression of differentiation-specific genes [C/EBPα (adipogenic), nestin and ß-tubulin (neurogenic), and COL2A1 (chondrogenic)] were significantly (p < 0.05) reduced under hypoxia. Overall, the results demonstrate that culturing cmGSCs under hypoxia augments the growth characteristics and stemness but not the multilineage differentiation of cmGSCs, as compared with normoxia. These data are important to develop robust methodologies for ex-vivo expansion and lineage-committed differentiation of cmGSCs for clinical applications.

Optimization of Serum-Free Culture Conditions for Propagation of Putative Buffalo (Bubalus bubalis) Spermatogonial Stem Cells.

Spermatogonial stem cells (SSCs) self-renew and produce a large number of differentiated germ cells to maintain normal spermatogenesis. However, the growth factors crucial for SSC self-renewal and the mechanism underlying this process remain unclear. In the present study, a serum-free culture media was used to evaluate the effect of several growth factors on the expression of some SSC markers and self-renewal related genes. The putative SSCs were cultured on buffalo Sertoli cell feeder layer in KO-DMEM +10% KOSR. The colony formation was observed between 7 and 10 days. The putative SSC colonies also expressed markers specific for undifferentiated type A spermatogonia and pluripotency markers. After 15 days, relative mRNA expression study revealed that 20 ng/mL concentration of Glial cell line-derived neurotrophic factor (GDNF) upregulated the expression of PLZF, TAF4B, and THY1. Furthermore, supplementation of a combination of 20 ng/mL GDNF, 10 ng/mL basic fibroblast growth factor (bFGF), 1000 IU/mL leukemia inhibitory factor (LIF), and 1 ng/mL colony stimulating factor 1 (CSF1) upregulated the expression of PLZF, TAF4B, BCL6B, and ID4 genes. These results demonstrated that our defined culture media in combination with GDNF, bFGF, LIF, and CSF1 well supported SSC self-renewal.

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.

BRCA-1 Gene Expression and Comparative Proteomic Profile of Primordial Follicles from Young and Adult Buffalo (Bubalus bubalis) Ovaries.

In our previous study, we demonstrated that the repair efficiency of DNA double-strand breaks declines with increasing age in rat primordial follicles. In the present study, we extended our studies to buffalo (Bubalus bubalis) wherein we studied the expression of BRCA-1 related DNA repair genes in primordial follicles of young (12 months-22 months) and adult (72-96 months) buffaloes. The relative expression of selected genes, as determined by RT-PCR, revealed a significant (p < 0.05) decrease in mRNA levels of BRCA1, MRE11, RAD51, ATM, and H2AX in adult primordial follicles as compared to the young. Western blot analysis revealed a significant (p < 0.05) decrease in the expression of phosphorylated protein levels of BRCA1 and H2AX in adult buffalo primordial follicles. The protein expression profile of young and adult buffalo primordial follicles revealed differential expression of proteins involved in mitochondrial function, cell survival and cell metabolism. Similar to reports from aging rodent and human primordial follicles, our findings support the fact that impairment of DNA repair may be an universal mechanism involved in oocyte aging.

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.

Activation and Inhibition of The Wnt3A Signaling Pathway in Buffalo (Bubalus bubalis) Embryonic Stem Cells: Effects of WNT3A, Bio and Dkk1.

BACKGROUND: This research studies the effects of activation and inhibition of Wnt3A signaling pathway in buffalo (Bubalus bubalis) embryonic stem (ES) cell-like cells. MATERIALS AND METHODS: To carry on this experimental study, the effects of activation and inhibition of Wnt3A signaling in buffalo ES cell-like cells were examined using Bio (0.5 mM) combined with WNT3A (200 ng/ml), as an activator, and Dickkopf-1 (Dkk1, 250 ng/ml), as an inhibitor, of the pathway. ES cells were cultured up to three weeks in ES cell medium without fibroblast growth factor-2 (FGF-2) and leukemia inhibitory factor (LIF), but in the presence of Bio, WNT3A, Bio+WNT3A and Dkk1. The effects of these supplements were measured on the mean area of ES cell colonies and on the expression levels of a number of important genes related to pluripotency (Oct4, Nanog, Sox2 and c-Myc) and the Wnt pathway (ß-catenin). ES cell colonies cultured in ES cell medium that contained optimized quantities of LIF and FGF-2 were used as the control. Data were collected for week-1 and week-3 treated cultures. In addition, WNT3A-transfected ES cells were compared with the respective mock-transfected colonies, either alone or in combination with Dkk1 for expression of ß-catenin and the pluripotency-related genes. Data were analyzed by ANOVA, and statistical significance was accepted at P<0.05. RESULTS: Among various examined concentrations of Bio (0.5-5 mM), the optimum effect was observed at the 0.5 mM dose as indicated by colony area and expressions of pluripotency-related genes at both weeks-1 and -3 culture periods. At this concentration,the expressions of Nanog, Oct3/4, Sox2, c-Myc and ß-catenin genes were nonsignificantly higher compared to the controls. Expressions of these genes were highest in the Bio+WNT3A treated group, followed by the WNT3A and Bio-supplemented groups, and lowest in the Dkk1-treated group. The WNT-transfected colonies showed higher expressions compared to both mock and Dkk1-treated mock transfected colonies. CONCLUSION: WNT3A functions to maintain the pluripotency of ES cell-like cells both as an exogenous growth factor as well as an endogenously expressed gene. It complements the absence of FGF-2 and LIF, otherwise propounded essential for buffalo ES cell culture. WNT3A antagonizes the inhibitory effects of Dkk1 and acts in combination with its activator, Bio, to activate the Wnt signaling pathway.

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 Buffalo (Bubalus bubalis) Embryonic Stem Cell Culture System.

OBJECTIVE: In order to retain an undifferentiated pluripotent state, embryonic stem (ES) cells have to be cultured on feeder cell layers. However, use of feeder layers limits stem cell research, since experimental data may result from a combined ES cell and feeder cell response to various stimuli. MATERIALS AND METHODS: In this experimental study, a buffalo ES cell line was established from in vitro derived blastocysts and characterized by the Alkaline phosphatase (AP) and immunoflourescence staining of various pluripotency markers. We examined the effect of various factors like fibroblast growth factor 2 (FGF-2), leukemia inhibitory factor (LIF) and Y-27632 to support the growth and maintenance of bubaline ES cells on gelatin coated dishes, in order to establish feeder free culture systems. We also analyzed the effect of feeder-conditioned media on stem cell growth in gelatin based cultures both in the presence as well as in the absence of the growth factors. RESULTS: The results showed that Y-27632, in the presence of FGF-2 and LIF, resulted in higher colony growth and increased expression of Nanog gene. Feeder-Conditioned Medium resulted in a significant increase in growth of buffalo ES cells on gelatin coated plates, however, feeder layer based cultures produced better results than gelatin based cultures. Feeder layers from buffalo fetal fibroblast cells can support buffalo ES cells for more than two years. CONCLUSION: We developed a feeder free culture system that can maintain buffalo ES cells in the short term, as well as feeder layer based culture that can support the long term maintenance of buffalo ES cells.

Construction of a recombinant human insulin expression vector for mammary gland-specific expression in buffalo (Bubalus bubalis) mammary epithelial cell line.

The aim of the present study was construction of mammary gland specific expression vector for high level of human insulin (hINS) expression in transgenic buffalo for therapeutic use. We have constructed mammary gland specific vector containing human insulin gene and there expression efficiency was checked into in vitro cultured buffalo mammary epithelial cells (BuMECs). Human pro-insulin coding region was isolated from human genomic DNA by intron skipping PCR primer and furin cleavage site was inserted between B-C and C-A chain of human insulin by overlap extension PCR. A mammary gland-specific buffalo beta-lactoglobulin promoter was isolated from buffalo DNA and used for human insulin expression in BuMEC cells. The construct was transfected into BuMECs by lipofection method and positive transgene cell clones were obtained by G418 selection after 3 weeks. Expression of hINS in transfected cells were confirmed by RT-PCR, Immunocytochemistry, Western Blotting and ELISA. The pAcISUBC insulin-expressing clones secreted insulin at varying levels between 0.18 - 1.43 ng/ml/24 h/2.0 × 10(6) cells.

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.

Isolation, characterization, and EGFP expression in the buffalo (Bubalus bubalis) mammary gland epithelial cell line.

This study was aimed to establish a buffalo mammary epithelial cells (BuMECs) line and maintain it for long-term by subculturing. BuMECs isolated from lactating buffalo mammary glands were cultured on a collagen matrix gel. BuMECs expressed significant amounts of the epithelial cell specific marker cytokeratin 18 as determined by immunohistochemistry. The BuMECs displayed monolayer, cobble-stone morphology, and formed lumen-, dome-, and duct-like structures. Furthermore, they were capable of synthesizing CSN2, BLG, ACACA, and BTN1A1, showed viability after thawing and expressed milk protein genes. The enhanced green fluorescent protein gene was transferred successfully into the BuMECs using lipofection method and the transfected cells could be maintained for long-term in culture by subculturing.

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.