Expression Of Pluripotency Markers OCT4 Research Articles

SPOP suppresses testicular germ cell tumors progression through ubiquitination and degradation of DPPA2

Dysregulation of the ubiquitin–proteasome pathway is strongly associated with cancer initiation and progression. Speckle-type POZ(pox virus and zinc finger protein) protein(SPOP) is an adapter protein of CUL3-based E3 ubiquitin ligase complexes. Gene expression profiling from the Cancer Genome Atlas (TCGA) suggests that SPOP is downregulated in testicular germ cell tumors (TGCTs), but the specific contribution of this protein remains to be explored. In this study, we show that the germ line-specific factor DPPA2 was identified as a proteolytic substrate for the SPOP-CUL3-RBX1 E3 ubiquitin-ligase complex. SPOP specifically binds to a SPOP-binding consensus (SBC) degron located in DPPA2 and targets DPPA2 for degradation via the ubiquitin–proteasome pathway. SPOP downregulation increases the expression of pluripotency markers OCT4 and Nanog but decreases that of early differentiation marker gene Fst. This effect is partly dependent on its activity toward DPPA2. In addition, the dysregulation of SPOP-DPPA2 axis contributes to the malignant transformation phenotypes of TGCT cells.

Episomal reprogramming of Duchenne muscular dystrophy patients derived CD3+ T cells towards induced pluripotent stem cells.

Objective:To derive Duchenne muscular dystrophy patient specific induced pluripotent stem cells (iPSCs) from CD3+T cells of DMD patients using episomal reprogramming and characterization of these DMD-iPSCs using immunofluorescence to confirm their pluripotent state.Methods:DMD patients were selected based upon their clinical history and examination. Peripheral blood mononuclear cells were isolated from peripheral blood of DMD patients (n=3) by density gradient centrifugation and were used to generate DMD patient specific T cells (DMD-T cells) using rhIL-2, plate bound anti CD3 antibody and T cell specific media along with specific culture conditions that promote T cell expansion. CD3+ T cells were characterized by flow cytometry and reprogrammed using episomal plasmid to generate DMD-iPSCs. These DMD-iPSCs were characterized using immunofluorescence. The study was carried out at Dow Research Institute of Biotechnology and Biomedical Sciences during August 2017- July 2018 for a period of approximately 12 months.Results:The peripheral blood mononuclear cells (PBMNC) derived T cells appeared as suspended cell clumps morphologically were positive for the expression of CD3 and negative for CD31. The DMD patient specific iPSCs appeared as round, compact and flat colonies with well-defined edges morphologically and were positive for the expression of pluripotency markers OCT4, SSEA-4 and TRA-1-81 on immunofluorescence.Conclusion:CD3+ T cell derived DMD-iPSCs were obtained under feeder free and xeno-free culture conditions using episomal reprogramming.

Generation of Human-Induced Pluripotent Stem Cells from Peripheral Blood Mononuclear Cells using Small-Molecule Compound VC6TFZ

BACKGROUND: Induced pluripotent stem cells (iPSCs) were generated from somatic cells through reprogramming process. Peripheral blood mononuclear cells (PBMNCs) were an attractive source cells due to the ease of accessibility, need minimal invasive procedure, and can be stored frozen. Small-molecule compound VC6TFZ has been successfully reprogrammed iPSCs from mouse fibroblast, but it has not been proven in human.
 AIM: This study aims to determine whether the small-molecule compound VC6TFZ can induce pluripotency of PBMNC to generate iPSCs.
 METHODS: Mononuclear cells were isolated from peripheral venous blood using centrifugation gradient density method. Mononuclear cells were cultured for 6 days in expansion medium and 48 h using hanging drop method. Pluripotency induction process using small-molecule compound VC6TFZ was done in 14 days then the medium changed to 2i medium for 7 days. Identification of iPSCs based on colony morphology and expression of pluripotency marker OCT4 and SOX2.
 RESULTS: Colonies appeared on day 9 of reprogramming process. These colonies had round, large, and cobble stone morphology like embryonic stem cell. These colonies had positive expression of pluripotency markers OCT4 and SOX2. All experimental groups had significantly higher expression of OCT4 and SOX2 than control group.
 CONCLUSION: Small-molecule compound VC6TFZ could induce pluripotency of human PBMNC to generate iPSCs.

Senescence-induced immunophenotype, gene expression and electrophysiology changes in human amniocytes.

The aim of the study was to evidence replicative senescence‐induced changes in human amniocytes via flow cytometry, quantitative reverse‐transcription‐polymerase chain reaction (qRT‐PCR) and automated/manual patch‐clamp. Both cryopreserved and senescent amniocytes cultured in BIO‐AMF‐2 medium featured high percentages of pluripotency cell surface antigens SSEA‐1, SSEA‐4, TRA1‐60, TRA1‐81 (assessed by flow cytometry) and expression of pluripotency markers Oct4 (Pou5f1) and Nanog (by qRT‐PCR). We demonstrated in senescent vs cryopreserved amniocytes decreases in mesenchymal stem cell surface markers. Senescence‐associated β‐galactosidase stained only senescent amniocytes, and they showed no deoxyuridine incorporation. The gene expression profile revealed a secretory phenotype of senescent amniocytes (increased interleukin (IL)‐1α, IL‐6, IL‐8, transforming growth factor β, nuclear factor κB p65 expression), increases for cell cycle‐regulating genes (p16INK4A), cytoskeletal elements (β‐actin); HMGB1, c‐Myc, Bcl‐2 showed reduced changes and p21, MDM2 decreased. Via patch‐clamp we identified five ion current components: outward rectifier K+ current, an inactivatable component, big conductance Ca2+‐dependent K+ channels (BK) current fluctuations, Na+ current, and inward rectifier K+ current. Iberiotoxin 100 nmol/L blocked 71% of BK fluctuations, and lidocaine 200 μmol/L exerted use‐dependent Na+ current block. Transient receptor potential (TRP)M7‐like current density at −120 mV was significantly increased in senescent amniocytes. The proinflammatory profile acquired by senescent amniocytes in vitro may prevent their use in clinical therapies for immunosuppression, antiapoptotic and healing effects.

The Role of Microenvironment in Preserving the Potency of Adult Porcine Pulmonary Valve Stem Cells In Vitro.

Background and ObjectiveThe potency of tissue resident stem cells is regulated primarily by inputs from the local microenvironment. Isolation of stem cells through enzymatic digestion of tissue may affect epigenetic regulation of cell fate and performance. Here we employ a non-enzymatic method to harvest and investigate tissue resident stem cells from the adult porcine pulmonary valve.Methods and ResultsThe presence of c-Kit+ stem cells within the valve tissue was confirmed by immunohistochemistry. An in vitro culture of minced valve leaflets was developed under the standard conditions (37°C with 5% CO2). The viability of the cellular outgrowths was evaluated over the subsequent 12 weeks. Under this culture condition, we identified a population of non-adherent c-Kit+ cells and multiple cellular structures mimicking the phenotype of embryonic stem cells at different stages of development. Formation of multinucleated cells through cell fusion provided an active niche area for homing and interaction of the non-adherent c-Kit+ cells. Expression of pluripotency markers Oct-4 and Nanog was detected in the newly formed multinucleated cells but not in mature colonies. Partial cell fusion was shown by fluorescent live-cell tracking, which confirmed intercellular molecular exchange between donor and recipient cells, resulting in altered cytoplasmic protein expression by the recipient cell.ConclusionsThese results suggest a role for the microenvironment in decrypting the potential of the valve somatic stem cells in vitro. In addition, our data provide evidence for cell fusion, which may play a critical role in reversing somatic cell fate and spontaneous cellular reprogramming.

NRP1-positive lung cancer cells possess tumor-initiating properties.

Tumor-initiating cells possess the capacity for self-renewal and to create heterogeneous cell lineages within a tumor. Therefore, the identification and isolation of cancer stem cells is an essential step in the analysis of their biology. The aim of the present study was to determine whether the cell surface protein neuropilin 1 (NRP1) can be used as a biomarker of stem-like cells in lung cancer tumors. For this purpose, NRP1-negative (NRP1−) and NRP1-positive (NRP1+) cell subpopulations from two lung cancer cell lines were sorted by flow cytometry. The NRP1+ cell subpopulation showed an increased expression of pluripotency markers OCT-4, Bmi-1 and NANOG, as well as higher cell migration, clonogenic and self-renewal capacities. NRP1 gene knockdown resulted not only in a decreased expression of stemness markers but also in a decrease in the clonogenic, cell migration and self-renewal potential. In addition, the NRP1+ cell subpopulation exhibited dysregulated expression of epithelial-to-mesenchymal transition-associated genes, including the ΔNp63 isoform protein, a previously reported characteristic of cancer stem cells. Notably, a genome-wide expression analysis of NRP1-knockdown cells revealed a potential new NRP1 pathway involving OLFML3 and genes associated with mitochondrial function. In conclusion, we demonstrated that NRP1+ lung cancer cells have tumor-initiating properties. NRP1 could be a useful biomarker for tumor-initiating cells in lung cancer tumors.

Abstract TMEM-024: CHARACTERIZATION OF STEM CELLS IN HIGH GRADE SEROUS OVARIAN CARCINOMA CELLS

Abstract PURPOSE: The objectives of this study are to understand how transcription factors and miRNAs impact stemness in epithelial ovarian cancer (EOC). Our goal is to target EOC cancer stem cells (CSC) in order to arrest disease progression. Ovarian Cancer is the most fatal gynecological diagnosis for women. It is typically treated with surgery and chemotherapy, which is initially successful in that tumors shrink; however, most patients experience relapse. Cancer Stem Cells (CSCs) express a similar set of stem cell markers as pluripotent cells, and are thought to contribute to chemoresistance and relapse. Chemotherapy is effective on differentiated cells of the tumor, however cancer stem cells survive, and have the ability to repair and renew the tumor. Cancer cells can be re-sensitized to chemotherapy if stem cells are targeted. Several stem cell markers are expressed in advanced ovarian malignancies. We study the effect of the epithelial to mesenchymal transition (EMT) on stemness. During EMT, cells acquire mesenchymal characteristics and lose epithelial ones. EMT is caused by SNAI1 and other transcription factors that repress epithelial and adhesion molecules such as E-cadherin. EMT results in a stem cell-like phenotype in breast cancer. There is evidence that the EMT factor SNAI1 represses the miRNA let-7, which we hypothesize results in a higher proportion of CSC in EOC cells. Let-7's major function is to promote terminal differentiation and tumor suppression by targeting oncogenes and pluripotency factors. EXPERIMENTAL PROCEDURES: We performed flow cytometry for CD133, CD44, CD117, and aldehyde dehydrogenase to determine proportion of positive cells using published markers. q-RT-PCR was used to determine expression of pluripotency markers Oct4, Lin28 and Nanog. We used immunofluorescence microscopy to identify CSCs. Using a panel of biomarkers specific to CSCs we labeled for SNAI1, NANOG, LIN28A, OCT4, SSEA4, ALDH, TRA1-60, CD133, E-CAD, and N-CAD followed by fluorescent secondary antibodies and nuclear labeling with DAPI. We characterized three epithelial ovarian cell (EOC) lines (OVCAR8, OVSAHO, and COV 318) and patient-derived cells, with and without Snai1 manipulation. RESULTS: Cells were positive for stem cell markers to varying degrees. OVCAR-8 was positive for LIN28A, NANOG, CD44, and ALDH; OVSAHO for Lin 28a and ALDH; and COV318 for NANOG and ALDH. OVSAHO displayed most epithelial (E) characteristics, COV318 and patient samples were most mesenchymal (M), and OVCAR8 appeared to be a M/E hybrid. There was imperfect correlation between mRNA and protein expression of pluripotency markers. CONCLUSIONS: Higher expression of Snai1 correlates with a stem cell phenotype on a population level. On a single cell level, most Nanog-positive cells are Snail positive. However, no ovarian cancer cell perfectly mirrors the pluripotent marker expression seen in NCCIT, our positive control. SNAI1 is a potential target for therapy targeting ovarian cancer stem cells. Citation Format: Maricela Gallardo, Alyse Huisken-Hill, Hanmin Wang, Christine Castanon, Juli J. Unternaehrer. CHARACTERIZATION OF STEM CELLS IN HIGH GRADE SEROUS OVARIAN CARCINOMA CELLS [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr TMEM-024.

TRPV3 Channel Negatively Regulates Cell Cycle Progression and Safeguards the Pluripotency of Embryonic Stem Cells.

Embryonic stem cells (ESCs) have tremendous potential for research and future therapeutic purposes. However, the calcium handling mechanism in ESCs is not fully elucidated. Aims of this study are (1) to investigate if transient receptor potential vanilloid-3 (TRPV3) channels are present in mouse ESCs (mESCs) and their subcellular localization; (2) to investigate the role of TRPV3 in maintaining the characteristics of mESCs. Western blot and immunocytochemistry showed that TRPV3 was present at the endoplasmic reticulum (ER) of mESCs. Calcium imaging showed that, in the absence of extracellular calcium, TRPV3 activators camphor and 6-tert-butyl-m-cresol increased the cytosolic calcium. However, depleting the ER store in advance of activator addition abolished the calcium increase, suggesting that TRPV3 released calcium from the ER. To dissect the functional role of TRPV3, TRPV3 was activated and mESC proliferation was measured by trypan blue exclusion and MTT assays. The results showed that TRPV3 activation led to a decrease in mESC proliferation. Cell cycle analysis revealed that TRPV3 activation increased the percentage of cells in G2 /M phase; consistently, Western blot also revealed a concomitant increase in the expression of inactive form of cyclin-dependent kinase 1, suggesting that TRPV3 activation arrested mESCs at G2 /M phase. TRPV3 activation did not alter the expression of pluripotency markers Oct-4, Klf4 and c-Myc, suggesting that the pluripotency was preserved. Our study is the first study to show the presence of TRPV3 at ER. Our study also reveals the novel role of TRPV3 in controlling the cell cycle and preserving the pluripotency of ESCs.

Effect of luteolin and apigenin on the expression of Oct-4, Sox2, and c-Myc in dental pulp cells with in vitro culture.

Introduction. Dental pulp cells (DPCs) are promising cell source for dental tissue regeneration. Recently, small molecules which optimize microenvironment or activate the reprogramming network provide a new way to enhance the pluripotency. Two promising bioflavonoids luteolin and apigenin were reported to enhance reprogramming efficiency in mouse embryonic fibroblast (MEF). However, their effect and underlying mechanism in cell fate determination of human DPCs remain unclear. Methods. To elucidate the effect of luteolin and apigenin on the cell fate determination of DPCs, we explored the cell proliferation, cell cycle, senescence, apoptosis, expression of pluripotency markers Oct-4, Sox2, and c-Myc, and multilineage differentiation capability of DPCs with luteolin or apigenin treatment. Results. We demonstrated that luteolin and apigenin inhibited cell proliferation, arrested DPCs in G2/M and S phase, and upregulated PI value and apoptosis. Moreover, luteolin and apigenin increased telomerase activity, maintained DPCs in a presenescent state, and activated the expression of Oct-4, Sox2, and c-Myc at a dose- and time-dependent pattern in DPCs even at late passages, albeit repressed lineage-specific differentiation. Conclusions. Addition of luteolin and apigenin in the culture medium might provide an effective way to maintain DPCs in an undifferentiated stage and inhibit lineage-specific differentiation.

337 PROMOTER-DEPENDENT SILENCING OF REPROGRAMMING TRANSCRIPTION FACTORS IN MOUSE INDUCED PLURIPOTENT STEM CELLS PRODUCED WITH SLEEPING BEAUTY TRANSPOSON VECTORS

Epigenetic silencing of the transgenes has been considered a prerequisite for complete reprogramming of mouse somatic cells to induced pluripotent stem cells (miPSC). Here, we examined the activity status of the reprogramming transcription factors in miPSC produced with Sleeping Beauty (SB) transposon vectors carrying expression cassettes with the porcine OCT4, SOX2, c-MYC, and KLF4 (pOSMK) under the control of doxycycline (DOX)-inducible (TetO) or constitutive (CAG) promoters. Mouse embryo fibroblasts (MEF) were electroporated with SB-TetO-rTA-SV40pA-TetO-pOSMK-IRES-tdTomato-bGHpA (TetO group) or with SB-loxP-CAG-pOSMK-IRES-tdTomato-SV40pA-loxP (CAG group) together with SB100x (SB transposase). The cells were cultured on mitotically inactivated MEF feeders with DMEM supplemented with 20% knockout serum replacement, 2 mM l-glutamine, penicillin-streptomycin, nonessential amino acids, 0.1 mM 2-mercaptoethanol, 1000 U mL–1 of ESGRO, and 5 µg mL–1 of DOX. The miPSC colonies were individually picked, disaggregated to single cells, and propagated further under the same culture conditions. Three cell lines from each experimental group were examined for pluripotency characteristics, and the activity of the transgenes was monitored by the presence of tdTomato fluorescence and by RT-PCR. The miPSC produced with TetO vector silenced the transgene expression within 11 days post-transfection (in the presence of DOX) and upregulated the endogenous pluripotency genes Oct4, Sox2, Nanog, Rex1, and Utf1. These cells showed typical miPSC morphology and ability to differentiate into cells from the 3 primary germ layers in vitro and in vivo (teratomas). At the same time, the miPSC from the CAG group did not silence the transgenes even after 20 passages of continuous propagation, although they upregulated the endogenous pluripotency genes similarly to the TetO group. Moreover, these cells also showed ability to differentiate in vitro into cells from the 3 germ layers (contracting cardiac myocytes, neurons, epithelia) expressing differentiation markers Afp, Sox17, Gata4, Gata6, cardiac troponin, nestin, and PGP 9.5. Following Cre-mediated excision of the reprogramming cassette, the miPSC from the CAG group continued to self-renew and the expression of pluripotency markers Oct4, Sox2, Nanog, and Rex1 did not change significantly, as evidenced by real-time RT PCR (all P > 0.1), showing that these cells were not dependent on the transgenes for maintaining their pluripotency characteristics. Currently, we are investigating the ability of the miPSC from the CAG group to differentiate in vivo by producing teratomas and chimeras. The results from our preliminary investigations suggest that porcine transcription factors can be used for production of miPSC and that the silencing of the reprogramming transcription factors in miPSC is promoter-dependent, but may not be absolutely necessary for complete reprogramming to pluripotency.

Small molecule induction promotes corneal epithelial cell differentiation from human pluripotent stem cells

AbstractPurpose Corneal epithelium is maintained by limbal stem cells, and their transplantation has been used to treat limbal stem cell deficiency (LSCD). However, this is only possible if enough healthy limbal tissue is available. Thus, novel cell sources for treating LSCD are needed. Human induced pluripotent stem cells (hiPSCs) provide unique opportunities for differentiation of limbal and corneal epithelial cells for cell transplantations.Methods In order to improve the efficiency and reproducibility of hiPSCs differentiation towards corneal epithelial progenitor cells, signaling cues active during ocular surface ectoderm development was replicated with two small‐molecule inhibitors in combination with growth factors. The extent of differentiation was evaluated by following the expression of key markers using immunocytochemistry and qPCR at several time‐points.Results Small‐molecule induction down‐regulated the expression of pluripotency marker OCT4 while up‐regulating the eye‐field transcription factor PAX6. Protein expression of the corneal epithelial progenitor marker p63 was greatly enhanced, with up to 95% of cells being p63‐positive after five weeks of differentiation. Finally, after a total of six weeks in differentiation culture, the two markers specific to terminally differentiated corneal epithelium, cytokeratins 3 and 12, were expressed in an average of 35% and 71% of cells, respectively.Conclusion In contrast to all earlier studies, corneal epithelial cells were differentiated in serum‐free culture conditions without the use of amniotic membrane or other undefined culture substrates. This highly efficient differentiation method could potentially be used for treating LSCD in the future. Commercial interest

Serum-free cryopreservation of human amniotic epithelial cells before and after isolation from their natural scaffold

Amniotic epithelial cells are a promising source for stem cell-based therapy through their potential capacity to differentiate into the cell lineages of all three germ layers. Long-term preservation is necessary to have a ready-to-use source of stem cells, when required. Reduced differentiation capability, decrease of viability and use of fetal bovine serum (FBS) are three drawbacks of clinical application of cryopreserved stem cells. In this study, we used human amniotic fluid instead of animal serum, and evaluated viability and multipotency of amniotic epithelial cells after cryopreservation in suspension and compared with those cryopreserved on their natural scaffold (in situ cryopreservation). There was no significant difference in viability of the cells cryopreserved in amniotic fluid and FBS. Also, the same results were achieved for expression of pluripotency marker OCT-4 when FBS was replaced by amniotic fluid in the samples with the same cryoprotectant. The cells cryopreserved in presence of scaffold had a higher level of viability compared to the cells cryopreserved in suspension. Although, the number of the cells expressed OCT-4 significantly decreased within cryopreservation in suspension, no decrease in expression of OCT-4 was observed when the cells cryopreserved with their natural scaffold. Upon culturing of post-thawed cells in specific lineage differentiating mediums, the markers of neuronal, hepatic, cardiomyocytic and pancreatic were found in differentiated cells. These results show that replacement of FBS by amniotic fluid and in situ cryopreservation of amniotic epithelial cells is an effective approach to overcome limitations related to long-term preservation including differentiation during cryopreservation and decrease of viability.

Primed Pluripotent Cell Lines Derived from Various Embryonic Origins and Somatic Cells in Pig

Since pluripotent embryonic stem cell (ESC) lines were first derived from the mouse, tremendous efforts have been made to establish ESC lines in several domestic species including the pig; however, authentic porcine ESCs have not yet been established. It has proven difficult to maintain an ESC-like state in pluripotent porcine cell lines due to the frequent occurrence of spontaneous differentiation into an epiblast stem cell (EpiSC)-like state during culture. We have been able to derive EpiSC-like porcine ESC (pESC) lines from blastocyst stage porcine embryos of various origins, including in vitro fertilized (IVF), in vivo derived, IVF aggregated, and parthenogenetic embryos. In addition, we have generated induced pluripotent stem cells (piPSCs) via plasmid transfection of reprogramming factors (Oct4, Sox2, Klf4, and c-Myc) into porcine fibroblast cells. In this study, we analyzed characteristics such as marker expression, pluripotency and the X chromosome inactivation status in female of our EpiSC-like pESC lines along with our piPSC line. Our results show that these cell lines demonstrate the expression of genes associated with the Activin/Nodal and FGF2 pathways along with the expression of pluripotent markers Oct4, Sox2, Nanog, SSEA4, TRA 1–60 and TRA 1–81. Furthermore all of these cell lines showed in vitro differentiation potential, the X chromosome inactivation in female and a normal karyotype. Here we suggest that the porcine species undergoes reprogramming into a primed state during the establishment of pluripotent stem cell lines.

Abstract 3373: Identification of the stem cells in the epithelium of human Fallopian tube

Abstract Fallopian tubes, are one of the critical components of the female genital tract, providing environment for transport of gametes, the fertilization process and passage of the zygote to the uterus. Recent clinical studies reinforced a focus on the Fallopian tube and its potential contribution to the etiology of serous ovarian carcinoma (Dietl et al. 2011). Previously, we have shown that the Wnt signaling pathway plays a role in regulation of epithelial homeostasis within a tubal mucosa and the tissue response during the infection processes (Kessler et al. 2011). We were interested in identifying epithelial progenitors which could mediate cell renewal and turnover in the epithelium. Primary epithelial cells were isolated, from the clinical fragments of human fallopian tube. In addition to expression of epithelial markers (EpCAM and Cdh1) we could confirm presence of cells with robust expression of pluripotency markers OCT4, NANOG, SOX2 and CD133. This suggests existence of not only differentiated epithelial cells within the culture but also of epithelial progenitor cells and actively proliferating cells, which might explain detected rapid growth of the culture. Cells were seeded in 3D within a Matrigel matrix, to ensure an in vitro environment which closely resembles the in vivo situation. Knowing about the importance of the Wnt pathway for epithelial homeostasis in the tube, as it is as well the case for well characterized ex vivo models of gastrointestinal tract cells (Sato et al 2009), we have provided a cocktail of growth factors stimulating Wnt (R-spondin1, Wnt3) in addition to the Noggin and epidermal growth factor (EGF). Only in the presence of EGF, cells aggregated in a ball-like compact mass. Stimulation of Wnt pathway on the other hand resulted in formation of “organoid” like hollow structures resembling the epithelium of mucosal folds. Indeed, confocal imaging of paraffin sections revealed an epithelial monolayer of apico-basal polarized cells within the organoid like structures as assessed by polarity markers like Muc1. Interestingly, individual cells within organoid like structuress were positive for SOX2 while OCT4 was detected in broader domains. Activity of Wnt signaling in the organoid like structures was confirmed using live cell imaging of a lentiviral GFP-TCF reporter. Organoid like structures could be grown and maintained in vitro by serial passage. Furthermore, testing of the effects of growth factors on polarization and growth of cells in 2D culture revealed a positive effect of Noggin on proliferation of epithelial progenitors, while the complete “organoid” cocktail promoted cell adhesion and differentiation. Taken together, we find evidence for existence of pluripotent progenitor cells within the Fallopian epithelium. Identification of a stem cell niche in vivo and investigation of its stemness potential would be of great importance for the understanding of pathological sequels in the female genital tract. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3373. doi:1538-7445.AM2012-3373

Isolation, culture and chondrogenic differentiation of canine adipose tissue- and bone marrow-derived mesenchymal stem cells–a comparative study

In the dog, mesenchymal stem cells (MSCs) have been shown to reside in the bone marrow (bone marrow-derived mesenchymal stem cells: BM-MSCs) as well as in the adipose tissue (adipose tissue-derived stem cells: ADSCs). Potential application fields for these multipotent MSCs in small animal practice are joint diseases as MSCs of both sources have shown to possess chondrogenic differentiation ability. However, it is not clear whether the chondrogenic differentiation potential of cells of these two distinct tissues is truly equal. Therefore, we compared MSCs of both origins in this study in terms of their chondrogenic differentiation ability and suitability for clinical application. BM-MSCs harvested from the femoral neck and ADSCs from intra-abdominal fat tissue were examined for their morphology, population doubling time (PDT) and CD90 surface antigen expression. RT-PCR served to assess expression of pluripotency marker Oct4 and early differentiation marker genes. Chondrogenic differentiation ability was compared and validated using histochemistry, transmission electron microscopy (TEM) and quantitative RT-PCR. Both cell populations presented a highly similar morphology and marker expression in an undifferentiated stage except that freshly isolated ADSCs demonstrated a significantly faster PDT than BM-MSCs. In contrast, BM-MSCs revealed a morphological superior cartilage formation by the production of a more abundant and structured hyaline matrix and higher expression of lineage specific genes under the applied standard differentiation protocol. However, further investigations are necessary in order to find out if chondrogenic differentiation can be improved in canine ADSCs using different protocols and/or supplements.

215 COMPARATIVE ANALYSIS OF PORCINE PLURIPOTENT CELL LINES DERIVED FROM SOMATIC CELLS AND VARIOUS EMBRYONIC ORIGINS

Since pluripotent cells were first derived from the inner cell mass (ICM) of mouse blastocysts, tremendous efforts have been made to establish embryonic stem cell (ESC) lines in several domestic species including the pig; however, authentic porcine ESCs have not yet been established. It has proven difficult to derive pluripotent cells of naïve state that represents full pluripotency, due to the frequent occurrence of spontaneous differentiation into an EpiSC-like state during culture in pigs. We have been able to derive EpiSC-like porcine embryonic stem cell (pESC) lines of a differentiated non-ES cell state from blastocyst stage porcine embryos of various origins, including in vitro fertilized (IVF), in vivo derived, IVF aggregated and parthenogenetic embryos. In addition, we have generated induced pluripotent stem cells (piPSCs) via plasmid transfection of reprogramming factors (Oct4, Sox2, Klf4 and c-Myc) into porcine fibroblast cells. In this study, we analysed characteristics such as marker expression, pluripotency and the X chromosome inactivation (XCI) status of our EpiSC-like pESC lines along with our piPSC line. Our results show that these cell lines demonstrate the expression of genes associated with the Activin/Nodal and FGF2 pathways along with the expression of pluripotent markers Oct4, Sox2, Nanog, SSEA4, TRA 1-60 and TRA 1-81. Furthermore all of these cell lines showed in vitro differentiation potential; female XCI activity and a normal karyotype. Here we provide preliminary results that suggest that, as a nonpermissive species, the porcine species undergoes reprogramming into a primed state during the establishment of pluripotent stem cell lines. This work was supported by the BioGreen 21 Program (#20070401034031, PJ0081382011), Rural Development Administration, Republic of Korea.

Primitive Cardiac Cells from Human Embryonic Stem Cells

Pluripotent stem cell-derived cardiomyocytes are currently being investigated for in vitro human heart models and as potential therapeutics for heart failure. In this study, we have developed a differentiation protocol that minimizes the need for specific human embryonic stem cell (hESC) line optimization. We first reduced the heterogeneity that exists within the starting population of bulk cultured hESCs by using cells adapted to single-cell passaging in a 2-dimensional (2D) culture format. Compared with bulk cultures, single-cell cultures comprised larger fractions of TG30(hi)/OCT4(hi) cells, corresponding to an increased expression of pluripotency markers OCT4 and NANOG, and reduced expression of early lineage-specific markers. A 2D temporal differentiation protocol was then developed, aimed at reducing the inherent heterogeneity and variability of embryoid body-based protocols, with induction of primitive streak cells using bone morphogenetic protein 4 and activin A, followed by cardiogenesis via inhibition of Wnt signaling using the small molecules IWP-4 or IWR-1. IWP-4 treatment resulted in a large percentage of cells expressing low amounts of cardiac myosin heavy chain and expression of early cardiac progenitor markers ISL1 and NKX2-5, thus indicating the production of large numbers of immature cardiomyocytes (~65,000/cm(2) or ~1.5 per input hESC). This protocol was shown to be effective in HES3, H9, and, to a lesser, extent, MEL1 hESC lines. In addition, we observed that IWR-1 induced predominantly atrial myosin light chain (MLC2a) expression, whereas IWP-4 induced expression of both atrial (MLC2a) and ventricular (MLC2v) forms. The intrinsic flexibility and scalability of this 2D protocol mean that the output population of primitive cardiomyocytes will be particularly accessible and useful for the investigation of molecular mechanisms driving terminal cardiomyocyte differentiation, and potentially for the future treatment of heart failure.

Klf5 regulates lineage formation in the pre-implantation mouse embryo

Kruppel-like transcription factors (Klfs) are essential for the induction and maintenance of pluripotency of embryonic stem cells (ESCs), yet little is known about their roles in establishing the three lineages of the pre-implantation embryo. Here, we show that Klf5 is required for the formation of the trophectoderm (TE) and the inner cell mass (ICM), and for repressing primitive endoderm (PE) development. Although cell polarity appeared normal, Klf5 mutant embryos arrested at the blastocyst stage and failed to hatch due to defective TE development. Klf5 acted cell-autonomously in the TE, downstream of Fgf4 and upstream of Cdx2, Eomes and Krt8. In the ICM, loss of Klf5 resulted in reduced expression of pluripotency markers Oct4 and Nanog, but led to increased Sox17 expression in the PE, suggesting that Klf5 suppresses the PE lineage. Consistent with this, overexpression of Klf5 in transgenic embryos was sufficient to suppress the Sox17(+) PE lineage in the ICM. Klf5 overexpression led to a dose-dependent decrease in Sox17 promoter activity in reporter assays in cultured cells. Moreover, in chimeric embryos, Klf5(-/-) cells preferentially contributed to the Sox17(+) PE lineage and Cdx2 expression was not rescued in Klf5(-/-) outer cells. Finally, outgrowths from Klf5(-/-) embryos failed to form an ICM/pluripotent colony, had very few Oct4(+) or Cdx2(+) cells, but showed an increase in the percentage of Sox17(+) PE cells. These findings demonstrate that Klf5 is a dynamic regulator of all three lineages in the pre-implantation embryo by promoting the TE and epiblast lineages while suppressing the PE lineage.

Establishment and Characterization of Novel Porcine Embryonic Stem Cell Lines Expressing hrGFP

The purpose of this study was to establish transgenic porcine embryonic stem (pES) cell lines that can stably express report gene. Established pES cell line at passage 44 was transfected with pAAV-hrGFP Control Plasmid by electroporation-mediated, viral vector-mediated, and liposome-mediated strategies. Although there were several pES colonies expressing green fluorescent protein (GFP) obtained from the retrovirus-mediated and liposome-mediated transfection methods, no stable GFP-expressing pES cell line was then derived. A total of 28 GFP-expressing pES cell colonies were obtained following electroporation with two DC pulses of 150 V/cm for 10 msec and three GFP-expressing pES (pES/GFP(+)) cell lines were established. These pES/GFP(+) cell lines stably expressed exogenous GFP and continuously proliferated in vitro for more than 90 passages in 20 months. They maintained normal karyotype of 36 + XX and typical characteristics of pluripotent stem cells, including expression of pluripotent markers Oct-4, AP, SSEA-4, TRA-1-60, and TRA-1-81, formation of embryoid bodies under suspension culture. They were able to differentiate in vitro into neural and cardiomyocytic lineage, respectively, under suitable induction. To our knowledge, there has been no report of establishing GFP-expressing pES cell lines. These novel pES/GFP(+) cell lines established in this study might serve as a nonrodent model and would benefit to the studies involving ES cell transplantation, cell replacement therapy, and tissue regeneration due to their traceable capacity.

FGF stimulation of the Erk1/2 signalling cascade triggers transition of pluripotent embryonic stem cells from self-renewal to lineage commitment

Pluripotent embryonic stem (ES) cells must select between alternative fates of self-replication and lineage commitment during continuous proliferation. Here, we delineate the role of autocrine production of fibroblast growth factor 4 (Fgf4) and associated activation of the Erk1/2 (Mapk3/1) signalling cascade. Fgf4 is the major stimulus activating Erk in mouse ES cells. Interference with FGF or Erk activity using chemical inhibitors or genetic ablations does not impede propagation of undifferentiated ES cells. Instead, such manipulations restrict the ability of ES cells to commit to differentiation. ES cells lacking Fgf4 or treated with FGF receptor inhibitors resist neural and mesodermal induction, and are refractory to BMP-induced non-neural differentiation. Lineage commitment potential of Fgf4-null cells is restored by provision of FGF protein. Thus, FGF enables rather than antagonises the differentiation activity of BMP. The key downstream role of Erk signalling is revealed by examination of Erk2-null ES cells, which fail to undergo either neural or mesodermal differentiation in adherent culture, and retain expression of pluripotency markers Oct4, Nanog and Rex1. These findings establish that Fgf4 stimulation of Erk1/2 is an autoinductive stimulus for naïve ES cells to exit the self-renewal programme. We propose that the Erk cascade directs transition to a state that is responsive to inductive cues for germ layer segregation. Consideration of Erk signalling as a primary trigger that potentiates lineage commitment provides a context for reconciling disparate views on the contribution of FGF and BMP pathways during germ layer specification in vertebrate embryos.