Differentiation of primate ES cells into retinal cells induced by ES cell-derived pigmented cells

Purpose: Photoreceptors cannot regenerate and recover their functions once disordered. Transplantation of retinal pigment epithelium (RPE) has recently become a possible therapeutic approach for retinal degeneration. In the present study, we investigated the induction of photoreceptors by coculturing primate embryonic stem cells (ESCs) with ESC-derived RPE cells. Methods: RPE cells were derived by coculturing ESCs and Sertoli cells. Photoreceptors were then induced by using ESC-derived RPE cells and retinoic acid (RA) Results: RPE cell generation was confirmed by morphological analysis, which revealed highly pigmented polygonal cells with a compact cell-cell arrangement. After coculturing ESCs and RPE cells, some ESC derivatives became immunopositive for rhodopsin. RT-PCR analysis demonstrated the expression of retina-related gene markers such as Pax6, CRX, IRBP, rhodopsin, rhodopsin kinase, and Muschx10A. When RA was added, a distinct increase in the expression of photoreceptor-specific proteins and genes was found. In addition, the differentiation of bipolar horizontal cells was demonstrated by protein and gene expression. The ESCs that were cocultured with RPE cells and treated with RA were transplanted into the renal capsule or intra-vitreal space of nude mice. Grafted ESC derivatives demonstrated extensive rhodopsin expression, and they survived and organized into recipient tissues, although they formed teratomas. Conclusion: These results indicate that coculturing ESCs with ESC-derived RPE cells is a useful and efficient method for inducing photoreceptors and providing an insight into the use of ESCs for retina regeneration.     

Polony analysis of gene expression in ES cells and blastocysts

Expression profiling of stem cells is challenging due to their small numbers and heterogeneity. The PCR colony (polony) approach has theoretical advantages as an assay for stem cells but has not been applied to small numbers of cells. An assay has been developed that is sensitive enough to detect mRNAs from small numbers of ES cells and from fractions of a single mouse blastocyst. Genes assayed include Oct3, Rex1, Nanog, Cdx2 and GLUT-1. The assay is highly sensitive so that multiple mRNAs from a single blastocyst were easily detected in the same assay. In its present version, the assay is an attractive alternative to conventional RT–PCR for profiling small populations of stem cells. The assay is also amenable to improvements that will increase its sensitivity and ability to analyze many cDNAs simultaneously.     

Differential expression of genes involved in cGMP-dependent nitric oxide signaling in murine embryonic stem (ES) cells and ES cell-derived cardiomyocytes.

Nitric oxide (NO) performs multiple physiological roles as a biological signaling molecule. The role of NO and cGMP signaling in embryonic stem (ES) cell-derived cardiomyocytes (CM) has been investigated but many questions remain. In this study, we examined the expression of the NO signaling pathway components nitric oxide synthase (NOS-1, 2, 3), soluble guanylyl cyclase (sGCalpha(1) and beta(1)) and protein kinase G (PKG) genes and sGC activity in murine ES cells subjected to differentiation by embryoid body (EB) formation. We found that in undifferentiated ES cells, NOS-1, NOS-3, and sGCbeta(1) were detected while NOS-2, sGCalpha(1), and PKG were very low or undetectable. When ES cells were subjected to differentiation, NOS-1 abruptly decreased within one day, NOS-2 mRNA became detectable after several days, and NOS-3 increased after 7-10 days. Levels of sGCalpha(1), sGCbeta(1), and PKG all increased gradually over a several day time course of differentiation in EB outgrowths. Analysis of sGC activity in cell lysates derived from undifferentiated ES cells revealed that NO could not stimulate cGMP. However, lysates from differentiated EB outgrowths produced abundant cGMP levels after NO stimulation. Purification of ES-cell derived CM revealed that mRNA expression of all the NOS isoforms was very low to absent while sGCalpha(1) and beta(1) subunit mRNAs were abundant and sGC-mediated cGMP production was apparent in this population of cells. These data suggest that cGMP-mediated NO signaling may play a minor role, if any, in undifferentiated ES cells but could be involved in the early differentiation events or physiological processes of ES cells or ES cell-derived lineages.     

Induction and monitoring of definitive and visceral endoderm differentiation of mouse ES cells

Preparation of specific lineages at high purities from embryonic stem (ES) cells requires both selective culture conditions and markers to guide and monitor the differentiation. In this study, we distinguished definitive and visceral endoderm by using a mouse ES cell line that bears the gfp and human IL2R alpha (also known as CD25) marker genes in the goosecoid (Gsc) and Sox17 loci, respectively. This cell line allowed us to monitor the generation of Gsc+ Sox17+ definitive endoderm and Gsc- Sox17+ visceral endoderm and to define culture conditions that differentially induce definitive and visceral endoderm. By comparing the gene expression profiles of definitive and visceral endoderm, we identified seven surface molecules that are expressed differentially in the two populations. One of the seven markers, Cxcr4, to which a monoclonal antibody is available allowed us to monitor and purify the Gsc+ population from genetically unmanipulated ES cells under the condition that selects definitive endoderm.     

Combined activin A/LiCl/Noggin treatment improves production of mouse embryonic stem cell-derived definitive endoderm cells

Induction of definitive endoderm (DE) cells is a prerequisite for the whole process of embryonic stem (ES) cells differentiating into hepatic or pancreatic progenitor cells. We have established an efficient method to induce mouse ES cell-derived DE cells in suspension embryonic body (EB) culture. Similar to previous studies, mouse ES cell-derived DE cells, which were defined as Cxcr4(+) c-Kit(+) , Cxcr4(+) E-cadherin(+) cells or Cxcr4(+) PDGFRa(-) cells, could be induced in the serum-free EBs at Day 4 of induction. The activations of Wnt, Nodal, and FGF signaling pathways in differentiating EBs promoted DE cell differentiation, while activation of BMP4 signaling inhibited the process. In the present study, we found that chemical activation of canonical Wnt signaling pathway by LiCl could synergize with Activin A-mediated Nodal signaling pathway to promote induction of DE cells, and inhibition of Bmp4 signaling by Noggin along with Activin A/LiCl further improved the efficiency of DE cell differentiation. The derived DE cells were proved for their capacities to become hepatic progenitor cells or pancreatic progenitor cells. In conclusion, we significantly improved the efficiency of generating mouse ES cell-derived DE cells by combined Activin A/LiCl/Noggin treatment. Our work will be greatly helpful to generate ES cell-derived hepatic cells and ES cell-derived pancreatic cells for future regenerative medicine.     

Coordinate expression of parietal endodermal functions in hybrids of embryonal carcinoma and endodermal cells.

A derivative, FOT5, of the F9 murine embryonal carcinoma cell line which is resistant to ouabain and thioguanine was fused with a near diploid parietal endodermal cell line, PFHR9, Hybrid clones (ENEC1 to ENEC5) were isolated in HAT Medium containing ouabain at a frequency of approximately 2 x 10(-4). The DNA contents and chromosome number of the ENEC hybrids were approximately the sum of those of the parents. Five hybrid cell lines examined in detail expressed the following parietal endodermal functions: plasminogen activator activity, basement membrane proteins, and endodermal cytoskeletal proteins. Embryonal carcinoma characteristic functions (tumorigenicity, a stage specific embryonic antigen, and high alkaline phosphatase activity) were extinguished in the hybrids. No hybrid clones with embryonal carcinoma morphology were observed among 1,358 hybrid clones examined. Hybrids, propagated for over 100 generations, continued to express endodermal functions and not embryonal carcinoma functions. The coordinate expression of endodermal functions and the extinction of embryonal carcinoma functions in the ENEC hybrids suggest that the parietal endodermal cells contain diffusible activities which extinguish embryonal carcinoma functions and possibly cause the embryonal carcinoma genome to express parietal endodermal characteristics.     

Induction of midbrain dopaminergic neurons from ES cells by stromal cell-derived inducing activity

We have identified a stromal cell-derived inducing activity (SDIA) that promotes neural differentiation of mouse ES cells. SDIA accumulates on the surface of PA6 stromal cells and induces efficient neuronal differentiation of cocultured ES cells in serum-free conditions without use of either retinoic acid or embryoid bodies. BMP4, which acts as an antineuralizing morphogen in Xenopus, suppresses SDIA-induced neuralization and promotes epidermal differentiation. A high proportion of tyrosine hydroxylase-positive neurons producing dopamine are obtained from SDIA-treated ES cells. When transplanted, SDIA-induced dopaminergic neurons integrate into the mouse striatum and remain positive for tyrosine hydroxylase expression. Neural induction by SDIA provides a new powerful tool for both basic neuroscience research and therapeutic applications.     

Pdx1 and Ngn3 overexpression enhances pancreatic differentiation of mouse ES cell-derived endoderm population

In order to define the molecular mechanisms regulating the specification and differentiation of pancreatic β-islet cells, we investigated the effect of upregulating Pdx1 and Ngn3 during the differentiation of the β-islet-like cells from murine embryonic stem (ES) cell-derived activin induced-endoderm. Induced overexpression of Pdx1 resulted in a significant upregulation of insulin (Ins1 and Ins2), and other pancreas-related genes. To enhance the developmental progression from the pancreatic bud to the formation of the endocrine lineages, we induced the overexpression express of Ngn3 together with Pdx1. This combination dramatically increased the level and timing of maximal Ins1 mRNA expression to approximately 100% of that found in the βTC6 insulinoma cell line. Insulin protein and C-peptide expression was confirmed by immunohistochemistry staining. These inductive effects were restricted to c-kit(+) endoderm enriched EB-derived populations suggesting that Pdx1/Ngn3 functions after the specification of pancreatic endoderm. Although insulin secretion was stimulated by various insulin secretagogues, these cells had only limited glucose response. Microarray analysis was used to evaluate the expression of a broad spectrum of pancreatic endocrine cell-related genes as well as genes associated with glucose responses. Taken together, these findings demonstrate the utility of manipulating Pdx1 and Ngn3 expression in a stage-specific manner as an important new strategy for the efficient generation of functionally immature insulin-producing β-islet cells from ES cells.     

Human mesenchymal stromal cells in adhesion to cell-derived extracellular matrix and titanium: Comparative kinome profile analysis

The extracellular matrix (ECM) physically supports cells and influences stem cell behaviour, modulating kinase-mediated signalling cascades. Cell-derived ECMs have emerged in bone regeneration as they reproduce physiological tissue-architecture and ameliorate mesenchymal stromal cell (MSC) properties. Titanium scaffolds show good mechanical properties, facilitate cell adhesion, and have been routinely used for bone tissue engineering (BTE). We analyzed the kinomic signature of human MSCs in adhesion to an osteopromotive osteoblast-derived ECM, and compared it to MSCs on titanium. PamChip kinase-array analysis revealed 63 phosphorylated peptides on ECM and 59 on titanium, with MSCs on ECM exhibiting significantly higher kinase activity than on titanium. MSCs on the two substrates showed overlapping kinome profiles, with activation of similar signalling pathways (FAK, ERK, and PI3K signalling). Inhibition of PI3K signalling in cells significantly reduced adhesion to ECM and increased the number of nonadherent cells on both substrates. In summary, this study comprehensively characterized the kinase activity in MSCs on cell-derived ECM and titanium, highlighting the role of PI3K signalling in kinomic changes regulating osteoblast viability and adhesion. Kinome profile analysis represents a powerful tool to select pathways to better understand cell behaviour. Osteoblast-derived ECM could be further investigated as titanium scaffold-coating to improve BTE.     

Differential expression of the Wnt and Frizzled genes in Flk1+ cells derived from mouse ES cells

Embryonic stem (ES) cells have the potential to develop into various cell lineages including hemangioblasts (Flk1+), a common progenitor for hematopoietic and vascular endothelial cells. Previous studies indicate that Flk1+ cells, a marker for hemangioblast, can be derived from ES cell and that Flk1+ can be differentiated into hematopoietic or endothelial cells depending on culture conditions. We developed an improved in vitro system to generate Flk1+-enriched cultures from mouse ES cells and used this in vitro system to study the role of Wnt signalling in early endothelial progenitor cells. We determined the expression of the Wnt and Frizzled genes in Flk1+ cells derived from mouse ES cells. RT-PCR analyses identified significantly higher expression of non-canonical Wnt5a and Wnt11 genes in Flk1+ cells compared to Flk1- cells. In contrast, expression of canonical Wnt3a gene was reduced in Flk1+ cells. In addition, Frizzled2, Frizzled5 and Frizzled7 genes were also expressed at a higher level in Flk1+ cells. The differential expression of Wnt and Frizzled genes in Flk1+ cells provides a novel insight into the role of non-canonical Wnt signalling in vascular endothelial fate determination.     

苹果PDHB-1基因家族的鉴定与表达分析

丙酮酸脱氢酶E1组分β亚基-1 (pyruvate dehydrogenase E1 component subunit beta-1,PDHB-1)基因是编码丙酮酸脱氢酶复合物E1酶β亚基的基因，在果实酸度积累过程中具有重要作用。为了探究苹果(Malus domestica L.) PDHB-1家族的进化特征及其在不同酸含量苹果中的表达情况，本研究利用NCBI、Pfam等数据库和Clustal X、MEGA、TBtools等软件进行生物信息学分析，通过结合可滴定酸含量测定与实时荧光定量PCR (quantitative real-time PCR,q RT-PCR)分析，获得该家族基因在‘艾斯达’和‘成纪1号’2个不同酸含量的苹果中的表达情况。PDHB-1家族主要定位于叶绿体、细胞质和线粒体中，α-螺旋和不规则卷曲是该家族二级结构形成的主要因素。组织特异性表达谱显示大部分成员的表达量在果实中高于其他组织。q RT-PCR结果表明，大部分成员其表达量变化趋势与可滴定酸含量变化趋势一致，在果皮中，有14个成员的表达水平在酸含量较高的‘艾斯达’苹果中显著高于酸含量较低的‘成纪1号’，其中M...     

Stromal cell-derived factor-1 increase alphavbeta3 integrin expression and invasion in human chondrosarcoma cells

Chondrosarcoma is a type of highly malignant tumor with a potent capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. The stromal cell-derived factor 1 (SDF-1), constitutively secreted by human lung epithelium cells, has been shown to function in a key role for recruitment of neutrophils. Here, we found that human chondrosarcoma tissues and chondrosarcoma cell lines had significant expression of CXCR4 (SDF-1 receptor), which was higher than normal cartilage and human chondrocyte. SDF-1alpha and lung epithelium cells conditioned medium (LECM) induced the invasiveness of chondrosarcoma cells. SDF-1 siRNA inhibited LECM-induced invasion of chondrosarcoma cells and SDF-1alpha also directly induced the cell surface expression of alphavbeta3 but not alpha2beta1 and alpha5beta1 integrin. Activations of ERK and NF-kappaB pathways after SDF-1 treatment was demonstrated, and SDF-1alpha-induced expression of alphavbeta3 integrin and invasion activity was inhibited by the specific inhibitor and mutant of ERK and NF-kappaB cascades. Taken together, our results indicate that lung derived-SDF-1alpha enhances the invasiveness of chondrosarcoma cells by increasing alphavbeta3 integrin expression through the CXCR4/ERK/NF-kappaB signal transduction pathway.