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San Carlos, CA, United States

Coppe J.-P.,Lawrence Berkeley National Laboratory | Coppe J.-P.,Buck Institute for Age Research | Patil C.K.,Lawrence Berkeley National Laboratory | Patil C.K.,Buck Institute for Age Research | And 16 more authors.

Cellular senescence irreversibly arrests cell proliferation in response to oncogenic stimuli. Human cells develop a senescence-associated secretory phenotype (SASP), which increases the secretion of cytokines and other factors that alter the behavior of neighboring cells. We show here that "senescent" mouse fibroblasts, which arrested growth after repeated passage under standard culture conditions (20% oxygen), do not express a human-like SASP, and differ from similarly cultured human cells in other respects. However, when cultured in physiological (3%) oxygen and induced to senesce by radiation, mouse cells more closely resemble human cells, including expression of a robust SASP. We describe two new aspects of the human and mouse SASPs. First, cells from both species upregulated the expression and secretion of several matrix metalloproteinases, which comprise a conserved genomic cluster. Second, for both species, the ability to promote the growth of premalignant epithelial cells was due primarily to the conserved SASP factor CXCL-1/KC/GRO-a. Further, mouse fibroblasts made senescent in 3%, but not 20%, oxygen promoted epithelial tumorigenesis in mouse xenographs. Our findings underscore critical mouse-human differences in oxygen sensitivity, identify conditions to use mouse cells to model human cellular senescence, and reveal novel conserved features of the SASP. © 2010 Coppe et al. Source

Giritharan G.,StemLifeLine Inc. | Ilic D.,StemLifeLine Inc. | Ilic D.,Kings College | Gormley M.,University of California at San Francisco | Krtolica A.,StemLifeLine Inc.

We have derived hESC from biopsied blastomeres of cleavage stage embryos under virtually the same conditions we used for the derivation of hESC lines from inner cell mass of blastocyst stage embryos. Blastomere-derived hESC lines exhibited all the standard characteristics of hESC including undifferentiated proliferation, genomic stability, expression of pluripotency markers and the ability to differentiate into the cells of all three germ layers both in vitro and in vivo. To examine whether hESC lines derived from two developmental stages of the embryo differ in gene expression, we have subjected three blastomere-derived hESC lines and two ICM-derived hESC lines grown under identical culture conditions to transcriptome analysis using gene expression arrays. Unlike previously reported comparisons of hESC lines which demonstrated, apart from core hESC-associated pluripotency signature, significant variations in gene expression profiles of different lines, our data show that hESC lines derived and grown under well-controlled defined culture conditions adopt nearly identical gene expression profiles. Moreover, blastomere-derived and ICM-derived hESC exhibited very similar transcriptional profiles independent of the developmental stage of the embryo from which they originated. Furthermore, this profile was evident in very early passages of the cells and did not appear to be affected by extensive passaging. These results suggest that during derivation process cells which give rise to hESC acquire virtually identical stable phenotype and are not affected by the developmental stage of the starting cell population. © 2011 Giritharan et al. Source

Krtolica A.,StemLifeLine Inc. | Giritharan G.,StemLifeLine Inc.
Systems Biology in Reproductive Medicine

Male reproductive toxicity examines harmful effects of various agents on all aspects and developmental stages of the male reproductive system, including germ cell development and spermatogenesis. In developing a model for reproductive toxicity screening it is important to define the developmental stage that this model is going to recreate in vitro and to identify critical molecular targets of this stage. In this review we focus our discussion on the potential for using embryonic stem cell (ESC)-derived models for male reproductive toxicity screening. The rationale for developing novel toxicity models is that despite significant advances in our biological understanding and clinical treatment of infertility, many unresolved cases still remain. This is likely due to our lack of knowledge about environmental influences on the critical stages of gamete development. Many practical and ethical difficulties are associated with the collection of human tissue samples to explore the unknown causes of infertility. Thus, a readily available in vitro model that mimics human gamete development would be an extremely valuable research tool for establishing novel toxicity assays. ESC exhibit a high degree of similarity with primordial germ cells (PGC) at the level of gene expression and molecular signaling. In addition, recent evidence shows that ESC can be differentiated into PGC and spermatids in culture. Multiple lines of evidence point to the differences between mouse and human ESC (hESC). In light of these data, we present the case that hESC are better suited as in vitro toxicity screening models than their mouse counterparts. We then describe some of the most promising hESC-based systems that are used today to model certain aspects of male gamete development and that have a potential to be used for toxicity screening. We conclude by discussing the potential of these existing models in toxicology studies and the possibilities for their improvement in the future. © 2010 Informa UK Ltd. Source

Krtolica A.,StemLifeLine Inc. | Larocque N.,University of California at San Francisco | Genbacev O.,University of California at San Francisco | Ilic D.,StemLifeLine Inc. | And 8 more authors.

Previously we reported that feeders formed from human placental fibroblasts (hPFs) support derivation and long-term self-renewal of human embryonic stem cells (hESCs) under serum-free conditions. Here, we show, using antibody array and ELISA platforms, that hPFs secrete ~6-fold higher amounts of the CXC-type chemokine, GROα, than IMR 90, a human lung fibroblast line, which does not support hESC growth. Furthermore, immunocytochemistry and immunoblot approaches revealed that hESCs express CXCR, a GROα receptor. We used this information to develop defined culture medium for feeder-free propagation of hESCs in an undifferentiated state. Cells passaged as small aggregates and maintained in the GROα-containing medium had a normal karyotype, expressed pluripotency markers, and exhibited apical-basal polarity, i.e., had the defining features of pluripotent hESCs. They also differentiated into the three primary (embryonic) germ layers and formed teratomas in immunocompromised mice. hESCs cultured as single cells in the GROα-containing medium also had a normal karyotype, but they downregulated markers of pluripotency, lost apical-basal polarity, and expressed markers that are indicative of the early stages of neuronal differentiation-ΒIII tubulin, vimentin, radial glial protein, and nestin. These data support our hypothesis that establishing and maintaining cell polarity is essential for the long-term propagation of hESCs in an undifferentiated state and that disruption of cell-cell contacts can trigger adoption of a neuronal fate. © 2011 International Society of Differentiation. Source

Ilic D.,StemLifeLine Inc. | Caceres E.,StemLifeLine Inc. | Lu S.,Nevada Center for Reproductive Medicine | Julian P.,Nevada Center for Reproductive Medicine | And 2 more authors.
Stem Cells and Development

The success rate of human embryonic stem cell (hESC) derivation depends on both culture conditions and embryo quality and is routinely determined by morphological criteria. However, high incidence of chromosomal abnormality even in high-grade cleavage embryos from in vitro fertilization (IVF) patients suggests that the morphological grade of supernumerary embryos obtained from IVF clinics may not be a good prediction factor for successful hESC derivation. We show here that from one donor under identical derivation conditions 12 karyotypically abnormal post-bioptic embryos did not yield hESC lines, whereas two out of four normal embryos did. This suggests that the capacity of embryos to give rise to hESC line is likely to be influenced by their genetic status. © Mary Ann Liebert, Inc. Source

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