Current Issue : July - September Volume : 2012 Issue Number : 3 Articles : 6 Articles
Background: Cancer-initiating cells (CICs) are proposed to be responsible for the generation of metastasis and\r\nresistance to therapy. Accumulating evidences indicates CICs are found among different human cancers and cell\r\nlines derived from them. Few studies address the characteristics of CICs in cervical cancer. We identify biological\r\nfeatures of CICs from four of the best-know human cell lines from uterine cervix tumors. (HeLa, SiHa, Ca Ski, C-4 I).\r\nMethods: Cells were cultured as spheres under stem-cell conditions. Flow cytometry was used to detect\r\nexpression of CD34, CD49f and CD133 antigens and Hoechst 33342 staining to identify side population (SP).\r\nMagnetic and fluorescence-activated cell sorting was applied to enrich and purify populations used to evaluate\r\ntumorigenicity in nude mice. cDNA microarray analysis and in vitro radioresistance assay were carried out under\r\nstandard conditions.\r\nResults: CICs, enriched as spheroids, were capable to generate reproducible tumor phenotypes in nu-nu mice and\r\nserial propagation. Injection of 1 Ã?â?? 103 dissociated spheroid cells induced tumors in the majority of animals,\r\nwhereas injection of 1 Ã?â?? 105 monolayer cells remained nontumorigenic. Sphere-derived CICs expressed CD49f\r\nsurface marker. Gene profiling analysis of HeLa and SiHa spheroid cells showed up-regulation of CICs markers\r\ncharacteristic of the female reproductive system. Importantly, epithelial to mesenchymal (EMT) transition-associated\r\nmarkers were found highly expressed in spheroid cells. More importantly, gene expression analysis indicated that\r\ngenes required for radioresistance were also up-regulated, including components of the double-strand break (DSB)\r\nDNA repair machinery and the metabolism of reactive oxygen species (ROS). Dose-dependent radiation assay\r\nindicated indeed that CICs-enriched populations exhibit an increased resistance to ionizing radiation (IR).\r\nConclusions: We characterized a self-renewing subpopulation of CICs found among four well known human\r\ncancer-derived cell lines (HeLa, SiHa, Ca Ski and C-4 I) and found that they express characteristic markers of stem\r\ncell, EMT and radioresistance. The fact that CICs demonstrated a higher degree of resistance to radiation than\r\ndifferentiated cells suggests that specific detection and targeting of CICs could be highly valuable for the therapy\r\nof tumors from the uterine cervix....
The efficient commitment of a specialized cell type from induced pluripotent stem cells (iPSCs) without contamination from\r\nunknown substances is crucial to their use in clinical applications. Here, we propose that CD34+ progenitor cells, which\r\nretain hematopoietic and endothelial cell potential, could be efficiently obtained from iPSCs derived from human bone\r\nmarrow mesenchymal stem cells (hBMMSC-iPSCs) with defined factors. By treatment with a cocktail containing mesodermal,\r\nhematopoietic, and endothelial inducers (BMP4, SCF, and VEGF, respectively) for 5 days, hBMMSC-iPSCs expressed the\r\nmesodermal transcription factors Brachyury and GATA-2 at higher levels than untreated groups (P,0.05). After culturing\r\nwith another hematopoietic and endothelial inducer cocktail, including SCF, Flt3L, VEGF and IL-3, for an additional 7ââ?¬â??9 days,\r\nCD34+ progenitor cells, which were undetectable in the initial iPSC cultures, reached nearly 20% of the total culture. This\r\nwas greater than the relative number of progenitor cells produced from human-skin-fibroblast-derived iPSCs (hFib-iPSCs) or\r\nfrom the spontaneous differentiation groups (P,0.05), as assessed by flow cytometry analysis. These induced cells\r\nexpressed hematopoietic transcription factors TAL-1 and SCL. They developed into various hematopoietic colonies when\r\nexposed to semisolid media with hematopoietic cytokines such as EPO and G-CSF. Hematopoietic cell lineages were\r\nidentified by phenotype analysis with Wright-Giemsa staining. The endothelial potential of the cells was also verified by the\r\nconfirmation of the formation of vascular tube-like structures and the expression of endothelial-specific markers CD31 and\r\nVE-CADHERIN. Efficient induction of CD34+ progenitor cells, which retain hematopoietic and endothelial cell potential with\r\ndefined factors, provides an opportunity to obtain patient-specific cells for iPSC therapy and a useful model for the study of\r\nthe mechanisms of hematopoiesis and drug screening....
Global gene expression profiling was performed using RNA from human embryonic neural stem cells (hENSC), and adult\r\nhuman olfactory bulb-derived neural stem cells (OBNSCs), to define a gene expression pattern and signaling pathways that\r\nare specific for each cell lineage. We have demonstrated large differences in the gene expression profile of human\r\nembryonic NSC, and adult human OBNSCs, but less variability between parallel cultures. Transcripts of genes involved in\r\nneural tube development and patterning (ALDH1A2, FOXA2), progenitor marker genes (LMX1a, ALDH1A1, SOX10),\r\nproliferation of neural progenitors (WNT1 and WNT3a), neuroplastin (NPTN), POU3F1 (OCT6), neuroligin (NLGN4X), MEIS2,\r\nand NPAS1 were up-regulated in both cell populations. By Gene Ontology, 325 out of 3875 investigated gene sets were\r\nscientifically different. 41 out of the 307 investigated Cellular Component (CC) categories, 45 out of the 620 investigated\r\nMolecular Function (MF) categories, and 239 out of the 2948 investigated Biological Process (BP) categories were significant.\r\nKEGG Pathway Class Comparison had revealed that 75 out of 171 investigated gene sets passed the 0.005 significance\r\nthreshold. Levels of gene expression were explored in three signaling pathways, Notch, Wnt, and mTOR that are known to\r\nbe involved in NS cell fates determination. The transcriptional signature also deciphers the role of genes involved in\r\nepigenetic modifications. SWI/SNF DNA chromatin remodeling complex family, including SMARCC1 and SMARCE1, were\r\nfound specifically up-regulated in our OBNSC but not in hENSC. Differences in gene expression profile of transcripts\r\ncontrolling epigenetic modifications, and signaling pathways might indicate differences in the therapeutic potential of our\r\nexamined two cell populations in relation to in cell survival, proliferation, migration, and differentiation following\r\nengraftments in different CNS insults....
Histone deacetylase inhibitors (HDACi) are small molecules that have important and pleiotropic effects on cell homeostasis. Under\r\ndistinct developmental conditions, they can promote either self-renewal or differentiation of embryonic stem cells. In addition,\r\nthey can promote directed differentiation of embryonic and tissue-specific stem cells along the neuronal, cardiomyocytic, and\r\nhepatic lineages. They have been used to facilitate embryo development following somatic cell nuclear transfer and induced pluripotent\r\nstem cell derivation by ectopic expression of pluripotency factors. In the latter method, these molecules not only increase\r\neffectiveness, but can also render the induction independent of the oncogenes c-Myc and Klf4. Here we review the molecular\r\npathways that are involved in the functions of HDAC inhibitors on stem cell differentiation and reprogramming of somatic cells\r\ninto pluripotency. Deciphering the mechanisms of HDAC inhibitor actions is very important to enable their exploitation for\r\nefficient and simple tissue regeneration therapies....
Tissue engineering is an emerging discipline that combines the principle of science and engineering. It offers an unlimited source\r\nof natural tissue substitutes and by using appropriate cells, biomimetic scaffolds, and advanced bioreactors, it is possible that tissue\r\nengineering could be implemented in the repair and regeneration of tissue such as bone, cartilage, tendon, and ligament. Whilst\r\nrepair and regeneration of ligament tissue has been demonstrated in animal studies, further research is needed to improve the biomechanical\r\nproperties of the engineered ligament if it is to play an important part in the future of human ligament reconstruction\r\nsurgery.We evaluate the current literature on ligament tissue engineering and its role in anterior cruciate ligament reconstruction....
Very small embryonic-like (VSEL) cells have been described as putatively pluripotent stem cells present in murine bone\r\nmarrow and human umbilical cord blood (hUCB) and as such are of high potential interest for regenerative medicine.\r\nHowever, there remain some questions concerning the precise identity and properties of VSEL cells, particularly those\r\nderived from hUCB. For this reason, we have carried out an extensive characterisation of purified populations of VSEL cells\r\nfrom a large number of UCB samples. Consistent with a previous report, we find that VSEL cells are CXCR4+, have a high\r\ndensity, are indeed significantly smaller than HSC and have an extremely high nuclear/cytoplasmic ratio. Their nucleoplasm\r\nis unstructured and stains strongly with Hoechst 33342. A comprehensive FACS screen for surface markers characteristic of\r\nembryonic, mesenchymal, neuronal or hematopoietic stem cells revealed negligible expression on VSEL cells. These cells\r\nfailed to expand in vitro under a wide range of culture conditions known to support embryonic or adult stem cell types and\r\na microarray analysis revealed the transcriptional profile of VSEL cells to be clearly distinct both from well-defined\r\npopulations of pluripotent and adult stem cells and from the mature hematopoietic lineages. Finally, we detected an\r\naneuploid karyotype in the majority of purified VSEL cells by fluorescence in situ hybridisation. These data support neither\r\nan embryonic nor an adult stem cell like phenotype, suggesting rather that hUCB VSEL cells are an aberrant and inactive\r\npopulation that is not comparable to murine VSEL cells....
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