参考文献

We report a paracrine effect whereby endothelial cells (ECs) promote the cancer stem cell (CSC) phenotype of human colorectal cancer (CRC) cells. We showed that,without direct cell-cell contact,ECs secrete factors that promoted the CSC phenotype in CRC cells via Notch activation. In human CRC specimens,CD133 and Notch intracellular domain-positive CRC cells colocalized in perivascular regions. An EC-derived,soluble form of Jagged-1,via ADAM17 proteolytic activity,led to Notch activation in CRC cells in a paracrine manner; these effects were blocked by immunodepletion of Jagged-1 in EC-conditioned medium or blockade of ADAM17 activity. Collectively,ECs play an active role in promoting Notch signaling and the CSC phenotype by secreting soluble Jagged-1. View Publication

The serological complement-dependent cytotoxicity crossmatch (CDC-XM) permits routine identification of anti-donor alloantibodies in the sera of allotransplant recipients. However,in a small group of recipients,antibodies below the threshold of detection may still be responsible for hyperacute rejection. For the same reason,approximately 20% of recipients develop acute rejection episodes. The flow cytometry crossmatch (FCXM) was designed to address these problems,but because of the presence of clinically insignificant antibodies (linked,non-lytic),the FCXM appears to be too sensitive yielding false-positive results. We compared FCXM with its modified version assessing cell viability (cytolytic flow cytometry crossmatch; cFCXM) using sera from previously sensitised kidney recipients. The presence of alloantibodies was detected using the Luminex platform. The cFCXM proved to be of greater sensitivity than CDC-XM,which was additionally confirmed with bead-based Luminex techniques. The cFCXM was also superior to FCXM because it distinguished lytic from non-lytic antibodies. The cFCXM was superior to assess donor specificity,sensitivity,and detection of clinically relevant lytic antibodies. View Publication

Pluripotent stem cells can differentiate into nearly all types of cells in the body. This unique potential provides significant promise for cell-based therapies to restore tissues or organs destroyed by injuries,degenerative diseases,aging,or cancer. The discovery of induced pluripotent stem cell (iPSC) technology offers a possible strategy to generate patient-specific pluripotent stem cells. However,because of concerns about the specificity,efficiency,kinetics,and safety of iPSC reprogramming,improvements or fundamental changes in this process are required before their effective clinical use. A chemical approach is regarded as a promising strategy to improve and change the iPSC process. Dozens of small molecules have been identified that can functionally replace reprogramming factors and significantly improve iPSC reprogramming. In addition to the prospect of deriving patient-specific tissues and organs from iPSCs,another attractive strategy for regenerative medicine is transdifferentiation-the direct conversion of one somatic cell type to another. Recent studies revealed a new paradigm of transdifferentiation: using transcription factors used in iPSC generation to induce transdifferentiation or called iPSC transcription factor-based transdifferentiation. This type of transdifferentiation not only reveals and uses the developmentally plastic intermediates generated during iPSC reprogramming but also produces a wide range of cells,including expandable tissue-specific precursor cells. Here,we review recent progress of small molecule approaches in the generation of iPSCs. In addition,we summarize the new concept of iPSC transcription factor-based transdifferentiation and discuss its application in generating various lineage-specific cells,especially cardiovascular cells. View Publication

BACKGROUND To evaluate the anticancer efficacy of the combination of epigenetic modifiers and cisplatin in human ovarian cancer. METHODS The effect of trichostatin A (TSA) and 5-aza-2'-deoxycytidine alone or in combination with low-dose cisplatin was evaluated on human ovarian cancer cell lines in vitro. We measured drug interaction by MTS assay,migration by transwell assay,expression of epithelial to mesenchymal transition (EMT) markers (Twist,Snail,Slug,E-cadherin,and N-cadherin),pluripotency markers (Oct4,Sox2,and Nanog),and epigenetic markers (DNMT3A,LSD1 and H3K4me2,H3K4me3,H3K9me2,and H3K9me3) by western blot,and the impact on and characteristics of spheroid growth when exposed to these drugs. Mouse xenografts were used to evaluate the anticancer effect of sequential drug treatment. RESULTS Combination treatment had greater efficacy than single drugs and significantly suppressed cell viability,migration,and spheroid formation and growth. Sequential treatment of cisplatin (1 mg kg(-1)) followed by TSA (0.3 mg kg(-1)) significantly suppressed tumorigenicity of HEY xenografts through inhibition of EMT and decreased pluripotency of ovarian cancer cells. CONCLUSION Epigenetic modifiers potentiate the anticancer efficacy of low-dose cisplatin in ovarian cancer through regulation of EMT and pluripotency,and may provide a promising treatment for ovarian cancer patients. View Publication

All trans-retinoic acid (ATRA) is widely used to direct the differentiation of cultured stem cells. When exposed to the pluripotent human embryonal carcinoma (EC) stem cell line,TERA2.cl.SP12,ATRA induces ectoderm differentiation and the formation of neuronal cell types. We have previously generated synthetic analogues of retinoic acid (EC23 and EC19) which also induce the differentiation of EC cells. Even though EC23 and EC19 have similar chemical structures,they have differing biochemical effects in terms of EC cell differentiation. EC23 induces neuronal differentiation in a manner similar to ATRA,whereas EC19 directs the cells to form epithelial-like derivatives. Previous MALDI-TOF MS analysis examined the response of TERA2.cl.SP12 cells after exposure to ATRA,EC23 and EC19 and further demonstrated the similarly in the effect of ATRA and EC23 activity whilst responses to EC19 were very different. In this study,we show that Fourier Transform Infrared Micro-Spectroscopy (FT-IRMS) coupled with appropriate scatter correction and multivariate analysis can be used as an effective tool to further investigate the differentiation of human pluripotent stem cells and monitor the alternative affects different retinoid compounds have on the induction of differentiation. FT-IRMS detected differences between cell populations as early as 3 days of compound treatment. Populations of cells treated with different retinoid compounds could easily be distinguished from one another during the early stages of cell differentiation. These data demonstrate that FT-IRMS technology can be used as a sensitive screening technique to monitor the status of the stem cell phenotype and progression of differentiation along alternative pathways in response to different compounds. View Publication

Magnesium alloys have attracted great interest for medical applications due to their unique biodegradable capability and desirable mechanical properties. When designed for medical applications,these alloys must have suitable degradation properties,i.e.,their degradation rate should not exceed the rate at which the degradation products can be excreted from the body. Cellular responses and tissue integration around the Mg-based implants are critical for clinical success. Four magnesium–zinc–strontium (ZSr41) alloys were developed in this study. The degradation properties of the ZSr41 alloys and their cytocompatibility were studied using an in vitro human embryonic stem cell (hESC) model due to the greater sensitivity of hESCs to known toxicants which allows to potentially detect toxicological effects of new biomaterials at an early stage. Four distinct ZSr41 alloys with 4 wt% zinc and a series of strontium compositions (0.15,0.5,1,and 1.5 wt% Sr) were produced through metallurgical processing. Their degradation was characterized by measuring total mass loss of samples and pH change in the cell culture media. The concentration of Mg ions released from ZSr41 alloy into the cell culture media was analyzed using inductively coupled plasma atomic emission spectroscopy. Surface microstructure and composition before and after culturing with hESCs were characterized using field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Pure Mg was used as a control during cell culture studies. Results indicated that the Mg–Zn–Sr alloy with 0.15 wt% Sr provided slower degradation and improved cytocompatibility as compared with pure Mg control. View Publication

The ST6Gal-I sialyltransferase adds an $$2-6-linked sialic acid to the N-glycans of certain receptors. ST6Gal-I mRNA has been reported to be upregulated in human cancer,but a prior lack of antibodies has limited immunochemical analysis of the ST6Gal-I protein. Here,we show upregulated ST6Gal-I protein in several epithelial cancers,including many colon carcinomas. In normal colon,ST6Gal-I localized selectively to the base of crypts,where stem/progenitor cells are found,and the tissue staining patterns were similar to the established stem cell marker ALDH1. Similarly,ST6Gal-I expression was restricted to basal epidermal layers in skin,another stem/progenitor cell compartment. ST6Gal-I was highly expressed in induced pluripotent stem (iPS) cells,with no detectable expression in the fibroblasts from which iPS cells were derived. On the basis of these observations,we investigated further an association of ST6Gal-I with cancer stem cells (CSC). Selection of irinotecan resistance in colon carcinoma cells led to a greater proportion of CSCs compared with parental cells,as measured by the CSC markers CD133 and ALDH1 activity (Aldefluor). These chemoresistant cells exhibited a corresponding upregulation of ST6Gal-I expression. Conversely,short hairpin RNA (shRNA)-mediated attenuation of ST6Gal-I in colon carcinoma cells with elevated endogenous expression decreased the number of CD133/ALDH1-positive cells present in the cell population. Collectively,our results suggest that ST6Gal-I promotes tumorigenesis and may serve as a regulator of the stem cell phenotype in both normal and cancer cell populations. View Publication

A goal in human embryonic stem cell (hESC) research is the faithful differentiation to given cell types such as neural lineages. During embryonic development,a basement membrane surrounds the neural plate that forms a tight,apico-basolaterally polarized epithelium before closing to form a neural tube with a single lumen. Here we show that the three-dimensional epithelial cyst culture of hESCs in Matrigel combined with neural induction results in a quantitative conversion into neuroepithelial cysts containing a single lumen. Cells attain a defined neuroepithelial identity by 5 days. The neuroepithelial cysts naturally generate retinal epithelium,in part due to IGF-1/insulin signaling. We demonstrate the utility of this epithelial culture approach by achieving a quantitative production of retinal pigment epithelial (RPE) cells from hESCs within 30 days. Direct transplantation of this RPE into a rat model of retinal degeneration without any selection or expansion of the cells results in the formation of a donor-derived RPE monolayer that rescues photoreceptor cells. The cyst method for neuroepithelial differentiation of pluripotent stem cells is not only of importance for RPE generation but will also be relevant to the production of other neuronal cell types and for reconstituting complex patterning events from three-dimensional neuroepithelia. View Publication

BACKGROUND: Fragile X syndrome (FXS) is a common form of inherited intellectual disability caused by an expansion of CGG repeats located in the 5' untranslated region (UTR) of the FMR1 gene,which leads to hypermethylation and silencing of this locus. Although a dramatic increase in DNA methylation of the FMR1 full mutation allele is well documented,the extent to which these changes affect DNA methylation throughout the rest of the genome has gone unexplored. METHODS: Here we examined genome-wide methylation in both peripheral blood (N = 62) and induced pluripotent stem cells (iPSCs; N = 10) from FXS individuals and controls. RESULTS: We not only found the expected significant DNA methylation differences in the FMR1 promoter and 5' UTR,we also saw that these changes inverse in the FMR1 gene body. Importantly,we found no other differentially methylated loci throughout the remainder of the genome,indicating the aberrant methylation of FMR1 in FXS is locus-specific. CONCLUSIONS: This study provides a comprehensive methylation profile of FXS and helps refine our understanding of the mechanisms behind FMR1 silencing. View Publication

The antitumor activity of LPS was first described by Dr. William Coley. However,its role in lung cancer remains unclear. The aim of our study was to elucidate the dose-dependent effects of LPS (0.1-10 μg/mouse) in a mouse model of B16-F10-induced metastatic lung cancer. Lung tumor growth increased at 3 and 7 d after the administration of low-dose LPS (0.1 μg/mouse) compared with control mice. This was associated with an influx of plasmacytoid dendritic cells (pDCs),regulatory T cells,myeloid-derived suppressor cells,and CD8(+) regulatory T cells. In contrast,high-dose LPS (10 μg/mouse) reduced lung tumor burden and was associated with a greater influx of pDCs,as well as a stronger Th1 and Th17 polarization. Depletion of pDCs during low-dose LPS administration resulted in a decreased lung tumor burden. Depletion of pDCs during high-dose LPS treatment resulted in an increased tumor burden. The dichotomy in LPS effects was due to the phenotype of pDCs,which were immunosuppressive after the low-dose LPS,and Th1- and T cytotoxic-polarizing cells after the high-dose LPS. Adoptive transfer of T cells into nude mice demonstrated that CD8(+) T cells were responsible for pDC recruitment following low-dose LPS administration,whereas CD4(+) T cells were required for pDC influx after the high-dose LPS. In conclusion,our data suggest differential effects of low-dose versus high-dose LPS on pDC phenotype and tumor progression or regression in the lungs of mice. View Publication