Human mesenchymal stem cells from adipose tissue: Differentiation into hepatic lineage.

Adipose tissue represents an accessible source of mesenchymal stem cells (ADSCs), with similar characteristics to bone marrow-derived stem cells. The aim of this work was to investigate the transdifferentiation of ADSCs into hepatic lineage cells in vitro. ADSCs were obtained from human adipose tissue from lipectomy. Cells were grown in medium containing 15% AB human serum. Cultures were serum deprived for two days and exposed to a two-step protocol with two different media using growth factors and cytokines. Hepatic differentiation was assessed by RT-PCR of liver-marker genes. ADSCs exhibited a fibroblastic morphology that changed to a cuboidal shape when cells differentiated. Expression of liver genes increased when using one of the two studied media consisting of DMEM supplemented with HGF, bFGF and nicotinamide for 14 days. The results indicate that, under certain specific inducing conditions, ADSCs can be induced to differentiate into hepatic lineage in vitro. Adipose tissue may be an ideal source of high amounts of autologous stem cells.     

人类胚胎干细胞分化研究

目的分别观察神经分化培养液和视黄酸对人类胚胎干细胞分化的作用。方法采用无滋养层细胞方法培养H9细胞,用化学成分确定的神经分化培养液诱导H9细胞神经分化,检测神经细胞特征蛋白表达;用视黄酸(RA)培养液诱导H9细胞分化,检测分化过程中内质网应激蛋白BIP蛋白表达变化。结果神经分化培养液诱导H9细胞分化成神经细胞;RA诱导的H9细胞分化过程中,BIP的表达随分化上调。结论人类胚胎干细胞分化提供了衍生神经细胞的潜在细胞来源和发育研究的平台。     

Pharmacological potential of embryonic stem cells.

Established embryonic stem (ES) cell lines have been at the forefront of approaches to understand gene function during embryogenesis and in adult vertebrate organisms, principally due to exploitation of two essential attributes; their pluripotency or ability to contribute to all three germinal layers and germ line in mice and their ease of genetic modification. Endeavours to routinely establish ES cells from species other than mice have met with limited success, although with rapid progress being made in our understanding of their basic cell biology, the regular derivation of lines from pre-implantation embryos will become easier for many species including humans. With a recent growing awareness of how these cells can be made to grow in an unlimited, but regulated manner plus how their fate can be directed or manipulated into diverse, mature phenotypes in culture, it has become clear that the biological resource offers additional attractive features applicable for future biomedical research and therapy. Advanced mouse ES-based technologies are being used in the industry for pharmaceutical discovery and development, while it is also anticipated that human ES cell reagents will revolutionise aspects of regenerative medicine. This review will summarise the advantages, potential and great hope for ES cell based systems in these contexts.     

Molecular markers in embryonic stem cells.

Embryonic stem cells are pluripotent cells derived from mouse blastocysts, which have the capacity to differentiate in vitro into a wide variety of cell types. Based on this potential the embryonic stem cell test (EST) has been developed, which represents an assay system for the classification of compounds for their teratogenic potential, based on the morphological evaluation of contracting myocard cells compared to the cytotoxic effects on undifferentiated stem cells and adult 3T3 fibroblasts. To expand the EST, the quantitative expression of the alpha- and beta-myosin heavy chain (MHC) genes under the influence of test compounds was studied employing real-time TaqMan PCR analysis. The molecular evaluation of the MHC genes allows a higher sensitivity for the classification of substances and the transfer of the EST to the molecular level allows to start experimental procedures at day 9 of culture. Thus, the modulated EST holds promise as a new easily quantifiable in vitro screening assay in teratology.     

Differentiation of embryoid-body cells derived from embryonic stem cells into hepatocytes in alginate microbeads in vitro

Aim： Embryonic stem （ES） cells are being widely investigated as a promising source of hepatocytes with their proliferative, renewable, and pluripotent capacities. However, controlled and scalable ES cell differentiation culture into functional hepatocytes is challenging. In this study, we examined the differentiat- ing potential of embryoid-body cells derived from ES cells into hepatocytes in alginate microbeads containing exogenous growth factors in vitro. Methods： Embryoid bodies were formed from ES cells by suspension methods. Embryoid bodies cultured for 5 d were treated with trypsin-EDTA. The disaggregated cells were encapsulated in alginate microbeads and stimulated with exogenous growth factors to induce hepatic differentiation. In the course of cell differentiation, cell morphology and viability were observed, and the expression patterns of some genes of the hepatocyte were confirmed by RT-PCR. An immunofluorescence analysis revealed the expression of albumin （ALB） and cytokeratin-18 （CK18）. Hepatocyte functional assays were confirmed by the secretion of ALB and urea. Results： We showed that embryoid-body cells could maintain cell viability in alginate microbeads in vitro. We also found that directed differentiated cells expressed several hepatocyte genes including ct-fetoprotein （AFP）, ALB, Cyp7a 1, CK18, transthyretin （TTR） and tyrosine aminotransferase （TAT） and produced ALB and urea in alginate microbeads. The directed differentiated cells expressed ALB and CK18 proteins on d 14. However, embryoid-body cells could not form hepatocytes without exogenous growth factors in alginate microbeads. Conclusion： The differentiation of embryoid-body cells into hepatocytes con- taining exogenous growth factors in alginate microbeads gives rise to functional hepatocytes and may develop scalable stem cell differentiation strategies for bioartificial livers and hepatocyte transplantation.     

Differentiation of embryonic stem cells into hepatocytes that coexpress coagulation factors VIII and IX

Aim:

To establish an efficient culture system to support embryonic stem (ES) cell differentiation into hepatocytes that coexpress F-VIII and F-IX.

Methods:

Mouse E14 ES cells were cultured in differentiation medium containing sodium butyrate (SB), basic fibroblast growth factor (bFGF), and/or bone morphogenetic protein 4 (BMP4) to induce the differentiation of endoderm cells and hepatic progenitor cells. Hepatocyte growth factor, oncostatin M, and dexamethasone were then used to induce the maturation of ES cell–derived hepatocytes. The mRNA expression levels of endoderm-specific genes and hepatocyte-specific genes, including the levels of F-VIII and F-IX, were detected by RT-PCR and real-time PCR during various stages of differentiation. Protein expression was examined by immunofluorescence and Western blot. At the final stage of differentiation, flow cytometry was performed to determine the percentage of cells coexpressing F-VIII and F-IX, and ELISA was used to detect the levels of F-VIII and F-IX protein secreted into the culture medium.

Results:

The expression of endoderm-specific and hepatocyte-specific markers was upregulated to highest level in response to the combination of SB, bFGF, and BMP4. Treatment with the three inducers during hepatic progenitor differentiation significantly enhanced the mRNA and protein levels of F-VIII and F-IX in ES cell–derived hepatocytes. More importantly, F-VIII and F-IX were coexpressed with high efficiency at the final stage of differentiation, and they were also secreted into the culture medium.

Conclusion:

We have established a novel in vitro differentiation protocol for ES-derived hepatocytes that coexpress F-VIII and F-IX that may provide a foundation for stem cell replacement therapy for hemophilia.     

Myocardial regeneration with stem cells: pharmacological possibilities for efficacy enhancement.

Cell therapy through the application of stem or progenitor cells to regenerate and repair damaged myocardium has gone from the bench to clinical trial. The functional benefits observed in clinical trials are, however, moderate, and many challenges need to be overcome before cell therapy can be put into widespread clinical use. Better understanding of the signals and molecules that promote cell proliferation, differentiation, engraftment and survival may lead to development of pharmacological agents that enhance the capacity of stem/progenitor cells for myocardial regeneration. The present review will provide a critical analysis of the merits and limitations of different populations of stem/progenitor cells and discuss the potential of pharmacological strategies for enhancing the efficacy of cell therapy for myocardial regeneration.     

Optimization of adenovirus vectors for transduction in embryonic stem cells and induced pluripotent stem cells

Because embryonic stem (ES) cells and induced pluripotent stem (iPS) cells can differentiate into various types of cells in vitro, they are considered as a valuable model to understand the processes involved in the differentiation into functional cells as well as an unlimited source of cells for therapeutic applications. Efficient gene transduction method is one of the powerful tools for the basic researches and for differentiating ES and iPS cells into lineage-committed cells. Recently, we have developed an adenovirus (Ad) vector for efficient transduction into ES and iPS cells. We showed that Ad vectors containing the cytomegalovirus enhancer/β-actin promoter with β-actin intron (CA) promoter or the elongation factor (EF)-1α promoter were the appropriate for the transduction into ES and iPS cells. We also found that enforced expression of a PPARγ gene or a Runx2 gene into mouse ES and iPS cells by an optimized Ad vector markedly augmented the differentiation of adipocytes or osteoblasts, respectively. Thus, a gene transfer technique using an Ad vector could be an advantage for the regulation of stem cell differentiation and could be applied to regenerative medicine based on ES and iPS cells.     

Cardiomyocytes from human embryonic stem cells

Terminal heart failure is characterized by a significant loss of cardiac myocytes. Stem cells represent a possibility for replacing these lost myocytes but the question of which stem cells are most ideally suited for cell transplantation therapies is still being addressed. Here, we consider human embryonic stem cells (HESC), derived from human embryos in this context. We review the methods used to induce their differentiation to cardiomyocytes in culture, their properties in relation to primary human cardiomyocytes and their ability to integrate into host myocardium. In addition, issues regarding their safety that need addressing before use in cell transplantation therapies, both generally and specifically in relation to the heart, are considered.     

Tailoring human embryonic stem cells for neurodegenerative disease therapy

Embryonic stem (ES) cells are expected to become a cell source and biological delivery system for use in a variety of neurodegenerative diseases, and will likely play a role in the development of novel cell-based therapies for these indications. These applications require the in vitro differentiation of ES cells into stable, safe and functional neural cell populations. Initial experiments with mouse ES cells are now in the process of being translated and developed into studies on human (h)ES cells. Despite their potential, several hurdles must be overcome to render hES cells a reliable and efficient system to produce cell types for therapeutic application and as a model system for therapy development. This review discusses the current state of research into hES cells, with an emphasis on neurodegenerative diseases.     

Glutathione transferases in hepatocyte-like cells derived from human embryonic stem cells.

Human embryonic stem cells (hESCs) offer a potential unlimited source for functional human hepatocytes, since hESCs can differentiate into hepatocyte-like cells displaying a characteristic hepatic morphology and expressing several hepatic markers. These hepatocyte-like cells could be used in various human in vitro hepatocyte assays, e.g. as a test system for studying drug metabolism and drug-induced hepatotoxicity. Since the toxic effect of a compound is commonly dependent on biotransformation into metabolites, the presence of drug metabolising enzymes in potential test systems must be evaluated. We have investigated the presence of glutathione transferases (GSTs) in hepatocyte-like cells by immunocytochemistry and Western blotting. Results show that these cells have high levels of GSTA1-1, whereas GSTP1-1 is not present in most cases. GSTM1-1 is detected by immunocytochemistry but not by Western blotting. In addition, GST activity is detected in hepatocyte-like cells at levels comparable to human hepatocytes. These results indicate that the hepatocyte-like cells have characteristics that closely resemble those of human adult hepatocytes.     

Human embryonic stem cells and lung regeneration

Human embryonic stem cells are pluripotent cells derived from the inner cell mass of preimplantation stage embryos. Their unique potential to give rise to all differentiated cell types has generated great interest in stem cell research and the potential that it may have in developmental biology, medicine and pharmacology. The main focus of stem cell research has been on cell therapy for pathological conditions with no current methods of treatment, such as neurodegenerative diseases, cardiac pathology, retinal dysfunction and lung and liver disease. The overall aim is to develop methods of application either of pure cell populations or of whole tissue parts to the diseased organ under investigation. In the field of pulmonary research, studies using human embryonic stem cells have succeeded in generating enriched cultures of type II pneumocytes in vitro. On account of their potential of indefinite proliferation in vitro, embryonic stem cells could be a source of an unlimited supply of cells available for transplantation and for use in gene therapy. Uncovering the ability to generate such cell types will expand our understanding of biological processes to such a degree that disease understanding and management could change dramatically.     

Neural stem cells: a pharmacological tool for brain diseases?

Stem cells are believed to provide a tool by which new cells and tissues can be made and by which damaged ones can be replaced or repaired. Over the past few years, the existence of a subset of stem cells has been documented in the fetal brain, therefore named neural stem cells (NSCs). To this regard, the more recent demonstration that similar cells are present in the adult mammalian brain and retain the capability to produce new neurons, has undermined the dogma that neurons are only generated during the fetal life and has stimulated investigations into the regulation and role of adult neurogenesis. Here, we will review the recent advancements on the biology of brain stem cells and discuss the mechanisms and drugs regulating adult neurogenesis, aiming at better estimating the possible future applications of NSCs for brain repair.     

人胚胎干细胞在药物毒性风险评估中的研究进展

人胚胎干细胞（hESCs）是来源于胚胎发育早期内细胞团的一类未分化的多能干细胞,具有自我更新和多向分化的生物学特性,在发育生物学、再生医学以及细胞治疗领域等方面已开展了广泛的研究。与常规药物毒性评估所采用的癌细胞或原代细胞不同,干细胞不仅能满足基础毒性评估,由于其多向分化的特点,可经诱导产生各种正常人体器官或组织细胞,为药物临床前评估提供多方面数据。与动物实验模型相比,hESCs不仅避免了种属差异,还具备高通量、低成本的优势,在预测药物毒性效应方面具有广阔的前景。对目前hESCs在药物毒性风险评估中的研究进展进行总结,为体外药物毒性筛选试验提供新思路。     

葡萄糖对小鼠胚胎干细胞生长的影响

目的：目前小鼠胚胎干细胞（mouse embryonic stem cells,mESC）常规应用高浓度葡萄糖（25mmol／L）培养基培养,但是在应用干细胞向糖尿病胰岛beta细胞分化的研究中发现,慢性高糖培养可促进干细胞的凋亡、降低细胞分化的效率及分化后胰岛beta细胞对葡萄糖的反应性,因此本研究拟选择合适的较低浓度的葡萄糖以优化胚胎干细胞的培养基、提高胚胎干细胞的生长、分化效率。方法：mESC传代4或12h后,将传统的25mmol／L葡萄糖培养基分别换为5、10、15、25mmol／L葡萄糖培养基培养,均用碱性磷酸酶（AP）染色计数细胞集落形成情况、台盼兰染色测定细胞数目,MTT法测定细胞活力及用4’,6-联脒-2-苯基吲哚（4’,6-diamidino-2-phenylindole,DAPI）染色检测细胞凋亡情况。结果：mESC传代4h后即调换葡萄糖浓度：（1）各葡萄糖浓度组（5、10、15mmol／L）与25mmol／L组相比,集落形成明显减少。（2）各葡萄糖浓度组与25mmol／L组相比,mESC增殖及细胞活力均受到不同程度明显影响。mESC传代12h后调换葡萄糖浓度：（1）各葡萄糖浓度组（5、10、15mmol／L）与25mmol／L组相比,集落形成无明显变化,且AP染色呈强阳性。（2）15mmol／L葡萄糖组对mESC增殖及细胞活力均无明显影响。（3）15mmol／L葡萄糖组与25mmol／L葡萄糖组细胞核形态正常,均未见明显凋亡。结论：ESC传代12h后将培养基中传统的高糖（25mmol／L）降低为15mmol／L,不影响mESC细胞活力及多能分化潜能和未分化状态。     

黄芪甲苷对脂肪源性干细胞体外生物学行为的影响

目的探讨黄芪甲苷(Astragaloside IV,Ast)对体外培养人脂肪源性间充质干细胞(human adipose-derived mesen-chymal stem cells,hADSCs)生物学行为的影响。方法应用CCK8和PCNA法检测不同浓度和时间Ast孵育对hADSCs增殖情况的影响,选取出Ast最适干预条件并对hADSCs进行培养,观察药物干预后细胞形态、表面标志物、成骨及成脂分化潜能。结果 CCK8和PCNA结果均显示,Ast 20 mg.L-1干预48 h后细胞增殖最为明显,进一步选取Ast20 mg.L-1干预hADSCs 48 h,与对照组相比,两组细胞CD29、CD44、CD105的阳性率均为96%-99%;两组细胞成骨诱导与成脂诱导结果也无差异。结论 Ast可促进ADSCs增殖,以20 mg.L-1、孵育48 h为最适干预条件,且该条件干预后并不影响hADSCs细胞形态,表面标志物水平及多向分化能力。     

Time- and dose-dependent effects of ethanol on mouse embryonic stem cells

Ethanol is a common solvent used with mouse embryonic stem (mES) cells in protocols to test chemicals for evidence of developmental toxicity. In this study, dose–response relationships for ethanol toxicity in mES cells were examined. For cells maintained in an undifferentiated state, ethanol significantly reduced viable cell numbers with estimated half maximal inhibitory concentrations of 1.5% and 0.8% ethanol after 24 and 48 h, respectively, observations which correlated with significantly increased expression of apoptotic markers. For cells cultured to induce cardiomyocyte formation, up to 0.5% ethanol during the first two days failed to alter the outcome of differentiation, whereas 0.3% ethanol for 11 days significantly reduced the fraction of cultures containing contracting areas, an observation that correlated with significantly reduced cell numbers. These results suggest that ethanol is not an inert solvent at concentrations that might be used for developmental toxicity testing.