科研快讯

《细胞研究》:研究建立高效诱导iPSCs向心肌细胞分化体系iPS研究由于在未来临床应用的的无限可能,而吸引了全球不少实验室的科学家们,来自中科院健康科学研究所干细胞生物学重点实验室的研究人员发表了题为"Ascorbic acid enhances cardiac differentiation of induced pluripotent stem cells through promoting the proliferation of cardiac progenitor cells"的文章,报道了诱导多能干细胞iPS细胞在临床上转化应用的最新成     

黑腹果蝇单胚培养技术的建立

过硬单胚培养十一项特殊的技术,运用此技术可以从果蝇单个原肠胚（同一基因型）中提取细胞进行体外培养,科观察到各种细胞的分化过程,从而能研究导致发生异常或致死突变的机制。通过反复摸索实验,我们在本实验室的条件下,建立了黑腹果蝇（D. melanogaster）单胚培养技术,并对野生型（Canton special, CS.）果蝇的单胚细胞进行体外培养,观察到了各种细胞,如肌肉细胞、神经细胞、脂肪细胞、以及成虫盘等的分化及其发生规律性,为今后研究突变奠定了基础。实验过程中,我们采用了载玻片法和培养皿法。两种方法各有特点及利弊,本文一并进行讨论。Abstract:We can culture the cells of single gastrula (the gene type of cells is same) in vitro,we now have cstablished the technique of single embryo culture in Drosophila.We have seen the differentiated state of myocytes, neurocytes,hemocyte cells,epithelical cells and imagical disk by this technique.     

《基因与发育》：细胞凋亡吞噬研究获进展

6月15日。《基因与发育》（Genes＆Development）杂志发表了中科院生物物理研究所刘迎芳实验室和北京生命科学研究所（NIBS）王晓晨实验室的合作研究成果”Structural Study of TTR-52 Reveals the Functional Mechanisms of a Bridging Molecule in Apoptotic Cell Engulfment”。该工作通过结构和功能研究，揭示了在秀丽线虫凋亡细胞的清除过程中。桥联分子TTR-52介导吞噬细胞识别凋亡细胞的作用机制。     

Cellular Reprogramming of Human Peripheral Blood Cells

Breakthroughs in cell fate conversion have made it possible to generate large quantities of patient-specific cells for regenerative medicine. Due to multiple advantages of peripheral blood cells over fibroblasts from skin biopsy, the use of blood mononuclear cells （MNCs） instead of skin fibroblasts will expedite reprogramming research and broaden the application of reprogramming technology. This review discusses current progress and challenges of generating induced pluripotent stem cells （iPSCs） from peripheral blood MNCs and of in vitro and in vivo conversion of blood cells into cells of therapeutic value, such as mesenchymal stem cells, neural cells and hepatocytes. An optimized design of lentiviral vectors is necessary to achieve high reprogramming efficiency of peripheral blood cells. More recently, non-integrating vectors such as Sendai virus and episomal vectors have been successfully employed in generating integration-free iPSCs and somatic stem cells.     

Dynamic distribution of Ser-10 phosphorylated histone H3 in cytoplasm of MCF-7 and CHO cells during mitosis

The dynamic distribution of phosphorylated Histone H3 on Serl 0 (phospho-H3) in cells was investigated to determine its function during mitosis. Human breast adenocarcinoma cells MCF-7, and Chinese hamster cells CHO were analyzed by indirect immunofluorescence staining with an antibody against phospho-H3. We found that the phosphorylation begins at early prophase, and spreads throughout the chromosomes at late prophase. At metaphase, most of the phospho-H3 aggregates at the end of the condensed entity of chromosomes at equatorial plate. During anaphase and telophase,the fluorescent signal of phospho-H3 is detached from chromosomes into cytoplasm. At early anaphase, phospho-H3 shows ladder bands between two sets of separated chromosome, and forms “sandwich-like structure” when the chromosomes condensed. With the cleavage progressing, the “ladders” of the histone contract into a bigger bright dot. Then the histone aggregates and some of compacted microtubules in the midbody region are composed into a “bar-like”complex to separate daughter cells. The daughter cells seal their plasma membrane along with the ends of the “bar”,inside which locates microtubules and modified histones, to finish the cytokinesis and keep the “bar complex” out of the cells. The specific distribution and kinetics of phospho-H3 in cytoplasm suggest that the modified histones may take part in the formation of midbody and play a crucial role in cytokinesis.     

《干细胞》：滋养层干细胞重编程研究获进展

来自北京生命科学研究所的研究人员于2月8日在《干细胞》（Stem Cells）杂志上发表了题为 ＂Reprogramming of trophoblast stem cells into pluripotent stem cells by Oct4＂ 的新研究文章。该文章首次报道了一个转录因子Oct4可以将滋养外胚层来源的滋养层干细胞重编程为具有分化为三胚层能力的多潜能干细胞。     

Biological character of human adipose-derived adult stem cells and influence of donor age on cell replication in culture

To investigate the biological character of human adipose-derived adult stem cells (hADAS cells) when cultured in vitro and the relationship between hADAS cell’s replication activity and the donor’s age factor, and to assess the stem cells as a new source for tissue engineering. hADAS cells are isolated from human adipose tissue of different age groups (from adolescents to olds: <20 years old, 21―40 years old, 41―60 years old and >61 years old groups). The protein markers (CD29, CD34, CD44, CD45, CD49d, HLA-DR, CD106) of hADAS cells were detected by flow cytometry (FCM) to identify the stem cell, and the cell cycle was examined for P20 hADAS cells to evaluate the safety of the subculture in vitro. The generative activity of hADAS cells in different age groups was also examined by MTT method. The formula “ log2T D = t logN t ? logN 0” was used to get the time doubling (TD) of the cells. The results showed that the cells kept heredity stabilization by chromosome analysis for at least 20 passages. The TD of these cells increased progressively by ageing, and the TD of the <20 years old group was lower than that of the >61 years old group (statistical analysis of variance (ANOVA), P=0.002, P<0.05). These find- ings suggested that a higher level of hADAS cells replication activity was found in the younger dona- tors, and they represent novel and valuable seed cells for studies of tissue engineering.     

NRR：白藜芦醇有助于治疗神经退行性疾病

发表于2013年2月第6期《中国神经再生研究（英文版）》（Neural Regeneration Research）杂志的一项研究“Effects of resveratrol on hydrogen peroxide-induced oxidative stress in embryonic neural stem cells”表明，白藜芦醇提高抗氧化酶活性的作用可减轻胚胎神经干细胞受到的氧化应激性损害。     

Regulation of P1-450 Gene Expression by Dimethylbenzanthracene in Human Lung Tumor Cells in Culture

Polycyclic aromatic hydrocarbons(PAHs),dimethyl beazanthracene(DMBA)and benzo-(a)-pyrene(BaP),stimulate the expression of the P1-450 gene in human lung tumor cells(ChaGo)in culture.A concentration-and time-dependent increase in the level of P1-450 specific mRNA sequences hasbeen observed in ChaGo cells treated with sublethal concentrations of DMBA.Results presentedsuggest that the parent compound causes the induction of P1-450 gene expression.The methylationpattern of the internal“-C-” residues of the “-CCGG-” sequence has been studied in a stretch ofabout 8000 base pairs(bp)of DNA sequence in and around the P1-450 gene in the control andDMBA-treated ChaGo cells.A comparative Southern blot analysis of the Msp Ⅰ/Hpa Ⅱ digestedDNA of the control and DMBA-treated ChaGo cells followed by hybridization with ~(32)P-labelledregion-specific probes,revealed that i)the internal “-C-” residues of the “-CCGG-” sequences ofdifferent regions of P1-450 gene were methylated to different degrees;ii)DMBA treatment of thecells induced hypomethylation of only the 5' end “-CCGG-” sequences of the gene;and iii)themethylation patterns of “-CCGG-” sequences of most of the coding region and of the 3' end regionof P1-450 gene were not affected by such DMBA treatment.     

Search for nave human pluripotent stem cells

Normal mouse pluripotent stem cells were originally derived from the inner cell mass(ICM) of blastocysts and shown to be the in vitro equivalent of those pre-implantation embryonic cells, and thus were called embryonic stem cells(ESCs). More than a decade later, pluripotent cells were isolated from the ICM of human blastocysts. Despite being called human ESCs, these cells differ significantly from mouse ESCs, including different morphology and mechanisms of control of pluripotency, suggesting distinct embryonic origins of ESCs from the two species. Subsequently, mouse pluripotent stem cells were established from the ICMderived epiblast of post-implantation embryos. These mouse epiblast stem cells(Epi SCs) are morphological and epigenetically more similar to human ESCs. This raised the question of whether cells from the human ICM are in a more advanced differentiation stage than their murine counterpart, or whether the available culture conditions were not adequate to maintain those human cells in their in vivo state, leading to a transition into Epi SC-like cells in vitro. More recently, novel culture conditions allowed the conversion of human ESCs into mouse ESC-like cells called nave(or ground state) human ESCs, and the derivation of nave human ESCs from blastocysts. Here we will review the characteristics of each type of pluripotent stem cells, how(and whether) these relate to different stages of embryonic development, and discuss the potential implications of nave human ESCs in research and therapy.     

Convergence of normal stem cell and cancer stem cell developmental stage: Implication for differential therapies

Increased evidence shows that normal stem cells may contribute to cancer development and progression by acting as cancer-initiating cells through their interactions with abnormal environmental elements.We postulate that normal stem cells and cancer stem cells (CSC) possess similar mechanisms of self-renewal and differentiation.CSC can be the key to the elaboration of anti-cancer-based therapy.In this article,we focus on a controversial new theme relating to CSC.Tumorigenesis may have a critical stage characterized as a "therapeutic window",which can be identified by asso-ciation of molecular,biochemical and biological events.Identifying such a stage can allow the production of more effective therapies (e.g.manipulated stem cells) to treat several cancers.More importantly,confirming the existence of a similar therapeutic window during the conversion of normal stem cells to malignant CSC may lead to targeted therapy specifically against CSC.This conversion information may be derived from investigating the biological behaviour of both normal stem cells and cancerous stem cells.Currently,there is little knowledge about the cellular and molecular mechanisms that govern the initiation and maintenance of CSC.Studies on co-evolution and interdependence of cancer with normal tissues may lead to a useful treatment paradigm of cancer.The crosstalk between normal stem cells and cancer formation may converge developmental stages of different types of stem cells (e.g.normal stem cells,CSC and embryonic stem cells).The differential studies of the convergence may result in novel therapies for treating cancers.     

The biology of melanocyte and melanocyte stem cell

The melanocyte stem cells of the hair follicle provide an attractive system for the study of the stem cells. Successful regeneration of a functional organ relies on the organized and timely orchestration of molecular events among dis- tinct stem/progenitor cell populations. The stem cells are regulated by communication with their specialized microenvironment known as the niche. Despite remarkable progress in understanding stem cell-intrinsic behavior, the molecular nature of the extrinsic factors provided to the stem cells by the niche microenvironment remains poorly understood. In this regard, the bulge niche of the mammalian hair follicle offers an excellent model for study. It holds two resident populations of SCs： epidermal stem cells and melanocyte stem cells. While their behavior is tightly coordinated, very little of the crosstaik involved is known. This review summarized the recent development in trying to understand the regulation of melanocyte and melanocyte stem cells. A better understanding of the normal regulation and behaviors of the melanocytes and the melanocyte stem cells will help to improve the clinical applications in regenerative medicine, cancer therapy, and aging.     

Pluripotency of Induced Pluripotent Stem Cells

Induced pluripotent stem （iPS） cells can be generated by forced expression of four pluripotency factors in somatic cells. This has received much attention in recent years since it may offer us a promising donor cell source for cell transplantation therapy. There has been great progress in iPS cell research in the past few years. However, several issues need to be further addressed in the near future before the clinical application of iPS cells, like the immunogenieity of iPS cells, the variability of differentiation potential and most importantly tumor formation of the iPS derivative cells. Here, we review recent progress in research into the pluripotency of iPS cells.     

Migration of bone marrow progenitor cells in the adult brain of rats and rabbits

Neurogenesis takes place in the adult mammalian brain in three areas:Subgranular zone of the dentate gyrus(DG);subventricular zone of the lateral ventricle;olfactory bulb.Different molecular markers can be used to characterizethe cells involved in adult neurogenesis.It has been recently suggested that a population of bone marrow(BM)progenitor cells may migrate to the brain and differentiate into neuronal lineage.To explore this hypothesis,we injected recombinant SV40-derived vectors into the BM and followed the potential migration of the transduced cells.Long-term BM-directed gene transfer using recombinant SV40-derived vectors leads to expression of the genes delivered to the BM firstly in circulating cells,then after several months in mature neurons and microglial cells,and thus without central nervous system(CNS)lesion.Most of transgene-expressing cells expressed NeuN,a marker of mature neurons.Thus,BM-derived cells may function as progenitors of CNS cells in adult animals.The mechanism by which the cells from the BM come to be neurons remains to be determined.Although the observed gradual increase in transgene-expressing neurons over 16mo suggests that the pathway involved differentiation of BM-resident cells into neurons,cell fusion as the principal route cannot be totally ruled out.Additional studies using similar viral vectors showed that BM-derived progenitor cells migrating in the CNS express markers of neuronal precursors or immature neurons.Transgene-positive cells were found in the subgranular zone of the DG of the hippocampus 16 mo after intramarrow injection of the vector.In addition to cells expressing markers of mature neurons,transgene-positive cells were also positive for nestin and doublecortin,molecules expressed by developing neuronal cells.These cells were actively proliferating,as shown by short term BrdU incorporation studies.Inducing seizures by using kainic acid increased the number of BM progenitor cells transduced by SV40vectors migrating to the hippocampus,and these cells were seen at earlier time points in the DG.We show that the cell membrane chemokine receptor,CCR5,and its ligands,enhance CNS inflammation and seizure activity in a model of neuronal excitotoxicity.SV40-based gene delivery of RNAi targeting CCR5 to the BM results in downregulating CCR5 in circulating cells,suggesting that CCR5 plays an important role in regulating traffic of BM-derived cells into the CNS,both in the basal state and in response to injury.Furthermore,reduction in CCR5 expression incirculating cells provides profound neuroprotection from excitotoxic neuronal injury,reduces neuroinflammation,and increases neuronal regeneration following this type of insult.These results suggest that BM-derived,transgeneexpressing,cells can migrate to the brain and that they become neurons,at least in part,by differentiating into neuron precursors and subsequently developing into mature neurons.     

Dynamic monitoring of changes in endothelial cell-substrate adhesiveness during leukocyte adhesion by microelectrical impedance assay

Adhesion of leukocytes to endothelial cells in inflammation processes leads to changes of endothelial cellsubstrate adhesiveness, and understanding of such changes will provide us with important information of inflammation processes. In this study, we used a noninvasive biosensor system referred to as real-time cell electronic sensor （RT-CES） system to monitor the changes in endothelial cell-substrate adhesiveness induced by human monoblastic cell line U937 cell adhesion in a dynamic and quantitative manner. This assay, which is based on cell-substrate impedance readout, is able to monitor transient changes in cell- substrate adhesiveness as a result of U937 cell adhesion. The U937 cell adhesion to endothelial cells was induced by lipopolysaccharide （LPS） in a dose-dependent manner. Although the number of adherent U937 cells to the endothelial cells was verified by a standard assay, the adhesiveness of endothelial cells after addition of U937 cells was monitored by the RT-CES system. Furthermore, focal adhesion kinase protein decrease and F-actin rearrangement in endothelial cells were observed after addition of U937 cells. Our results indicated that the adhesion of U937 cells to LPS-treated endothelial cells reduced the substrate, and such infiltration of leukocytes. the cell adhesiveness to reduction might facilitate     

Neural stem cells could serve as a therapeutic material for age-related neurodegenerative diseases

Progressively loss of neural and glial cells is the key event that leads to nervous system dysfunctions and diseases. Several neurodegenerative diseases, for instance Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, are associated to aging and suggested to be a consequence of deficiency of neural stem cell pool in the affected brain regions. Endogenous neural stem cells exist throughout life and are found inspecific niches of human brain. These neural stem cells are responsible for the regeneration of new neurons to restore, in the normal circumstance, the functions of the brain. Endogenous neural stem cells can be isolated, propagated, and, notably, differentiated to most cell types of the brain. On the other hand, other types of stem cells, such as mesenchymal stem cells, embryonic stem cells, and induced pluripotent stem cells can also serve as a source for neural stem cell production, that hold a great promise for regeneration of the brain. The replacement of neural stem cells, either endogenous or stem cell-derived neural stem cells, into impaired brain is highly expected as a possible therapeutic mean for neurodegenerative diseases. In this review, clinical features and current routinely treatments of agerelated neurodegenerative diseases are documented. Noteworthy, we presented the promising evidence of neural stem cells and their derivatives in curing such diseases, together with the remaining challenges to achieve the best outcome for patients.     

Expression of Bcl—2 inhibited Fas—mediated apoptosis in human hepatocellular carcinoma BEL—7404 cells

Apoptosis plays an important role in embryonic development,tissue remodeling,immune regulation and tumor regression.Two groups of molecules(Bcl-2 family and “Death factor” family) are involved in regulating apoptosis.In order to know about the effect of Bcl-2 on apoptosis induced by Fas,a typical member of “Death factor” family,the transfection experiments with expression vectors pcDNA3-fl and pcDNA3-bcl-2 were performed in BEL-7404 cells,a human hepatocellular carcinoma cell line which expresses endogenous Fas,but not FasL and Bcl-2.The data showed that the expression of FasL in pcDNA3-fl transfected hepatoma cells obviously induced the apoptosis of the cells.However,the overexpression of Bcl-2 in pcDNA3-bcl-2 transfected 7404/b-16 cells counteracted pcDNA3-fl transient transfection mediated apoptosis.Further study by cotransfection experiments indicated that Bid but not Bax (both were pro-apoptotic proteins of Bcl-2 family) blocked the inhibitory effect of Bcl-2 on Fas-mediated apoptosis.These results suggested that Fas-mediated apoptosis in human hepatoma cells is possibly regulated by Bcl-2 family proteins via mitochondria pathway.     

Origin of cells and network information

All cells are derived from one cell, and the origin of different cell types is a subject of curiosity. Cells construct life through appropriately timed networks at each stage of development. Communication among cells and intracellular signaling are essential for cell differentiation and for life processes. Cellular molecular networks establish cell diversity and life. The investigation of the regulation of each gene in the genome within the cellular network is therefore of interest. Stem cells produce various cells that are suitable for specific purposes. The dynamics of the information in the cellular network changes as the status of cells is altered. The components of each cell are subject to investigation.     

Different roles of TGF-β in the multi-lineage differentiation of stem cells

Stem cells are a population of cells that has infinite or long-term self-renewal ability and can produce various kinds of descendent cells.Transforming growth factor β(TGF-β) family is a superfamily of growth factors,including TGF-β1,TGF-β2 and TGF-β3,bone morphogenetic proteins,activin/inhibin,and some other cytokines such as nodal,which plays very important roles in regulating a wide variety of biological processes,such as cell growth,differentiation,cell death.TGF-β,a pleiotropic cytokine,has been proved to be differentially involved in the regulation of multi-lineage differentiation of stem cells,through the Smad pathway,non-Smad pathways including mitogen-activated protein kinase pathways,phosphatidylinositol-3-kinase/AKT pathways and Rholike GTPase signaling pathways,and their cross-talks.For instance,it is generally known that TGF-β promotes the differentiation of stem cells into smooth muscle cells,immature cardiomyocytes,chondrocytes,neurocytes,hepatic stellate cells,Th17 cells,and dendritic cells.However,TGF-β inhibits the differentiation of stem cells into myotubes,adipocytes,endothelial cells,and natural killer cells.Additionally,TGF-β can provide competence for early stages of osteoblastic differentiation,but at late stages TGF-β acts as an inhibitor.The three mammalian isoforms(TGF-β1,2 and 3) have distinct but overlapping effects on hematopoiesis.Understanding the mechanisms underlying the regulatory effect of TGF-β in the stem cell multi-lineage differentiation is of importance in stem cell biology,and will facilitate both basic research and clinical applications of stem cells.In this article,we discuss the current status and progress in our understanding of different mechanisms by which TGF-β controls multi-lineage differentiation of stem cells.