Rictor对小鼠胚胎干细胞来源心肌细胞线粒体钙信号的调控

目的:探索Rictor在小鼠胚胎干细胞来源心肌细胞(ESC-CM)中的表达、定位及其对线粒体钙信号的调控作用。方法:通过经典“悬滴一悬浮一贴壁”三步法建立ESC-CM模型。利用免疫荧光法及蛋白质印迹法观察Rictor在ESC-CM中的定位。慢病毒技术干扰小鼠胚胎干细胞Rictor表达后,采用免疫荧光法考察ESC-CM内质网与线粒体的叠加情况;通过透射电镜观察ESC-CM的超微结构;活细胞工作站测定分化后心肌细胞线粒体钙瞬变;免疫共沉淀法检测ESC-CM中1,4,5-三磷酸肌醇受体(IP3R)、葡萄糖调节蛋白75(Grp75)、线粒体外膜的电压依赖性阴离子通道1(VDAC1)间的相互作用;蛋白质印迹法检测线粒体融合蛋白2(Mfn2)的表达情况。结果:Rictor在ESC-CM中主要定位于内质网及线粒体一内质网结构偶联(MAM)域,且其表达定位与线粒体及内质网有很好的叠加。干扰Rictor后,心肌细胞线粒体部分呈散点状,线粒体与内质网的叠加率降低(P<0.01);ESC-CM超微MAM形成减少;ATP刺激引起的ESC-CM线粒体钙瞬变幅度下降,其中钙瞬变斜率和上升峰值均降低(均P<0.01);MAM中IP3R、GTp75、VDAC1相互作用明显减弱,且Mfn2蛋白表达降低(P<0.01)。结论:干扰小鼠胚胎干细胞中Rictor表达可降低ESC-CM中钙从内质网到线粒体的释放,这可能是通过影响IP3R、Grp75、VDAC1间相互作用,减少Mfn2表达,进而破坏MAM来实现的。

Nanog and transcriptional networks in embryonic stem cell pluripotency

Several extrinsic signals such as LIF, BMP and Wnt can support the self-renewal and pluripotency of embryonic stem （ES） cells through regulating the ＂pluripotent genes.＂ A unique homeobox transcription factor, Nanog, is one of the key downstream effectors of these signals. Elevated level of Nanog can maintain the mouse ES cell self-renewal independent of LIF and enable human ES cell growth without feeder cells. In addition to the external signal pathways, intrinsic transcription factors such as FoxD3, P53 and Oct4 are also involved in regulating the expression of Nanog. Functionally, Nanog works together with other key pluripotent factors such as Oct4 and Sox2 to control a set of target genes that have important functions in ES cell pluripotency. These key factors form a regulatory network to support or limit each other＇s expression level, which maintains the properties of ES cells.

Establishment of customized mouse stem cell lines by sequential nuclear transfer

Therapeutic cloning, whereby embryonic stem cells （ESCs） are derived from nuclear transfer （NT） embryos, may play a major role in the new era of regenerative medicine. In this study we established forty nuclear transfer-ESC （NTESC） lines that were derived from NT embryos of different donor cell types or passages. We found that NT-ESCs were capable of forming embryoid bodies. In addition, NT-ESCs expressed pluripotency stem cell markers in vitro and could differentiate into embryonic tissues in vivo. NT embryos from early passage RI donor cells were able to form full term developed pups, whereas those from late passage RI ES donor cells lost the potential for reprogramming that is essential for live birth. We subsequently established sequential NT-RI-ESC lines that were developed from NT blastocyst of late passage R 1 ESC donors. However, these NT-R I-ESC lines, when used as nuclear transfer donors at their early passages, failed to result in live pups. This indicates that the therapeutic cloning process using sequential NT-ESCs may not rescue the developmental deficiencies that resided in previous donor generations.

Human embryonic stem cell lines derived from the Chinese population

Six human embryonic stem cell lines were established from surplus blastocysts. The cell lines expressed alkaline phosphatase and molecules typical of primate embryonic stem cells, including Oct-4, Nanog, TDGF1, Sox2, EBAF, Thy-1, FGF4, Rex-1, SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81. Five of the six lines formed embryoid bodies that expressed markers of a variety of cell types; four of them formed teratomas with tissue types representative of all three embryonic germ layers. These human embryonic stem cells are capable of producing clones of undifferentiated morphology, and one of them was propagated to become a subline. Human embryonic stem cell lines from the Chinese population should facilitate stem cell research and may be valuable in studies of population genetics and ecology.

In vitro cultivation and differentiation of fetal liver stem cells from mice

During embryonic development, pluripotent endoderm tissue in the developing foregut may adopt pancreatic fate or hepatic fate depending on the activation of key developmental regulators. Transdifferentiation occurs between hepato- cytes and pancreatic cells under specific conditions. Hepatocytes and pancreatic cells have the common endodermal progenitor cells. In this study we isolated hepatic stem/progenitor cells from embryonic day (ED) 12-14 Kun-Ming mice with fluorescence-activated cell sorting (FACS). The cells were cultured under specific conditions. The cultured cells deploy dithizone staining and immunocytochemical staining at the 15th, 30th and 40th day after isolation. The results indicated the presence of insulin-producing cells. When the insulin-producing cells were transplanted into alloxan- induced diabetic mice, the nonfasting blood glucose level was reduced. These results suggested that fetal liver stem/ progenitor cells could be converted into insulin-producing cells under specific culture conditions. Fetal liver stem/ progenitor cells could become the potential source of insulin-producing cells for successful cell transplantation therapy strategies of diabetes.

The Comparison of Biologic Characteristics between Mice Embryonic Stem Cells and Bone Marrow Derived Dendritic Cells

OBJECTIVE This research was to induce dendritic cells （DCs） from mice embryonic stem cells and bone marrow mononuclear cells in vitro, and then compare the biologic characteristics of them. METHODS Embryonic stem cells （ESCs） suspending cultured in petri dishes were induced to generate embryonic bodies （EBs）. Fourteen-day well-developed EBs were transferred to histological culture with the same medium and supplemented 25 ng/ml GM- CSF and 25 ng/ml IL-3. In the next 2 weeks, there were numerous immature DCs outgrown. Meantime, mononuclear cells isolated from mice bone marrow were induced to derive dendritic cells by supplementing 25 ng/ml GM-CSF and 25 ng/ml IL-4, and then the morphology, phenotype and function of both dendritic cells from different origins were examined. RESULTS Growing mature through exposure to lipopolysaccharide （LPS）, both ESC-DCs and BM-DCs exhibited dramatic veils of cytoplasm and extensive dendrites on their surfaces, highly expressed CD11c, MHC-II and CD86 with strong capacity to stimulate primary T cell responses in mixed leukocyte reaction （MLR）. CONCLUSION ESC-DC has the same biologic characteristics as BM-DC, and it provides a new, reliable source for the functional research of DC and next produce corresponding anti-tumor vaccine.

A Critique on the Application of the Principle of Subsidiarity Concerning Human Embryonic Stem Cell Research in South Africa

Researchers from all around the world emphasize on the enormous possible benefits that stem cells may have for the treatment of diseases. However, this technology is considered morally problematic when the source of the stem cell is from a human embryo. Nonetheless, there is a consensus that of all the types of stem cells, hESC （human embryonic stem ceils） are the most promising for particular and important research and therapies. Yet, there are controversial issues regarding the ＂killing＂ of the human embryo for stem cell derivation. There are two general ethical conditions that should govern the instrumental use of embryo. One of them, the principle of subsidiarity, which is defined as ＂a state we have that we have to choose the less contentious means of achieving the intended goal＂. Based on this principle, we ought only to use hESC when there are no other alternatives, which are less morally controversially. Subsidiarity is based on the assumption that there is something ethically unsound about the use ofhESC. However, this principle only makes sense if it is based on consistently upheld views of the moral status of embryo, moreover, the law should also not limit or prohibit hESC research based on this principle. In this paper, I argue---using the South African law for hESC technology--that criterion for deciding which type of stem cells to use should be based on their potential and suitability for advancing scientific knowledge and development of new therapies which will be greatly beneficial in alleviating human suffering.

"Artificial Sperms" Induced from Mice Oocytes

On Nov 17th,a team of researchers from the Shanghai Institute of Biochemistry and Cell Biology（SIBCB）,Shanghai Institutes for Biological Sciences,CAS led by Prof.LI Jinsong reports online in Cell Research a novel technique to induce from mice oocytes haploid embryonic stems cells（haESCs）that can fully replace the reproductive functions of sperms,greatly simplifying the otherwise complicated techniques to produce such stem cells and semi-cloned（SC）mice.It is anticipated that this will further facilitate research in the field of stem cells and embryonic development;

Advances in cell lineage reprogramming

As a milestone breakthrough of stem cell and regenerative medicine in recent years, somatic cell reprogramming has opened up new applications of regenerative medicine by breaking through the ethical shackles of embryonic stern cells. However, induced pluripo- tent stem （iPS） cells are prepared with a complicated protocol that results in a low reprogramming rate. To obtain differentiated target cells, iPS cells and embryonic stem cells still need to be induced using step-by-step procedures. The safety of induced target cells from iPS cells is currently a further concerning matter. More broadly conceived is lineage reprogramming that has been investigated since 1987. Adult stem cell plasticity, which triggered interest in stem cell research at the end of the last century, can also be included in the scope of lineage reprogramming. With the promotion of iPS cell research, lineage reprogramming is now considered as one of the most promising fields in regenerative medicine, will hopefully lead to customized, personalized therapeutic options for patients in the future.