Dynamic three‐dimensional micropatterned cell co‐cultures within photocurable and chemically degradable hydrogels

In this paper we report on the development of dynamically controlled three‐dimensional (3D) micropatterned cellular co‐cultures within photocurable and chemically degradable hydrogels. Specifically, we generated dynamic co‐cultures of micropatterned murine embryonic stem (mES) cells with human hepatocellular carcinoma (HepG2) cells within 3D hydrogels. HepG2 cells were used due to their ability to direct the differentiation of mES cells through secreted paracrine factors. To generate dynamic co‐cultures, mES cells were first encapsulated within micropatterned photocurable poly(ethylene glycol) (PEG) hydrogels. These micropatterned cell‐laden PEG hydrogels were subsequently surrounded by calcium alginate (Ca‐Alg) hydrogels containing HepG2 cells. After 4 days, the co‐culture step was halted by exposing the system to sodium citrate solution, which removed the alginate gels and the encapsulated HepG2 cells. The encapsulated mES cells were then maintained in the resulting cultures for 16 days and cardiac differentiation was analysed. We observed that the mES cells that were exposed to HepG2 cells in the co‐cultures generated cells with higher expression of cardiac genes and proteins, as well as increased spontaneous beating. Due to its ability to control the 3D microenvironment of cells in a spatially and temporally regulated manner, the method presented in this study is useful for a range of cell‐culture applications related to tissue engineering and regenerative medicine. Copyright © 2013 John Wiley & Sons, Ltd.     

Systematic review of plasma-membrane ecto-ATP synthase: A new player in health and disease

This review summarizes recent studies on plasma-membrane ecto-ATP synthase from structural and functional standpoints to possible pathophysiological roles. This review discusses significant new contributions and perspectives in the area of ecto-ATP synthase since the topic was last reviewed in 2015. Following an extensive summary of the cell types in which the ecto-ATP synthase is present, its structural and functional mechanism are discussed and physiological and pathological roles of the ecto-ATP synthase are reviewed and evaluated. Attempts to define the possible role of ecto-ATP synthase as possible target for anti-cancer and anti-obesity interventions are discussed.     

Somatostatin receptor type 2 contributes to the self-renewal of murine embryonic stem cells

Aim:

The roles of G-protein coupled receptors (GPCRs) in stem cell biology remain unclear. In this study, we aimed to identify GPCRs that might contribute to the self-renewal of mouse embryonic stem cells (mESCs).

Methods:

The expression levels of pluripotent genes and GPCR gene were detected in E14 mESCs using PCR array and RT-PCR. Immunofluorescent staining was used to examine the expression of pluripotent markers and the receptor translocation. Western blot analysis was used to detect phosphorylation of signal proteins. Knock-down of receptor was conducted to confirm its role in pluripotency maintenance.

Results:

In leukemia inhibitory factor (LIF)-free medium, mESCs lost the typical morphology of pluripotency, accompanied by markedly decreases in expression of somatostatin receptor type 2 (SSTR2), as well as the pluripotency biomarkers Oct4, Sox2, Rex1 and Nanog. Addition of the SSTR2 agonist octreotide or seglitide (0.1–30 μmol/L) in LIF-free medium dose-dependently promoted the self-renewal of mESCs, whereas the SSTR2 antagonist S4 (0.03–3 μmol/L) dose-dependently blocked octreotide-induced self-renewal. Knock-down of SSTR2 significantly decreased the self-renewal of mESCs even in the presence of LIF. Addition of LIF (1000 U/mL) or octreotide (1 μmol/L) in LIF-free medium significantly increased both phosphorylation and nuclear ocalization of STAT3.

Conclusion:

The activation of SSTR2 contributes to the self-renewal of mESCs via activation of the STAT3 pathway.     

Discovering novel anti-HCV compounds with inhibitory activities toward HCV NS3/4A protease

Aim:

To discover novel hepatitis C virus (HCV) inhibitors and elucidate the mechanism of action of the active compounds.

Methods:

HCV subgenomic replicon-based luciferase reporter cell line was used to screen 1200 synthetic compounds with novel structures. Huh7.5.1 cell line stably transfected with HCV NS3/4A protease reporter was established to investigate the anti-HCV mechanism of the active compounds. The active compounds were further examined in an in vitro HCV infection assay to confirm their anti-HCV activity.

Results:

After two-round screening in the anti-HCV replicon assay, some 2,4-diaminoquinazoline derivatives and carboxamide analogues were found to possess anti-HCV replicon activities (the IC₅₀ values were less than 5 μmol/L). Among them, two representative compounds HZ-1157 and LZ-110618-6 inhibited HCV NS3/4A protease with IC₅₀ values of 1.0 and 0.68 μmol/L, respectively. Furthermore, HZ-1157 and LZ-110618-6 inhibited HCV infection in vitro with IC₅₀ values of 0.82 and 0.11 μmol/L, respectively.

Conclusion:

Some 2,4-diaminoquinazoline derivatives and carboxamide analogues have been identified as novel anti-HCV compounds.     

胚胎干细胞体外分化为肝细胞和心肌细胞的研究进展

胚胎干细胞是从早期胚胎或原始性腺分离后能在体外长期传代培养的全能细胞系。胚胎干细胞体外可以诱导分化为各种体细胞,并且用这些体细胞治疗相应的疾病,一直以来是生物医药领域的研究焦点。目前,在该领域用于诱导胚胎干细胞分化的方法很多,其中的一些方法就用到化合物和部分中药提取物。整理近5年来胚胎干细胞体外通过拟胚体途径、细胞单层诱导分化为肝细胞和心肌细胞的有关文献,做一简要综述。     

Chir99021联合PD0325901对小鼠胚胎干细胞中miRNAs差异表达的影响

目的：通过研究Chir99021联合PD0325901对小鼠胚胎干细胞中miRNAs差异表达的影响,为揭示胚胎干细胞的自我更新和分化的机制提供更多线索。方法采用miRNA基因芯片技术检测Chir99021联合PD0325901处理组和PD0325901处理组miRNAs的表达谱差异。选取3倍以上及通过查文献与胚胎干细胞自我更新相关的1.5倍以上3倍以下的miRNAs,采用实时荧光定量PCR法验证,利用miRDB、Miranda两个数据库交叉预测差异表达的靶基因,并应用KEGG Pathway进行靶基因功能富集分析。结果与PD0325901单独处理相比,Chir99021联合PD0325901处理组有47种miRNAs上调1.5倍以上,75种miRNAs下调1.5倍以上;用实时荧光定量PCR验证差异表达的miRNAs,结果显示13个miRNAs与芯片结果相符。靶基因预测分析显示,miR-466a-5p、miR-466d-5p处于重要位置,Plcb1、Prkcb处于关键基因位置。结论 Chir99021可引起小鼠胚胎干细胞中的miRNAs差异表达,差异表达的miRNAs可能通过调控Plcb1、Prkcb基因而影响胚胎干细胞的自我更新。     

The mycotoxin beauvericin induces apoptotic cell death in H4IIE hepatoma cells accompanied by an inhibition of NF-κB-activity and modulation of MAP-kinases

Beauvericin is a world-spread mycotoxin with a high toxicity in mammalian cells. However, its molecular mechanism of action is not fully understood. Using different cancer cell lines (HepG2, C6, Hct116 and H4IIE), we could show that the cyclic peptide is highly toxic (MTT assay) with IC₅₀ values in low micromolar range. As a molecular mechanism of cell death, necrosis was detected in C6 glioma cells (PI staining), but apoptosis prevails in H4IIE hepatoma cells (caspase 3/7 activity, nuclear fragmentation). In H4IIE cells, beauvericin rapidly decreases the phosphorylation of ERK and strongly increases JNK phosphorylation, while p38 phosphorylation was not affected. Furthermore, a strong inhibition of NF-κB signalling was detectable in H4IIE cells. A screening of 21 protein kinases involved in signal transduction pathways (cell proliferation, survival, angiogenesis and metastasis) showed a selective inhibition of src kinase by beauvericin (IC₅₀ = 9.8 μg/ml). We suggest that beauvericin mediates its toxic effects in H4IIE cells, at least in parts, by a distinct modulation of intracellular signalling molecules.     

Identification of toxicants in cinnamon-flavored electronic cigarette refill fluids

In a prior study on electronic cigarette (EC) refill fluids, Cinnamon Ceylon was the most cytotoxic of 36 products tested. The purpose of the current study was to determine if high cytotoxicity is a general feature of cinnamon-flavored EC refill fluids and to identify the toxicant(s) in Cinnamon Ceylon. Eight cinnamon-flavored refill fluids, which were screened using the MTT assay, varied in their cytotoxicity with most being cytotoxic. Human embryonic stem cells were generally more sensitive than human adult pulmonary fibroblasts. Most products were highly volatile and produced vapors that impaired survival of cells in adjacent wells. Cinnamaldehyde (CAD), 2-methoxycinnamaldehyde (2MOCA), dipropylene glycol, and vanillin were identified in the cinnamon-flavored refill fluids using gas chromatography–mass spectrometry and high-pressure liquid chromatography (HPLC). When authentic standards of each chemical were tested using the MTT assay, only CAD and 2MOCA were highly cytotoxic. The amount of each chemical in the refill fluids was quantified using HPLC, and cytotoxicity correlated with the amount of CAD/product. Duplicate bottles of the same product were similar, but varied in their concentrations of 2MOCA. These data show that the cinnamon flavorings in refill fluids are linked to cytotoxicity, which could adversely affect EC users.