Effects of encapsulated rabbit mesenchymal stem cells on ex vivo expansion of human umbilical cord blood hematopoietic stem/progenitor cells

The expansion of umbilical cord blood mononuclear cells (UCB MNCs) was investigated in a novel co-culture system by means of encapsulation of rabbit bone marrow (BM) mesenchymal stem cells (MSCs) in alginate beads (Alg beads). Three kinds of media were applied and the experiments lasted for 7 days. The total nucleated cell density was measured every 24 h. Flow cytometric assay for CD34⁺ cells and methylcellulose colony assays were carried out at 0, 72 and 168 h. It was found that the encapsulated MSCs illustrated remarkable effects on UCB MNCs expansion regardless of whether serum is present in culture media or not. At the end of 168 h co-culture, the total nucleated cell number was multiplied by 15 ± 2.9 times, and CD34⁺ cells 5.3 ± 0.3 times and colony-forming units in culture (CFU-Cs) 5.6 ± 1.2 times in the serum-free media supplemented with conventional dose of cytokines, which was very similar to the results in the containing 20% serum media. While in the control, i.e. MNC expansion without encapsulated MSCs, however, total nucleated cells density changed mildly, CD34⁺ cells and CFU-Cs showed little effective expansion. It is demonstrated that the encapsulated stromal cells can support the expansion of UCB MNCs effectively under the experimental condition.     

人脐血CD34^ 内皮祖细胞的体外分化

目的：研究人脐血CD34^ 细胞群体中内皮祖细胞在体外分化为内皮细胞的过程中,干细胞标志以及内皮细胞表型随时间的变化。方法：将免疫磁珠细胞分选法（MACS）得到的CD34^ 细胞体外培养于纤连蛋白和无纤连蛋白处理的培养皿中,以免疫细胞化学鉴定贴壁细胞的内皮标志Flk-1和vWF,并以流式细胞仪分析其干细胞标志AC133。结果：贴壁细胞的内皮标志Flk-1和vWF是逐步出现的,d3时有27.0%贴壁细胞表达Flk-1,vWF不表达,d7时已100%表达vWF和Flk-1,纤连蛋白促进贴壁细胞内皮标志Flk-1和vWF的表达,d3时的表达百分率分别为34.0%和47.0%,d7时Flk-1和vWF的表达均为100%,在培养过程中,AC133阳性细胞的比例迅速下降,但纤连蛋白对AC133的表达无显著影响。结论：在内皮祖细胞分化的过程中,干细胞标志迅速消失,向内皮细胞分化,内皮细胞的表型是逐步出现的,纤连蛋白促进内皮祖细胞的分化。     

Activation of K+ channel by 1-EBIO rescues the head and neck squamous cell carcinoma cells from Ca2+ ionophore-induced cell death

Ion channels in carcinoma and their roles in cell proliferation are drawing attention. Intracellular Ca²⁺ ([Ca²⁺]_i)-dependent signaling affects the fate of cancer cells. Here we investigate the role of Ca²⁺-activated K⁺ channel (SK4) in head and neck squamous cell carcinoma cells (HNSCCs) of different cell lines; SNU-1076, OSC-19 and HN5. Treatment with 1 µM ionomycin induced cell death in all the three cell lines. Whole-cell patch clamp study suggested common expressions of Ca²⁺-activated Cl^- channels (Ano-1) and Ca²⁺-activated nonselective cation channels (CAN). 1-EBIO, an activator of SK4, induced outward K⁺ current (ISK4) in SNU-1076 and OSC-19. In HN5, ISK4 was not observed or negligible. The 1-EBIO-induced current was abolished by TRAM-34, a selective SK4 blocker. Interestingly, the ionomycin-induced cell death was effectively prevented by 1-EBIO in SNU-1076 and OSC-19, and the rescue effect was annihilated by combined TRAM-34. Consistent with the lower level of ISK4, the rescue by 1-EBIO was least effective in HN5. The results newly demonstrate the role of SK4 in the fate of HNSCCs under the Ca²⁺ overloaded condition. Pharmacological modulation of SK4 might provide an intriguing novel tool for the anti-cancer strategy in HNSCC.     

Voltage-gated K+ channels in adipogenic differentiation of bone marrow-derived human mesenchymal stem cells

Aim:

To determine the presence of voltage-gated K⁺ (Kv) channels in bone marrow-derived human mesenchymal stem cells (hMSCs) and their impact on differentiation of hMSCs into adipocytes.

Methods:

For adipogenic differentiation, hMSCs were cultured in adipogenic medium for 22 d. The degrees of adipogenic differentiation were examined using Western blot, Oil Red O staining and Alamar assay. The expression levels of Kv channel subunits Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv2.1, Kv3.1, Kv3.3, Kv4.2, Kv4.3, and Kv9.3 in the cells were detected using RT-PCR and Western blot analysis.

Results:

The expression levels of Kv2.1 and Kv3.3 subunits were markedly increased on d 16 and 22. In contrast, the expression levels of other Kv channel subunits, including Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv4.2, Kv4.3, and Kv9.3, were decreased as undifferentiated hMSCs differentiated into adipocytes. Addition of the Kv channel blocker tetraethylammonium (TEA, 10 mmol/L) into the adipogenic medium for 6 or 12 d caused a significant decrease, although not complete, in lipid droplet formation and adipocyte fatty acid-binding protein 2 (aP₂) expressions. Addition of the selective Kv2.1 channel blocker guangxitoxin (GxTX-1, 40 nmol/L) into the adipogenic medium for 21 d also suppressed adipogenic differentiation of the cells.

Conclusion:

The results demonstrate that subsets of Kv channels including Kv2.1 and Kv3.3 may play an important role in the differentiation of hMSCs into adipocytes.     

Pyrimido[4,5-b]indole derivatives and use thereof in the expansion of hematopoietic stem cells US2015011543 (a1): a patent evaluation

Introduction: There is an unmet need of strategies for ex-vivo expansion of hematopoetic stem cells (HSCs) without loss of their primitive nature or stemness. We evaluate here a patent that attempts to address this need via key small molecules 1 and 40 that possess a pyrimido[4,5-b]indole core.

Areas covered: (i) Discussion on literature reports of diverse strategies for ex-vivo expansion of stem cells. (ii) Synthetic scheme to 1, and general synthetic schemes for compounds 1-55 reported in the patent application. (iii) Analysis of the in vitro biological data for 1 and 40. Highlight here is: 1 and 40 when used in combination with StemReginin1 (SR1), an established aryl hydrocarbon receptor antagonist known for ex-vivo HSC expansion, demonstrate better HSC expansion relative to SR1 alone. (iv) Analysis of the in vivo biological data for 1 and 40.

Expert opinion: Compelling evidence on the molecular mechanism of action of 1 and 40 is not provided making it difficult to optimize this series. It is suggested here that combining these molecules with homing molecules will possibly improve overall engraftment time and hematopoietic recovery. The numerous literature reports and biological data indicates that these pyrimido[4,5-b]indole derivatives are promising candidates for the development of potential therapies for hematopoietic ailments.     

Ginsenoside Rg1 enhances the resistance of hematopoietic stem/progenitor cells to radiation- induced aging in mice

Aim： To investigate the effects of ginsenoside Rg1 on the radiation-induced aging of hematopoietic stem/progenitor cells （HSC/HPCs） in mice and the underlying mechanisms.
Methods： Male C57BL/6 mice were treated with ginsenoside Rg1 （20 mg·kg-1·d-1, ip） or normal saline （NS） for 7 d, followed by exposure to 6.5 Gy X-ray total body irradiation. A sham-irradiated group was treated with NS but without irradiation. Sca-1^＋ HSC/HPCs were isolated and purified from their bone marrow using MACS. DNA damage was detected on d 1. The changes of anti-oxidative activities, senescence-related markers senescence-associated β-galactosidase （SA-β-gal） and mixed colony-forming unit （CFU-mix）, P16INK4a and P21Cip1/Waf1 expression on d 7, and cell cycle were examined on d 1, d 3, and d 7.

Results： The irradiation caused dramatic reduction in the number of Sca-1^＋ HSC/HPCs on d 1 and the number barely recovered until d 7 compared to the sham-irradiated group. The irradiation significantly decreased SOD activity, increased MDA contents and caused DNA damage in Sca-1^＋ HSC/HPCs. Moreover, the irradiation significantly increased SA-β-gal staining, reduced CFU-mix forming, increased the expression of P16INK4a and P21Cip1/Waf1 in the core positions of the cellular senescence signaling pathways and caused G1 phase arrest of Sca-1^＋ HSC/HPCs. Administration of ginsenoside Rg1 caused small, but significant recovery in the number of Sca-1^＋ HSC/HPCs on d 3 and d 7. Furthermore, ginsenoside Rg1 significantly attenuated all the irradiation-induced changes in Sca-1^＋ HSC/HPCs, including oxidative stress reaction, DNA damage, senescence-related markers and cellular senescence signaling pathways and cell cycle, etc.

Conclusion： Administration of ginsenoside Rg1 enhances the resistance of HSC/HPCs to ionizing radiation-induced senescence in mice by inhibiting the oxidative stress reaction, reducing DNA damage, and regulating the cell cycle.     

APE1/Ref-1 promotes the effect of Angiotensin II on Ca2+-activated K+ channel in human endothelial cells via suppression of NADPH Oxidase

The effects of angiotensin II (Ang II) on whole-cell large conductance Ca²⁺-activated K⁺ (BK_Ca) currents was investigated in control and Apurinic/apyrimidinic endonuclease1/redox factor 1 (APE1/Ref-1)-overexpressing human umbilical vein endothelial cells (HUVECs). Ang II blocked the BK_Ca current in a dose-dependent fashion, and this inhibition was greater in APE1/Ref-1-overexpressing HUVECs than in control HUVECs (half-inhibition values of 102.81 ± 9.54 nM and 11.34 ± 0.39 nM in control and APE1/Ref-1-overexpressing HUVECs, respectively). Pretreatment with the NADPH oxidase inhibitor diphenyleneiodonium (DPI) or knock down of NADPH oxidase (p22 phox) using siRNA increased the inhibitory effect of Ang II on the BK_Ca currents, similar to the effect of APE1/Ref-1 overexpression. In addition, application of Ang II increased the superoxide and hydrogen peroxide levels in the control HUVECs but not in APE1/Ref-1-overexpressing HUVECs. Furthermore, direct application of hydrogen peroxide increased BK_Ca channel activity. Finally, the inhibitory effect of Ang II on the BK_Ca current was blocked by an antagonist of the Ang II type 1 (AT₁) receptor in both control and APE1/Ref-1-overexpressing HUVECs. From these results, we conclude that the inhibitory effect of Ang II on BK_Ca channel function is NADPH oxidase-dependent and may be promoted by APE1/Ref-1. These authors contributed equally to this work.     

Differential regulation of cyclo-oxygenase-2 and 5-lipoxygenase-activating protein (FLAP) expression by glucocorticoids in monocytic cells

1. The objective of the present study was to determine the effects of dexamethasone on key constituents of prostaglandin and leukotriene biosynthesis, cyclo-oxygenase-2 (COX-2) and 5-lipoxygenase activating protein (FLAP). The human monocytic cell line THP-1 was used as a model system. mRNA and protein levels of COX-2 and FLAP were determined by Northern and Western blot analyses, respectively.
2. Low levels of COX-2 and FLAP mRNA were expressed in undifferentiated THP-1 cells, but were induced upon differentiation of the cells along the monocytic pathway by treatment with phorbol ester (TPA, 5 nM). Maximal expression was observed after two days.
3. Coincubation of the undifferentiated cells with dexamethasone (10⁻⁹–10⁻⁶ M) and phorbol ester prevented induction of COX-2 mRNA, but did not affect the induction of FLAP mRNA.
4. Dexamethasone downregulated COX-2 mRNA and protein in differentiated, monocyte-like THP-1 cells. In contrast, FLAP mRNA and protein were upregulated by dexamethasone in differentiated THP-1 cells. After 24 h, FLAP mRNA levels were increased more than 2 fold. Dexamethasone did not change 5-lipoxygenase mRNA expression.
5. Release of prostaglandin E₂ (PGE₂) and peptidoleukotrienes was determined in cell culture supernatants of differentiated THP-1 cells by ELISA. Calcium ionophore-dependent PGE₂ synthesis was associated with COX-2 expression, whereas COX-1 and COX-2 seemed to participate in arachidonic acid-dependent PGE₂ synthesis. Very low levels of peptidoleukotrienes were released from differentiated THP-1 cells upon incubation with ionophore. Treatment with dexamethasone did not significantly affect leukotriene release.
6. These data provide evidence that prostaglandin synthesis is consistently downregulated by glucocorticoids. However, the glucocorticoid-mediated induction of FLAP may provide a mechanism to maintain leukotriene biosynthesis through more efficient transfer of arachidonic acid to the 5-lipoxygenase reaction, in spite of inhibitory effects on other enzymes of the biosynthetic pathway.

     

Urocortin induced expression of COX-2 and ICAM-1 via corticotrophin-releasing factor type 2 receptor in rat aortic endothelial cells

Background and purpose:

Our previous study showed that urocortin (Ucn1) exacerbates the hypercoagulable state and vasculitis in a rat model of sodium laurate-induced thromboangiitis obliterans. Furthermore, the inflammatory molecules COX-2 and ICAM-1 may participate in this effect. In the present study, the effects of Ucn1 on COX-2 and ICAM-1 expression in lipopolysaccharide (LPS)-induced rat aortic endothelial cells (RAECs) were investigated and the mechanisms involved explored.

Experimental approach:

RAECs were isolated from adult male Wistar rats, and identified at the first passage. Experiments were performed on cells, from primary culture, at passages 5–8. The expression of COX-2 and ICAM-1 at both mRNA and protein levels was determined by semi-quantitative RT-PCR and Western blot analysis. Levels of PGE₂ and soluble ICAM-1 (sICAM-1) in culture medium were measured by enzyme-linked immunosorbent assay. Furthermore, the phosphorylation status of p38MAPK, ERK1/2, JNK, Akt and NF-κB was analysed by Western blot; nuclear translocation of NF-κB was observed by immunofluorescence.

Key results:

Ucn1 augmented LPS-induced expression of COX-2 and ICAM-1 in RAECs in a time- and concentration-dependent manner. Ucn1 increased PGE₂ and sICAM-1 levels. These effects were abolished by the CRF₂ receptor antagonist, antisauvagine-30, but not by the CRF₁ receptor antagonist, NBI-27914. Moreover, Ucn2 activated p38MAPK and augmented NF-κB nuclear translocation and phosphorylation, whereas ERK1/2, JNK and Akt pathways were not involved in this process.

Conclusions and implications:

These findings suggest that Ucn1 exerts pro-inflammatory effects by augmenting LPS-induced expression of COX-2 and ICAM-1 in RAECs via CRF₂ receptors and the activation of p38MAPK and NF-κB.     

Regulation of glutathione S-transferase P1-1 gene expression by NF-kappaB in tumor necrosis factor alpha-treated K562 leukemia cells

Glutathione S-transferases (GSTs) play an important role in the protection of cells against xenobiotics and lipid hydroperoxides generated by oxidative stress. In human, the GSTP1-1 expression is commonly increased in many tumors and involved in the development of antineoplastic drug resistance. Reactive oxygen species are released at inflammation sites and oxidative stress conditions enhance the expression of genes encoding antioxidant enzymes such as GSTs. Here we investigated the regulation of the GSTP1-1 gene expression in the K562 cell line by nuclear factor kappaB (NF-kappaB) and the pro-inflammatory cytokine tumor necrosis factor alpha (TNFalpha). By studying GSTP1-1 mRNA expression and NF-kappaB/GSTP1-1 promoter interactions, we showed the implication of NF-kappaB in the GSTP1-1 gene expression and we described a new specific TNFalpha-inducible NF-kappaB binding site upstream of the minimal promoter. Moreover, TNFalpha treatment as well as cotransfection of NF-kappaB signaling pathway intermediates induced an activation of the GSTP1-1 gene promoter in K562 cells. Site-directed mutagenesis of the NF-kappaB site strongly inhibited TNFalpha- and NF-kappaBp65-induced promoter activation. Altogether, we showed that a sequence located at -323/-314 within the GSTP1-1 promoter bound NF-kappaB p50/65 and p65/p65 dimers and that this kappaB site was involved in the regulation of the gene by TNFalpha.     

Influence and related mechanism of Retn gene expression on glucose uptake in 3T3-L1 cells

The aim of this article was to investigate the influence and the related mechanism of the Retn gene on glucose uptake and insulin resistance in 3T3-L1 cells. Radioimmuno-assay was used to determine glucose uptake in 3T3-L1 cells with different Retn gene expression levels, whether cells were stimulated by insulin or not. RT-PCR and real-time RT-PCR analysis were used to determine the mRNA levels of several glucose transport proteins in 3T3-L1 cells with different Retn gene expression levels, including insulin receptor substrate-1(IRS-1), phosphatidylinositol 3-kinase (PI-3K), AKT-2, glucose transporter-4 (GLUT-4), p38 mitogen-activated protein kinase (p38MAPK) and glycogen synthase kinase-3β (GSK-3β). The glucose uptake decreased with the increase in Retn gene expression in 3T3-L1 cells, which was independent of whether the cells were stimulated by insulin or not. The mRNA expression of two signal proteins PI-3K and AKT-2 decreased and the other two signal proteins, GSK-3β and p38MAPK, increased with Retn overexpression in 3T3-L1 cells. Resistin could induce insulin resistance in adipocytes, which might be related to the changes of some proteins in PI-3K and Ras pathways. Translated from Academic Journal of Second Military Medical University, 2006, 27(10): 1,067–1,071 [译自: 第二军医大学学报] The authors contributed equally to the study.     

Chrysin induces G1 phase cell cycle arrest in C6 glioma cells through inducing p21Waf1/Cip1 expression: involvement of p38 mitogen-activated protein kinase

Flavonoids are a broadly distributed class of plant pigments, universally present in plants. They are strong anti-oxidants that can inhibit carcinogenesis in rodents. Chrysin (5,7-dihydroxyflavone) is a natural and biologically active compound extracted from many plants, honey, and propolis. It possesses potent anti-inflammatory, anti-oxidant properties, promotes cell death, and perturbing cell cycle progression. However, the mechanism by which chrysin inhibits cancer cell growth remains poorly understood. Therefore, we developed an interest in the relationship between MAPK signaling pathways and cell growth inhibition after chrysin treatment in rat C6 glioma cells. Cell viability assay and flow cytometric analysis suggested that chrysin exhibited a dose-dependent and time-dependent ability to block rat C6 glioma cell line cell cycle progression at the G1 phase. Western blotting analysis showed that the levels of Rb phosphorylation in C6 glioma cells exposed to 30 microM chrysin for 24h decreased significantly. We demonstrated the expression of cyclin-dependent kinase inhibitor, p21(Waf1/Cip1), to be significantly increased, but the p53 protein level did not change in chrysin-treated cells. Both cyclin-dependent kinase 2 (CDK2) and 4 (CDK4) kinase activities were reduced by chrysin in a dose-dependent manner. Furthermore, chrysin also inhibited proteasome activity. We further showed that chrysin induced p38-MAPK activation, and using a specific p38-MAPK inhibitor, SB203580, attenuated chrysin-induced p21(Waf1/Cip1) expression. These results suggest that chrysin exerts its growth-inhibitory effects either through activating p38-MAPK leading to the accumulation of p21(Waf1/Cip1) protein or mediating the inhibition of proteasome activity.