The RhoA-ROCK-PTEN pathway as a molecular switch for anchorage dependent cell behavior

The proliferation of anchorage-dependent cells of mesenchymal origin requires the attachment of the cells to substrates. Thus, cells that are poorly attached to substrates exhibit retarded cell cycle progression or apoptotic death. A major disadvantage of most polymers used in tissue engineering is their hydrophobicity; hydrophobic surfaces do not allow cells to attach firmly and, therefore, do not allow normal proliferation rates. In this study, we investigated the molecular mechanism underlying the reduced proliferation rate of cells that are poorly attached to substrates. There was an inverse relationship between the activity of the small GTPase RhoA (RhoA) and the cell proliferation rate. RhoA activity correlated inversely with the strength of cell adhesion to the substrates. The high RhoA activity in the cells poorly attached to substrates caused an increase in the activity of Rho-associated kinase (ROCK), a well-known effector of RhoA that upregulated the activity of phosphatase and tensin homolog (PTEN). The resulting activated PTEN downregulated Akt activity, which is essential for cell proliferation. Thus, the cells that were poorly attached to substrates showed low levels of cell proliferation because the RhoA-ROCK-PTEN pathway was hyperactive. In addition, RhoA activity seemed to be related to focal adhesion kinase (FAK) activity. Weak FAK activity in these poorly attached cells failed to downregulate the high RhoA activity that restrained cell proliferation. Interestingly, reducing the expression of any component of the RhoA-ROCK-PTEN pathway rescued the proliferation rate without physico-chemical surface modifications. Based on these results, we suggest that the RhoA-ROCK-PTEN pathway acts as a molecular switch to control cell proliferation and determine anchorage dependence. In cells that are poorly attached to substrates, its inhibition is sufficient to restore cell proliferation without the need for physico-chemical modification of the material surface.     

力学应变对体外培养动物细胞的影响

介绍了生物力学领域中细胞生长、增殖与分泌方面的实验研究进展.着重介绍了基底加载实验中不同环境对细胞分裂与增殖的作用;力学载荷对细胞黏附及生长的影响;力学应变对体外培养成骨细胞增殖与分泌的影响;流体环境对细胞生长增殖的作用.     

可对细胞施加双向应变的体外培养系统

为考察体外培养细胞在动应变作用下的响应，参考Winston等人的方法，我们制作了一套细胞体外培养系统，培养皿用有机玻璃作成，培养皿底为硅橡胶膜，下面有一封闭压力腔，通过对硅橡胶管和挤压轮间隙的调整，压力腔内的液压使硅橡胶膜产生设计应变，其应变范围可从0～4％调整，改变步进电机的转动方式，加载频率可从0．1～5Hz变化。     

E-cadherin表达缺失在白血病细胞行为中的作用

目的:确定上皮-钙黏蛋白(E-cadherin)表达缺失在白血病细胞行为中的作用,最终阐明E-cadherin介导的骨髓微环境与造血细胞相互作用改变在白血病发生中的作用。 方法:细胞黏附实验测定 HL-60细胞经5-氮杂脱氧胞苷（5-Aza-CdR）诱导E-cadherin表达后细胞黏附能力的改变,MTT法测定细胞增殖能力,细胞迁移实验确定细胞的迁移能力。结果:HL-60细胞经5-Aza-CdR诱导E-cadherin表达后,其对E-cadherin-Fc的黏附能力增加,细胞在E-cadherin-Fc上的增殖能力下降,细胞黏附导致细胞迁移能力下降。结论:白血病细胞中由于E-cadherin表达丧失,引起细胞黏附降低,增殖能力增强,细胞迁移活跃,表明E-cadherin表达缺失与白血病细胞行为的获得有关。     

蛇六谷提取物抑制K562细胞增殖并诱导分化的作用

目的:探讨蛇六谷提取物(TuAKe)抑制人慢性髓系白血病K562细胞增殖和诱导分化的作用机制。方法:不同浓度的TuAKe处理K562细胞,MTT比色法和半固体集落形成实验检测K562细胞的增殖能力;瑞氏-姬姆萨染色观察细胞形态;流式细胞术检测分化相关抗原CD11b、CD14和CD42b的阳性表达率;Western blot法检测细胞周期蛋白依赖性激酶2(CDK2)、细胞周期蛋白E1(cyclin E1)和红系分化核转录因子GATA-1的蛋白表达水平。结果:TuAKe能够抑制K562细胞增殖,改变细胞形态,抑制K562细胞进入S期,并阻滞在G_2/M期,提高分化相关抗原CD11b、CD14和CD42b阳性表达率,上调GATA-1蛋白表达,同时下调CDK2和cyclin E1蛋白表达(P0.05)。结论:TuAKe可能通过调控细胞周期抑制K562细胞增殖,同时诱导K562细胞多向分化。     

Targeting cells in motion: Migrating toward improved therapies

The development of clinical therapeutics that interfere with the migration of leukocytes has revolutionized the treatment of multiple sclerosis and holds great promise for the treatment of a wide range of inflammatory diseases. As the molecules essential for the multi‐step adhesion cascade that mediates cellular migration have been elucidated, the number of potential targets available to modulate leukocyte trafficking has increased exponentially. In this Viewpoint, we briefly review our current understanding of these mole‐cular targets and how these targets vary by tissue and leukocyte subset with emphasis on T cells. We then describe the two currently approved therapeutics that target cell migration, natalizumab and fingolimod, and discuss how an improved understanding of their function could pave the way for the development of safer and more efficacious therapies for inflammatory and autoimmune diseases.     

自体甲状腺组织与干细胞移植治疗甲状腺功能减退症的研究进展

不可逆性甲减患者需要终身服用甲状腺激素，对患者的日常工作和生活造成了很大的不便。随着近年来对自体甲状腺组织与干细胞移植研究的进展，有望解决甲减病人终身服药这一问题。自体甲状腺组织移植的动物实验以及人体试验均表明：甲状腺移植物不但能够存活，而且能够发挥作用。最新的胚胎干细胞（Embryonic stemcell，ESC）研究证明，ESC可以分化为甲状腺滤泡细胞。     

Self-loading and cell culture in one layer microfluidic devices

We report on a simple method for self loading and culture of mammalian cells in microfluidic multi-chambers for high throughput screening. The device was obtained by using one layer soft lithography with polydimethylsiloxane (PDMS) and thermal bonding on a glass slide. Self loading of cell suspension could be possible after degassing of the PDMS device for 30 min. Both cell loading efficiency and cell proliferation behaviors have been analyzed with triangle chambers of different sizes, all connected to the main flow channels with small entrances. We found that the number of cells loaded into the micro-chamber increased with the side length of the triangle, showing well size dependence and that self loading at a single cell level was possible for small chambers. For large chambers, the cell area density after loading and proliferation is however quite heterogeneous. For demonstration, HeLa cell growth behavior has been followed for 11 days until the total area of the largest chambers was fully filled.     

rhHGF/cHGF体外抑制SMMC-7721人肝细胞癌细胞生长

目的:观察重组人肝细胞生长因子(rhHGF)和天然小牛肝细胞生长因子(cHGF)对SMMC-7721人肝细胞癌细胞株的生长效应。方法:传代后处于指数生长期的SMMC-7721细胞经过(HGF处理组)或不经(对照组)rhHGF/cHGF处理培养1-4d,采用四甲基偶氮唑盐(MTT)法检测细胞数。并通过流式细胞仪对rhHGF处理细胞作细胞周期分析。结果:rhHGF(5-20μg/L)和cHGF(25-100mg/L)对SMMC-7721细胞增殖具有类似的剂量依赖性抑制作用。在实验浓度内,使用最高浓度时(rhHGF为20μg/L、cHGF为100mg/L)对细胞增殖抑制作用最强。使用不同浓度(5μg/L、10μg/L、20μg/L)rhHGF处理3d的培养细胞均有一半以上停留在G₀/G₁期。结论:rhHGF和cHGF对SMMC-7721人肝细胞癌细胞的体外生长都有强烈的抑制效应。这是由于受HGF的作用细胞生长易于终止在G₀/G₁期。     

An electron microscopical study of neuronal cell clustering in postnatal mouse striatum, with special emphasis on neuronal cell death

Summary In this study, electron microscopy was used to study cell clustering in the postnatal mouse striatum. From the date of birth (PO) through postnatal day 7 (P7), groupings of eight to ten striatal neurons were delimited easily in low magnification electron micrographs. Often, within individual groupings, adjacent neurons were separated only by a thin, 10 nm gap, and formed cell pairs or cell triads. Coincident with marked expansion of the striatal neuropil in the second postnatal week, striatal neurons formed more dispersed cell clusters consisting only occasionally of cell pairs or triads.Single, pyknotic neuronal nuclei were seen in clusters of normal neurons exhibiting different stages of maturation but were absent from clusters consisting only of well-differentiated neurons. The neuropil surrounding cell clusters with pyknotic neurons or that adjacent to neighboring cell clusters often contained degenerating dendrites and axon terminals. Whereas this naturally occurring neuronal cell death was present in the tissue throughout the first postnatal week, only degenerating dendritic and axonal profiles were seen in the P15 striatum. This latter fact suggests that the occurrence of pyknotic neuronal somata does not account entirely for the more localized degeneration of other neuronal profiles and raises the possibility that other degenerative processes may be occurring simultaneously in the tissue.Preliminary reports of portions of this work were presented at the NINCDS Huntington's Disease Symposium, San Diego, Ca., November 16–18, 1978, and at the Ninety-first annual meeting of the American Association of Anatomists, Vancouver, British Columbia, April 3–6, 1978     

冬凌草甲素对人肝癌MHCC-97H细胞系侵袭和迁移的作用

目的:探讨冬凌草甲素(oridonin)对肝癌细胞侵袭和迁移的影响及其机制。方法:采用细胞培养技术培养人肝细胞癌MHCC-97H细胞,用不同浓度的冬凌草甲素处理肝癌细胞,采用划痕实验检测细胞的迁移能力;Transwell实验测定细胞的侵袭能力;黏附实验评价细胞的黏附能力;Western blot法检测LIM激酶1(LIMK-1)、丝切蛋白(cofilin)和磷酸化cofilin(p-cofilin)蛋白水平的改变。结果:冬凌草甲素可明显降低肝癌细胞的体外侵袭、迁移及黏附能力(P0.05),且在一定浓度范围内具有明显的量效关系。冬凌草甲素干预处理细胞后,cofilin的蛋白水平无明显变化,LIMK-1和p-cofilin的蛋白水平明显下调。结论:冬凌草甲素体外具有抑制肝癌MHCC-97H细胞侵袭和迁移的作用,其机制可能与调控LIMK-1/cofilin信号通路有关。     

A 3D microfibrous scaffold for long-term human pluripotent stem cell self-renewal under chemically defined conditions

Realizing the potential of human pluripotent stem cell (hPSC)-based therapy requires the development of defined scalable culture systems with efficient expansion, differentiation and isolation protocols. We report an engineered 3D microfiber system that efficiently supports long-term hPSCs self-renewal under chemically defined conditions. The unique feature of this system lies in the application of a 3D ECM-like environment in which cells are embedded, that affords: (i) uniform high cell loading density in individual cell-laden constructs (∼10⁷ cells/ml); (ii) quick recovery of encapsulated cells (<10 min at 37 °C) with excellent preservation of cell viability and 3D multicellular structure; (iii) direct cryopreservation of the encapsulated cells in situ in the microfibers with >17-fold higher cell viability compared to those cultured on Matrigel surface; (iv) long-term hPSC propagation under chemically defined conditions. Four hPSC lines propagated in the microfibrous scaffold for 10 consecutive passages were capable of maintaining an undifferentiated phenotype as demonstrated by the expression of stem cell markers and stable karyotype in vitro and the ability to form derivatives of the three germ layers both in vitro and in vivo. Our 3D microfibrous system has the potential for large-scale cultivation of transplantable hESCs and derivatives for clinical applications.     

CADM1过表达对人胃癌MKN-45细胞增殖和侵袭的影响及其分子机制

 目的：研究细胞黏附分子1（cell adhesion molecule 1,CADM1）过表达对人胃癌MKN-45细胞增殖和侵袭的影响并探讨其可能的分子机制。方法：采用Western blotting检测3株胃癌细胞系中CADM1蛋白的表达。构建pcDNA-CADM1真核表达载体,并将其转染MKN-45细胞,采用G418筛选稳定表达CADM1的细胞株,利用Western blotting鉴定所筛选的稳定细胞株。采用CCK-8试剂和Boyden小室分析过表达CADM1对MKN-45细胞增殖和侵袭的影响。利用Western blotting检测细胞增殖和侵袭相关蛋白表达。结果：MKN-45细胞中CADM1蛋白的相对表达水平显著低于MKN-28和SGC-7901细胞（P<0.05）。此外,成功构建pcDNA-CADM1真核表达载体,并获得稳定过表达CADM1的MKN-45细胞株。CCK-8结果显示,与未处理组和pcDNA3.1组相比,pcDNA-CADM1组中MKN-45细胞的增殖明显受到抑制（P<0.05）。Boyden小室体外侵袭实验结果显示,与未处理组（101.53±6.89）和pcDNA3.1组（98.77±7.03）相比,pcDNA-CADM1组中MKN-45细胞穿膜的细胞数（52.35±3.89）显著减少（P<0.05）。Western blotting结果显示,与未处理组和pcDNA3.1组相比,pcDNA-CADM1组中p21蛋白表达显著上调,而MMP-2和MMP-9表达显著下调（P<0.05）。结论：CADM1过表达能明显抑制胃癌细胞的增殖和侵袭能力,因而CADM1有望成为胃癌治疗的新靶点。     

EB病毒LMP1表达对鼻咽癌细胞增殖及细胞周期分布的影响

目的:观察EB病毒潜伏膜蛋白1(LMP1)表达对鼻咽癌细胞系增殖和细胞周期分布的作用。方法:用免疫组化(LSAB)法检测LMP1蛋白的表达;用MTT法测定鼻咽癌细胞系的增殖能力;用流式细胞术检测细胞周期的分布。结果:表达LMP1的鼻咽癌细胞系L-CNE1的OD值明显高于LMP1阴性的鼻咽癌细胞系V-CNE1和CNE1(P＜0.001)。L-CNE1细胞系的G₁期细胞百分率明显减少和S期细胞百分率明显增加,与V-CNE1和CNE1细胞系比较均有非常显著性差异(P＜0.001)。而V-CNE1与CNE1细胞系之间各期细胞百分率则无明显差异(P＞0.05)。结论:EBV-LMP1表达可使鼻咽癌细胞系细胞周期分布改变和增殖能力增强。     

The influence of physiological matrix conditions on permanent culture of induced pluripotent stem cell-derived cardiomyocytes

Cardiomyocytes (CMs) from induced pluripotent stem (iPS) cells mark an important achievement in the development of in vitro pharmacological, toxicological and developmental assays and in the establishment of protocols for cardiac cell replacement therapy. Using CMs generated from murine embryonic stem cells and iPS cells we found increased cell–matrix interaction and more matured embryoid body (EB) structures in iPS cell-derived EBs. However, neither suspension-culture in form of purified cardiac clusters nor adherence-culture on traditional cell culture plastic allowed for extended culture of CMs. CMs grown for five weeks on polystyrene exhibit signs of massive mechanical stress as indicated by α-smooth muscle actin expression and loss of sarcomere integrity. Hydrogels from polyacrylamide allow adapting of the matrix stiffness to that of cardiac tissue. We were able to eliminate the bottleneck of low cell adhesion using 2,5-Dioxopyrrolidin-1-yl-6-acrylamidohexanoate as a crosslinker to immobilize matrix proteins on the gels surface. Finally we present an easy method to generate polyacrylamide gels with a physiological Young's modulus of 55 kPa and defined surface ligand, facilitating the culture of murine and human iPS-CMs, removing excess mechanical stresses and reducing the risk of tissue culture artifacts exerted by stiff substrates.     

miRNA-22在卵巢癌组织的表达及其对卵巢癌细胞增殖、迁移与侵袭的影响

目的:观察在不同卵巢组织中miRNA-22的表达,并研究上调miRNA-22表达对卵巢癌细胞株SKOV-3增殖、迁移与侵袭的影响。方法:实时荧光定量PCR(q PCR)检测不同卵巢组织样本miRNA-22的表达;随机将SKOV-3细胞分为正常对照组(control组)、空白载体组(miRNA-22-NC组)和转染miRNA-22-mimic组(miRNA-22-m组),q PCR检测各组细胞miRNA-22的表达,CCK-8法检测细胞存活率,划痕实验与Transwell小室法分别检测细胞的迁移与侵袭能力,Western blot法检测VEGF和P53蛋白表达。结果:卵巢癌组织中miRNA-22的水平显著低于正常卵巢组织;与control组相比,miRNA-22-m组细胞miRNA-22的表达显著增加,细胞存活率显著降低,细胞迁移数和侵袭数下降,VEGF和P53的蛋白表达水平显著下降。结论:miRNA-22的低表达可能与卵巢癌的发生发展有关。过表达miRNA-22能够抑制卵巢癌细胞株的增殖、迁移和侵袭,其机制可能与下调VEGF和P53的蛋白表达有关。     

EB病毒感染对鼻咽癌细胞生长和凋亡的影响

目的:探讨EB病毒(EBV)感染对鼻咽癌细胞系生长和细胞凋亡的影响。方法:用EBV直接感染人鼻咽癌细胞系CNE1;用免疫组化(LSAB)法检测EBV-LMP1和bcl-2蛋白的表达;用MTT法测定鼻咽癌细胞系的生长能力;用流式细胞术和TUNEL法检测癌细胞凋亡。结果:感染EBV的鼻咽癌细胞系(E-CNE1)的EBV-LMP1表达阳性,生长能力较未感染EBV的CNE1明显增强(P＜0.01),2种鼻咽癌细胞系均无凋亡发生,而均仅有2%~3%的细胞表达bcl-2蛋白。结论:EBV感染和LMP1表达可促进鼻咽癌细胞生长,但对鼻咽癌细胞的bcl-2表达和细胞凋亡无影响。     

淫羊藿苷对前列腺癌细胞株活力、迁移与侵袭的作用

目的:探讨淫羊藿苷对前列腺癌细胞株Du145与PC3的存活、迁移与侵袭能力的影响,并初步研究其机制。方法:CCK-8法检测不同浓度淫羊藿苷(0、5、10、20、40和80μmol/L)对Du145细胞与PC3细胞活力的影响;Transwell小室实验检测细胞的迁移和侵袭能力;Western blot检测Notch-1、MMP-2、MMP-9和Hes-1蛋白水平。结果:MTT法检测结果显示淫羊藿苷呈浓度依赖性抑制Du145与PC3细胞的活力,当浓度到达40μmol/L时,抑制作用达到最大;经淫羊藿苷干预后,Du145和PC3细胞迁移和侵袭能力显著下降,Notch-1、MMP-2、MMP-9和Hes-1蛋白表达水平显著下降。结论:淫羊藿苷具有抑制前列腺癌细胞株Du145与PC3生长、迁移和侵袭的作用,其作用机制可能与淫羊藿苷抑制Notch-1、MMP-2、MMP-9和Hes-1蛋白的表达有关。     

Evidence that a significant number of naive T cells enter non-lymphoid organs as part of a normal migratory pathway

Only activated and effector memory T cells are thought to access non-lymphoid tissues. In contrast, naive T cells are thought to circulate only between the blood, lymph and secondary lymphoid organs. We examined the phenotype of endogenous T cells in various non-lymphoid organs and showed that a subset of cells exhibited an apparently naive phenotype and were functionally inactive. FTY720 treatment selectively depleted this population from the non-lymphoid tissues. In addition, RAG-deficient TCR transgenic CD4 and CD8 T cells were present in non-lymphoid tissues in bone marrow chimeric mice and in situ imaging analysis revealed their location in the parenchymal tissues. Moreover, migration of TCR transgenic T cells to non-lymphoid tissues after adoptive transfer was pertussis-toxin resistant. Overall, the results suggest that naive T cells may circulate through non-lymphoid tissues as part of their normal migratory pathway.