Paracrine mechanisms of endothelial progenitor cells in vascular repair

Endothelial progenitor cells (EPCs) play an important role in repairing damaged blood vessels and promoting neovascularization. However, the specific mechanism of EPCs promoting vascular repair is still unclear. Currently, there are two different views on the repair of damaged vessels by EPCs, one is that EPCs can directly differentiate into endothelial cells (ECs) and integrate into injured vessels, the other is that EPCs act on cells and blood vessels by releasing paracrine substances. But more evidence now supports the latter. Therefore, the paracrine mechanisms of EPCs are worth further study. This review describes the substances secreted by EPCs, some applications based on paracrine effects of EPCs, and the studies of paracrine mechanisms in cardiovascular diseases--all of these are to support the view that EPCs repair blood vessels through paracrine effects rather than integrating directly into damaged vessels.     

间质细胞衰老诱导上皮细胞癌变的研究进展

细胞衰老是根据永久性细胞周期阻滞而定义的。普遍认为,细胞衰老具有保护机体避免癌变的进化优势。然而,间质细胞的衰老却可以显著加快上皮肿瘤的发生,这种促瘤效应很可能是由衰老成纤维细胞激活的炎症网络造成的。对该调节机制的深入了解,可为研究细胞衰老在肿瘤发生中的作用提供理论基础,同时也可为肿瘤的治疗提供新思路。     

Targeted ablation of gonadotrophs in transgenic mice affects embryonic development of lactotrophs

Ablation of pituitary gonadotrophs was obtained in transgenic mice expressing diphtheria toxin A (DTA) under control of the −313/+48 bovine glycoprotein hormone -subunit (SU) promoter, previously shown to be active in mouse gonadotrophs but not in thyrotrophs. Development of hormone-producing cell types was assessed on the day of birth by computer-assisted image analysis on paraffin-embedded, immunostained pituitary sections. Six out of 50 transgenic F₀ (‘founder’) mice (3 males and 3 females) showed a nearly complete disappearance of gonadotrophs but not of thyrotrophs. The number of lactotrophs and the relative area occupied by PRL-immunoreactivity were significantly reduced in the gonadotroph-depleted mice. The size of lactotroph clusters was smaller in the absence of gonadotrophs. The number and immunoreactive area of corticotrophs and somatotrophs, on the other hand, were not significantly affected by gonadotroph ablation. Based on the reported evidence that fetal ovaries do not produce steroid hormones as a result of lack of expression of at least three of the steroidogenic enzymes, P450scc, P450c17, and P450arom, the present observations can hardly be explained by a decline in estrogen levels due to gonadotroph ablation. Rather, the present data indicate that gonadotrophs directly stimulate the development of lactotrophs during fetal and early postnatal life, consistent with previous in vitro observations, and/or that gonadotrophs may share a cell-lineage relationship with a subpopulation of lactotrophs.     

卵巢旁/自分泌及降调节对其的影响

卵巢内卵和颗粒细胞间的双向交流既调节卵泡生成也调控卵的发生。卵和卵泡来源因子在调控窦卵泡发育和卵活性中具有阶段特异作用。转化生长因子-β(TGF-β)超家族成员,包括抑制素、激活素、卵泡抑素、骨形态形成蛋白(BMP)、生长分化因子(GDF)、抗苗勒氏管激素(AMH)等均属生长因子,可通过卵巢旁分泌和/或自分泌起到调控卵泡发育和卵成熟的作用。其它涉及旁分泌/自分泌的因子还包括表皮生长因子(EGF)、成纤维细胞生长因子(FGFs)家族、胰岛素样生长因子(IGFs)家族、血管内皮生长因子(VEGF)家族、细胞因子(cytokin)家族、白细胞介素(interleukins)、肿瘤坏死因子-α(TNF-α)等。促性腺激素释放激素(GnRH)可以作为一种自分泌因子。GnRH受体还在一些垂体以外的组织表达,GnRH可以上调GnRH受体及其基因表达。虽不清楚GnRH受体在人卵巢中是否具有功能,但GnRH拮抗剂(GnRH-ant)可能干扰人卵巢细胞内GnRH的自分泌和旁分泌信号,改变卵泡微环境。尽管存在争议,GnRH-ant对人卵巢和生长因子(如EGF,IGF-I和IGF-II等)的影响至少部分反映在卵泡生成方面,虽然其机理尚未完全阐明。故GnRH激动剂(GnRH-a)/GnRH-ant降调可能影响卵巢旁分泌/自分泌,从而影响卵泡生成/卵质量/着床/胚胎发育。     

内皮祖细胞培养上清对高氧暴露新生大鼠肺结构的改善作用

目的:研究内皮祖细胞培养上清(endothelial progenitor cell-conditioned medium,EPC-CM)对高氧暴露新生大鼠肺损伤时肺泡结构的改善作用及其机制。方法:从新生SD大鼠骨髓中获取内皮祖细胞并鉴定,收集第3代细胞的培养上清备用。另取新生SD大鼠40只随机分为4组,即空气组:仔鼠在空气(21%O_2)中喂养21天;高氧组:仔鼠在85% O_2中喂养21天;内皮细胞基础培养基(endothelial cell basal medium,EBM)干预组:仔鼠在85%O_2中喂养至第14天时,经气道给予100μL EBM,然后喂养至第21天;EPC-CM干预组:仔鼠在85% O_2中喂养至第14天,经气道给予100μL EPC-CM,喂养至第21天。第21天处死小鼠,左肺用4%多聚甲醛固定,留作石蜡切片,随后HE染色进行肺组织病理形态学观察,并做辐射状肺泡计数(radical alveolar count,RAC)及肺泡平均线性截距(mean linear intercept,MLI)测量;免疫组织化学方法对血管内皮细胞FVIII染色,计数肺组织微血管密度;右肺留作实时荧光定量PCR检测肺组织KGF、VEGF、SP-A和SP-C的mRNA表达。结果:培养所得细胞具有典型的EPCs形态改变,能结合异硫氰酸荧光素标记的荆豆凝集素1并摄取Di I荧光标记的乙酰化低密度脂蛋白。高氧组及EBM干预组的仔鼠体重、RAC、MLI和微血管密度较空气组显著降低(P0.05),EPC-CM干预组的RAC和微血管密度较高氧组和EBM干预组明显增加(P0.05),而体重和MLI的变化无明显差异,但有增高的趋势。高氧组和EBM干预组肺组织KGF、VEGF、SP-A和SP-C的mRNA表达较空气组显著降低(P0.05),EPC-CM干预组的表达显著高于高氧组和EBM干预组(P0.05)。结论:EPC-CM可改善高氧暴露新生大鼠的肺泡化和肺血管发育,可能与促进肺内KGF和VEGF mRNA的表达相关。     

Autonomous Expressions of Cytokine Genes by Human Lung Cancer Cells and Their Paracrine Regulation

Cell-to-cell interaction between tumors and host inflammatory cells is important for the subsequent cancer progression or regression. We examined the expressions of mRNAs for various proinflammatory cytokines by nine human lung cancer cell lines and the influences of cytokines on their gene expressions. The cytokines used were interleukin 1β (IL-1β), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), granulocyte-macrophage colony stimulating factor (GM-CSF) and monocyte chemotactic and activating factor. Gene expressions of cytokines were measured by Northern blot analysis. Substantial expressions of cytokine genes were detected in several lung cancer cell lines such as RERF-LC-MS, RERF-LC-OK and VMRC-LCD, although the levels of expression of each cytokine varied in different cell lines. Four lung cancer cell lines (RERF-LC-MS, RERF-LC-OK, A549 and YO-88) were used to examine the effects of exogenous cytokines (IL-1β, TNF-α and GM-CSF) on cytokine gene expressions by the cells. TNF-α and IL-1β caused significant changes in the levels of mRNA expressions of certain cytokines. Moreover, on stimulation with TNF-α, RERF-LC-OK cells produced IL-6 extracellularly. These extensive differences in the levels of gene expressions and productions of cytokines could have profound effects on the interactions between human lung cancer cells and the corresponding host cells.     

人间充质干细胞外泌体通过p38丝裂素活化蛋白激酶信号通路促进小鼠胚胎成骨细胞前体增殖和成骨分化

目的 观察人间充质干细胞(hMSC)分泌的外泌体对小鼠胚胎成骨细胞前体细胞(MC3T3-E1细胞)增殖和成骨分化的作用,并基于p38丝裂素活化蛋白激酶(p38MAPK)信号通路探讨相关分子机制.方法 采用流式细胞术检测hMSC表面标志物;以成骨诱导液干预hMSC,通过茜素红染色检测钙化结节以反映其成骨能力;采用差速离心法提取hMSC外泌体,通过电镜观察检测外泌体粒径.将MC3T3-E1细胞分为4组,分别给予外泌体干预(外泌体组)、p38MAPK抑制剂SB203580干预(抑制剂组)、SB203580干预6 h后再加入外泌体干预(抑制剂+外泌体组),以未干预组作为对照组.通过蛋白质印迹法和实时荧光定量PCR检测各组细胞中Ⅰ型胶原蛋白alpha1(COL1A1)、ruh相关转录因子2(Runx2)、碱性磷酸酶(Alp)、骨桥蛋白(Opn)的蛋白和mRNA表达量,蛋白质印迹法检测p38MAPK和磷酸化p38MAPK(p-p38MAPK)的表达量,MTT法检测细胞增殖情况,茜素红染色检测细胞成骨能力,采用Alp试剂盒检测细胞上清液中Alp活力.结果 hMSC表面CD90和CD105呈阳性表达,CD34和CD45呈阴性表达;hMSC具有成骨分化能力;分离的外泌体粒径为40～160 nm.与对照组比较,外泌体组MC3T3-E1细胞增殖能力,成骨能力,Alp活力,细胞中COL1A1、Runx2、Alp、Opn的蛋白和mRNA表达量,p-p38/p38MAPK蛋白表达量比值均增高,差异有统计学意义(P<0.05);抑制剂组结果与外泌体组相反,与对照组比较,差异均有统计学意义(P<0.05);与抑制剂组比较,抑制剂+外泌体组MC3T3-E1细胞增殖能力、矿化结节、Alp活力无明显变化,细胞中COL1A1、Runx2、Alp、Opn的蛋白和mRNA表达量及p-p38/p38MAPK蛋白的表达量比值均无明显变化,差异无统计学意义(P>0.05).结论 hMSC分泌的外泌体可通过p38MAPK信号通路促进MC3T3-E1细胞的增殖和成骨分化.     

Long-term immunomodulatory effect of amniotic stem cells in an Alzheimer's disease model

Amyloid beta (Aβ) plays a major role in Alzheimer's disease (AD), and neuroinflammatory processes mediated by Aβ plaque-induced microglial cells and astrocytes contribute to AD pathogenesis. The present study examined human placenta amniotic membrane-derived mesenchymal stem cells (AMSCs), which have potent immunomodulatory and paracrine effects in a Tg2576 (APPswe) transgenic mouse model of AD. AMSCs secreted high levels of transforming growth factor-β under in vitro inflammatory environment conditions. Six weeks after the intravenous injection of AMSCs, APPswe mice showed evidence of improved spatial learning, which significantly correlated with the observation of fewer Aβ plaques in brain. The number of ED1-positive phagocytic microglial cells associated with Aβ plaques was higher in AMSC-injected mice than in phosphate-buffered saline-injected mice, and the level of Aβ-degrading enzymes (matrix metallopeptidase-9 and insulin-degrading enzyme) was also significantly higher. Furthermore, the level of proinflammatory cytokines, interleukin-1 and tumor necrosis factor-α, was lower and that of anti-inflammatory cytokines, interleukin-10 and transforming growth factor-β, was higher in AMSC-injected mice than phosphate-buffered saline-injected mice. These effects lasted until 12 weeks after AMSC injection. Taken together, these results collectively suggest that injection of AMSCs might show significant long-lasting improvement in AD pathology and memory function via immunomodulatory and paracrine mechanisms.