体外缺血缺氧条件下大鼠骨髓间充质干细胞凋亡发生的机制研究

目的:研究体外大鼠骨髓间充质干细胞(Bone marrow-derived mesenchymal stem cells,BMSCs)在缺血缺氧条件下发生凋亡的作用机制。方法:采取大鼠骨髓,以密度梯度离心分离出单个核细胞(MNCs),于体外培养并由牛垂体提取物(PEX)诱导扩增传代培养出骨髓间充质干细胞(MSCs)。经形态学和流式细胞仪检测MSCs表面标志物鉴定后,骨髓间充质干细胞(BMSCs)在缺血缺氧条件下培养,通过Annexin V/PI双染细胞凋亡检测比较不同组别细胞的凋亡率和蛋白印迹法(western blot)来观察细胞中蛋白的变化。结果:①经形态学观察和流式细胞仪检测MSCs表面标志物鉴定,提示骨髓间充质干细胞培养成功。②对照组(无缺血缺氧)与缺血缺氧组比较,缺血缺氧组的凋亡率显著性增加,而通过磷酸化Akt的表达量显著性增加提示PI3K(Phosphoinosi-tide-3kinase)/Akt(ProteinkinaseB,PKB)信号通路被激活(P<0.05);同时缺血缺氧组与缺血缺氧+PI3K/Akt抑制剂(LY294002)组比较,缺血缺氧+PI3K/Akt抑制剂(LY294002)组的凋亡率显著降低,而通过磷酸化Akt的表达量显著减少提示PI3K/Akt信号通路被抑制(P<0.05)。结论:PI3K/Akt信号通路对体外缺血缺氧条件下培养的骨髓间充质干细胞凋亡发生有关键性作用。     

体外缺血缺氧条件下大鼠骨髓间充质干细胞凋亡发生的机制研究

目的：研究体外大鼠骨髓间充质干细胞（Bone marrow-derived mesenchymal stem cells, BMSCs）在缺血缺氧条件下发生凋亡的作用机制。方法：采取大鼠骨髓,以密度梯度离心分离出单个核细胞（MNCs）,于体外培养并由牛垂体提取物（PEX）诱导扩增传代培养出骨髓间充质干细胞（MSCs）。经形态学和流式细胞仪检测MSCs表面标志物鉴定后,骨髓间充质干细胞（BMSCs）在缺血缺氧条件下培养,通过Annexin V／PI双染细胞凋亡检测比较不同组别细胞的凋亡率和蛋白印迹法（western blot）来观察细胞中蛋白的变化。结果：①经形态学观察和流式细胞仪检测MSCs表面标志物鉴定,提示骨髓间充质干细胞培养成功。②对照组（无缺血缺氧）与缺血缺氧组比较,缺血缺氧组的凋亡率显著性增加,而通过磷酸化Akt的表达量显著性增加提示PI3K（Phosphoinositide-3kinase）／Akt（ProteinkinaseB,PKB）信号通路被激活（P〈0．05）;同时缺血缺氧组与缺血缺氧＋PI3K／Akt抑制剂（LY294002）组比较,缺血缺氧＋PI3K／Akt抑制剂（LY294002）组的凋亡率显著降低,而通过磷酸化Akt的表达量显著减少提示PI3K/Akt信号通路被抑制（P〈0．05）。结论：PI3K／Akt信号通路对体外缺血缺氧条件下培养的骨髓间充质干细胞凋亡发生有关键性作用。     

TNF-α刺激大鼠骨髓间充质干细胞的机制研究

目的:研究肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)刺激大鼠骨髓间充质干细胞(marrow-derived mesenchymalstem cells,MSCs)的作用机制。方法:采取大鼠骨髓,以密度梯度离心分离出单个核细胞(MNCs),于体外培养并由牛垂体提取物(PEX)诱导扩增传代培养出骨髓间充质干细胞(MSCs)。经形态学和流式细胞仪检测MSCs表面标志物鉴定后,用TNF-α刺激骨髓间充质干细胞(MSCs),通过酶联免疫吸附剂测定法(enzyme linked immunosorbent assay,ELISA)观察比较不同组别细胞的生长因子分泌和蛋白印迹法(western blot)来观察细胞中蛋白的变化。结果:①经形态学观察和流式细胞仪检测MSCs表面标志物鉴定,提示骨髓间充质干细胞的培养成功。②无TNF-α刺激组与TNF-α刺激组比较,TNF-α刺激组的生长因子分泌显著性增加,而通过磷酸化IκB的表达量显著性增加提示NF-κB被激活(P<0.05);同时TNF-α刺激组与TNF-α+NF-κB抑制剂组比较,TNF-α+NF-κB抑制剂组的生长因子分泌显著降低,而通过磷酸化IκB的表达量显著减少提示NF-κB的活性被抑制(P<0.05)。结论:NF-κB对TNF-α刺激下的骨髓间充质干细胞分泌生长因子有关键性作用。     

TNF-α刺激大鼠骨髓间充质干细胞的机制研究

目的：研究肿瘤坏死因子-α（Tumor necrosis factor-α,TNF-α）刺激大鼠骨髓间充质干细胞（marrow-derived mesenchymalstem cells,MSCs）的作用机制。方法：采取大鼠骨髓,以密度梯度离心分离出单个核细胞（MNCs）,于体外培养并由牛垂体提取物（PEX）诱导扩增传代培养出骨髓间充质干细胞（MSCs）。经形态学和流式细胞仪检测MSCs表面标志物鉴定后,用TNF-α刺激骨髓间充质干细胞（MSCs）,通过酶联免疫吸附剂测定法（enzyme linked immunosorbent assay,ELISA）观察比较不同组别细胞的生长因子分泌和蛋白印迹法（western blot）来观察细胞中蛋白的变化。结果：①经形态学观察和流式细胞仪检测MSCs表面标志物鉴定,提示骨髓间充质干细胞的培养成功。②无TNF-α刺激组与TNF-α刺激组比较,TNF-α刺激组的生长因子分泌显著性增加,而通过磷酸化IκB的表达量显著性增加提示NF-κB被激活（P〈0.05）;同时TNF-α刺激组与TNF-α＋NF-κB抑制剂组比较,TNF-α＋NF-κB抑制剂组的生长因子分泌显著降低,而通过磷酸化IκB的表达量显著减少提示NF-κB的活性被抑制（P〈0.05）。结论：NF-κB对TNF-α刺激下的骨髓间充质干细胞分泌生长因子有关键性作用。     

氯化锂对兔骨髓间充质干细胞增殖影响

目的研究Wnt/β-catenin通路激活剂氯化锂（LiCl）对兔骨髓间充质干细胞（bone marrowmesen-chymal stem cells,BMSCs）增殖的影响。方法体外纯化培养兔BMSCs,流式细胞仪检测细胞表面抗体,以不同浓度的LiCl作用兔骨髓间充质干细胞24h后,采用Cell Counting Kit-8（CCK-8）检测各组细胞的增殖活性。结果低浓度LiCl促进兔BMSCs增殖,高浓度LiCl抑制兔BMSCs增殖。结论低浓度LiCl抑制GSK3β,模拟激活Wnt/β-catenin信号途径,从而促进细胞增殖,而高浓度LiCl增加了对细胞的毒性而抑制其增殖。     

Snail基因修饰对骨髓基质干细胞骨架结构稳定作用及促迁移和对无血清培养诱导细胞凋亡的保护作用研究

转录因子Snail是调控肿瘤细胞迁徙转移的重要调控分子,基于干细胞与肿瘤细胞分子机制的重叠性,提出通过借鉴肿瘤细胞迁移的相关机制以用于提高骨髓基质干细胞向缺氧受损组织迁移能力的假设和研究思路,探讨Snail基因在人骨髓基质干细胞(MSCs)中的转染和表达情况,及转染后对基质干细胞促迁移作用、骨架结构的稳定作用及对无血清培养诱导细胞凋亡的保护作用。密度梯度离心法及细胞体外培养分离纯化人骨髓MSCs,脂质体法将重组表达载体pCAGGSneo-Snail-HA转染MSCs,G418筛选稳定表达,流式细胞仪检测MSCs表面抗原,采用免疫荧光染色技术检测转染后MSCs报告基因HA及目的基因Snail表达,Transwell细胞迁移实验和Western-blot评估细胞迁移能力和检测有关细胞信号转导通路分子水平变化,荧光染色分析细胞骨架,Sub-G1凋亡峰流式细胞仪检测细胞凋亡率并评估细胞抗凋亡能力。经流式细胞仪选择检测分离纯化扩增MSCs表面分子特点为CD34(-)/CD29( ),Snail及报告基因在转染后MSCs呈阳性表达,Snail质粒转染MSCs(MSCs-Sna)较对照空质粒转染MSCs(MSCs-neo)细胞迁移率增加(P<0.05),PI-3K信号通路特异性抑制剂Wortmannin能显著抑制此迁移率的增加,无血清培养72h后,MSCs-Sna凋亡率较MSCs-neo低(P<0.05)。经Snail基因转染,MSCs迁移能力、骨架结构的稳定性及在无血清培养环境中抗凋亡能力增加。     

MG-132对缺氧、血清饥饿诱导的MSCs凋亡和旁分泌的影响

本研究采用缺氧、血清饥饿(hypoxia and serum deprivation,H/SD)联合处理骨髓间充质干细胞(mesenchymal stem cells,MSCs),模拟MSCs移植的心脏缺血微环境,研究蛋白酶体抑制剂MG-132对H/SD诱导的MSCs凋亡和旁分泌的影响.采用Annexin V/PI流式...     

M-CSF诱导人骨髓间充质干细胞分化为肝样细胞的分子机制

本研究主要目的是明确M-CSF诱导骨髓间充质干细胞分化为肝样细胞的分子机制,为临床中的肝移植和治疗肝病提供新思路。对取自于本院骨科治疗的患者的股骨骨髓间充质干细胞进行提取、分离、传代培养及鉴定。流式细胞仪检测BMSCs的表面表型。为了诱导BMSCs的肝分化,本研究将BMSCs加入到培养基中。骨髓间充质干细胞诱导21 d后,BMSCs表达了肝细胞特异性标志物a-蛋白(AFP)和细胞角蛋白18(CK18),通过免疫荧光染色证实了分化与为分化的BMSCs表达的差异性。分化的BMSCs还显示了肝细胞的体外功能特征,包括白蛋白产生、尿素分泌和糖原储存。本研究结果表明,BMSCs在M-CSF诱导下可分化为功能性肝细胞样细胞,可作为肝病治疗的细胞来源。     

超顺磁性氧化铁纳米粒子标记骨髓间充质干细胞实验研究

目的:研究不加转染剂,超顺磁性氧化铁纳米粒子(superparamagnetic iron oxide,SPIO)对骨髓间充质干细胞(bonemarrow-derived mesenchymal stem cells,MSCs)的标记效果.方法:全骨髓法培养猪骨髓间充质干细胞,用50 ug/ml铁浓度的SPIO标记MSCs,普鲁士蓝染色鉴定标记效果,流式细胞仪测定标记MSCs的增殖及凋亡,台盼蓝染色检测标记细胞的活力.结果:不加转染剂,SPIO标记MSCs达100%,50 ug/ml铁浓度标记对MSCs活力、增殖及凋亡无影响.结论:不加转染剂,50 ug/ml铁浓度SPIO可安全、有效的标记MSCs.     

Overexpressing cellular repressor of E1A-stimulated genes protects mesenchymal stem cells against hypoxia- and serum deprivation-induced apoptosis by activation of PI3K/Akt

Bone marrow-derived mesenchymal stem cells (MSCs) have great potential for repair after myocardial infarction. However, poor viability of transplanted MSCs in the ischemic heart has limited their therapeutic potential. Cellular repressor of E1A-stimulated genes (CREG) has been identified as a potent inhibitor of apoptosis. The aim of this study was to investigate the anti-apoptotic effects of CREG on MSCs under hypoxic and serum deprivation (SD) conditions. We also investigated the potential mechanism(s) that may mediate the actions of CREG. All experiments were performed on rat bone marrow MSCs. Apoptosis was induced by exposure of cells to hypoxia/SD in a sealed GENbox hypoxic chamber. Effects of CREG were investigated in the absence or presence of inhibitors that target phosphoinositide 3-kinase (PI3K). We found that the overexpression of CREG markedly protected MSCs from hypoxia/SD-induced apoptosis through inhibition of the mitochondrial apoptotic pathway, leading to attenuation of caspase-3. Moreover, CREG enhanced Akt phosphorylation and decreased the expression of p53 in MSCs under hypoxic/SD conditions. The PI3K/Akt inhibitor LY294002 significantly increased the amount of p53 protein and attenuated the anti-apoptotic effects of CREG on MSCs. This study indicates that CREG is a novel and potent survival factor for MSCs, therefore, it may be a useful therapeutic adjunct for transplanting MSCs into damaged heart after myocardial infarction.     

Lovastatin protects mesenchymal stem cells against hypoxia- and serum deprivation-induced apoptosis by activation of PI3K/Akt and ERK1/2

Cell therapy with bone marrow-derived mesenchymal stem cells (MSCs) has been shown to have great promises in cardiac repair after myocardial infarction. However, poor viability of transplanted MSCs in the infracted heart has limited the therapeutic efficacy. Our previous studies have shown in vitro that rat MSCs undergo caspase-dependent apoptosis in response to hypoxia and serum deprivation (Hypoxia/SD). Recent findings have implicated statins, an established class of cholesterol-lowering drugs, enhance the survival of cells under various conditions. In this study, we investigated the effect of lovastatin on rat MSCs apoptosis induced by Hypoxia/SD, focusing in particular on regulation of mitochondrial apoptotic pathway and the survival signaling pathways. We demonstrated that lovastatin (0.01-1 microM) remarkably prevented MSCs from Hypoxia/SD-induced apoptosis through inhibition of the mitochondrial apoptotic pathway, leading to attenuation of caspase-3 activation. The loss of mitochondrial membrane potential and cytochrome-c release from mitochondria to cytosol were significantly inhibited by lovastatin. Furthermore, the antiapoptotic effect of lovastatin on mitochondrial apoptotic pathway was effectively abrogated by both PI3K inhibitor, LY294002 and ERK1/2 inhibitor, U0126. The phosphorylations of Akt/GSK3 beta and ERK1/2 stimulated by lovastatin were detected. The activation of ERK1/2 was inhibited by a PI3K inhibitor, LY294002, but U0126, a ERK1/2 inhibitor did not inhibit phosphorylation of Akt and GSK3 beta. These data demonstrate that lovastatin protects MSCs from Hypoxia/SD-induced apoptosis via PI3K/Akt and MEK/ERK1/2 pathways, suggesting that it may prove a useful therapeutic adjunct for transplanting MSCs into damaged heart after myocardial infarction.     

Akt基因转染对骨髓间充质干细胞缺氧时凋亡和增殖的影响

目的采用Akt基因转染鼠骨髓MSCs探讨Akt基因是否减轻MSCs缺氧时的凋亡和提高缺氧时的增殖能力,即耐缺氧能力。方法将转染和未转染Akt基因的MSCs置于94%N2、1%O2和5%CO2缺氧箱中37℃孵育不同时间（常氧、缺氧0.5h、1h、2h、4h和8h）后,Annexin V/PI双染法行流式细胞仪分析凋亡率（apoptoticrate,AR）和死亡率（deadrate,DR）、MTT法分析细胞增殖状态、Rt-PCR和Western blot等检测Akt和p-Akt表达以及放射同位素法检测MSCs对氚标-葡萄糖（^3H-G）的摄取等。结果1.Akt基因显著降低MSCs缺氧时AR和DR（P〈0.01）,而各缺氧时间点没有统计学意义（P〉0.05）;2.Akt基因显著增高MSCs常氧和缺氧（与未转染Akt基因MSCs同等条件下比较）时增殖能力（P〈0.01）,缺氧时增殖能力显著低于常氧时（P〈0.01）;3.Akt基因显著增高常氧时MSCsAkt mRNA（P〈0.01）和蛋白（P〈0.01）表达,而不增高p-Akt蛋白（P〉0.05）表达;Akt基因显著提高缺氧时p-Akt蛋白（P〈0.01）表达,而不提高常氧时p-Akt蛋白（P〉0.05）表达;4.Akt基因显著增高MSCs常氧和缺氧（与未转染Akt基因MSCs同等条件下比较）时^3H-G的摄取（P〈0.01）,缺氧时^3H-G的摄取显著性低于常氧培养时（P〈0.01）;^3H-G的摄取与细胞增殖显著正相关（r=0.79,P=0.015）而与细胞凋亡显著负相关（r=-1.47,P=0.023）。结论Akt基因转染可显著提高MSCs耐缺氧能力,此可能与缺氧时改善MSCs葡萄糖摄取等有关。     

SDF-1α inhibits hypoxia and serum deprivation-induced apoptosis in mesenchymal stem cells through PI3K/Akt and ERK1/2 signaling pathways

Bone marrow-derived mesenchymal stem cells (BMSCs) have been demonstrated to be a promising cell sources for cardiac regeneration. Poor survival rate of transplanted BMSCs in infarcted myocardium attenuated its clinical application. It’s reported that stromal-derived factor-1 (SDF-1) could protect progenitor cells including endothelial progenitor cells and embryonic stem cells from apoptosis. But little is known whether SDF-1α protein has the same protective effects on BMSCs under conditions of hypoxia and serum deprivation (hypoxia/SD). In present study, we verified that SDF-1α (0.50–2.0 μg/ml) inhibited hypoxia/SD induced apoptosis of BMSCs through mitochondrial pathway. After administration of SDF-1α, the loss of mitochondrial membrane potential and cytochrome c released from mitochondria to cytosol were significantly inhibited, and caspase 3 activity also declined. Furthermore, the effect of SDF-1α on mitochondrial pathway was neutralized by using PI3K inhibitor (Wortmannin) and ERK1/2 inhibitor (U0126). Our observations suggested that SDF-1α inhibits hypoxia/SD induced BMSCs apoptosis through PI3K/Akt and ERK1/2 signaling pathways. These data also imply that the anti-apoptotic effect mediated by SDF-1α may enhance cell survival after cell transplantation.     

Transcriptional regulation of livin by β-catenin/TCF signaling in human lung cancer cell lines

Heregulin can regulate the survival of cardiomyocytes, epithelial cells, neuron, glial cells, and other cell types through binding with the ErbB receptors. The aim of this study is to investigate the effects of heregulin (HRG) on the apoptosis of Bone marrow Mesenchymal stem cells (MSCs). We used the MSCs from adult Sprague–Dawley rats and the model of serum deprivation (SD) and hypoxia-induced apoptosis. The apoptosis was detected by TUNEL method. The apoptosis of MSCs significantly increased 12 h or 18 h after SD and hypoxia, but treatment with HRG significantly decreased the apoptosis induced by SD and hypoxia. Tyrphostin AG1478 (ErbB3/4 inhibitor) or Tyrphostin AG825 (ErbB2 inhibitor) could block this effects of HRG. Akt and ERK were activated by HRG under SD and hypoxia conditions, but HRG had no effects on the activation of JNK and p38. HRG also increased the ratio of Bcl-2/Bax and decreased the activation of caspase3 induced by SD and hypoxia. These results suggested HRG could decrease the apoptosis of MSCs induced by SD and hypoxia through the activation of Akt and ERK, the increase of Bcl-2/Bax ratio and the inhibition of caspase3 activation.     

LPA rescues ER stress‐associated apoptosis in hypoxia and serum deprivation‐stimulated mesenchymal stem cells

Poor viability of transplanted mesenchymal stem cells (MSCs) in the infracted heart has limited their therapeutic efficacy in cardiac repair after myocardial infarction. We previously demonstrated that hypoxia and serum deprivation (hypoxia/SD) induced mitochondria‐dependent apoptosis in MSCs, while lysophosphatidic acid (LPA) could almost completely block this apoptotic process. However, the role of endoplasmic reticulum (ER) stress and its upstream signaling events in hypoxia/SD‐induced MSC apoptosis remain largely unknown. Here we found that hypoxia/SD‐induced MSC apoptosis was associated with ER stress, as shown by the induction of CHOP expression and procaspase‐12 cleavage, while the effects were abrogated by LPA treatment, suggesting ER stress is also a target of LPA. Furthermore, hypoxia/SD induced p38 activation, inhibition of which resulted in decreases of apoptotic cells, procaspase‐12 cleavage and mitochondrial cytochrome c release that function in parallel in MSC apoptosis. Unexpectedly, p38 inhibition enhanced hypoxia/SD‐induced CHOP expression. Interestingly, p38 activation, a common process mediating various biological effects of LPA, was inhibited by LPA in this study, and the regulation of p38 pathway by LPA was dependent on LPA_1/3/Gi/ERK1/2 pathway‐mediated MKP‐1 induction but independent of PI3K/Akt pathway. Collectively, our findings indicate that ER stress is a target of LPA to antagonize hypoxia/SD‐induced MSC apoptosis, and the modulation of mitochondrial and ER stress‐associated apoptotic pathways by LPA is at least partly dependent on LPA_1/3/Gi/ERK/MKP‐1 pathway‐mediated p38 inhibition. This study may provide new anti‐apoptotic targets for elevating the viability of MSCs for therapeutic potential of cardiac repair. J. Cell. Biochem. 111: 811–820, 2010. © 2010 Wiley‐Liss, Inc.     

Identification of MicroRNAs involved in hypoxia- and serum deprivation-induced apoptosis in mesenchymal stem cells

The use of bone marrow mesenchymal stem cell- (MSC) transplantation therapy for cardiac diseases is limited due to poor survival of implanted cells. MicroRNAs (miRNAs) have been reported to be involved in regulating almost all cellular processes, including apoptosis. In this study, we found that the miRNA profile was altered during apoptosis induced by hypoxia and serum deprivation (hypoxia/SD). We further revealed that over-expression of miR-21, miR-23a and miR-210 could promote the survival of MSCs exposed to hypoxia/SD. In contrast, down-regulation of miR-21, miR-23a and miR-503 aggravated apoptosis of MSCs. It was indicated that these miRNAs may play important roles during MSC apoptosis induced by hypoxia/SD.