骨髓间充质干细胞体外定向诱导分化为心肌样细胞的实验研究

目的 研究大鼠骨髓间充质干细胞的体外培养及向心肌样细胞转化的条件。方法 获取成年大鼠胫骨干骨髓，采用贴壁法进行间充质干细胞的培养、传代，观察经5-氮胞苷诱导后骨髓间充质干细胞的生长和分化。结果 大鼠骨髓基质细胞贴壁旱集落生长，5-氮胞苷诱导骨髓基质细胞转化为心肌样细胞，结论 骨髓基质细胞能够在体外被诱导分化为心肌样细胞，为自体心肌细胞移植提供了一种良好的来源。     

5-氮杂胞苷诱导大鼠骨髓间充质干细胞分化为心肌细胞的实验研究

目的 :观察 5 氮杂胞苷 （5 Azacytidine）能否诱导骨髓间充质干细胞分化为心肌样细胞及其分化率 ,并探明骨髓间充质干细胞分化为心肌样细胞外 ,尚有哪些细胞类型存在 ?方法 :以成年SD大鼠为研究对象 ,分离单个核细胞 ,用 5 氮杂胞苷诱导骨髓间充质干细胞的分化。通过倒置显微镜观察受到诱导的骨髓间充质干细胞形态的变化 ,用免疫组化的方法标测分化的心肌样细胞的肌钙蛋白I（troponinI）和结蛋白 （desmin）是否存在 ?并用放免试剂盒测定分化的心肌样细胞能否分泌心房钠尿肽 ,透射电镜可以观察到分化的心肌样细胞内是否有肌丝和肌丝团的存在 ,RT PCR方法可以测定分化的心肌样细胞是否有Nkx2 .5和troponinI的cDNA的表达 ?从不同的层面鉴定诱导分化的心肌样细胞是否具有心肌细胞的特性和功能 ?并用流式细胞仪测定分化的心肌样细胞占细胞总数的百分比。结果 :① 5 氮杂胞苷可以诱导骨髓间充质干细胞分化为心肌样细胞。②在骨髓间充质干细胞分化为心肌样细胞的过程中 ,有部分成纤维细胞生长和未分化的单个核细胞存在。结论 :5 氮杂胞苷可以诱导骨髓间充质干细胞分化为心肌样细胞 ,5 氮杂胞苷诱导骨髓间充质干细胞分化为心肌样细胞后再做细胞移植 ,可能有改善受损心脏的功能。     

流体剪切力对5-氮杂胞苷诱导大鼠骨髓间充质干细胞向心肌样细胞分化的影响

目的观察5-氮杂胞苷诱导大鼠骨髓间充质干细胞向心肌样细胞分化,并探讨流体剪切力对诱导过程的影响。方法贴壁法从大鼠骨髓中分离骨髓间充质干细胞,进行纯化传代培养,取第4代骨髓间充质干细胞以3、5、10、15及20μmol/L 5-氮杂胞苷分别作用12、24及48 h,用免疫荧光法鉴定分化的心肌样细胞α-肌动蛋白表达率,10μmol/L作用24 h为最佳诱导浓度。通过建立流体剪切力模型,设立以下四组:不加载流体剪切力组、加载5 dyn/cm2流体剪切力组、加载15 dyn/cm2流体剪切力组和加载25 dyn/cm2流体剪切力组,作用24 h,倒置显微镜观察诱导后骨髓间充质干细胞形态的变化,4周后逆转录聚合酶链反应测定分化的心肌样细胞心肌肌钙蛋白ImRNA的表达。结果骨髓间充质干细胞随着传代逐渐变成梭形,5-氮杂胞苷诱导后骨髓间充质干细胞胞体逐渐增大并伸出细长突起,部分相邻细胞的突起连接成网,形态学上表现出向心肌细胞方向转化的特征。免疫荧光显示α-肌动蛋白表达阳性。经过流体剪切力作用细胞后,心肌肌钙蛋白I的表达增高,阳性条带均比未进行力学刺激的细胞表达明显,以15 dyn/cm2剪切力最明显。但是25 dyn/cm2剪切力作用结果并没有随着力的增大而增大。结论 5-氮杂胞苷可以诱导大鼠骨髓间充质干细胞向心肌样细胞分化,5-氮杂胞苷可联合剪应力诱导大鼠骨髓间充质干细胞向心肌样细胞分化,且诱导效果优于单独使用5-氮杂胞苷。     

犬骨髓间充质干细胞体外分离培养、诱导分化为心肌细胞实验研究

目的 观察犬骨髓间充质干细胞(BMSCs)分离体外培养的生长特性及诱导分化为心肌细胞.方法 利用骨髓穿刺,Percoll分离液密度梯度离心法分离穿刺骨髓细胞继而通过贴壁筛选纯化骨髓间充质干细胞进行接种培养、体外扩增经5-氮胞苷(5-azacytidine)诱导分化为心肌样细胞.倒置显微镜观察诱导前后细胞形态变化,流式细胞分析及免疫化学进行相关免疫抗原检测.结果 分离细胞流式细胞分析细胞表面分子抗原CD105(间充质干细胞抗原)阳性,CD34(造血干细胞表面抗原)阴性,CD31(内皮主细胞表面抗原)阴性.利用5-溴-2-尿嘧啶脱氧核苷(Brdu)进行细胞增殖标记,结果增殖细胞核标记率为(77.2±6.1)%.传4代后,经5-aza诱导,细胞形态发生改变,由梭形变为"心肌样",同时有自发性细胞搏动和"肌管"样结构.免疫化学检测分化细胞肌球蛋白重链(MHC)、心肌特异性肌钙蛋白I(cTnI)、连接蛋白-43(Cx-43)等心肌细胞特异蛋白表达阳性.结论 BMSCs分离纯化在体外培养条件下可以实现大量扩增,同时维持其未分化状态.与5-氮杂苷(5-azacytidine)共培养,可以诱导其分化为心肌样细胞.BMSCs是细胞移植"心肌再生"治疗缺血性心脏病的理想种子细胞来源.     

犬骨髓间叶干细胞体外定向诱导分化心肌细胞的实验研究

目的:旨在建立骨髓间叶干细胞(MSCs)体外定向诱导分化心肌细胞的方法,为心肌疾患的移值修复治疗提供成体干细胞来源.方法:利用Percoll密度梯度法及MSCs黏附贴壁生长特性进行分离培养与扩增骨髓MSCs,并予以鉴定证实.应用5-氮胞苷对培养早期的骨髓MSCs进行定向诱导分化心肌细胞.通过细胞形态学、细胞免疫组化、透射电镜等技术观察分化细胞的肌管,心肌细胞特异性蛋白与细胞特异性超微结构以鉴定诱导分化的效果.结果:利用Percoll密度梯度法与细胞黏附贴壁生长特性,可分离培养与扩增足量骨髓MSCs.应用化学诱导剂5-氮胞苷10～20 μmol/L孵育早期培养的骨髓MSCs4～5周,可见细胞形成肌管;肌细胞特异性蛋白α-肌动蛋白,肌球蛋白以及心肌细胞特异性分子标志肌钙蛋白I免疫组化染色阳性;透射电镜可见肌丝与房性颗粒.结论:骨髓MSCs可在体外5-氮胞苷的诱导下定向转化为具有典型结构的心肌细胞.     

大鼠骨髓基质干细胞体外培养方法的实验研究

目的研究培养骨髓基质干细胞(MSCs)的简易方法和其在体外经5-氮胞苷诱导为心肌细胞,为心肌梗死后心力衰竭的干细胞移植治疗提供理想的种子细胞。方法采用传统的密度梯度离心分离加贴壁法和略加改进的Wakitani方法。具体操作是:取SD大鼠分离出股骨和胫骨,用10%DMEM培养基冲出骨髓液,以2×105/ml密度接种于培养瓶中,培养出的骨髓基质干细胞连续传3代,使细胞纯化后,用5-氮胞苷诱导,观察细胞形态改变。结果大鼠骨髓液接种于培养瓶中后,第2天大部分细胞已经贴壁,贴壁生长的细胞以分散、克隆集落的方式增殖,细胞大多呈梭形,7～10d后克隆集落逐渐增多,细胞融合,传代培养后细胞呈分布均匀的纺锤形细胞生长。MSCs经10!mol/L5-氮胞苷诱导3周后,发现细胞形态较前更加细长,呈梭形,类似心肌细胞样形态。结论应用略加改进的Wakitani方法,能较好地进行骨髓基质干细胞的培养和扩增,且操作简便;在体外培养的骨髓基质干细胞经诱导可转化为心肌细胞,有望成为心肌梗死后心力衰竭干细胞移植治疗的细胞材料。     

诱导骨髓间充质干细胞向心肌细胞分化及相关信号通路的研究进展

骨髓间充质干细胞具有自我更新、增殖及多向分化的特点,在体外可通过5-氮胞苷、共培养等多种途径诱导分化为心肌样细胞。相关研究表明,Notch、W nt等信号通路在这一过程中发挥着重要作用。     

骨髓间(充)质干细胞体外定向诱导心肌样细胞超微结构特征研究

目的：研究兔骨髓间（充）质干细胞（mesenchymal stem cell，MSC）经5～氮杂胞苷（5-azacytidine，5-aza）诱导在体外定向分化的心肌样细胞超微结构特征。方法：取兔髂骨骨髓，分离并培养骨髓MSC，用5～aza定向诱导向心肌样细胞分化。以相差显微镜、透射电镜观察心肌样钏胞形态学变化及超微结构特征。结果：5-aza诱导后，部分细胞体积增大，呈“捧状”或“珠状”结构，有肌管样结构形成，透射电镜下见有肌丝、心房颗粒及线粒体等心肌样细胞超微等结构。结论：经5-氮杂胞苷诱导分化的骨髓间（充）质干细胞具有心肌样细胞超微结构特征．     

5-氮胞苷体外诱导骨髓间质干细胞分化为心肌细胞的实验研究

目的观察5-氮胞苷对骨髓间质干细胞(BMMSC)体外向心肌细胞诱导分化的影响.方法分离大鼠BMMSC体外培养,使用终浓度为10 μmol/L的5-氮胞苷(5-aza)对其定向诱导,观察细胞形态学的变化,荧光免疫组织化学方法进行鉴定,电镜观察细胞的超微结构.结果BMMSC体外经5-aza诱导4周,肌钙蛋白及Connexin43表达阳性,电镜下在部分细胞内肌节样结构及细胞间形成缝隙连接.结论BMMSC可以在体外经5-氮胞苷诱导分化为心肌细胞.     

骨髓间充质干细胞移植修复心肌梗死的可行性研究

目的初步观察骨髓间充质干细胞(MSCs)移植后在大鼠心肌梗死周边区的定位、存活及分化情况. 方法采用密度梯度离心法及贴壁分离法分离纯化大鼠骨髓间充质干细胞,流式细胞术鉴定细胞表面抗原,体外定向诱导分化为具有心肌特异性结构蛋白的心肌样细胞,同时进行形态学及免疫组化鉴定.     

Glucose-induced replicative senescence in mesenchymal stem cells

Mesenchymal stem cells (MSCs) show great promise for use in a variety of cell-based therapies. Because isolated primary mesenchymal stem cells are low in numbers, in vitro expansion is necessary. However, the expansion potential is limited and in vitro aging leads to loss of multipotency and replicative senescence. Stress induced by culture conditions is likely to be a major cause of replicative senescence and reduced multipotency of MSC and optimization of culture conditions might be able to reduce this. Caloric restriction (CR) is the only established method to delay aging and extend lifespan. In vitro caloric restriction experiments are rare, but have demonstrated beneficial effects. Therefore, we investigated the effect of culture medium glucose concentration on the proliferative and differentiation potential of mesenchymal stem cells. Reduction in glucose concentrations led to decreased apoptosis and an increased rate of MSC proliferation and increased the number and size of fibroblastic colonies in the colony-forming unit assay.     

自体骨髓间叶干细胞诱导分化移植重建窦房结起搏功能的实验研究

目的:探索应用骨髓干细胞治疗病态窦房结综合征的生物介入方法.方法:选取犬6只,随机分为实验组和对照组,每组3只.抽取犬自体骨髓,分离培养扩增骨髓间叶干细胞,并在体外应用5-氮胞苷进行诱导分化.应用射频技术损伤犬窦房结,建立动物病态窦房结综合征模型.将溴脱氧尿嘧啶核苷(BrdU)标记的且诱导分化的骨髓间叶干细胞自体移植到窦房结区,应用心电图、组织病理、免疫组化等技术观察干细胞移植治疗效果.结果:在动物病态窦房结综合征模型,自体移植骨髓干细胞后,心电图示窦房结功能明显改善;病理与免疫组化示移植的骨髓干细胞在窦房结区分化为拟窦房结细胞与血管内皮细胞,并与宿主细胞建立缝隙连接.结论:自体移植诱导分化的骨髓间叶干细胞可改善窦房结自律起搏功能.     

几种影响小鼠气管上皮基底干细胞体外增殖及分化潜能因素的研究

目的 探讨多种细胞组分、细胞因子、信号转导分子等在气管上皮基底干细胞(airway basal stem cells,ABSCs)体外增殖和分化过程中的调控作用.方法 采用细胞外基质替代物Matrigel三维体外培养体系,辅以免疫组化分析,观察了几种常见的对干细胞增殖分化发挥重要作用的因素对ABSCs体外集落形成数量、集落大小及分化潜能的影响.结果 成纤维细胞较内皮细胞能显著提高ABSCs集落增殖和分化潜能.成纤维细胞生长因子(FGFs)能增加ABSCs体外集落形成数量与直径,并诱导其向分泌性细胞分化.同时给予FGFs及其受体阻滞剂处理,FGFs诱导的集落增殖效应消失.LIF、ALK5-I或ROCK-I处理后,ABSCs形成的集落数量和直径也显著增加,并诱导其向纤毛上皮细胞或分泌性细胞分化.结论 小鼠ABSCs不依赖成纤维细胞,但共培养能增强其增殖和分化能力;内皮细胞对ABSCs增殖和分化能力促进作用有限;FGFs促进ABSCs的增殖和分化,其效应能被其受体阻滞剂消除;LIF、ALK5-I或ROCK-I亦促进ABSCs的增殖和分化.研究结果将为小鼠ABSCs的生物学特性及其影响因素的深入研究奠定基础,为未来ABSCs修复性治疗相关疾病和损伤提供了实验学依据.     

Hepatogenic differentiation of human mesenchymal stem cells from adipose tissue in comparison with bone marrow mesenchymal stem cells

INTRODUCTIONMost liver diseases lead to hepatocyte dysfunction with the possibility of eventual organ failure. The replacement of diseased hepatocytes and the stimulation of endogenous or exogenous regeneration by stem cells are the main aims of liver-dir…     

Embryonic stem cells release potentially novel hematopoietic factors

We have observed that a severe decrease in the number of erythroid progenitor cells follows the long-term culture (LTC) of human primitive stem cells on an established mouse fibroblast feeder layer. This suggests that one, or several, factors necessary to support erythroid differentiation might be missing in these culture conditions. To improve the erythroid differentiation and stem cell output of LTCs, we have examined the hypothesis that the factors that regulate pluripotent stem cell proliferation and erythroid commitment can be found in media conditioned by embryonic stem (ES) cells. We have found that media conditioned by undifferentiated and differentiating ES cells can affect differentiation patterns in both short-term culture and LTC assays. Medium conditioned by undifferentiated ES cells increases the numbers of estimated LTC-initiating cells (est.LTC-IC) and potentiates granulocytic differentiation. In contrast, medium conditioned by ES cells undergoing differentiation increases the number of est.LTC-IC and is a powerful promoter of erythroid differentiation. In the presence of this medium, the number of erythroid progenitors generated after 5 weeks of LTC was increased up to 100-fold as compared with controls, and the number of est.LTC-IC was amplified up to 140-fold. These results offer a new approach for the identification of factors implicated in stem cell proliferation, self-renewal and commitment. In addition, the improved LTC conditions for the expansion of stem cells without reduction of their in vitro differentiation potential should be useful for a wide range of applications.     

Differentiation, engraftment and functional effects of pre-treated mesenchymal stem cells in a rat myocardial infarct model

BACKGROUND: Mesenchymal stem cells (MSCs) offer a novel therapeutic option in the treatment of acute myocardial infarction. MSCs are able to differentiate into myogenic cells after 5-azacytitdine treatment. However, 5-azacytidine might have genotoxic effects. Recently, it was reported that combined treatment with bone morphogenetic protein-2(BMP-2) and fibroblast growth factor-4(FGF-4) caused cardiac differentiation in non-precardiac mesoderm explants. Therefore, we investigated whether MSCs treated with combined BMP-2 and FGF-4 showed evidence of myogenic differentiation in vitro, and whether these cells resulted in sustained engraftment, myogenic differentiation, and improved cardiac function after implantation in infarcted myocardium. METHODS AND RESULTS: In vitro study: MSCs were treated with BMP-2 + FGF-4 (GF-MSCs) and myogenic phenotype was evaluated immunohistochemically. Cell growth curve was used to compare MSC proliferative capacity between the growth factors and 5-azacytidine treatments. In vivo study: two weeks after coronary artery occlusion, GF-MSCs (n=15), MSCs (n=5) labelled with PKH26 were injected into infarcted myocardium. Control animals (n=5) received a culture medium into the infarcted myocardium.Two weeks after implantation, some engrafted GF-MSCs or MSCs expressed sarcomeric-alpha-actinin and cardiac myosin heavy chain, as was observed in culture. Echocardiography showed that the GF-MSC group had a better (p < 0.05) left ventricular performance than the other groups. CONCLUSION: GF-MSCs induced myogenic differentiation in vitro. Moreover, GF-MSCs engrafted into the infarcted myocardium increased myogenic differentiation, prevented dilation of the infarcted region, and eventually improved heart function.     

老年人骨髓基质干细胞体外培养的最适生长因子组合的筛选

目的　筛选老年人骨髓基质干细胞 (MSCs)体外培养的最佳因子组合。方法　应用分数因子分析的方法从 1 2种对MSCs的增殖和分化有影响的可溶性因子中筛选出最佳组合并确定其最佳浓度。结果　成纤维生长因子 2 (FGF 2 ) 胰岛素是最佳的因子组合 ,50 0ng/mlFGF 2和 5mg/ml胰岛素是最佳浓度。FGF 2和胰岛素培养的MSCs较正常对照组有较高的骨源性和软骨源性分化能力。结论　FGF 2 胰岛素在促进MSCs增殖的同时可以保持干细胞的特性 ,维持其分化能力。     

5-Azacytidine-treated human mesenchymal stem/progenitor cells derived from umbilical cord, cord blood and bone marrow do not generate cardiomyocytes in vitro at high frequencies

Background and Objectives   Mesenchymal stem/progenitor cells (MSCs) are multipotent progenitors that differentiate into such lineages as bone, fat, cartilage and stromal cells that support haemopoiesis. Bone marrow MSCs can also contribute to cardiac repair, although the mechanism for this is unclear. Here, we examine the potential of MSCs from different sources to generate cardiomyocytes in vitro , as a means for predicting their therapeutic potential after myocardial infarction.
Materials and Methods   Mesenchymal stem/progenitor cells were isolated from the perivascular tissue and Wharton's jelly of the umbilical cord and from cord blood. Their immunophenotype and differentiation potential to generate osteoblasts, chondrocytes, adipocytes and cardiomyoxcytes in vitro was compared with those of bone marrow MSCs.
Results   Mesenchymal stem/progenitor cells isolated from umbilical cord and cord blood were phenotypically similar to bone marrow MSCs, the exception being in the expression of CD106, which was absent on umbilical cord MSCs, and CD146 that was highly expressed in cord blood MSCs. They have variable abilities to give rise to osteoblasts, chondrocytes and adipocytes, with bone marrow MSCs being the most robust. While a small proportion (~0·07%) of bone marrow MSCs could generate cardiomyocyte-like cells in vitro, those from umbilical cord and cord blood did not express cardiac markers either spontaneously or after treatment with 5-azacytidine.
Conclusion   Although MSCs may be useful for such clinical applications as bone or cartilage repair, the results presented here indicate that such cells do not generate cardiomyocytes frequently enough for cardiac repair. Their efficacy in heart repair is likely to be due to paracrine mechanisms.     

Liver-specific gene expression in mesenchymal stem cells is induced by liver cells

AIM: The origin of putative liver cells from distinct bone marrow stem cells, e.g. hematopoietic stem cells or multipotent adult progenitor cells was found in recent in vitro studies. Cell culture experiments revealed a key role of growth factors for the induction of liver-specific genes in stem cell cultures. We investigated the potential of rat mesenchymal stem cells (MSC) from bone marrow to differentiate into hepatocytic cells in vitro. Furthermore, we assessed the influence of cocultured liver cells on induction of liver-specific gene expression. METHODS: Mesenchymal stem cells were marked with green fluorescent protein (GFP) by retroviral gene transduction. Clonal marked MSC were either cultured under liver stimulating conditions using fibronectin-coated culture dishes and medium supplemented with SCF, HGF, EGF, and FGF-4 alone, or in presence of freshly isolated rat liver cells. Cells in cocultures were harvested and GFP+ or GFP-cells were separated using fluorescence activated cell sorting. RT-PCR analysis for the stem cell marker Thy1 and the hepatocytic markers CK-18, albumin, CK-19, and AFP was performed in the different cell populations. RESULTS: Under the specified culture conditions, rat MSC cocultured with liver cells expressed albumin-, CK-18, CK-19, and AFP-RNA over 3 weeks, whereas MSC cultured alone did not show liver specific gene expression. CONCLUSION: The results indicate that (1) rat MSC from bone marrow can differentiate towards hepatocytic lineage in vitro, and (2) that the microenvironment plays a decisive role for the induction of hepatic differentiation of rMSC.     

乙型肝炎病毒感染对造血干细胞活性的影响

目的 了解HBV感染对脐血来源的造血干细胞活性的影响.方法 将分离纯化的健康脐血CD34+细胞,在含有干细胞生长因子(SCF)、酪氨酸激酶受体家族Ⅲ配体(FL)、促血小板生成素(TPO)、IL-3和10%FBS的IMDM培养基中扩增,同时加入高拷贝HBV,观察干细胞扩增与病毒复制规律;干细胞扩增后,在巨细胞集落刺激因子(GM-CSF)和IL-4作用下诱生树突状细胞,对干细胞及树突细胞进行形态学观察,并检测其表面分子的表达.两组间比较采用独立t检验,多组间比较采用方差分析.结果 感染HBV的造血干细胞自然增殖能力明显低于正常干细胞(P<0.01);加入细胞因子后细胞增殖增加(P<0.01),细胞内HBV DNA复制也增加(P<0.01),但其干细胞增殖仍低于正常干细胞加细胞因子组(P<0.05).电子显微镜观察发现HBV感染干细胞后胞质内出现Dane颗粒;HBV感染的干细胞经诱导为树突状细胞后,其免疫表型CD80、CD86、CD1a、HLA-DR的表达均低于未感染组(P<0.01).结论 HBV可以感染CD34+造血干细胞,并随干细胞增殖而复制增加,HBV不仅抑制造血干细胞增殖,而且下调干细胞分化来源的树突状细胞免疫表型的表达.