Differentiation of mesenchymal stem cells and embryonic stem cells into steroidogenic cells using steroidogenic factor-1 and liver receptor homolog-1

Previously, we have demonstrated that mesenchymal stem cells could be differentiated into steroidogenic cells through steroidogenic factor-1 and 8bromo-cAMP treatment. Use of liver receptor homolog-1, another of the nuclear receptor 5A family nuclear receptors, with 8bromo-cAMP also resulted in the differentiation of human mesenchymal stem cells into steroid hormone-producing cells. The same approaches could not be applied to other undifferentiated cells such as embryonic stem cells or embryonal carcinoma cells, because the over-expression of the nuclear receptor 5A family is cytotoxic to these cells. We established embryonic stem cells carrying tetracycline-regulated steroidogenic factor-1 gene at the ROSA26 locus. The embryonic stem cells were first differentiated into a mesenchymal cell lineage by culturing on collagen IV-coated dishes and treating with pulse exposures of retinoic acid before expression of steroidogenic factor-1. Although the untreated embryonic stem cells could not be converted into steroidogenic cells by expression of steroidogenic factor-1 in the absence of leukemia inhibitory factor due to inability of the cells to survive, the differentiated cells could be successfully converted into steroidogenic cells when expression of steroidogenic factor-1 was induced. They exhibited characteristics of adrenocortical-like cells and produced a large amount of corticosterone. These results indicated that pluripotent stem cells could be differentiated into steroidogenic cells by the nuclear receptor 5A family of protein via the mesenchymal cell lineage. This approach may provide a source of cells for future gene therapy for diseases caused by steroidogenesis deficiencies.     

人类胚胎干细胞定向分化为胰岛素分泌细胞的研究进展

人类胚胎干(hES)细胞具有极其强大的增殖能力,理论上具有分化为机体所有组织细胞的潜能.治疗性克隆技术可用于制备带有患者基因型的hES细胞及其分化而来的胰岛素分泌细胞,但存在激烈的伦理学争论.新近,通过体外转基因处理可诱导人类体细胞重构形成hES样的多潜能干细胞.本文着重介绍hES细胞定向分化为胰岛素分泌细胞的研究进展.     

Differentiation of embryonic stem cells into insulin-producing cells promoted by Nkx2.2 gene transfer

AIM: To investigate the ability of a genetically altered embryonic stem (ES) cell line to generate insulin-producing cells in vitro following transfer of the Nkx2.2 gene. METHODS: Hamster Nkx2.2 genes were transferred into mouse ES cells. Parental and Nkx2.2-transfected ES cells were initiated toward differentiation in embryoid body (EB) culture for 5 d and the resulting EBs were transferred to an attached culture system. Dithizone (DTZ), a zinc-chelating agent known to selectively stain pancreatic beta cells, was used to detect insulin-producing cells. The outgrowths were incubated in DTZ solution (final concentration, 100 μg/mL) for 15 min before being examined microscopically. Gene expression of the endocrine pancreatic markers was also analyzed by RT-PCR. In addition, insulin production was determined immunohistochemically and its secretion was examined using an ELISA. RESULTS: DTZ-stained cellular clusters appeared after approximately 14 d in the culture of Nkx2.2-transfected ES cells (Nkx-ES cells), which was as much as 2 wk earlier, than those in the culture of parental ES cells (wt-ES). The frequency of DTZ-positive cells among total cultured cells on day 28 accounted for approximately 1.0% and 0.1% of the Nkx-ES- and wt-ES-derived EB outgrowths, respectively. The DTZ-positive cellular clusters were found to be immunoreactive to insulin, while the gene expressions of pancreatic-duodenal homeobox 1 (PDX1), proinsulin 1 and proinsulin 2 were observed in the cultures that contained DTZ-positive cellular clusters. Insulin secretion was also confirmed by ELISA, whereas glucose-dependent secretion was not demonstrated. CONCLUSION: Nkx2.2-transfected ES cells showed an ability to differentiate into insulin-producing cells.     

Differentiation of pluripotent embryonic stem cells into cardiomyocytes

Embryonic stem (ES) cells have been established as permanent lines of undifferentiated pluripotent cells from early mouse embryos. ES cells provide a unique system for the genetic manipulation and the creation of knockout strains of mice through gene targeting. By cultivation in vitro as 3D aggregates called embryoid bodies, ES cells can differentiate into derivatives of all 3 primary germ layers, including cardiomyocytes. Protocols for the in vitro differentiation of ES cells into cardiomyocytes representing all specialized cell types of the heart, such as atrial-like, ventricular-like, sinus nodal-like, and Purkinje-like cells, have been established. During differentiation, cardiac-specific genes as well as proteins, receptors, and ion channels are expressed in a developmental continuum, which closely recapitulates the developmental pattern of early cardiogenesis. Exploitation of ES cell-derived cardiomyocytes has facilitated the analysis of early cardiac development and has permitted in vitro "gain-of-function" or "loss-of-function" genetic studies. Recently, human ES cell lines have been established that can be used to investigate cardiac development and the function of human heart cells and to determine the basic strategies of regenerative cell therapy. This review summarizes the current state of ES cell-derived cardiogenesis and provides an overview of how genomic strategies coupled with this in vitro differentiation system can be applied to cardiac research.     

In vitro transformation of mesenchymal cells derived from embryonic muscle into cartilage in response to extracellular matrix components of bone.

Subcutaneous implantation of demineralized diaphyseal bone matrix into rats induces cartilage and bone formation in vivo. When minced skeletal muscle is cultured on hemicylinders of demineralized bone in vitro, mesenchymal cells are transformed into chondrocytes. In the present investigation, the potential of extracellular matrix components of bone to trigger cartilage differentiation in vitro was examined. Extraction of bone hemicylinders with 6 M guanidine X HCl resulted in the absence of chondrogenesis in vitro and endochondral bone formation in vivo. Biologically inactive hemicylinders of bone were then reconstituted with the guanidine extract and also with partially purified components extracted from bone matrix and bioassayed. Reconstitution completely restored the ability to elicit chondrogenesis in vitro and endochondral bone differentiation in vivo. Reconstitution of the whole guanidine extract on Millipore filters coated with gels of tendon collagen (type I) and subsequent culture with minced skeletal muscle also resulted in cartilage induction in vitro. These observations show that the extracellular matrix of bone is a repository of factors that govern local cartilage and bone differentiation.     

利拉鲁肽诱导骨髓间充质干细胞定向分化及移植治疗1型糖尿病大鼠的研究

目的 体外研究利拉鲁肽诱导骨髓间充质干细胞（BM-MSCs）分化为胰岛素分泌细胞（IPCs）,并在体内进一步观察IPCs移植对1型糖尿病（T1DM）大鼠的治疗作用.方法 （1）体外采用密度梯度离心联合差壁培养法分离、纯化大鼠BM-MSCs,进一步分为未诱导组、高糖＋尼克酰胺诱导组、胰高血糖素样肽1（GLP-1）诱导组和利拉鲁肽诱导组;（2）倒置显微镜下观察各组细胞形态变化,双硫腙染色鉴定诱导后细胞,荧光定量PCR检测巢蛋白（Nestin）、胰十二指肠同源盒1（PDX-1）、葡萄糖转运蛋白2（Glut-2）、葡萄糖激酶（GK）、胰岛素和胰高血糖素等基因,细胞免疫荧光检测胰岛素和胰高血糖素等蛋白;（3）将180 ～ 220 g的30只雄性SD大鼠以60 mg/kg剂量腹腔注射链脲佐菌素制备T1DM模型,造模成功后按随机数字表法分为对照组（T1DM组,n=8）、未诱导的BM-MSCs移植组（BM-MSCs组,n=9）和经利拉鲁肽诱导的BM-MSCs移植组（LIRA＋ BM-MSCs组,n=9）,给予相应干预8周,待血糖基本稳定后,选取4只正常、同龄、雄性SD大鼠作为对照,行腹腔注射的葡萄糖耐量试验（IPGTT）进一步观察移植后细胞对高糖刺激的反应性.结果 （1）利拉鲁肽诱导后BM-MSCs形态逐渐变圆,呈明显的聚集性生长状态,双硫腙染色为阳性;与高糖＋尼克酰胺诱导组比较,利拉鲁肽诱导组细胞Nestin mRNA表达下调（0.003 8±0.000 4比0.007 5±0.003 0,P＜0.05）,胰岛素（0.000 20±0.000 03比0.000 08±0.000 02）和胰高血糖素（0.001 1±0.0004比0.000 7±0.000 1）等mRNA表达上调（F=7.26、10.06、4.92,均P＜0.05）,PDX-1、Glut-2、GK mRNA表达亦上调;利拉鲁肽诱导组和GLP-1诱导组细胞胰岛素或胰高血糖素蛋白表达均呈阳性.（2）体内实验示,与T1DM组比较,LIRA＋ BM-MSCs组和BM-MSCs组大鼠8周末血糖均明显降低[分别为（28.0±1.2）、（8.9±1.1）、（14.5±0.9）mmol/L,F=719.61,均P＜0.05];IPGTT提示移植IPCs后的大鼠血糖在30 min时升至峰值,150 min时降至空腹水平,血糖变化曲线与正常组类似.结论 体外利拉鲁肽可以在一定程度上促进BM-MSCs分化成为IPCs,且移植后的IPCs能够在体内进一步发挥降糖作用.     

Effect of BMI1 gene overexpression on hematopoietic differentiation colony-forming assay of human embryonic stem cells

正Objective To study the effect of Bmil gene overexpression on hematopoietic differentiation colony-forming assay of human embryonic stem cells.Methods Human embryonic stem cell H1 was co-cultured with mouse bone marrow mesenchymal stem cells OP9 to simulate hematopoietic differentiation in vitro.On the 8th day of co-culture,CD34+hematopoietic progenitor cells were selected     

5-氮胞苷体外诱导骨髓间充质干细胞向心肌样细胞的分化

目的: 研究5-氮胞苷（5-Aza）对培养人骨髓间充质干细胞（MSC）的作用,并对分化后的心肌样细胞进行鉴定。方法: 采用密度梯度离心法分离到骨髓单个核细胞（MB-MNC）,用含200 ml/L胎牛血清的低糖型DMEM培养液进行培养。采用差速贴壁法纯化MSC,用流式细胞仪检测细胞表面抗原。以5-Aza诱导第3代MSC 24 h后继续培养。培养4周,用免疫细胞化学染色法检测肌系标记抗原:α-肌动蛋白（α-actin）及心肌细胞特异性标记抗原:肌钙蛋白T（cTnT）;在透射电镜下观察细胞的超微结构。结果: MSC经5-Aza诱导分化后,可表达α-actin和cTnT,未经诱导的同培养天数的MSC中均未见表达。透射电镜可观察到肌丝等心肌细胞的特异性结构。结论: 5-Aza可诱导MSC分化为心肌样细胞。     

Differentiation of rat intestinal epithelial cells is induced by organotypic mesenchymal cells in vitro.

Stromal-epithelial interaction is a potent driving force in the developing intestinal mucosa which ensures tissue specific cellular differentiation. The mechanisms involved are relevant to tissue renewal in adult organs yet they have not been elucidated because of the lack of appropriate in vitro models. In this study, we have investigated the interaction between intestinal mesenchymal and epithelial cells at the cellular level in vitro. Fetal rat intestinal epithelial cell colonies explanted in vitro on the 15th day of gestation, which failed to mature in plain monocultures, were reassociated in coculture with three different types of mesenchyme:fetal skin, gastric and intestinal mesenchyme. Only fetal epithelial cells cocultured with intestinal (homologous) mesenchyme acquired definite signs of differentiation within three to six days. These primitive epithelial cells were shown by electronmicroscopy to become highly polarized, connected by tight junctions and covered with a regular brush border. Three brush border enzymes were strongly expressed in homologous cocultures and their activity was sensitive to dexamethasone. In contrast, fetal epithelial cells cocultured with skin or stomach derived mesenchyme under identical conditions failed to differentiate in vitro: they remained flat, unpolarised and expressed only low enzyme activity. The unique potential of the small intestinal mesenchyme to promote intestinal epithelial differentiation is discussed.     

Differentiation of rat embryonic stem cells into functional cardiomyocytes

Rats(Rattus norvegicus) have many advantages over mice in scientific studies,for example, they are more relevant to human in physiological and pharmacological responses.Therefore,rats are broadly used in experimental studies.The recent breakthrough in the generation of rat embryonic stem cells(rESCs) opens the door to application of gene targeting to create models for the study of human diseases.In addition,the in vitro differentiation of rESCs into derivatives of three germ lines will serve as a powerful tool and resource for the investigation of mammalian development,cell function, tissue repair,and drug discovery.However, the distinct culture condition and signal inhibitor-depended maintenance of rESCs stand as a considerable challenge for its in vitro differentiation.To address it,we investigated whether rESCs are capable of forming terminal differentiated cardiomyocytes. We found that the embryoid bodies(EBs)-based method used in mouse ESC(mESC) differentiation failed to work in the cultivation of rESCs.We then modified the differentiation protocol and successfully developed an in vitro differentiation system to differentiate rESCs into three embryonic germ layers.By using this method,the rESCs form spontaneous beating cardiomyocytes with the properties similar to those derived from fetal rat hearts and mESCs.This unique cellular system will provide a new approach to study the early development and cardiac function as well as to perform pharmacological test and cell therapy study(Grants:the State Major Research Program of China(2009ZX09503-024,2010CB945603) and CAS(XDA01030000).     

Notch1蛋白在胚胎干细胞向神经细胞诱导分化过程中的表达及意义

目的探讨胚胎干细胞（ESC）向神经细胞（NC）定向诱导分化过程中跨膜信号分子Notch1蛋白的表达情况及意义。方法体外培养ESC,在培养基内添加5×10^-7mol/L维甲酸（RA）进行诱导分化。分别取ESC及RA诱导分化1、5、9d的细胞,倒置相差显微镜观察细胞形态变化,免疫细胞化学、Western Blot法及流式细胞术检测各相应时间点Notch1蛋白的表达。结果随诱导时间延长,ESC分化出的成熟神经元标志微管相关蛋白（MAP-2）阳性神经细胞逐渐增多,并形成较为单一密集的神经网络结构。ESC阶段Notch1蛋白为高水平表达,诱导分化后Notch1蛋白表达随时间延长逐渐下降。结论在ESC向NC的诱导分化过程中,Notch1信号逐渐关闭;Notch1可能对ESC向NC的特异性分化起重要作用。     

体外诱导大鼠骨髓间充质干细胞分化为胆碱能样神经元

目的 探讨大鼠骨髓间充质干细胞能否分化为胆碱能样神经元.方法 分离纯化大鼠骨髓间充质干细胞(MSCs),取2～4代MSCs,进行诱导其向胆碱能神经元分化.诱导方案:10% 胎牛血清诱导2 d; 换液为DMEM/F12培养基,加入碱性成纤维细胞生长因子(bFGF)、巯基乙醇(ME)、维甲酸(RA)、神经生长因子(NGF),诱导8 d;加入表皮生长因子(EGF),肝素(Heparin)继续诱导8 d.空白对照组不作任何处理.观察诱导后的形态变化.采用RT-PCR检测巢蛋白(nestin),核受体相关因子(Nurr1),胆碱乙酰转移酶(ChAT)mRNA 的表达,间接免疫荧光法检测表达 nestin、ChAT、神经核蛋白(NeuN),乙酰胆碱酯酶(AchE) 的阳性细胞.结果 诱导后细胞形态逐渐由长梭形变为圆形或椭圆形,突起形成;RT-PCR显示,诱导后的细胞高表达 nestin、Nurr1、ChAT,且基因表达相对强度与未诱导的MSCs比较有显著差异(P<0.01).免疫荧光法检测显示,诱导后的细胞高表达nestin、ChAT、NeuN、AchE,且阳性细胞大于80%,而对照组除ChAT 阳性细胞为1%外,其他均为阴性.结论 大鼠MSCs可诱导为胆碱能样神经细胞.     

多种生长因子分阶段诱导小鼠胚胎干细胞分化为胰岛素分泌细胞

目的以一种5个阶段的诱导方法诱导小鼠胚胎干(ES)细胞分化为胰岛素分泌细胞。方法以一种5个阶段的、包含胰高血糖素样肽1(GLP-1)、肝细胞生长因子(HGF)、神经生长因子(NGF)、β细胞素(betaceuulin)、激活素A(activin A)、碱性成纤维细胞生长因子(bFGF)和尼克酰胺等7种生长因子的诱导方法诱导ES细胞30d,应用RT-PCR、双硫腙染色和免疫组化检测胰岛素表达,以流式细胞仪检测胰岛素阳性细胞百分比,用RIA法测定培养液胰岛素水平。结果分化细胞中可检测到胰岛素和一些其他胰岛相关基因mRNA表达。双硫腙染色和胰岛素免疫组化染色阳性。分化细胞胰岛素阳性细胞百分比为(24.0±2.5)%(n=6)。在5.6mmol/L和25mmol/L葡萄糖浓度作用下,培养液胰岛素水平分别为(0.05±0.01)μg/L和(0.13±0.02)μg/L(n=6)。结论应用上述分阶段诱导方法可将小鼠ES细胞诱导分化为胰岛素分泌细胞,在葡萄糖作用下该细胞能释放胰岛素到培养液中,胰岛素分泌水平随着葡萄糖浓度的增高而增高。     

骨髓间充质干细胞向肝细胞样细胞的诱导分化

目的:探讨大鼠骨髓间充质细胞向肝细胞祥细胞的诱导分化,观察诱导分化细胞的形态和分子生物学特性,及其对急性肝损伤大鼠的治疗作用.方法:分离、培养并纯化大鼠骨髓间充质细胞.培养基中加入肝细胞生长因子(HGF)、纤维生长因子-4(FGF-4)及上皮细胞生长因子(EOF),分别于7、14、21、28 d观察细胞形态变化,采用RT-PCR方法检测细胞白蛋白(ALB)、甲种胎儿球蛋白(AFP)、细胞角蛋白-18(CK-18)的mRNA表达.将诱导分化28 d的细胞经DAPI染料染色后,经门静脉注入同种异体大鼠体内,经24、48、72及168 h分批处死大鼠,观察大鼠肝组织内荧光细胞的分布.大鼠腹腔注射硫代乙酰胺制作急性肝衰竭模型,将1×106及5×106个诱导分化细胞经门静脉注入大鼠体内,经48、168 h采血查肝功,168 h处死大鼠,取肝组织病理学检查.结果:大鼠间充质细胞经上述3种细胞因子诱导后,形态和生物学行为方面都发生向肝细胞样细胞方面的转化,经门静脉注入大鼠体内后,有大量该种细胞在肝组织内分布,24 h荧光细胞最多,随时间延长逐渐减少,可持续7 d.骨髓间充质细胞的诱导分化细胞经门静脉注入肝损伤模型大鼠体内后,大鼠肝功能有所好转,注入1×106细胞大鼠ALT由注入前238.0±113.5 U/L,48 h后降至189±68.4 U/L,168 h后降至149.0±54.2 U/L,TBIL由注入前2.9±1.6 μmol/L,48 h至3.0±1.4 μmoI/L,168 h至1.3±0.3 μmol/L;注入5×106个细胞者(ALT)由注入前238.0±113.5 U/L,48 h后降至169.7±46.0U/L,168 h后降至103.7±46.0 U/L,TBIL由注入前2.9±1.6μmol/L,48 h至2.9±1.3μmol/L,168 h至0.9±0.3 μmol/L.结论:大鼠骨髓间充质细胞可在某些细胞因子的诱导作用下发生类肝细胞样转化,将转化细胞经门静脉植入同种异体大鼠体内后可在肝组织内存活并对大鼠肝损伤有一定修复作用.     

Differentiation of human embryonic stem cells on three-dimensional polymer scaffolds

Human embryonic stem (hES) cells hold promise as an unlimited source of cells for transplantation therapies. However, control of their proliferation and differentiation into complex, viable 3D tissues is challenging. Here we examine the use of biodegradable polymer scaffolds for promoting hES cell growth and differentiation and formation of 3D structures. We show that complex structures with features of various committed embryonic tissues can be generated, in vitro, by using early differentiating hES cells and further inducing their differentiation in a supportive 3D environment such as poly(lactic-co-glycolic acid)/poly(L-lactic acid) polymer scaffolds. We found that hES cell differentiation and organization can be influenced by the scaffold and directed by growth factors such as retinoic acid, transforming growth factor beta, activin-A, or insulin-like growth factor. These growth factors induced differentiation into 3D structures with characteristics of developing neural tissues, cartilage, or liver, respectively. In addition, formation of a 3D vessel-like network was observed. When transplanted into severe combined immunodeficient mice, the constructs continue to express specific human proteins in defined differentiated structures and appear to recruit and anastamose with the host vasculature. This approach provides a unique culture system for addressing questions in cell and developmental biology, and provides a potential mechanism for creating viable human tissue structures for therapeutic applications.     

利用共培养法诱导人胎盘间充质干细胞向成骨细胞分化

目的观察体外人足月胎盘间充质干细胞(h PMSCs)和成骨细胞共培养体系条件下成骨细胞对h PMSCs分化的影响。方法采用胶原酶消化法从人足月胎盘中分离纯化间充质干细胞(MSCs),检测细胞表面标志物、生长曲线、细胞超微结构及成骨能力并对h PMSCs进行鉴定。共培养组将成骨细胞接种于Transwell双层培养皿底层,h PMSCs接种于上层;对照组上层与底层均接种h PMSCs。对诱导后细胞进行碱性磷酸酶染色鉴定。结果胎盘分离细胞经形态、生长速度、细胞表面标志物(CD44和CD29阳性表达为99%,CD34和CD106为1%),确定为胎盘间充质干细胞;头盖骨分离细胞经碱性磷酸酶染色确定为成骨细胞。采用Transwell共培养h PMSCs和成骨细胞组碱性磷酸酶活性染色阳性率为(21.7±5.3)%,表现成骨细胞特性,对照组染色呈阴性。结论人足月胎盘含MSCs,与其他来源MSCs生物学特性相似,成骨细胞生长过程提供的微环境对h PMSCs分化为成骨细胞具有诱导促进作用。