含淤胆血清的培养体系体外诱导胚胎干细胞表达肝细胞功能的研究

目的探讨病理微环境体外诱导对小鼠胚胎干细胞(ESC)表达肝细胞功能的作用。方法悬滴培养ESC发育5～7d的拟胚体，将其离散细胞种植于不同的分化体系，观察ESC在自主分化、肝细胞生长因子(HGF)或5％淤胆血清 HGF诱导下每天的分化情况(倒置相差显微镜)，以及细胞的糖原、甘油三酯、白蛋白及尿素氮合成功能，细胞吲哚氰绿(ICG)和荧光二乙酯(FDA)染色的情况。结果ESC自主分化难以控制，分化为3个胚层的细胞。HGF促进ESC向内脏内胚层和中胚层(心肌)分化，但两者仅能表达低水平的肝细胞特异性功能。引入淤胆血清的HGF诱导体系中ESC能分化为较为均一的多角形细胞，具有较高水平的糖原、甘油三酯、白蛋白和尿素氮合成能力，ICG和FDA染色阳性。结论自主分化和HGF诱导ESC表达肝细胞代谢的能力有限。体外模拟病理性微环境可诱导ESC定向分化为肝系细胞，并具有较高水平的肝细胞代谢功能。     

aFGF、HGF体外诱导小鼠ESC向肝细胞定向分化及标志物研究

目的观察酸性成纤维细胞生长因子(acid fibroblast growth factor,a FGF)、肝细胞生长因子(hepatocyte growth factor,HGF)对小鼠胚胎干细胞(embryonic stem cell,ESC)体外定向诱导分化作用及诱导后肝细胞标志物的表达水平。方法体外培养小鼠ESC使其发育成拟胚体,然后加入a FGF、HGF诱导ESC定向分化成肝细胞。收集培养上清液,RIA法测定甲胎蛋白(alpha fetoprotein,AFP)、白蛋白(albumin,ALB)浓度。PCR和免疫印迹法检测ALB、细胞角蛋白8(CK8)以及细胞角蛋白18(CK18)在细胞内mRNA和蛋白表达水平。结果 ESC培养5 d后发育成为拟胚体,加入不同浓度a FGF继续培养,5 d后AFP浓度降低,ALB浓度升高,与对照组相比有显著性差异。细胞内ALB、CK8及CK18表达水平明显升高。一次诱导后加入HGF,继续诱导5 d,上清液中AFP浓度降低,ALB浓度升高,具有浓度依赖性。ALB、CK8及CK18在细胞内表达升高。结论体外培养小鼠ESC,加入a FGF、HGF后可诱导其向肝细胞定向分化。肝细胞标志物AFP水平明显降低,ALB、CK8以及CK18表达水平明显升高。     

骨形态发生蛋白和白血病抑制因子诱导肝干细胞分化

目的 在永生化的小鼠肝干（祖）细胞(HP)模型上筛选并优化高效的肝细胞定向分化诱导方法,探讨HP向肝细胞定向分化过程及分子机制。 方法分别采用含人白血病抑制因子(LIF)、骨形态发生蛋白(BMP)2和BMP9基因的重组腺病毒感染HP,在病毒感染后第4天、第7天和第10天用糖原染色和吲哚花青绿(ICG)摄取实验观察HP的分化成熟度,并在第4、7、10、14天通过检测白蛋白启动子调控的荧光素酶报告基因活性,观察细胞合成白蛋白情况。计量资料比较用t检验。结果 BMP2和BMP9对HP的诱导作用最强,荧光素酶活性、PAS染色和ICG摄取细胞阳性率随诱导时间的延长明显上升,在诱导后第7天最高,HP对BMP9的诱导应答最强,与对照组相比,酶活性增加了近9倍（t=17.30,P＜0.01）,BMP2处理组增加了5倍（t=16.41,P＜0.01）,LIF处理组增加了3倍（t=6.04,P＜0.01）。诱导第7天时,PAS染色细胞阳性率在BMP2和BMP9组分别为30％和45％; ICG细胞阳性率在BMP2和BMP9组分别为40％和30％。LIF诱导后,PAS染色、ICG摄取细胞阳性率以及荧光素酶活性有一定增加。结论 BMP2、BMP9和LIF能够诱导HP向发育晚期肝细胞分化,并初步具备成熟肝细胞的一些功能。     

体外诱导人脐血间充质干细胞向肝细胞样细胞分化的研究

目的 探讨人脐血间充质干细胞能否在体外诱导分化为肝细胞样细胞,并探索其定向诱导分化为肝细胞样细胞的分化机制。方法 无菌条件下采集正常产妇脐血,用相对密度为1.077的淋巴细胞分离液分离脐血MNC,进而采用贴壁培养法获得MSC,流式细胞仪检测其表面际志。分别用HGF、FGF4、俩者联合、无生长因子四种处理因素,及含2％FBS的DMEM,1×ITS讲行诱导培养,并于诱导前及诱导后的第7、14、21、28天留取细胞,RT～PCR法检测AFP、白蛋白及C-met FGFR2mRNA的表达,免疫细胞化学法检测AFP、白蛋白、抗肝细胞抗体和CK18的表达,PAS法进行糖原染色,分析是否诱导出肝细胞样细胞。结果 MSC强表达CD29、CD44,不表达CD34。诱导后7,21天分别检测出AFP,白蛋白mRNA及蛋白的表达,28天检测出CK18、抗肝细胞抗体的表达,21天、28天均可检测到糖原染色阳性细胞,随诱导时间的延长C-met,FGFR2 mRNA表达增高,HGF FGF4诱导组肝系细胞标志阳性率均高于单独生长因子诱导组(P<0.05);单独生长因子诱导组间无明显差异(P>0.05)。无生长因子诱导组在以上时间点均未检测到上述指标。结论HGF、FGF4均能诱导人脐血MSC分化为具有肝系细胞表型和功能的细胞,且二者在一定程度上有联合作用。生长因子与其相幢受体之间,可能存在正反馈调节机制。     

小鼠骨髓基质干细胞的鉴定及体外诱导分化为肝细胞的可行性

目的:分离、鉴定小鼠骨髓基质干细胞(MSCs)并探讨在体外多种细胞因子的诱导下分化为肝细胞的可行性.方法:获取小鼠骨髓干细胞,进行体外贴壁培养、纯化,观察不同传代次数细胞形态特点.流式细胞法检测不同传代细胞的表面标志物CD45和CD90.分离后的MSCs再经含有HGF,FGF-4,EGF三种细胞因子的诱导体系继续培养21 d,分别以半定量逆转录聚合酶链反应(RT-PCR)和Western blot方法检测诱导后细胞的白蛋白(ALB)、细胞角化蛋白18(Cg18)、以及甲胎蛋白(AFP)在基因和蛋白水平的表达.结果:培养的骨髓干细胞随传代次数增多细胞形态趋向为长梭形.传代到第5代,基质干细胞的表面标志CD90阳性细胞从原代的25.42%增加到93.47%,造血干细胞的表面标志CD45表达阳性细胞从原代的86.49%降低到2.77%.通过RT-PCR可检测出诱导第7天细胞表达AFP mRNA,ALB mRNA及CK18 mRNA;通过Western blot可检测出诱导第21天的细胞表达ALB和CK18.结论:小鼠MSCs可以在体外被有效地分离纯化,可以被诱导为表达肝细胞表面标志的肝细胞样细胞.     

曲古菌素A联合细胞因子体外诱导小鼠胚胎干细胞分化为肝细胞

目的:建立细胞因子和曲古菌素A(trichostatin A,TSA)联合诱导小鼠胚胎干细胞(embryonic stem cell,ESC)向肝细胞分化的3步法.方法:ESC在含激活素A的不含白血病抑制因子的培液中培养3 d分化为定形内胚层细胞;然后加入酸性成纤维细胞生长因子和T S A联合诱导5 d,再加入肝细胞生长因子(hepatocyte growth factor,HGF)等诱导因子培养5 d,向肝细胞方向分化,最后以致瘤素M、地塞米松继续培养5 d形成成熟肝细胞.自发分化组做阴性对照组不加上述因子,不含白血病抑制因子(leukemia inhibitory factor,LIF)的培养液进行自发分化培养.结果:诱导分化18 d后,用光镜、免疫荧光、RT-PCR检测显示诱导18 d后,出现了大量类肝脏细胞表型的上皮细胞,RT-PCR检测显示这些细胞表达成体肝脏细胞特异标记如酪氨酸转氨酶、白蛋白(albumin,ALB)、天冬氨酸转氨酶、甲状腺激素结合蛋白等.细胞免疫荧光也显示为甲胎蛋白、ALB、细胞角蛋白18阳性,分化细胞具有成熟肝脏细胞所具有的糖原储存、吲哚菁绿摄取和释放功能.其分化效率用ALB阳性率表示,诱导分化率可达57.38%.结论:组蛋白去乙酰化酶抑制剂TSA联合细胞因子体外诱导ESC可以成功分化为肝细胞,从而为体外获得大量肝细胞对肝病的临床细胞移植治疗及其研究提供理论和实践基础.     

共同培养诱导骨髓基质干细胞向肝细胞分化的研究

目的 探索大鼠骨髓皋质干细胞（MsCS）向肝细胞分化的能力，及肝细胞生长的微环境埘其诱导分化的作用。方法 采用梯度离心法，获取大鼠骨髓基质干细胞；改良的两步法获取大鼠肝细胞。将鉴定的MsCS和肝细胞以半透膜相隔共同培养，以单独培养的MSCs作对照。在第1、3、7．14．21、28天，分别以逆转录聚合酶链反应（RT-PCR）和免疫细胞化学分析检测甲胎蛋白（AFP）、白蛋白、细胞角蛋白l8（CK-l8）的基因和蛋白表达。结果在MSCs与肝细胞共同培养过程中，MSCs出现明显的细胞形态、体积和数量变化，可见双核或多核细胞，细胞轮廓较清晰。RT-PCR检测：共同培养的MSCs第7天即出现AFP基因表达，第14天表达增强，第21天表达减弱；第14天开始出现白蛋白、CK-18基因表达，并持续表达。单独培养的MSCs均无表达。共同培养的MSCs，于第7天进行免疫细胞化学检测，AFP即呈阳性；第14天白蛋白和CK-18也呈阳性；单独培养的MSCs未见AFP、白蛋白及CK-18表达。结论 大鼠骨髓基质干细胞与肝细胞共同培养，可被诱导分化为肝细胞。     

肝细胞条件培养液对人脂肪问充质干细胞向肝细胞分化和增殖的作用

目的 探讨人脂肪间充质干细胞在改良的诱导体系下向肝细胞的分化和增殖情况,为肝组织工程提供新的种子细胞来源.方法 从人脂肪组织分离出脂肪间充质干细胞,用含有碱性成纤维细胞生长因子、肝细胞生长因子、成纤维细胞生长因子-4的肝细胞诱导液进行诱导,并于诱导7 d后加入抑瘤素M.用细胞计数试剂盒-8法检测整个诱导过程细胞的增殖情况;通过光学显微镜观察诱导细胞的形态变化;用RT-PCR法和免疫荧光法分别检测肝细胞特异性基因和蛋白的表达;并对多种肝细胞特异性功能进行检测.组间比较采用t-test检验.结果 用改良肝细胞诱导液培养的人脂肪间充质干细胞在培养第5、7、14、21天时,细胞数均明显多于用对照培养液培养的细胞(f值分别为6.59、8.69、15.94和24.64,P值均＜0.05).诱导细胞表现出上皮样肝细胞形态,表达肝细胞特异性基因和蛋白;具有多种肝细胞特异性功能,如靛青绿摄取/排泌、糖原合成以及白蛋白分泌功能.结论 人脂肪间充质干细胞在含碱性成纤维细胞生长因子、肝细胞生长因子、成纤维细胞生长因子-4和抑瘤索M的诱导体系中能够分化为更加成熟的具有多种肝细胞特异性功能的细胞,且此诱导体系同时具有促进细胞增殖的作用.     

生物反应器内EBs来源细胞的肝细胞分化与成熟

目的 观察微重力生物反应器内拟胚体(EBs)来源细胞的肝细胞分化与成熟.方法 将未分化鼠胚胎干细胞(ES细胞)以1×106/mL移入微重力反应器内,在DMSO、地塞米松、FGF4、HGF等刺激作用下,进行15 d的旋转培养.采用ELISA法动态检测培养液中鼠白蛋白的产生量.培养结束时转移EBs于载玻片和培养板,分别检测EBs来源细胞的糖原储存和对靛青绿(ICG)、荧光素标记低密度脂蛋白(DiI-Ac-LDL)的摄取能力.结果 在生物反应器旋转培养的第5、10 d,未从培养液中检出特异的鼠白蛋白,而在第15 d的培养液中检出一定量的鼠白蛋白.与原代培养的成熟肝细胞一样,转种的EBs来源细胞periodic acid-Schiff(PAS)糖原染色阳性,ICG摄取试验阳性,DiI-Ac-LDL摄取试验阳性.未分化的ES细胞均呈阴性.结论 微重力生物反应器不仅能加快EBs的形成与肝细胞分化,而且能促进分化肝细胞的成熟.     

肝细胞生长因子联合成纤维细胞生长因子-4诱导人骨髓来源的多能成体祖细胞向肝样细胞分化

目的 探索肝细胞生长因子（HGF）-4成纤维生长因子4-（FGF-4）诱导人骨髓来源多能成体祖细胞（hMAPCs）分化为肝细胞的可行性，为肝组织工程提供新的种子细胞来源。方法 （1）取志愿者适量骨髓后采用梯度密度离心＋贴壁培养获取骨髓间充质干细胞（MSCs），将MSCs通过CD45、GlyA免疫微磁珠负分选得到hMAPCS。（2）将hMAPCs用HGF＋FGF-4进行诱导分化。实验分组：A组：HGF（20ng／m1）＋（FGF-4）10ng／m1诱导hMAPCS；B组（阳性对照组）：L-02人肝细胞株；C组（阴性对照组）：未加任何诱导因素的hMAPCs。（3）免疫细胞化学鉴定不同诱导分化阶段细胞的白蛋白（A1b）、甲胎蛋白（AFP），细胞角蛋白-18（CK-18）等肝细胞特征的表型变化评计数阳性细胞比率。（4）逆转录-聚合酶链反应检测不同诱导分化阶段细胞的A1b、AFP，CK-18的mRNA转录。（5）Western blot检测诱导分化第21，35天后细胞的A1b表达。结果（1）免疫细胞化学结果：A1b、CK18在诱导组中不同时间段基本为阳性着色；AFP在诱导分化第7天为阳性着色，在诱导第14，21天为阴性着色。（2）逆转录聚合酶链反应结果：作为不成熟肝细胞表型的AFP，在诱导分化的第7天有mRNA阳性表达；作为成熟肝细胞表型的A1b及CK-18，在不同时间段mRNA均为阳性表达。（3）Western blot检测诱导分化第21、35天后细胞的A1b表达。结论hMAPCS在一定诱导条件下具有向肝样细胞分化的潜能。     

转基因肝星状细胞株对肝细胞生长的支持作用

目的 探讨转基因肝星状细胞株CFSC／HGF对大鼠肝细胞生长的支持作用。方法将大鼠原代肝细胞培养于稳定表达肝细胞生长因子(HGF)的肝星状细胞株CFSC／HGF所构建的饲养层上,连续动态观察肝细胞的形态、超微结构、白蛋白分泌、尿素合成以及吲哚氰绿摄取排泌功能的变化,同时与传统胶原贴壁培养的肝细胞进行比较,并通过半定量逆转录聚合酶链反应(RT-PCR)检测HGF受体c-Met表达的变化。结果共培养的肝细胞体外培养至7～10d时细胞增殖、白蛋白分泌及尿素合成达到峰值,以后逐渐下降,至35d时仍保持一定的存活和功能。与传统胶原上培养的肝细胞相比,其寿命、形态和功能的维持时间明显延长;RT-PCR结果显示,与CFSC／HGF饲养层细胞共培养1周后,肝细胞表面c-Met表达上调2．23倍。结论转基因肝星状细胞株CFSC／HGF对肝细胞较长时间内保持高活性、高密度的生长有显著的支持作用,CFSC／HGF诱导的肝细胞表面c-Met表达上调可能参与了该支持作用。     

Embryonic stem cell-derived endothelial cells may lack complete functional maturation in vitro

Stem cell therapies will only become clinically relevant if the stem cells differentiated in vitro function as their in vivo counterparts. Here, we employed our previously developed techniques for deriving endothelial cells (>96% purity) from mouse embryonic stem cells (ESC) and compared these with mouse aortic endothelial cells (MAEC) obtained from thoracic aortas. Immunocytochemical analysis of ESC-derived endothelial cells (EC) demonstrates that both cell types are positive for the EC markers endothelial nitric oxide synthase (eNOS), Flk-1, Flt-1, vascular endothelial cadherin (VEcad), platelet-endothelial cell adhesion molecule-1 (PECAM-1), and CD34. However, ESC-derived EC express slightly lower levels of PECAM-1 and VE-cadherin, and significantly lower levels of acetylated low-density lipoprotein (LDL) uptake and von Willebrand factor. Although ESC-derived EC do express VE-cadherin, the VE-cadherin in the ESC-derived EC did not localize as well at the cell-cell junctions as in the MAEC. Interestingly, ESC-derived EC express much greater levels of the endothelial and hematopoietic stem cell marker CD34 and vasculogenic and angiogenic sprouting than MAEC. These results indicate that ESC-derived EC share some key characteristics of 'mature' EC, while retaining markers of alternate phenotypes including immature endothelium.     

Direct measurement of hepatic indocyanine green clearance with near-infrared spectroscopy: Separate evaluation of uptake and removal

We continuously measured hepatic absorbance of indocyanine green (ICG) using near-infrared (NIR) spectroscopy after intravenous bolus injection in rabbits. Hepatic ICG concentration was obtained by subtracting out the absorbance of hemoglobin and other pigments within the liver. Two exponential rate constants, the first reflecting the dye uptake from plasma to the hepatocytes, and the second representing the dye removal from the liver by cytoplasmic transport and biliary excretion, were determined by fitting the time-course curve of hepatic ICG concentration to a two-compartment model with irreversible transfer between the two compartments, as defined by the double-exponential equation: [ICG]_liver(t) = -A exp(-alpha t) + B exp(-beta t). The results showed that treatment with bilirubin, a competitive inhibitor of ICG uptake, caused a decrease in alpha. Treatment with either colchicine, which is toxic to microtubules, or with ouabain, an inhibitor of Na⁺,K⁺-ATPase, caused a decrease in beta. These results were compatible with the kinetic model. This new method was then used in liver-injured rabbits inflicted with hemorrhagic shock and ischemia-reperfusion, to show that the first rate constant is primarily affected by hepatic microcirculatory condition, and the second refers closely to parenchymal liver damage. In another series of partial liver ischemia- reperfusions, it was possible to simultaneously and separately monitor the ICG profiles of post-ischemic and nonischemic areas. Thus, the kinetic analysis of hepatic ICG concentration curves, as directly measured by NIR spectroscopy, led to the separate evaluation of different clearance process of ICG in the liver, suggesting the advanced utility as a comprehensive liver function test. (Hepatology 1996 Jan;23(1):137-44)     

Rapid effects of lipopolysaccharides on indocyanine green clearance in rat liver

BACKGROUND: Lipopolysaccharides (LPSs) are thought to be one of the triggers of organ reactions to sepsis, which causes hepatocellular dysfunction. This dysfunction can be demonstrated by a reduction of organic anion transport. The aim of our study was to assess whether the transport of indocyanine green (ICG) is affected by LPS, and whether Kupffer cells are involved. METHODS: Single-pass liver perfusion with ICG at a concentration of 57.8 mg/kg/min was performed for 130 min. pH, oxygen tension and perfusion pressure were continuously measured in influent and effluent. Taurocholate was infused at 48.3 mg/kg/min to achieve a stable bile flow. LPS was added at concentrations of 0.45, 0.9 and 1.44 mg/kg/min for 30 min. ICG was determined photometrically in perfusate and bile. To depress the function of Kupffer cells male Wistar rats were treated with GdCl3 24 h in advance. Primary cultured hepatocytes were used for studying the direct effect of LPS on the uptake rate of ICG. RESULTS: Forty-five minutes after administration of LPS a significant dose-dependent decrease of ICG uptake was seen in animals treated with LPS. Livers of animals pretreated with GdCl3 did not show this decrease. LPS had no direct effect on the uptake of ICG into primary cultured hepatocytes, whereas treatment of these cells with 8-bromo-cGMP resulted in a significant increase of ICG uptake. CONCLUSION: LPS has a rapid dose-dependent effect on the detoxification properties of the liver for ICG. The rapid effect of LPS on ICG uptake in hepatocytes is mediated by Kupffer cells.     

Hematopoietic differentiation of rhesus monkey embryonic stem cells

Several lines of embryonic stem cells (ESC) have been established from rhesus monkey blastocysts. We have examined two of these cell lines for their potential for generating hematopoietic progenitors in cell culture, and we identified culture conditions, including supplementation with bone morphogenetic proteins (BMP), that result in hematopoietic differentiation of rhesus ESC with high efficiency. We have also characterized the resulting hematopoietic progenitor cells for their patterns of gene expression, as compared to those of hematopoietic progenitor cells harvested from rhesus monkey bone marrow. Of more than 60 genes examined in this manner, CD34+/CD38- cells derived from embryonic stem cells and those obtained from bone marrow demonstrated very similar patterns of gene expression. However, with integrin alphaL, IL-6 receptor, and flt-3 gene expression was greatly diminished or absent in CD34+/CD38- cells derived from the ESC, whereas the bone marrow-derived progenitors showed substantial expression of all of these genes. When the same type of comparison was done with mouse (D3 and CCE) as well as human (H1) embryonic stem cells, in each case comparing ESC-derived hematopoietic progenitors with those harvested from bone marrow, the only consistent deficiency of gene expression was that of flt-3. In hematopoietic precursors derived from mouse ESC, globin-gene expression has previously been shown to be a useful index of the embryological maturity of the cells, and we also examined globin-gene expression in rhesus monkey ESC-derived hematopoietic precursor cells, using a semiquantitative technique. CD34+/CD38- cells demonstrated expression of the epsilon- and gamma-globin genes, but negligible levels of beta globin, suggesting that these cells were at the developmental stage in which the yolk sac and fetal liver are the primary sites of hematopoiesis.     

Efficient generation of functional hepatocytelike cells from mouse liver progenitor cells via indirect co-culture with immortalized human hepatic stellate cells

BACKGROUND: Differentiation of liver progenitor cells(LPCs) to functional hepatocytes holds great potential to develop new strategies for hepatocyte transplantation and the screening of drug-induced cytotoxicity. However, reports on the efficient and convenient hepatic differentiation of LPCs to hepatocytes are few. The present study aims to investigate the possibility of generating functional hepatocytes from LPCs in an indirect co-culture system.METHODS: Mouse LPCs were co-cultured in Transwell plates with an immortalized human hepatic stellate cell line(HSCLi) we previously established. The morphology, expression of hepatic markers, and functions of mouse LPC-derived cells were monitored and compared with those of conventionally cultured LPCs. RESULTS: Co-culturing with HSC-Li cells induced differentiation of mouse LPCs into functional hepatocyte-like cells. The differentiated cells were morphologically transformed into hepatocyte-like cells 3 days after co-culture initiation. In addition, the differentiated cells expressed liver-specific genes and possessed hepatic functions, including glycogen storage, lowdensity lipoprotein uptake, albumin secretion, urea synthesis, and cytochrome P450 1A2 enzymatic activity.CONCLUSIONS: Our method, which employs indirect co-culture with HSC-Li cells, can efficiently induce the differentiation of LPCs into functional hepatocytes. This finding suggests that this co-culture system can be a useful method for the efficient generation of functional hepatocytes from LPCs.