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。     

人脐带间充质干细胞生物学特性及向类肝细胞的分化

目的: 研究脐带间充质干细胞(umbilical cord-mesenchymal stem cells, UC-MSCs)生物学的特性及向肝细胞分化的可能性.方法:从脐带中分离间充质干细胞, 体外行传代培养, 检测脐带间充质干细胞表面免疫标志、细胞周期和生长活性等, 利用肝细胞生长因子、成纤维生长因子4和抑瘤素等细胞因子诱导脐带间充质干细胞向肝细胞分化, 用免疫细胞方法对诱导和未诱导的细胞进行免疫学检测, 糖原染色进行功能鉴定.结果: 从人脐带中可分离到贴壁生长的间充质干细胞, 细胞形态类似成纤维细胞,可在体外进行长期稳定培养; CD29、CD105和Vimentin表达阳性, 基本不表达CD34、CD31, 经加入细胞因子可成功将间充质干细胞向肝细胞诱导分化, 分化的细胞表达肝细胞表面标志物ALB、AFP、CK18和CK19, 糖原染色呈现阳性.结论:人脐带中可成功分离到间充质干细胞, 细胞可实现体外长期培养, 表达脐带间充质干细胞的表面标志, 在体外脐带间充质干细胞诱导分化为肝细胞, 有望成为细胞替代治疗的理想来源之一.     

人骨髓间充质干细胞体外分化为肝细胞样细胞

目的 探讨人骨髓间充质干细胞(MSCs)的体外培养及特异性诱导为肝细胞样细胞的能力。方法 骨髓标本来源于健康志愿者的胸骨,年龄2～35岁,采用淋巴细胞分离液(密度1.077)分离人MSCs,并分别采用HGF、FGF4、HGF FGF4以及无生长因子四种处理因素体外诱导第三代人MSC向肝细胞样细胞分化。通过流式细胞术分析鉴定.MSCs的纯度,于诱导培养的0、7、14、21、28天时留取细胞检测CK18、AFP和白蛋白的表达情况,同时进行糖原染色验证细胞功能。结果 用淋巴细胞分离液分离出的人MSCs纯度可达90％,采用HGF、FGF4及HGF FGF4三种处理因素均可在体外诱导人MSCs特异分化为具有肝细胞样细胞表型和功能的细胞。结论 人MSCs能在体外扩增并定向诱导为肝细胞样细胞。     

肝脏细胞条件培养基诱导大鼠骨髓间质细胞分化为肝细胞的作用

目的:探讨肝脏细胞条件培养基诱导大鼠骨髓间质细胞分化为肝细胞的作用.方法:从大鼠骨髓中分离纯化培养间质细胞,诱导前24小时加1μg/L碱性成纤维生长因子(bFGF)入培养液中以促进细胞分裂,再以肝脏细胞条件培养基作诱导剂,分别在诱导培养0、7、14、21、28天时,留取细胞,观察细胞形态的变化,并采用免疫细胞化学方法检测肝细胞功能标志物(AFP、白蛋白、CK18)、用PAS法进行糖元染色试验,以验证诱导分化的结果.结果:诱导后3天间质细胞表现为肝细胞样,随着诱导时间的延长,肝细胞功能标志逐渐出现和成熟.AFP在7、14天时表达较高,21、28天时表达显著减少;白蛋白、CK18和糖元随着诱导时间的延长表达逐渐增多.结论:肝脏细胞条件培养基能诱导骨髓间质细胞分化为肝细胞.     

不同诱导条件对大鼠骨髓间充质干细胞体外诱导类肝细胞的影响

目的:探讨实验性大鼠骨髓间充质干细胞(MSCs)体外培养、诱导的最优条件,为MSCs治疗临床重症肝病患者提供参考依据.方法:采用密度梯度离心法和贴壁法分离大鼠MSCs.经培养传代获得纯化的MSCs.采用析因实验,设不同诱导时间、不同浓度的FBS、不同浓度的细胞因子为3个因素,每个因素设不同水平,对纯化的MSCs进行分组诱导培养.留取15、2l、27 d细胞培养液进行白蛋白(A1b)、甲胎蛋白(AFP)检测;于27 d时收集细胞爬片,采用过碘酸希夫(PAs)实验进行糖原染色和免疫细胞化学染色检测MSCs中CK-18和CK-19.结果:诱导15、21、27 d,各MSCs诱导组AFP水平均高于MSCs非诱导组(P＜0.01),21 d诱导组AFP水平最高:15 d各MSCs诱导组与MSCs非诱导组白蛋白水平无统计学意义,21、27d各MSCs诱导组白蛋白水平均高于MSCs非诱导组(P＜0.01),27 d诱导组白蛋白水平最高.27d各MSCs诱导组糖原染色阳性,免疫细胞化学染色CK-18、CK-19均阳性,而MSCs非诱导组糖原染色、CK-18、CK-19均阴性.多因素方差分析表明,Mscs体外最佳诱导条件为含200mL/LFBS的DMEM 肝细胞生长因子(HGF)20Ug/L 成纤维细胞生长因子-4(FGF-4)20UG/L.结论:HGF和FGF-4可在体外诱导实验性大鼠Mscs分化为具有肝细胞样细胞表型和功能的类肝细胞:不同浓度的FBS、HGF和FGF-4影响MSCs的体外分化;MSCs可作为治疗临床重症肝病的一种细胞来源.     

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.     

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。     

脂肪间充质干细胞向肝细胞横向分化的研究

目的探讨脂肪源性间充质干细胞（AMSC）向肝细胞横向分化的可能性。方法胶原酶消化脂肪组织,贴壁培养,体外扩增后以流式细胞仪鉴定其表面标志。取扩增3代的AMSC分为2组,诱导分化组在含有2％FBS的DMEM-F12培养基中加入肝细胞生长因子20 ng/ml和成纤维细胞生长因子4 10 ng/ml、1×ITS和地塞米松0．1μmol/L,培养14 d；空白对照组则不加任何细胞因子。RT-PCR检测诱导分化过程中肝细胞核因子1、GATA4等基因转录水平的变化。2周后,采用流式细胞术检测AFP和Alb阳性细胞在两组细胞中的比例,检测肝细胞特异性细胞角蛋白（CK） 18、CK19的表达。结果分离、培养的AMSC呈成纤维细胞样生长,可以稳定传代。流式细胞术检测结果显示第3代脂肪间充质干细胞高表达表面CD29、CD44；不表达CD34、CD45。RT-PCR检测诱导5、8、11、14 d的细胞,显示有肝细胞特异性转录因子GATA4和肝细胞核因子1A基因的表达,并随时间延长而逐渐增多。流式细胞术检测诱导14 d的细胞,发现30．0％的细胞表达Alb,17．8％细胞表达AFP,双阳性的细胞为6．9％；免疫荧光检测发现诱导细胞表达CK18、CK19。空白对照组脂肪间充质干细胞则未见上述各项变化。结论在低血清培养体系中,采用细胞因子联合诱导,显示脂肪间充质细胞在体外能定向分化为肝细胞样细胞。     

骨形态发生蛋白2在骨髓间充质干细胞向肝细胞分化中的作用

目的：观察骨形态发生蛋白2（BMP2）在骨髓间充质干细胞（BMSCs）向肝细胞分化中的作用。方法采用贴壁法分离培养大鼠股骨BMSCs ,将体外扩增的第3代BMSCs制作细胞爬片,并行肝细胞定向诱导。根据诱导因子不同分为：肝细胞生长因子（ HGF）组、HGF＋BMP2组、BMP2组及空白对照组。培养10 d左右收集细胞,观察各组细胞形态的变化,并采用ELISA法检测培养液上清中肝细胞特异性标志物甲胎蛋白（ AFP）、白蛋白（ ALB）,免疫细胞化学法检测诱导分化后细胞CK-18的表达。结果 HGF组和HGF＋BMP2组可检测到ALB、AFP及CK-18,且HGF＋BMP2组ALB、AFP及CK-18明显高于HGF组（P均＜0．05）。结论 BMP2不能单独诱导BMSCs向肝细胞分化,但能增强HGF诱导BMSCs向肝细胞分化的作用。     

人胎肝非实质间充质干细胞体外诱导分化为类肝细胞

目的体外诱导人胎肝非实质间充质干细胞(NPMSCs)分化为类肝细胞,对类肝细胞进行分子生物学及功能鉴定。方法采用体外细胞培养技术,分离培养人胎肝NPMSCs,在1%基质胶作基质,2.5 mmol/L氮胞苷预处理10～12 h,肝细胞生长因子10μg/L加成纤维细胞生长因子4 10μg/L加肝细胞生长培养基中诱导。用显微摄像和四甲基偶氮唑盐研究细胞增殖及生长特征,用流式细胞仪、免疫组织化学和逆转录聚合酶链反应鉴定细胞表型。采用酶联免疫吸附法检测培养上清液中人Alb水平,过碘酸希夫试验进行糖原染色。结果从人胎肝获得贴壁细胞种植后生长分裂良好,连续传10代后,每份人胎肝NPMSCs可扩增达109个细胞。NPMSCs表型为CD166阳性,CD34阴性。在添加成纤维细胞生长因子4和肝细胞生长因子的基质胶上诱导培养的NPMSCs在21～28 d时,形态由长梭形变为三角形、多角形或类圆形。细胞转圆率为40%,双核细胞比率5%。免疫组织化学和逆转录聚合酶链反应检测显示未诱导培养的NPMSCs中,有较少的细胞表达甲胎蛋白及其mRNA,未见其他肝脏特有的转录因子或者细胞质蛋白标志。诱导早期可见较多细胞表达GATA4、甲胎蛋白和CK18及其mRNA,至诱导后期表达下降,而Alb、CK18、谷胱甘肽S转移酶-π和肝细胞核因子1α表达逐渐上升。Alb、CK18阳性细胞比例达60%。未诱导分化的NPMSCs不分泌Alb,诱导分化的NPMSCs以时间依赖方式产生Alb。NPMSCs诱导14d时首先见到部分细胞出现红紫色染色的糖原积聚物,28 d后阳性染色细胞数量增多。结论在本实验诱导条件下可获得在复制及翻译各环节肝细胞标志阳性的类肝细胞。诱导后NPMSCs已具备肝细胞特有的功能性特征。     

Differentiation of hepatocytoid cell induced from whole-bone-marrow method isolated rat myeloid mesenchymal stem cells

AIM: To explore the expansion and differentiation of hepatocytoid cell induced from myeloid mesenchymal stem cell (MSC) in vitro, in order to find suitable resource of hepatocytes for bioartificial liver or liver transplantation. METHODS: The rat myeloid MSC was isolated and divided into three groups which were cultured by Frieden-steion method, and then were induced by culture fluid, culture fluid plus cholestatic serum and culture fluid plus hepatocyte growth factor (HGF), respectively. Hepatocytoid cell as well as expression of CK18 and AFP was observed by immunohistochemistry. RESULTS: After the induction for 21 d, hepatocytoid cell was observed, and its expression of CK18 and AFP was detected by immunohistochemistry in MSC cultured with cholestatic serum. Furthermore, on the 35th d, albumin mRNA was expressed in the cell, suggesting the inducing effect was similar to that by HGF. CONCLUSION: Rat myeloid MSC can differentiate into hepatocyte lineage under appropriate condition. This method is easy to operate.     

Differentiation of hepatocytoid cell induced from whole-bone-marrow method isolated rat myeloid mesenchymal stem cells

AIM: To explore the expansion and differentiation of hepatocytoid cell induced from myeloid mesenchymal stem cell (MSC)in vitro, in order to find suitable resource of hepatocytes for bioartificial liver or liver transplantation. METHODS: The rat myeloid MSC was isolated and divided into three groups which were cultured by Frieden steion method, and then were induced by culture fluid, culture fluid plus cholestatic serum and culture fluid plus hepatocyte growth factor (HGF), respectively. Hepatocytoid cell as well as expression of CK18 and AFP was observed by immunohistochemistry. RESULTS: After the induction for 21 d, hepatocytoid cell was observed, and its expression of CK18 and AFP was detected by immunohistochemistry in MSC cultured withcholestatic serum. Furthermore, on the 35th d, albumin mRNA was expressed in the cell, suggesting the inducing effect was similar to that by HGF. CONCLUSION: Rat myeloid MSC can differentiate into hepatocyte lineage under appropriate condition. This method is easy to operate.     

Fibroblast growth factor-4 and hepatocyte growth factor induce differentiation of human umbilical cord blood-derived mesenchymal stem cells into hepatocytes

AIM: To investigate the differentiation of human umbilical cord blood (HUCB)-derived mesenchymal stem cells (MSCs) into hepatocytes by induction of fibroblast growth factor-4 (FGF-4) and hepatocyte growth factor (HGF), and to find a new source of cell types for therapies of hepatic diseases. METHODS: MSCs were isolated by combining gradient density centrifugation with plastic adherence. When HUCB-derived MSCs reached 70% confluence, they were cultured in Iscove modified Dulbecco medium (IMDM) supplemented with 10 mL/L FBS, 20 ng/mL HGF and 10 ng/mL FGF-4. The medium was changed every 4 d and stored for albumin, alpha-fetoprotein (AFP) and urea assay. Expression of CK-18 was detected by immunocytochemistry. Glycogen storage in hepatocytes was determined by PAS staining. RESULTS: By combining gradient density centrifugation with plastic adherence, we could isolate MSCs from 25.6% of human umbilical cord blood. When MSCs were cultured with FGF-4 and HGF, approximately 63.6% of cells became small, round and epithelioid on d 28 by morphology. Compared with the control, the level of AFP increased significantly from d 12 to 18.20±1.16 μg/L (t = 2.884, P<0.05) in MSCs cultured with FGF-4 and HGF, and was higher (54.28±3.11 μg/L) on d 28 (t = 13.493, P<0.01). Albumin increased significantly on d 16 (t = 6.68, P<0.01) to 1.02±0.15 μg/mL, and to 3.63±0.30 μg/mL on d 28 (t = 11.748, P<0.01). Urea (4.72±1.03 μmol/L) was detected on d 20 (t = 4.272, P<0.01), and continued to increase to 10.28±1.06 μmol/L on d 28 (t = 9.276,P<0.01). Cells expressed CK-18 on d 16. Glycogen storage was observed on d 24. CONCLUSION: HUCB-derived MSCs can differentiate into hepatocytes by induction of FGF-4 and HGF. HUCB-derived MSCs are a new source of cell types for cell transplantation therapy of hepatic diseases.     

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。     

小鼠骨髓干细胞诱导分化为肝细胞的实验研究

目的探讨成年小鼠骨髓干细胞在肝细胞生长因子(HGF)作用下分化为肝细胞的可能性及其分化特性，为肝细胞移植提供实验基础。方法HGF100ng／ml体外诱导小鼠骨髓干细胞向肝细胞分化，于诱导的第0、7、l4、21、28天，观察细胞形态特征；半定量逆转录聚合酶链反应(RT-PCR)法检测细胞白蛋白(ALB)、甲胎蛋白(AFP)mRNA水平的表达；免疫细胞化学法检测ALB、AFP和细胞角蛋白l9(CK19)蛋白水平的表达。结果新鲜分离的骨髓干细胞ALB及AFP mRNA呈弱阳性。在非诱导组，培养7d时ALB mRNA已检测不到，AFP mRNA明显减弱，14d时消失。在诱导组，7d时ALB mRNA检测不到，14d时再次出现阳性条带，21d时表达量最大，而AFP mRNA在诱导组始终呈阳性，14d时表达量最大，以后逐渐减少。免疫细胞化学结果与RT-PCR结果基本一致，但CK19蛋白始终阴性。结论小鼠骨髓干细胞在HGF单独作用下能诱导分化为肝细胞样细胞，诱导分化的最佳时期是2～3周。     

Selection, proliferation and differentiation of bone marrow-derived liver stem cells with a culture system containing cholestatic serum in vitro

AIM: To explore the feasibility of direct separation, selective proliferation and differentiation of the bone marrow-derived liver stem cells (BDLSC) from bone marrow cells with a culture system containing cholestatic serum in vitro. METHODS: Whole bone marrow cells of rats cultured in routine medium were replaced with conditioning selection media containing 20mL/L, 50mL/L, 70mL/L, and 100mL/L cholestatic sera, respectively, after they attached to the plates. The optimal concentration of cholestatic serum was determined according to the outcome of the selected cultures. Then the selected BDLSC were induced to proliferate and differentiate with the addition of hepatocyte growth factor (HGF). The morphology and phenotypic markers of BDLSC were characterized using immunohistochemistry, RT-PCR and electron microscopy. The metabolic functions of differentiated cells were also determined by glycogen staining and urea assay. RESULTS: Bone marrow cells formed fibroblast-like but not hepatocyte-like colonies in the presence of 20mL/L cholestatic serum. In 70mL/L cholestatic serum, BDLSC colonies could be selected but could not maintain good growth status. In 100mL/L cholestatic serum, all of the bone marrow cells were unable to survive. A 50mL/L cholestatic serum was the optimal concentration for the selection of BDLSC at which BDLSC could survive while the other populations of the bone marrow cells could not. The selected BDLSC proliferated and differentiated after HGF was added. Hepatocyte-like colony-forming units (H-CFU) then were formed. H-CFU expressed markers of embryonic hepatocytes (AFP, albumin and cytokeratin 8/18), biliary cells (cytokeratin 19), hepatocyte functional proteins (transthyretin and cytochrome P450-2b1), and hepatocyte nuclear factors (HNF-1α and HNF-3β). They also had glycogen storage and urea synthesis functions, two of the critical features of hepatocytes. CONCLUSION: The selected medium containing cholestatic serum can select BDLSC from whole bone marrow cells. It will be a new way to provide a readily available alternate source of cells for clinical hepatocyte therapy.     

Rat bone marrow mesenchymal stem cells differentiate into hepatocytes in vitro

AIM: To investigate the mechanism and regulation of differentiation from bone marrow mesenchymal stem cells (MSCs) into hepatocytes and to find a new source of cell types for therapies of hepatic diseases. METHODS: MSCs were isolated by combining gradient density centrifugation with plastic adherence. The cells were cultured in osteogenic or adipogenic differentiation medium and determined by histochemical staining. MSCs were plated in plastic culture flasks that were not coated with components of extracellular matrix (ECM). When MSCs reached 70% confluence, they were cultured in low glucose Dulbecco's modified Eagle's medium supplemented with 10 mL/L fetal bovine serum, 20 ng/mL hepatocyte growth factor (HGF) and 10 ng/mL fibroblast growth factor-4 (FGF-4). The medium was changed every 3 d and stored for albumin, alpha-fetoprotein (AFP) and urea assay. Glycogen store of hepatocytes was determined by periodic acid-Schiff staining. RESULTS: By combining gradient density centrifugation with plastic adherence, we isolated a homogeneous population of cells from rat bone marrow and differentiated them into osteocytes and adipocytes. When MSCs were cultured with FGF-4 and HGF, approximately 56.6% of cells became small round and epithelioid on d 24 by morphology. Compared with the control, levels of AFP increased significantly from d 12 to 15.5±1.4 μg/L (t = 2.31,P<0.05) in MSCs cultured with FGF-4 and HGF, and were higher (46.2±1.5 μg/L) on d 21 (t = 41.926, P<0.01), then decreased to 24.8±2.2 μg/L on d 24 (t = 10.345, P<0.01). Albumin increased significantly on d 21 (t = 3.325,P<0.01) to 1.4±0.2 μg/mL, and to 2.1±0.7 μg/mL on d 24 (t= 3.646, P<0.01). Urea (2.3±0.4 mmol/L) was first detected on d 21 (t= 6.739, P<0.01), and continued to increase to 2.6±0.9 mmol/L on d 24 (t = 4.753, P<0.01). Glycogen storage was first seen on d 21. CONCLUSION: The method combining gradient density centrifugation with plastic adherence can isolate MSCs. Rat MSCs may be differentiated into hepatocytes by FGF-4 and HGF. Cytokines may play a more important role in differentiation from rat MSCs into hepatocytes.     

Human skin fibroblasts: From mesodermal to hepatocyte-like differentiation

The phenotypic homology of fibroblasts and mesenchymal stem cells (MSCs) has been recently described. Our study investigated the in vitro potential of human skin fibroblasts to differentiate into mesodermal (osteocyte and adipocyte) and endodermal (hepatocyte) cell lineages by comparison with human bone marrow (hBM) MSCs. The endodermal potential of fibroblasts was then explored in vivo in a mouse model of liver injury. Fibroblasts were able to acquire osteocyte and adipocyte phenotypes as assessed by cytochemistry and gene expression analyses. After exposure to a specific differentiation cocktail, these cells presented hepatocyte-like morphology and acquired liver-specific markers on protein and gene expression levels. Furthermore, these fibroblast-derived hepatocyte-like cells (FDHLCs) displayed the ability to store glycogen and synthesize small amounts of urea. By gene expression analysis, we observed that fibroblasts remained in a mesenchymal-epithelial transition state after hepatocyte differentiation. Moreover, FDHLCs lost their hepatocyte-like phenotype after dedifferentiation. In vivo, human fibroblasts infused directly into the liver of hepatectomized severe combined immunodeficient (SCID) mice engrafted in situ and expressed hepatocyte markers (albumin, alpha-fetoprotein, and cytokeratin 18) together with the mesodermal marker fibronectin. Despite lower liver-specific marker expression, the in vitro and in vivo differentiation profile of fibroblasts was comparable to that of mesenchymal-derived hepatocyte-like cells (MDHLCs). In conclusion, our work demonstrates that human skin fibroblasts are able to display mesodermal and endodermal differentiation capacities and provides arguments that these cells share MSCs features both on the phenotypic and functional levels.