Differentiation of human embryonic stem cells to hepatocytes using deleted variant of HGF and poly-amino-urethane-coated nonwoven polytetrafluoroethylene fabric

Human embryonic stem (hES) cells have recently been studied as an attractive source for the development of a bioartificial liver (BAL). Here we evaluate the differentiation capacity of hES cells into hepatocytes. hES cells were subjected to suspension culture for 5 days, and then cultured onto poly-amino-urethane (PAU)-coated, nonwoven polytetrafluoroethylene (PTFE) fabric in the presence of fibroblast growth factor-2 (bFGF) (100 ng/ml) for 3 days, then with deleted variant of hepatocyte growth factor (dHGF) (100 ng/ml) and 1% dimethyl sulfoxide (DMSO) for 8 days, and finally with dexamethasone (10(-7) M) for 3 days. The hES cells showed gene expression of albumin in a time-dependent manner of the hepatic differentiation process. The resultant hES-derived hepatocytes metabolized the loaded ammonia and lidocaine at 7.8% and 23.6%, respectively. A million of such hepatocytes produced albumin and urea at 351.2 ng and urea at 7.0 microg. Scanning electron microscopy showed good attachment of the cells on the surface of the PTFE fabric and well-developed glycogen rosettes and Gap junction. In the present work we have demonstrated the efficient differentiation of hES cells to functional hepatocytes. The findings are useful to develop a BAL.     

Hepatic differentiation of mouse iPS cells in vitro

Induced pluripotent stem (iPS) cells are pluripotent and are able to unlimitedly proliferate in vitro. This technical breakthrough in creating iPS cells from somatic cells has noteworthy implications for overcoming the immunological rejection and the ethical issues associated with the derivation of embryonic stem cells from embryos. In the current work, we present an efficient hepatic differentiation of mouse iPS cells in vitro. iPS cells were cultured free floating to induce the formation of embryoid bodies (EB) for 5 days. EB were transferred to a gelatin-coated plate and treated with 100 ng/ml activin A and 100 ng/ml basic fibroblast growth factor (bFGF) for 3 days to induce definitive endoderm. Cells were further cultured for 8 days with 100 ng/ml hepatocyte growth factor (HGF) to generate hepatocytes. Characterization was performed by RT-PCR assay. Functional analysis for albumin secretion and ammonia removal was also carried out. iPS cell-derived hepatocyte-like cells (iPS-Heps) were obtained at the end of the differentiation program. Expression levels of a gestational hepatocyte gene and lineage-specific hepatic genes intensified in iPS-Heps. The production of albumin increased in a time-dependent manner. iPS-Heps were capable of metabolizing ammonia. We present here instant hepatic differentiation of mouse iPS cells using combined 3-day treatments of activin A and bFGF with subsequent 8-day HGF. Our study will be an important step to generate hepatocytes from human iPS cells as a new source for liver-targeted cell therapies.     

Transplantation of human hepatocytes cultured with deleted variant of hepatocyte growth factor prolongs the survival of mice with acute liver failure

BACKGROUND: Considering the scarcity of donor livers, it is extremely important to establish a functional culture method for isolated hepatocytes. As a tool for maintaining hepatocyte functions in vitro, dHGF, a variant of HGF (hepatocyte growth factor) with a deletion of five amino acids, attracted our attention because it is less cytotoxic compared with HGF. METHODS: We evaluated growth, albumin production, metabolizing abilities of ammonia, lidocaine, and diazepam of human hepatocytes in the presence of dHGF (10-1000 ng/ml). The gene expression of liver markers was comparatively analyzed. The effect of intrasplenic transplantation of dHGF-treated human hepatocytes into severe combined immunodeficient (SCID) mice was evaluated in an acute liver failure (ALF) model induced by D-galactosamine (D-gal). RESULTS: When 100 ng/ml of dHGF was utilized, metabolism rates of ammonia, lidocaine, and diazepam and albumin production per unit cell significantly increased. The gene expression analysis demonstrated the enhanced expression of albumin, HNF-4alpha, and C/EBPalpha in the hepatocytes treated with 100 ng/ml of dHGF. Transplantation of such hepatocytes prolonged the survival of the SCID mice with ALF induced by D-gal. CONCLUSIONS: The present work clearly demonstrates the usefulness of dHGF (100 ng/ml) for maintaining the differentiated functions of human hepatocytes in tissue culture.     

Comparative analysis of endoderm formation efficiency between mouse ES cells and iPS cells

Definitive endoderm (DE) derived from stem cells holds potential to differentiate into hepatocytes. Stem cell therapy using those cells has potential for a treatment of liver disease. To date, various ways of inducing hepatocytes from embryonic stem (ES) cells have been reported by researchers. However, it has not been proved enough that induced pluripotent stem (iPS) cells behave in the same manner as ES cells in endoderm differentiation. The purpose of this study was to establish an efficient method to induce DE from iPS cells, through comparatively analyzing the efficacy of endoderm formation from mouse ES cells. Furthermore, the efficiency of a serum-free medium in the differentiation into DE was investigated. Mouse ES cells and iPS cells were floated in culture medium for 2 or 5 days and embryoid bodies (EB) were formed. Subsequently, DE was induced with 100 ng/ml activin A and 100 ng/ml basic fibroblast growth factor (bFGF). RT-PCR and real-time PCR analyses were carried out at each step to determine the gene expression of EB markers. The difference in cellular proliferation between serum-containing and serum-free media was examined by an MTS assay in EB and DE induction. iPS cells showed the paralleled mRNA expression to ES cells in each step of differentiation into EB, but the levels of expression of Sox17 and Foxa2 were relatively higher in ES cell-derived DE, whereas Cxcr4 expression was higher in iPS cell-derived DE. The utilization of serum-free medium for iPS cells showed significantly favorable cellular proliferation during EB formation and subsequent DE induction. Forming EB for 5 days and subsequently DE induction with activin A and bFGF with serum-free medium was an appropriate protocol in iPS cells. This may represent an important step for generating hepatocytes from iPS cells for the development of cell therapy.     

Deleted form of hepatocyte growth factor ameliorates the mortality rate of severe thermal injury in rats

BACKGROUND: The modulating effects of the deleted form of hepatocyte growth factor (dHGF) on burn-induced mortality rates and hepatic protein synthesis were studied in rats. METHODS: Rats were anesthetized, subjected to a 40% full-thickness scald burn, and divided into 2 groups receiving dHGF and vehicle. RESULTS: In normal rats, dHGF-treatment (1 mg/kg intravenously, twice daily) for 5 days increased the circulating plasma volume. In burned rats that were receiving vehicle, the survival rate on day 23 after the burn was 27%. The serum albumin levels were decreased and did not reverse to the normal levels until day 23 after the burn. Serum alpha 2-concentration in the injured rats was increased, whereas serum levels of transferrin, total protein, and high-density lipoprotein-cholesterol were decreased. The treatment of animals with dHGF (1 mg/kg intravenously, 3 times daily) for 3 days increased the survival rate on day 23 by 64%. In the animals treated with dHGF for 3 or 6 days, serum alpha 1-, alpha 2-, and beta-globulin concentrations were increased by the dHGF treatment. The serum levels of albumin, transferrin, total protein, and high-density lipoprotein-cholesterol reversed to normal levels or higher. CONCLUSIONS: Our data show that dHGF treatment may attenuate the decrease of the circulating plasma volume after burn and reduce a high risk of burn shock. It is also indicated that dHGF accelerates synthesis of not only acute-phase reactants but also other hepatic proteins such as albumin and transferrin on severe burn injury. These findings suggest that the appropriate upregulation of hepatic protein synthesis induced by dHGF may accelerate the physiologic recovery process after thermal injury and contribute to ameliorating the burn-induced death.     

Effects of deletion-type human hepatocyte growth factor on murine septic model.

BACKGROUND: Sepsis is known to be the main cause of multiple organ failure. The liver especially is vulnerable to the stress of infection. In this study, the effects of deletion-type human hepatocyte growth factor (dHGF) on a murine septic model were studied. MATERIALS AND METHODS: Sepsis was induced in male adult Sprague-Dawley rats by cecal ligation and puncture method (CLP). Controls were given a sham operation. Intravenous injection of 1000 micrograms/kg dHGF or the same volume of vehicle was given every 12 h for 3 days before and/or after the CLP from a central vein catheter inserted 1 week prior to the operation. The daily percentage of survival after CLP was followed up for 1 week, and blood samples and liver specimens were collected from the surviving animals 72 h after CLP or sham operation. RESULTS: The survival rate, the degree of liver damage and liver protein synthesis, and coagulation function were all favorable in the dHGF-treated animals compared to the untreated animals. Immunohistochemical staining showed that dHGF prevented the disappearance of thrombomodulin (TM) in liver sinusoid endothelium. CONCLUSIONS: dHGF appears to prevent liver injury caused by disturbance of microcirculation through preservation of TM expression and the antithrombotic function in the endothelium of sinusoids. dHGF also facilitates repair of damaged hepatic tissue by stimulating regeneration of the cells and by preserving hepatic functions such as protein synthesis. dHGF exerts protective effects on even quiescent hepatocytes, but is most effective on injured but competent hepatocytes.     

体外定向诱导小鼠胚胎干细胞向内皮细胞分化的研究

目的探讨体外定向诱导胚胎干细胞(embryonic stem cell,ESC)向内皮细胞分化的条件,为组织工程血管提供种子细胞。方法取怀孕12.5d的昆明小白鼠1只,断颈处死,取其胚胎,培养制备小鼠胚胎成纤维细胞(mouse embryonic fibroblast,MEF)。常规复苏ESC后进行体外培养,采用悬滴-悬浮法制备拟胚体(embryoid body,EB)。将EB分两组:实验组加入含有3ng/ml转化生长因子β1、50ng/ml血管内皮细胞生长因子及1μmol/L激活素受体样激酶选择性抑制剂的EB培养基;对照组只加入EB培养基。倒置显微镜下观察细胞生长情况。采用RT-PCR及免疫组织化学染色检测诱导细胞vWF和CD34的表达,验证细胞性质。结果原代MEF生长迅速,第3天细胞融合达90%左右,细胞呈长梭形,有少量侧支,细胞核饱满,有2~3个核仁,细胞排列紧密。传至3~5代,细胞呈多角形,胞浆饱满,有3~4个核仁,细胞表面分泌较多细胞颗粒。ESC在饲养层上保持未分化状态,细胞团形态呈鸟巢样,边缘平整,单个细胞体积小,折光性强,核质比高,增长速度快。悬滴培养3d的EB肉眼可见,再经悬浮培养3d后,形成较大的透亮EB;EB贴壁后第2天,球体略摊开。实验组第4~7天,EB周围有许多圆形细胞产生,第10~14天,可见由大量圆形细胞组成的血管样结构自EB周围生长;对照组EB周围未见血管样结构生长。免疫组织化学染色见EB周围大量vWF染色阳性细胞,RT-PCR检测到vWF和CD34的表达。结论ESC在特定的条件下可以分化为内皮细胞,有可能为组织工程血管提供大量的种子细胞。     

改进传代诱导法高效诱导人胚胎干细胞定向分化为内胚层细胞

目的 比较不同诱导方法将人类胚胎干细胞(hESCs)诱导分化为纯度较高的人类内胚层细胞的分化效率,探寻最佳的分化体系.方法 用两种不同诱导方法培养人类胚胎干细胞(hESCs)H9细胞株,第1组采用最新改进的体外传代诱导方法,用IV型胶原酶消化成团的hESCs为单个hESC细胞后,使用含有100 ng/ml的胚胎干细胞诱...     

Deletion variant of hepatocyte growth factor prolongs allograft survival after liver transplantation in rats.

BACKGROUND: Despite continued progress in the development of immunosuppressive agents, allograft rejection remains an important cause of morbidity and mortality after liver transplantation. We examined the effect of the deletion variant of hepatocyte growth factor (dHGF) on allograft rejection after liver transplantation. METHODS: Male Dark Agouti rats (RT1a) were selected as donors and male Lewis rats (RT1l) as recipients for a rejection model. The recipients were divided into 2 groups after orthotopic liver transplantation (OLTx): in the dHGF group dHGF was given intravenously twice a day (1 mg/kg/day) after OLTx, whereas in the control group vehicle buffer was given intravenously daily twice after OLTx. The survival period, serum chemistry studies, and histopathologic findings were then compared between the 2 groups. RESULTS: The mean survival period after OLTx in the dHGF group was significantly longer than that in the control group (21.4 +/- 1.3 days vs 11.8 +/- 0.4 days, P < .001). On the 10th posttransplant day the serum albumin level significantly improved in the dHGF group (P < .01), and the serum total bilirubin and aspartate aminotransferase levels were significantly lower in the dHGF group (P < .01 and P < .05, respectively). On the 10th posttransplant day a histologic examination revealed no apparent difference in the severity of rejection between the 2 groups. The number of proliferating cell nuclear antigen-positive hepatocytes in the dHGF group significantly increased (P < .01), whereas the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling-positive hepatocytes were significantly reduced in the dHGF group (P < .01) in comparison with those in the control group. CONCLUSION: dHGF has an antiapoptotic property as well as a proliferative and protective effect on hepatocytes under allograft rejection. dHGF might serve as a novel agent for reducing the harmful effects of hepatic allograft rejection in rats.     

Effects of deletion variant of hepatocyte growth factor on reduced-size liver transplantation in rats.

BACKGROUND: The deletion variant of hepatocyte growth factor (dHGF) exerts mitogenic and antifibrotic effects. The purpose of this study was to evaluate the effect of dHGF on rats that had undergone syngeneic or allogeneic reduced-size (60%) orthotopic liver transplantation (ROLT). METHODS: Starting immediately after the syngeneic (Lewis to Lewis) and allogeneic (Lewis to Brown Norway) ROLT, 500 microg/kg dHGF was administered i.v. twice a day until the day the rats were killed. Its effect on hepatic graft weight, regeneration, and biochemical parameters was evaluated. RESULTS: dHGF promoted restoration of the liver volume and liver regeneration as well as protein synthesis in the rats that underwent syngeneic ROLT. In the rats that underwent allogeneic ROLT, dHGF reduced the level of serum cytosolic enzymes related to acute cellular rejection, but a significant improvement in liver regeneration and protein synthesis was not seen. When tacrolimus was administered to prevent rejection of the allogeneic grafts, the beneficial effect of dHGF was apparent, and was as beneficial as in syngeneic ROLT. CONCLUSIONS: Administering dHGF after liver transplantation augments the regeneration and functional recovery of partial liver grafts and reduces hepatocyte injury in acute cellular rejection.     

Effect of keratinocyte growth factor and activin on cell growth in the human prostatic cancer cell line LNCaP

Keratinocyte growth factor (KGF) has paracrine properties in the human prostate which stimulate epithelial cell growth. Activins have profound effects on cell growth and function in the human prostate, and are expressed in LNCaP, DU 145 and PC3 cells. LNCaP cells were characterized by immuncytochemistry, an immunoassay and polymerase chain reaction. A 3[H]thymidine assay was used with 0.01–10 nM dihydrotestosterone, 10 µM flutamide, 1–100 ng/ml KGF and 3 nM activin. LNCaP cells expressed Ki67, PSA, cytokeratins (8, 18, 19, 14, 15) androgenreceptor but no KGF protein. LNCaP cells showed telomerase activity. Furthermore, ARmRNA (365 bp), but no KGF or KGFRmRNA were expressed. KGF ELISA detected no intracellular or secreted KGF. DHT (1, 10 and 100 nM) and KGF (10 and 100 ng/ml) significantly stimulated LNCaP cell proliferation. However, flutamide and 3 nM activin A significantly decreased cell proliferation in the presence and absence of KGF. The results of our experiments support the hypothesis that cell growth and proliferative characteristics of LNCaP cells are modulated by KGF and activin A.     

Generation of hepatocyte-like cells from human embryonic stem cells

Use of human hepatocytes for therapeutic and drug discovery applications is hampered by limited tissue source and the inability of hepatocytes to proliferate and maintain function long term in vitro. Human embryonic stem (hES) cells are immortal and pluripotent and may provide a cell source for functional human hepatocytes. We report here that hES cells can be induced to differentiate into hepatocyte-like cells. Treatment with sodium butyrate induced hepatic differentiation as well as significant cell death, resulting in approximately 10-15% yield of a homogeneous population of cells. The differentiated cells have morphological features similar to that of primary hepatocytes and 70-80% of the cells express liver-associated proteins (albumin, alpha-1-antitrypsin, cytokeratin 8 and 18), accumulate glycogen, have inducible cytochrome P450 activity, and do not express alpha-fetoprotein. Because of the inherent proliferative capacity of hES cells, these cells may provide a reliable source of normal human hepatocytes for research and transplantation.     

骨形成蛋白对骨骼肌卫星细胞增殖与胶原蛋白合成的影响

目的　探讨骨形成蛋白 (BMP)对骨骼肌卫星细胞增殖与胶原蛋白合成的影响。　方法　体外获取与培养 Wistar大鼠骨骼肌卫星细胞 ,分别用含 BMP浓度为 0、50、1 0 0、50 0和 1 0 0 0 ng/ml的诱导培养基培养 72小时。通过 MTT法测定细胞的增殖 ,光镜观察细胞融合率 ,3 H-脯氨酸掺入法测定细胞胶原蛋白合成量。　结果　 BMP可促进骨骼肌卫星细胞的增殖 ,降低其细胞融合率 ,同时增加胶原蛋白的合成量。这种作用在 BMP浓度为 50 0 ng/ml即可表现出来 ,并随着浓度的增加越明显。　结论　 BMP可促进骨骼肌卫星细胞的增殖 ,抑制成肌表型促进向成骨细胞分化     

Long-term culture of Japanese human embryonic stem cells in feeder-free conditions

Human pluripotent embryonic stem cells (hESCs) have great promise for research into human developmental biology, development of cell therapies for the treatment of diseases, toxicology, and drug discovery. Traditionally, undifferentiated hESCs are maintained on mouse embryonic fibroblasts (MEFs), which impede the clinical applications of hESCs. Here we have examined the long-term stability of the Japanese hESC line (KhES-1) in feeder-free culture. KhES-1 cells were cultured with MEF conditioned medium (CM) and different doses of basic fibroblast growth factor (bFGF) in six-well-plates of which the surface was coated with Matrigel. KhES-1 cells were maintained for at least 40 passages. In this culture system, the cells maintained stable proliferation rates and steadily expressed Oct-4, Nanog, and alkaline phosphatase. In addition, KhES-1 cells maintained without direct feeder contact formed embryonic bodies with expression of markers from the three germ layers. Here we demonstrated that Japanese human embryonic stem cells KhES-1 were cultured long term in a feeder-free method, while retaining pluripotency in vitro.     

Activin A and betacellulin: effect on regeneration of pancreatic beta-cells in neonatal streptozotocin-treated rats

Activin A and betacellulin (BTC) are thought to regulate differentiation of pancreatic beta-cells during development and regeneration of beta-cells in adults. In the present study, we used neonatal rats treated with streptozotocin (STZ) to investigate the effects of activin A and BTC on regeneration of pancreatic beta-cells. One-day-old Sprague-Dawley rats were injected with STZ (85 micro g/g) and then administered for 7 days with activin A and/or BTC. Treatment with activin A and BTC significantly reduced the plasma glucose concentration and the plasma glucose response to intraperitoneal glucose loading. The pancreatic insulin content and beta-cell mass in rats treated with activin A and BTC were significantly increased compared with the control group on day 8 and at 2 months. Treatment with activin A and BTC significantly increased the DNA synthesis in preexisting beta-cells, ductal cells, and delta-cells. The number of islet cell-like clusters (ICCs) and islets was significantly increased by treatment with activin A and BTC. In addition, the number of insulin/somatostatin-positive cells and pancreatic duodenal homeobox-1/somatostatin-positive cells was significantly increased. These results indicate that, in neonatal STZ-treated rats, a combination of activin A and BTC promoted regeneration of pancreatic beta-cells and improved glucose metabolism in adults.     

诱导骨髓间充质干细胞向软骨细胞分化的体外研究

目的 探讨转化生长因子β1（transforming growth factor β1，TGF—β1）、胰岛素样生长因子1（insulinlike growth factor1，IGF-1）在诱导骨髓间充质干细胞（marrow mesenchymal stem ceils，MSCs）向软骨细胞分化过程中的相互作用，并研究细胞密度对MSCs向软骨细胞分化的影响。方法 取健康昆明种小白鼠骨髓，用全骨髓贴壁法筛选获得MSCs，体外培养传代。采用特定的诱导培养使MSCs向软骨细胞分化，按培养基内添加生长因子的不同分成3个实验组和对照组。实验组分别为：TGF—β1＋IGF-1联合应用组（TGF—β1 10ng／ml、IGF-1 50ng／m1）；TGF—β1单独应用组（TGF—β1 10ng／m1）；IGF-1单独应用组（IGF-1 50ng／m1）；对照组不添加任何生长因子。TGF—β1＋IGF-1联合应用组于诱导14d和21d，分别进行甲苯胺蓝染色及免疫荧光双染法鉴定；于诱导7、14和21d各组分别提取诱导细胞总RNA，进行RT—PCR扩增，检测TGF—β1、IGF-1对诱导细胞Ⅱ型胶原表达量的影响；比较MSCs在平板培养及细胞团培养时，Ⅱ型胶原表达量的差异。结果TGF—β1＋IGF-1联合应用组诱导培养14d，诱导软骨细胞甲苯胺蓝染色呈阳性，免疫荧光染色可见诱导软骨细胞的细胞外基质含有Ⅱ型胶原。各组基因扩增产物的凝胶电泳可见，TGF—β1＋IGF-1联合应用组和TGF—β1单独应用组Ⅱ型胶原扩增片段呈阳性；IGF-1单独应用组和对照组，未见Ⅱ型胶原扩增条带；凝胶成像系统灰度扫描示Ⅱ型胶原表达量TGF—β1＋IGF-1联合应用组各时间点均比TGF—β1单独应用组明显增加（P〈0．05）。细胞团培养模式下，诱导细胞表达Ⅱ型胶原比平板培养模式更加显著。结论 MSCs向软骨细胞诱导分化时，IGF-1对TGF—β1有明显的促进作用；细胞培养密度提高有利于MSCs成软骨细胞表型。     

Experimental study of the effects of deletion variant of hepatocyte growth factor on hepatic ischaemia-reperfusion injury

BACKGROUND: Hepatic ischaemia-reperfusion (IR) injury is still a serious complication following liver surgery. The effect of the deletion variant of hepatocyte growth factor (dHGF) on hepatic IR injury was examined in rats. METHODS: Male Wistar rats were divided into two groups after 90 min of partial liver ischaemia: the dHGF group which was given dHGF 0.5 mg/kg intravenously immediately after reperfusion, followed by 0.5 mg/kg every 12 h, and the control group, which received vehicle buffer only. Serum chemistry, histopathological findings and liver weights were compared between the groups. RESULTS: In the dHGF group, the increase in serum alanine transaminase and hyaluronic acid levels was significantly reduced, and the serum albumin level increased after reperfusion. The extent of hepatic necrosis 24 h after reperfusion was decreased in the dHGF group. Moreover, the proportion of terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labelling-positive hepatocytes 6 h after reperfusion was reduced in the dHGF group. The non-ischaemic-, ischaemic- and whole-liver weight : body-weight ratio significantly increased in the dHGF group after reperfusion. The proportion of proliferating cell nuclear antigen-positive hepatocytes in the dHGF group markedly increased after 6 h after reperfusion in the non-ischaemic lobes, while in the ischaemic lobes it increased 24 h after reperfusion. CONCLUSION: These data suggest that dHGF not only improves recovery from IR injury, but also accelerates recovery from these injuries. dHGF may be an effective pharmacological agent for prevention and treatment of hepatic IR injury.     

直接贴壁法诱导人胚胎干细胞分化为心肌细胞

摘要：目的利用直接贴壁法体外诱导人胚胎干细胞分化为心肌细胞,并检测其分化效率。方法人胚胎干细胞以1×10’个／cm2的细胞密度传代到铺备有基质胶的培养皿中培养,用带8ng／ml碱性成纤维细胞生长因子（bFGF）的条件培养基培养6d后,更换为RPMI1640．B27培养基,同时加入100ng／ml的人重组activinA处理24h,接着再加入10ng／ml的人重组骨形态发生蛋白4（BMP4）处理4d,之后更换为不带诱导因子的RPMI1640．B27培养基,每隔2～3d换1次培养基,持续2～3周。在光学显微镜下观察记录出现跳动心肌细胞的时间和跳动频率,并计算跳动克隆百分比,24孔板一组,共记录4组96孔;用免疫荧光染色法检测心肌细胞特异标志物心肌肌钙蛋白T（cTnT）;膜片钳实验检测心肌细胞自发性动作电位;跳动心肌细胞经过24h缺氧刺激后,用凋亡试剂盒检测心肌细胞凋亡比例。结果大量的自发跳动心肌细胞在诱导分化13d左右开始出现。分化出现自发跳动心肌细胞的时间为（13．0±1．1）d,百分比为66．7％,跳动频率为（63．0±7．0）次／分;跳动心肌细胞cTnT染色阳性;跳动心肌细胞检测到自发性动作电位;跳动心肌细胞缺氧24h后检测到凋亡比率为8．0％±0．5％。结论国内首次利用直接贴壁法在体外诱导人胚胎干细胞分化为心肌细胞,分化效率达到66．7％,分化时间13d左右。     

rhBMP-2对骨骼肌卫星细胞增殖与粘附的影响

目的探讨人重组骨形态发生蛋白(rhBMP)-2对骨骼肌卫星细胞增殖与粘附的影响.方法体外分离与培养骨骼肌卫星细胞,分别用0、50、100、500、1000 ng/ml的rhBMP-2诱导培养基培养48h.利用MTT法测定细胞增殖能力的变化,通过荧光法测定接种后1h的粘附细胞率.结果rhBMP-2可促进骨骼肌卫星细胞的增殖,这种作用从BMP浓度为500ng/ml即可表现出来,并随着浓度的增加而越发明显.在rhBMP-2作用下骨骼肌卫星细胞的粘附率增高,在500ng/ml的浓度时达最高,但当BMP浓度进一步增大时,细胞粘附率却不再增加.结论rhBMP-2可促进骨骼肌卫星细胞的增殖,增强其粘附特性.     

Alphafetoprotein in congenital biliary atresia and neonatal hepatitis

Alphafetoprotein (AFP) production was investigated clinically and histologically in cases of congenital biliary atresia and neonatal hepatitis. While serum AFP levels were all higher than 16,000 ng/ml in seven patients with neonatal hepatitis, they were less than 10,000 ng/ml in 50 per cent of 12 patents with biliary atresia. Therefore, serum AFP levels below 10,000 ng/ml were suggestive of a diagnosis of biliary atresia. A number of AFP granules were identified in the liver cells and multinucleated giant cells in patients with neonatal hepatitis and biliary atresia, using an immunoperoxidase method. The serum AFP levels paralleled the number of cells with AFP granules. However, no characteristic differences in distribution of these granules occurred in the hepatic cells and giant cells. The AFP producing mechanism was qualitatively the same in neonatal hepatitis and biliary atresia. These phenomena suggest that congenital biliary atresia and neonatal hepatitis may have the same pathogenesis.