In vitro directed differentiation of mouse embryonic stem cells into insulin-producing cells

Aims/hypothesis We recently demonstrated that insulin-producing cells derived from embryonic stem cells normalise hyperglycaemia in transplanted diabetic mice. The differentiation and selection procedure, however, was successful in less than 5% of the assays performed. Thus, to improve its effectiveness, new strategies have been developed, which increase the number of islet cells or islet progenitors. Methods Mouse embryonic stem cells transfected with a plasmid containing the Nkx6.1 promoter gene followed by a neomycin-resistance gene, were cultured with factors known to participate in endocrine pancreatic development and factors that modulate signalling pathways involved in these processes. Neomycin was used to select the Nkx6.1-positive cells, which also express insulin. The transfected cells were differentiated using several exogenous agents, followed by selection of Nkx6.1-positive cells. The resulting cells were analysed for pancreatic gene and protein expression by immunocytochemistry, RT-PCR and radioimmunoassay. Also, proliferation assays were performed, as well as transplantation to streptozotocin-induced diabetic mice.Results The protocols yielded cell cultures with approximately 20% of cells co-expressing insulin and Pdx-1. Cell trapping selection yielded an almost pure population of insulin-positive cells, which expressed the beta cell genes/proteins Pdx-1, Nkx6.1, insulin, glucokinase, GLUT-2 and Sur-1. Subsequent transplantation to streptozotocin-induced diabetic mice normalised their glycaemia during the time period of experimentation, proving the efficiency of the protocols.Conclusions/interpretation These methods were both highly efficient and very reproducible, resulting in a new strategy to obtain insulin-containing cells from stem cells with a near 100% success rate, while actively promoting the maturation of the exocytotic machinery.Abbreviations Anti-Shh antibody against sonic hedgehog - D3 undifferentiated D3 stem cell line - EB embryoid bodies - ES embryonic stem - FBS fetal bovine serum - LIF leukaemia inhibitory factor - mES mouse embryonic stem - Ngn3 neurogenin 3 - P gelatine-coated plates - Pdx-1 pancreatic duodenum homeobox 1     

丁酸钠诱导体外培养的大鼠肝卵圆细胞分化为成熟肝细胞

目的探讨分化刺激剂丁酸钠对体外培养的大鼠肝卵圆细胞分化的影响。方法从喂养含0．1%乙硫氨酸的胆碱缺乏性饮食4～6周的人鼠肝脏中分离出盱卵圆细胞,用免疫细胞化学和逆转录聚合酶链反应(RT-PCR)等方法对其进行鉴定。用0．75mmol/L酸钠处理大鼠肝卵圆细咆后．姬姆萨染色观察细胞表型改变,western blot检测细胞白蛋白的表达水平。结果免疫细胞化学结果显示分离出的细胞既表达成熟肝细咆的标志物白蛋白,也表达胆管细胞的标志物细胞角蛋白19,RT-PCR结果显示这些细胞还表达干细胞的标志物c-kit,但不表达造血干细胞的标志物CD34,表明这些细胞是大鼠肝前体细胞——肝卵圆细胞。0．75mmol/L丁酸钠能诱导大鼠肝卵圆细胞出现明显的表型改变,细胞变大,变圆,核浆比减小,且双核细胞数增多,约占总细胞数的50%左右,同时western blot的结果显示0．75mmol/L丁酸钠能够提高大鼠肝卵圆细胞白蛋白的表达水平。。结论分化刺激剂丁酸钠能诱导体外培养的大鼠肝卵圆细胞向成熟肝细胞分化。     

In vitro cultivation of human fetal pancreatic ductal stem cells and their differentiation into insulin-producing cells

AIM: To isolate, culture and identify the human fetal pancreatic ductal stem cells in vitro, and to observe the potency of these multipotential cells differentiation into insulin-producing cells.METHODS: The human fetal pancreas was digested by i g/L collagease type IV and then 2.5 g/L trypsin was used to isolate the pancreatic ductal stem cells, followed by culture in serum-free, glucose-free DMEM media with some additional chemical substrates in vitro (according to the different stage). The cells were induced by glucose-free (control),5 mmol/L, 17.8 mmol/L and 25 mmol/L glucose, respectively.The cell types of differentiated cells were identified using immunocytochemical staining.RESULTS: The shape of human fetal pancreatic ductal stem cells cultured/n vitro was firstly fusiform in the first 2 wk,and became monolayer and cobblestone pattern after another 3 to 4 wk. After induced and differentiated by the glucose of different concentrations for another 1 to 2 wk,the cells formed the pancreatic islet-like structures. The identification and potency of these cells were then identified by using the pancreatic ductal stem cell marker, cytokeratin-19 (CK-19), pancreatic β cell marker, insulin and pancreatic cell marker, glucagons with immunocytochemical staining.At the end of the second week, 95.2% of the cells were positive for CK-19 immunoreactivity. Up to 22.7% of the cells induced by glucose were positive for insulin immunoreactivity, and less than 3.8% of the cells were positive for glucagon immunoreactivity in pancreatic isletlike structures. The positive ratio of immunoreactive staining was dependent on the concentration of glucose, and it was observed that the 17.8 mmol/L glucose stimulated effectively to produce insulin- and glucagons-producing cells.CONCLUSION: The human fetal pancreatic ductal stem cells are capable of proliferation in vitro. These cells have multidifferentiation potential and can be induced by glucose and differentiated into insulin-producing cells in vitro.     

In vitro pancreas duodenal homeobox-1 enhances the differentiation of pancreatic ductal epithelial cells into insulin-producing cells

AIM: To observe whether pancreatic and duodenal homeobox factor-1 enhances the differentiation of pancreatic ductal epithelial cells into insulin-producing cells in vitro. METHODS: Rat pancreatic tissue was submitted to digestion by collegenase, ductal epithelial cells were separated by density gradient centrifugation and then cultured in RPMI1640 medium with 10% fetal bovine serum. After 3-5 passages, the cells were incubated in a six-well plate for 24 h before transfection of recombination plasmid XlHbox8VP16. Lightcycler quantitative real-time RT-PCR was used to detect the expression of PDX-1 and insulin mRNA in pancreatic epithelial cells. The expression of PDX-1 and insulin protein was analyzed by Western blotting. Insulin secretion was detected by radioimmunoassay. Insulin- producing cells were detected by dithizone-staining. RESULTS: XlHbox8 mRNA was expressed in pancreatic ductal epithelial cells. PDX-1 and insulin mRNA as well as PDX-1 and insulin protein were signifi cantly increased in the transfected group. The production and insulin secretion of insulin-producing cells differentiated from pancreatic ductal epithelial cells were higher than those of the untransfected cells in vitro with a significant difference (1.32 ± 0.43 vs 3.48 ± 0.81, P < 0.01 at 5.6 mmol/L; 4.86 ± 1.15 vs 10.25 ± 1.32, P < 0.01 at 16.7 mmol/L). CONCLUSION: PDX-1 can differentiate rat pancreaticductal epithelial cells into insulin-producing cells in vitro. In vitro PDX-1 transfection is a valuable strategy for increasing the source of insulin-producing cells.     

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。     

In vitro generation of insulin-producing beta cells from adult exocrine pancreatic cells

Aims/hypothesis Transplantation of insulin-producing beta cells from donors can cure diabetes, but they are available in insufficient quantities. In this study, we investigated the possibility of generating insulin-producing cells from adult rat exocrine cells cultured in the presence of growth factors.Methods Rat exocrine pancreatic cells were isolated and treated in vitro with epidermal growth factor (EGF) and leukaemia inhibitory factor (LIF). Analysis was performed by immunocytochemistry, DNA measurement and radioimmunoassay. Cells were transplanted to alloxan-treated (70 mg/kg) nude mice and glycaemia was monitored for 21 days. Nephrectomy was performed on day 15.Results In a 3-day culture period, addition of LIF plus EGF to the medium resulted in an 11-fold increase of the beta cell mass. This could not be attributed to the very low mitotic activity of contaminating beta cells. Furthermore, when contaminating beta cells were initially destroyed with alloxan, this effect was even more pronounced. The newly formed cells secreted insulin in response to glucose and were immunoreactive for C-peptide-I, Pdx-1 and GLUT-2, which are characteristics of mature beta cells. Electron microscopy showed that they also contained insulin-immunoreactive secretory granules. Some insulin-positive cells were immunoreactive for amylase and cytokeratin-20, or were binucleated, which are characteristics of exocrine cells. The cells were able to restore normoglycaemia when transplanted to alloxan-diabetic mice, and hyperglycaemia recurred upon removal of the graft.Conclusions/interpretation Our study shows that functional beta cells can be generated from exocrine tissue by transdifferentiation and thereby may offer a new perspective for beta cell therapy.     

尼克酰胺联合Exendin-4促进大鼠骨髓间充质干细胞体外转分化为胰岛素分泌细胞团的研究

尼克酰胺联合Exendin-4能明显促进大鼠骨髓间充质干细胞（BM-MSCs）转分化为胰岛素分泌细胞团，表达胰岛素、C肽和相应基因。     

骨髓间充质干细胞在小鼠肝脏局部分化为肝细胞的实验研究

目的 探讨小鼠骨髓间充质干细胞（bone marrow mesenchymal stem cells，BMSCs）在肝内分化为肝细胞的可行性。方法腹腔注射丙烯醇致雌性C57BL／6小鼠全肝损伤后局部接受雄性同品系绿色荧光蛋白（green fluorescence protein，GFP）转基因小鼠骨髓间充质干细胞移植。移植后3周取骨髓嵌合小鼠肝脏做冰冻切片，荧光显微镜下观察GFP阳性细胞在肝内分布，石蜡切片行GFP抗体和白蛋白（albumin，Alb）抗体免疫组化双标法检测GFP阳性细胞在受体小鼠肝内的分化情况。结果移植后3周小鼠肝内可见GFP阳性细胞，并可见GFP和Alb双阳性细胞。结论异体骨髓间充质干细胞可在小鼠肝内分化为表达Alb的肝细胞，为肝组织的再生和修复提供了新思路，显示了其在肝病治疗中的应用潜力。     

In vitro transdifferentiation of adult bone marrow Sca-1+ cKit- cells cocultured with fetal liver cells into hepatic-like cells without fusion

Several research groups have recently reported that certain bone marrow cells (BMCs) differentiate into hepatocytes in vitro as well as in vivo in rodents. However, it has yet to be elucidated what factors effectively trigger and sustain transdifferentiation of BMCs. In the present study, we specifically asked whether the presence of murine fetal liver cells (FLCs) triggered and supported in vitro transdifferentiation of murine BMCs. Fractionated BMCs from green fluorescence protein (GFP)-expressing transgenic mice and FLCs from ROSA26 mice (X-gal(+) FLCs) were cocultured in the presence of hepatocyte growth factor in laminin-coated dishes. We found that Sca-1(+) BMCs gave rise to adherent hepatic-like cells, which expressed albumin as assessed with immunocytochemistry and RNA-polymerase chain reaction (PCR), and alpha-fetoprotein and cytokeratin 19 as examined with RNA-PCR. When GFP(+)Sca-1(+)cKit(-) cells were cocultured with X-gal(+) FLCs, all GFP(+) albumin-producing cells were negative for X-gal, showing that cell fusion was not associated in the observed BMCs' differentiation into hepatic-like cells. Titration analysis revealed that 1 of 5,943 Sca-1(+)cKit(-) cells had the ability to proliferate and differentiate into hepatic-like cells. These data strongly suggest that BMCs differentiate into hepatic-like cells in the presence of FLCs and that the present method may be useful for propagating BMC-derived hepatocytic progenitors and for investigating the nature of those cells.     

Cytokine mobilization of bone marrow cells and pancreatic lesion do not improve streptozotocin-induced diabetes in mice by transdifferentiation of bone marrow cells into insulin-producing cells

OBJECTIVE: Transdifferentiation of bone marrow cells (BMC) into insulin-producing cells might provide a new cellular therapy for type I diabetes, but its existence is controversial. Our aim was to determine if those cells could transdifferentiate, even at low frequency, into insulin-producing cells, in testing optimized experimental conditions. METHODS: We grafted mice with total BMC, genetically labeled either ubiquitarily, or with a marker conditionally expressed under the control of the insulin beta-cell specific promoter. We treated some of the recipients with an agent toxic to beta-cells (streptozotocin) and with cytokines stem cell factor (SCF) and granulocyte-colony stimulating factor (G-CSF). RESULTS: The contribution of grafted cells could be detected neither for natural turnover (n=6), nor for beta-cell regeneration after pancreatic lesion (n=7), 90 days post-transplantation. Cytokine mobilization of BMC in the blood stream, reported to favor their transdifferentiation into cardiac and neural cells, had never been tested before for beta-cell generation. Here, we showed that injection of SCF and G-CSF did not lead to a detectable level of transdifferentiation (n=7). CONCLUSIONS: We conclude that BMC cannot spontaneously transdifferentiate into insulin-producing cells in vivo, even after beta-cell lesion and mobilization induced by cytokines. Interestingly, however, treatment by cytokines may have beneficial indirect effects on STZ-induced hyperglycaemia.     

间充质干细胞分化为心肌样细胞与P120连环蛋白mRNA表达

目的：研究5-氮杂胞苷（5-azacytidine，5-aza）诱导体外骨髓间充质干细胞（marrow measenchymal stem cells，MSCs）向心肌细胞发展的作用及其机制。方法：从Wistar大鼠骨髓中获得MSCs，培养传代后用不同浓度的5-aza诱导，倒置光显微镜和透射电镜观察诱导前后细胞形态变化；流式细胞术检测细胞周期改变；MTT法检测5-aza对MSCs生长的影响；免疫细胞化学法检测肌红蛋白、结蛋白和肌动蛋白的表达；RT-PCR检测P120连环蛋白1A mRNA的表达。结果：5-aza对MSCs有抑制增殖的作用（P〈0．05）；在光镜和透射电镜下可见有心肌样细胞的形态变化；免疫细胞化学检测结果表明，MSCs的经5-aza诱导14d，肌红蛋白、结蛋白和肌动蛋白的表达均较对照组显著增高（P〈0．01）；PT—PCR结果表明P120连环蛋白mRNA表达明显，而对照组未见表达。结论：MSCs可在体外被5-aza诱导分化成心肌样细胞，这可能与P120连环蛋白1A mRNA表达有关。     

兔骨髓基质细胞诱导分化为胰岛素分泌细胞的方法

目的 探讨将骨髓基质细胞（MSCs）诱导成为胰岛素分泌细胞（IPCs）的方法。方法 体外培养新西兰兔骨髓及胰腺基质细胞和SD大鼠胰腺基质细胞，利用含有胰腺基质细胞培养基的混合培养基诱导培养MSCs。结果 以兔及SD大鼠胰腺基质细胞培养基均可诱导兔MSCs生成IPCs。结论 兔及SD大鼠的胰腺基质细胞培养基均可将兔MSCs诱导分化为IPCs。     

Thy1-positive bone marrow stem cells express liver-specific genes in vitro and can mature into hepatocytes in vivo

The bone marrow contains stem cells that have the potential to differentiate into a variety of organ-specific mature cells, including the liver and the pancreas. Recently, the origin of hepatic progenitors and hepatocytes was identified to be the bone marrow. However, evidence that describes which cells, among all bone marrow cells, differentiate into hepatocytes, has not yet been presented. Based on recent reports, hematopoietic and hepatic stem cells share characteristic markers such as CD34, c-kit, and Thy1. In particular, both hematopoietic and hepatic stem cells express the Thy1 antigen. We investigated whether rat Thy1-positive bone marrow cells express liver-specific genes in vitro, and whether transplanted Thy1 BM cells differentiate into mature hepatocytes in vivo. For collection of Thy1 cells from bone marrow, FITC-conjugated anti-Thy1.1 monoclonal antibody was used with a Fluorescence-Activated Cell Sorter system. A coculture system of 2 separate layers was used for culture of Thy bone marrow cells. Cultured Thy1 cells expressed albumin protein, which was analyzed by immunofluorescent staining. Thy1 bone marrow cells obtained from wild-type dipeptidyl peptidase IV (DPPIV(+)) male rat were directly transplanted into the injured liver of DPPIV mutant (DPPIV(−)) Fisher 344 female rats and differentiated into mature hepatocytes in recipient liver on 60 days. Donor-derived hepatocytes were confirmed by DPPIV staining and Y-chromsome in situ hybridization. Our results suggest that Thy1-positive bone marrow cells have the potential to generate liver-specific genes in vitro and can differentiate into mature hepatocytes in adult liver in vivo. Thy1-positive bone marrow stem cells may represent preexisting hepatocyte-specific stem cells.