In vitro differentiation of exocrine pancreatic cells from mouse embryonic stem cells

AIM: To explore the effects of sodium butyrate, activin A and dexamthasone on inducing mouse embryonic stem (ES) cells to differentiate into exocrine pancreatic cells in vitro. METHODS: E14 mouse ES cells were cultured in suspension to form embryonic bodies (EBs). The EBs were cultured with differentiating medium containing different concentrations of sodium butyrate, and the spontaneously differentiated ES cells were used as control. Exocrine pancreatic genes such as amylase, chymotrypsinogen, elastase 1, elastase 2 and carboxypeptidase were detected by RT-PCR at different time points to determine the optimal concentration and exposure time of sodium butyrate. Furthermore, activin A or dexamthasone was also used to explore the effects on exocrine differentiation. After that, the combination of sodium butyrate, activin A and dexamthasone was used to promote the differentiation of exocrine pancreatic cells from ES cells. During the differentiation course, the gene expressions of amylase, chymotrypsinogen, elastase 1, elastase 2 and carboxypeptidase were detected by RT-PCR. Morphological changes were investigated by phase contrast microscopy. Amylase expression was examined by immunofluorescence staining. RESULTS: Exocrine pancreatic gene expressions such as amylase, chymotrypsinogen, elastase 1, elastase 2 and carboxypeptidase were detected in spontaneously differentiated EBs. A relatively lower concentration of sodium butyrate with a shorter exposure time significantly promoted those above gene expressions as compared to that of spontaneously differentiated EBs. Activin A and dexamethasone induced upregulation of exocrine gene expression. The combination of activin A, sodium butyrate and dexamethasone significantly enhanced the mRNA levels of amylase, chymotrypsinogen, elastase 1, elastase 2 and carboxypeptidase. Under the treatment of activin A, sodium butyrate and dexamethasone, differentiated cells were polygonal in shape with large, round, and center-situated nuclei. According to the observation of immunofluorescence staining, amylase was positive expressed at the final stage. CONCLUSION: These data indicate that exocrine pancreatic differentiation of ES cells is induced by sodium butyrate, activin A and dexamethasone. The combination of pancreatic inducing factors improves the differentiating efficiency.     

Hepatic differentiation of mesenchymal stem cells derived from rats in three-dimensional microenvironment formed by hanging drops

AIM: To establish an optimal differentiated three-dimensional microenvironment formed by hanging drops for the high efficiency of hepatic differentiation from rat mesenchymal stem cells(rMSCs).METHODS: rMSCs were cultured in the hanging drops, which provided a three-dimensional microenvironment, for 21 days in the presence of hepatocyte growth factor(HGF, 20 μg/L). The expression of albumin(ALB), alpha-fetoprotein(AFP) and cytokeratin-18(CK-18) was detected by RT-PCR and immunofluorescence staining at 7th, 14th and 21st days. The secretion of albumin in the culture supernatants was measured by ELISA. RESULTS: rMSCs were aggregated in spheroid with a tubiform medium altitude in the center. In rMSCs cultured in the hanging drops with HGF, the expression of albumin, AFP and CK-18 was all detectable by RT-PCR and immunofluorescence staining at 7th day. The production of albumin in the cells cultured in the hanging drops with HGF was 50.25±5.32, 55.03±7.45 and 54.92±3.18(ng·dish^-1·d^-1) at 7th, 14th and 21st days, respectively, significantly higher than that in the cells in the plate cultivation with or without HGF induction at corresponding time points(P<0.01).CONCLUSION: In the presence of HGF, rMSCs are induced to differentiate into hepatocyte-like cells cultured in the hanging drops, where the three-dimensional spheroidal cultures are promising microenvironment for hepatic transdifferentiation of MSCs.     

Isolation and differentiation of stem cells derived from human placenta into cardiomyocytes

AIM: To isolate the stem cells from human placenta and induce them into cardiomyocytes. METHODS: Stem cells were isolated from human placenta and characterized by morphologic analysis. The “hanging drop” methods were used to inducte stem cells into cardiomyocytes. The expressions of atrial natriuretic factor(Anf) and β-myosin heavy chain(β-MHC) genes were analyzed by RT-PCR. RESULTS: Stem cells derived from human placenta were self-renewed and differentiated into cardiomyocytes in vitro. RT-PCR showed that Anf and β-MHC genes were expressed in the “beating cells”.CONCLUSION: Human placenta is an abundant source of stem cells.     

Hepatocyte growth factor enhances the neural differentiation from human embryonic stem cells

AIM: To investigate the possibility that hepatocyte growth factor (HGF) directly induces differentiation of human embryonic stem cells (hESCs) into neural progenitors (NPs). METHODS: hESCs colonies were induced to form the embryoid body (EB). Four-day-old EBs were randomly divided into 4 groups: control group (EBs were cultured in neural induction medium); G5 supplement group (EBs were cultured in neural induction medium supplied with G5 supplement); HGF group (EBs were cultured in neural induction medium supplied with 10 mg/L HGF), and HGF+G5 group (EBs were cultured in neural induction medium supplied with 10 mg/L HGF and G5 supplement). After induced in suspension system for 7 days, EBs with various treatments were cultured in poly-D-lysine/laminin-coated plates for 7-10 days for selection of NPs. NPs were gathered by 0.3 g/L dispase treatment and characterized by immunofluorescence staining. The percentages of the nestin+ cells in NPs in various groups were detected by fluorescent activated cell sorter (FACS). The multipotency of NPs was determined by immunofluorescence staining after the NPs were cultured without G5 and HGF for 7 days. The expression of region markers of neural progenitors treated with sonic hedgehog (Shh) protein (one of the neural inductive signals), was detected by RT-PCR. RESULTS: HGF+G5 supplement induced hESCs differentiation into neural progenitors. Immunofluorescence staining indicated that NPs differentiated from hESCs expressed NP markers including nestin, Pax6 and musashi-1. FACS data showed that the proportion of nestin positive cells in HGF+G5 supplement group (87.3%±3.9%) was the highest in all treatment groups. The time of HGF and G5 supplement treatment was important to differentiate into NPs, the maximal effect was observed at 7th day. After treated with Shh, the expression of ventral forebrain/hindbrain marker genes (Nkk2.1, and Nkk2.2) and hindbrain progenitor marker gene Gbx2 in NPs were upregulated, while the forebrain progenitor marker genes Otx2 and Bf1 were downregulated. CONCLUSION: The neural induction system containing HGF and G5 supplement effectively induces the differentiation of hESCs into NPs, which might be a potent model for investigating the mechanism of neural development and differentiation.     

The correlation between differentiation and apoptosis in the process of differentiation from adult rat mesenchymal stem cells into neuron-like cells

AIM:To supply the theoretic evidences of elongating the lifetime of neuron-like cells differentiated from adult rat mesenchymal stem cells, we investigated the relationship between the differentiation and apoptosis in the process of induction. METHODS: The mesenchymal stem cells(MSCs) were isolated primarily from rat bone marrow, and purified by passage culture. The 5th passage of MSCs was induced by β-mercaptoethanol and all-trans-retinoic acid (ATRA). After 1 h, 3 h and 5 h of induction, the cells were stained immunocytochemically with anti-MAP-2 and anti-GFAP antibodies, respectively. In addition to counting the ratio of neuron-like cells in MSCs, DAPI staining was employed to identify whether the differentiated cells have an apoptotic morphological changes. The ratio of apoptotic cells at 1 h, 3 h and 5 h after induction were detected by flow cytometry (FCM). CONCLUSIONS:1. β-mercaptoethanol and ATRA had the different ability that induced MSCs to differentiate to neuron-like cells. 2. Apoptosis was also initiated in the process of differentiation, and there is positive correlation between the ratio of differentiation and apoptosis.     

Direct differentiation of embryonic stem cells into neural cells without embryonic body culture period in vitro

AIM:To investigate the feasibility and effect of directly differentiation of embryonic stem cells (ESC) into neural cells induced by retinoid acid (RA) without embryonic body (EB) culture period in vitro. METHODS:ESC were digested and divided into 4 groups:group A and B were undergone EB culturing. After that, cells in group A were induced by RA, cells in group B were differentiated spontaneously, cells in group C were committedly induced by RA directly without EB culturing, and cells in group D were differentiated spontaneously without EB period. Morphologic changes were observed under inverted microscope and scanning electron microscope. MAP-2 and GFAP were detected by immunocytochemistry and flow cytometry after differentiated for 9 days. RESULTS:In groups A or C, neuron-like cells increased gradually, forming neural network. At the 9th day, a large part of cells in these groups were MAP-2 positive cells, and the positive rate was higher than that in groups B or D (P<0.01). Groups B and D were almost epithelial-like cells. At the 9th day, GFAP positive cells were predominant. The rate of GFAP staining cells in groups A or C was significantly lower than that in groups B or D (P<0.01). There was no significant difference of MAP-2 or GFAP positive rates between group A and C, nor between group B and D (P>0.05). CONCLUSION:ESC was directly induced into neural cells by RA without EB culture period in vitro. This modified method has the same effect as the traditional RA 4－/4＋ assay and can replace the traditional method.      

Differentiation of dendritic cells from embryonic stem cells

AIM：To investigate the method of directed differentiation dendritic cells (DC) from embryonic stem cells,and to amplify high purity dendritic cells in vitro for immunolgical therapy.METHODS：E14 embryonic stem cell line was generated ES-DC in complete medium supplemented with GM-CSF and IL-3.Flow cytometry was used to determine CD11c,CD80,CD86,MHC-II cell-surface phenotype in immatured ES-DC.Lipopolysaccharide (LPS) was added to induce the ES-DC maturation.The matured ES-DC was harvested 24 hours later to identifying with morphology and transmission electron microscopy.The phenotype of matured ES-DC was analyzed by flow cytometry and compared with the immatured ES-DC.The antigen presenting was evaluated by mixed lymphocyte responses (MLR).RESULTS：The ES-DC had obviously dendritic processes under scanning electron microscope.The immature DCs expressed low level of CD11c (4.33±0.23)%,CD80 (7.62±0.19) %,CD86 (4.77±1.22) % and MHC-II (9.68±0.15) %.The mature DCs expressed higher level of CD11c (47.36±2.68)%,CD80 (74.40±1.47) %,CD86 (29.77±2.00) % and MHC-II (87.56±2.75) %.MLR showed that ES-DCs effectively stimulated lymphocyte proliferation.CONCLUSIONS：These results provide evidence that dendritic cells can be generated from E14 embryonic cells with the stimulations of GM-CSF and IL-3.The differentiated cells expresse high level of CD11c,CD80,CD86,MHC-II and effectively stimulate lymphocytes to proliferate.ES cells may become new origin of DC for immunotherapy.     

Enhanced proliferation and neuronal differentiation of neural stem cells by bone marrow stromal cells

AIM:To evaluate whether bone marrow stromal cells (BMSCs) could provide a supportive microenvironment for proliferation and differentiation of neural stem cells (NSCs). METHODS:The proliferation and differentiation of NSCs were compared, in media without growth factors or in BMSCs-conditioned media. RESULTS:The proportion of neurons to total NSCs was significantly increased when NSCs were cultured in BMSCs-conditioned media (41.1%±3.2% vs 23.3%±16.5%, P<0.05), while the proportion of astrocytes was significantly decreased (33.8%±4.9% vs 65.0%±10.4%, P<0.01), as compared with the NSCs cultured in media without growth factors. The proportion of proliferated cells was also significantly increased (74.7%±4.7% vs 51.4%±12.3%, P<0.01). CONCLUSION:These finding indicates that BMSCs support the proliferation and neuronal differentiation of NSCs and suggests that their addition may be useful to improve outcomes of NSCs transplantation.     

In vitro hematopoietic stem cells from embryonic stem cells reconstruct hematopoiesis in mice

AIM: To investigate the potential of hematopoietic stem cells (HSCs) derived from mouse embryonic stem cells (ESCs) to reconstruct hematopoiesis in vivo. METHODS: Using a three-step method, a mice embryonic stem cell line, E14.1 was induced into hematopoietic stem cells. The cell markers with CD34+/ Sca-1+ were identified by flow cytometry analysis, then HSCs (1×109 cells/L) from third-step were injected into SCID mice for observing teratoma formation. To validate function of HSCs, colonogenic cell assay was conducted and the hematopoiesis in lethally irradiated mice was reconstituted. RESULTS: The method of three-step differentiation, combined to use more hematopoietic stimulating factor promoted the E14.1 cell differentiation into HSCs with highest percent of CD34+/Sca-1+ cells (as high as 58.64%±4.20%) with more CFU-E, CFU-GM and CFU-GEMM populations. The cells showed the character of hematopoietic progenitors by Wright-Giemsa staining. Positive selected CD34+/Sca-1+ cells by magnetic sorting from third-step differentiation were transplanted into 7 lethally irradiated female mice while predominant hematopoietic reconstitution were observed in 10 d after transplantation, with 71.4% (5/7) successful engraftment rate. Three recipients showed that the cell population of the peripheral blood leukocytes, red blood cells and hemoglobin approached to normal index at 40 d after transplantation, but followed relative slow renew in platelet count. Survival rate in transplant group was 43%, compared to 100% mortality in control mice. Karyotyping assays confirmed the female mice with XY. CONCLUSION: The three-step differentiation and the culture conditions described here support the differentiation of mouse ESCs into HSCs. HSCs derived from mouse ESCs can reconstruct hematopoiesis.     

Ultrastructural characteristics of neural stem cells derived from adipose-derived stromal cells during their differentiation into neurons and astrocytes

AIM: To observe the ultrastructural characteristics of neural stem cells derived from adipose-derived stromal cells (ADSC) differentiating into neurons and astrocytes. METHODS: ADSC were cultured, amplified and induced with β-mercaptoethanol or 3-isobutyl-1-methylxanthine (IBMX). The expression of nestin in the induced cells was determined by the method of immunofluorescence. The ultrastructure of the induced neural stem cells was observed under transmission electron microscope.RESULTS: The expression of nestin reached the peak at 3 h in β-mercaptoethanol group and at 14 d in IBMX group, and the positive rate of the former (86%) was significantly higher than that of the latter (23%). However, the duration of the induction in IBMX group was obviously longer than that in β-mercaptoethanol group. The ultrastructure of the induced neural stem cells in the two groups was similar under the transmission electron microscope, only with some differences in organelles.CONCLUSION: In the process of ADSC differentiating into astrocytes or neurons with the induction of β-mercaptoethanol or IBMX, the different changes of ultrastructure in ADSC-derived neural stem cells occur in some organelles in cytoplasm, not in nucleus.     

Supportive effects of human aorta-gonad-mesonephero stromal cells on the directed differentiation of embryonic stem cells into hematopoietic stem cells

AIM: To direct embryonic stem cells (ESCs) into hematopoietic stem cells (HSCs) in vitro by simulating the hematogenic microenvironment in human early embryonic aorta-gonad-mesonephero (AGM) region.METHODS: Murine E14 embronic stem cell line was used for two-step differentiation.In the first step of primary differentiation,E14 ESCs were seeded into semisolid methylcellulose-based medium containing bone morphogenesis protein 4 (BMP4) and vascular endothelial growth factor (VEGF) for embryoid body (EB) formation.On days 3,6,9,12 and 15,single EB cells were analyzed for Flk-1+ cells amount through flow cytometry.In the second step,single cell from EB containing most Flk-1+ cells was further co-cultured with human AGM stromal cells in non-contact system.On co-culture days of 3,6,9 and 12 days,cells were collected for cell count,flow cytometry for Sca-1+c-kit+ cells analysis,and colony forming cell assay.RESULTS: During the EB formation,BMP4+VEGF promoted Flk-1+ cell genesis on day 9 at peak pencentage value of 27.53%±2.84％,which was statistically higher than that in control group as 8.77±1.10 (P<0.05).Collagenase-disassociated single cell from day 9 EB was co-cultured with human AGM stromal cells of hAGMS3 or hAGMS4 for further hematopoietic differentiation.On day 6 Sca-1+c-kit+ cells got to peak value as 7.31%±1.21％ ［(2.57±0.48) folds］ and 7.62%±1.52％ ［(2.35±0.36) folds］ in hAGMS3 and hAGMS4 feeder systems,respectively,both of which were greater than those values of no-stroma groups at the same culture duration (P<0.05).Colonogenic cell assay showed that these Sca-1+c-kit+ cells had ability of forming multiple lineage hematopoietic colonies.CONCLUSION: BMP4 in combination with VEGF promotes Flk-1+ cell genesis during EB formation in vitro.Stromal cells from early human embryonic AGM region further enhance the directed differentiation of these primitive cells into HSCs.This two-step induction differentiation model can be used for molecular mechanism study of ESCs hematopoietic differentiation.     

Study on inducing differentiation of mouse embryonic stem cells into cardiomyocytes in vitro

AIM: To set up a method of inducing mouse embryonic stem cells (mESC) to differentiate into cardiomyocyte after treatment with 5-azacytidine. METHODS: Cytotoxicity of 5-azacytidine was measured by MTT assay. Treatment of mESC with conditioned culture mediums, which were composed of 5-azacytidine alone or combined with retinoic acid, induced the cell differentiation to cardiomyocytes. The cells induced were identified by detecting the expression of cardiac proteins (myosin, desmin, α-actin and α-actinin). Gene MLC-2v, a specific gene of ventricular-like cardiomyocyte, was also detected by RT-PCR. RESULTS: The non-cytotoxic dose of 5-azacytidine was 8 μmol/L, which was able to induce mESC to differentiate into cardiac syncytiums. Cells induced expressed many cardiac proteins and MLC-2v mRNA. However, combined with retinoic acid inhibited mESC differentiation into cardiomyocyte. CONCLUSION: 5-azacytidine is able to promote mESC differentiation into cardiomyocytes. A method of inducing mESC to differentiate into cardiomyocytes in vitro has been established.     

Progress of embryonic stem cells during directional differentiation regulated by epigenetic modification

Embryonic stem cells undergo extensive self-renewal and have the capacity to differentiate along multiple cell lineages. Research on totipotency and directional differentiation of embryonic stem cells in order to treat intractable disease, such as cancer, heart failure, atherosclerosis by tissue regeneration and cell transplantation are investigated. Epigenetic modification, including DNA methylation, chromatin restructure, and non-coding RNA-mediated regulatory events, regulate the differentiation of embryonic stem cells without detectable genetic changes. These mechanisms are often associated with starting-up and maintenance of epigenetic silence. The achievement and focuses on the molecular mechanism of embryonic stem cells during directional differentiation regulated by epigenetic modification are reviewed.     

Directed differentiation of embryonic stem cells into epithelial cells by co-culture with human laryngeal epithelial cell conditioned medium

AIM:To explore the culture and inductive condition for the directed differentiation of embryonic stem cells into epithelial cells in human laryngeal epithelial cell conditioned medium.METHODS:E14 murine stem cells were induced into embryoid body in vitro first,then the cells of embryoid body were cultured in the induction system containing human laryngeal epithelial conditioned medium and epithelial cell growth factors.On day 14 of culture,samples were detected for the cytokeratins 4,14,19 expressions at protein level.Morphology of the cells was also observed under microscope.RESULTS:During the process of epithelial induction,cells with epithelial cell morphology were seen under contrast microscope.Immunofluorescent assay showed that cytokeratins 4,14,and 19 were all expressed at protein level in differentiated cell.CONCLUSION:This study suggests that epithelial cells could be induced from the directed differentiation of embryonic stem cells in the conditioned medium of human laryngeal epithelial cell cultures.This work has provided basic data for artificial laryngeal epithelia preparation.     

Mast cells derived from stem cells of umbilical cord blood

Mast cells (MCs) play a key role in the pathogenesis of allergic diseases. Tissue MCs are originated from hematopoietic stem cells in bone marrow. In recent years, it was reported that human mast cells could be differentiated from stem cells of umbilical cord blood. In this review, we summarize the development in this novel area.     

The culture and differentiation of adult bone marrow-derived pluripotential mesenchymal stem cells into insulin-producing cells

AIM: To study the culture and characteristics of mouse adult bone marrow-derived pluripotential mesenchymal stem cells and its potential to differentiate into insulin secretion cells. METHODS: Cells were plated on 60% DMEM-LG and 40% MCDB-201 medium supplemented with 2% fetal calf serum and 10 μg/L PDGF-BB, 10 μg/L EGF and 1×106 U/L LIF. The proliferation rate, phenotype and oct-4 mRNA were tested. After it was plated on serum-free medium DMEM/F12 with GLP-1 and nicotinamide, the nkx2.2 ngn3, pdx-1 and insulin 2 mRNA were tested. RESULTS: The cells were round with large nucleus and scant cytoplasma. They were CD13+, CD44-, CD45- and MHCⅡ-. Oct-4 mRNA were present. The nkx2.2 pdx-1 and insulin 2 mRNA were presented in cells plated on the inducing medium at 14 days. CONCLUSION: The adult bone marrow-derived pluripotent stem cells were cultured and they has the possibilities to be induced into insulin-secreting cells.     

Supportive effects of human AGM region and fetal liver stromal cells on differentiation of murine embryonic stem cells into hematopoietic stem cells and in vivo hematopoietic reconstitution

AIM: To investigate the differentiation of murine embryonic stem cells (ESCs) into hematopoietic stem cells (HSCs) by the supportive effects of human aorta-gonad-mesonephros (AGM) region and fetal liver (FL) stromal cells.METHODS: E14 ESCs were induced into embryoid body (EB) first. Then the cells from EB were further co-cultured with human AGM region and FL stromal cells in non-contact system. On day 6, the cells derived from EB were collected for Sca-1⁺c-Kit⁺ cell analysis by flow cytometry, colony forming unit (CFU) assay and teratoma formation checking. BALB/c female mice conditioned with lethal dose of γ-ray irradiation were transplanted with EB cells from different culture systems. The survival rates, engraftment of donor cells, reconstitution of hematopoietic were monitored.RESULTS: Sca-1⁺c-Kit⁺ cells in EB cells co-cultured with human AGM region and FL stromal cells had the value of (21.96±2.54)%, and the total CFU was as (520±52)/10⁵ cells, which were statistically greater than those in EB cells only cultured with human AGM region stromal cells (P＜0.05). No teratoma was found in NOD-SCID mice after subcutaneous injection of EB cells co-cultured with human AGM region and FL stromal cells. In BALB/c female mice transplanted of EB cells co-cultured with human AGM region and FL stromal cells, the survival rate was 77.8%, and the peripheral blood cell count was obviously improved on day 14. PCR results showed the recipients all had sry gene copies from donor in bone marrow. The recipient mice transplanted with EB cells only cultured with human AGM region stromal cells all died within 15 days.CONCLUSION: Stromal cells from human AGM region and FL enhance the directed differentiation of ESCs into HSCs which can reconstruct hematopoiesis in vivo.