Objective To investigate the feasibility of committed differentiation of rhesus bone marrow mesenchymal stem cells (MSCs) into tenocytes induced by BMP12. Methods MSCs were transfected with pTARGETTM bearing BMP12 gene by electroporation. The transfected cells were identified by morphological observation and molecular biological measure. Results Under the observation of light microscope, the morphological features of transfected cells changed significantly compared to parental MSCs. RT-PCR data showed the transfected cells had the mRNA expression of BMP12 and collagen Ⅰ, but without that of collagen Ⅲ. 98.39% of the transfected cells were CD44+ and negative for HLA-DR. Conclusion BMP12 could induce MSCs into tenocytes, and bone marrow MSCs might be the optional seed cells for tendon tissue engineering.

BACKGROUND: The increasing prevalence of diabetes mellitus has been become one of the diseases which threaten the heath of human being in the 21st century. Islet transplantation is considered to be the most effective approach to cure type Ⅰ diabetes mellitus. However, lack of donor tissue limits the application of this therapy. However, recent progress of stem cell research shows that stem cell therapy may be a potential means to solve this problem.OBJECTIVE: To take activin A and all-trans retinoic acid (AR) in inducing the differentiation of bone marrow mesenchymal stem cells (MSCs) and explore its possibility DESIGN: A randomized controlled experiment.SETTING: Institute of Biotechnology, Academy of Military Medical SciencesMATERIALS: This experiment was conducted at the Institute of Biotechnology, Academy of Military Medical Sciences from November 2004to June 2005. Six male Sprague-Dawley rats, with body mass of 150-160g, were provided by the Experimental Animal Center of Academy of Military Medical Sciences.METHODS: Femoral bone marrow of the rats was extracted under aseptic condition. Bone marrow mesenchymal stem cells (MSCs) were isolated with density gradient centrifugation. Passaged MSCs were randomly divided into 4 groups: high concentration of glucose (HG), AR, beta-mercaptoethanol (ME) and negative control groups. MSCs were induced to differentiate into IPCs with conditional medium containing high concentration glucose, activin A, RA and ME etc. After induction, phenotypes of differentiated cells were examined by immunocytochemistry and reverse transcription-polymerase chain reaction (RT-PCR).MAIN OUTCOME MEASURES: Expression of insulin and glucagon of differentiated cells were examined by immunocytochemistry. Insulin-1 mR-NA expression of differentiated cells was detected by RT-PCR.RESULTS: After bone marrow mesenchymal stem cells were induced,there were scattered insulin-and glucagon-positive cells in the HG group,many insulin-and glucagon-positive cells in the AR and ME groups, and these cells formed insulin-like structure. The expression of insulin-1mRNA could be observed in the HG, AR and ME groups. Insulin-and glucagonpositive cells and the expression of insulin-1mRNA were not observed in the negative control group.CONCLUSION: We adopt an induction scheme based on AR and other matured factors, and successfully make bone marrow mesench.ymal stem cells induce and differentiate into insulin positive reaction cells and form insulin-like structure, but its induction efficiency needs further improvement.

Hepatitis B surface antigen (HBsAg) carrying preS sequences could be an ideal candidate for a new hepatitis B virus (HBV) vaccine with higher efficacy. Here we report the success in achieving efficient and stable expression of hepatitis B virus S antigen and preS1 epitope fusion protein (S/preS1) in CHO cells. The HMRCHEF53u/Neo-S/preS1 expression vector carrying S/preS1 gene was constructed and transfected into CHO-S cells. A stable and high-expression CHO cell line, named 10G6, was selected by ELISA and limiting dilution analysis. Western blotting analysis showed S/preS1 expressed from 10G6 cells possessed both S and preS1 antigenicity. 10G6 cells displayed characters of favorable growth and stable S/preS1 expression in repeated batch cultures as evaluated by viable cell density, viability and S/preS1 concentration. And cultivation of 10G6 cells in fed-batch mode resulted in S/preS1 production at 17-20 mg/L with viable cell density at 7 x 10(6)-10 x 10(6) cells/mL.
Animals ; CHO Cells ; Cricetulus ; Epitopes ; biosynthesis ; genetics ; Hepatitis B Surface Antigens ; biosynthesis ; genetics ; immunology ; Hepatitis B Vaccines ; biosynthesis ; genetics ; Hepatitis B virus ; Protein Precursors ; biosynthesis ; genetics ; immunology ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Transfection

To establish a gene regulation system compatible with biopharmaceutical industry and gene therapy, we constructed a fusion protein of biotin ligase from Bacillus subtilis (BS-BirA) and the trans-activation domain, and used its expression vector as the regulatory vector. Meanwhile, BS-BirA-specific operators were ligated upstream of attenuated CMV promoter to obtain the response vector. In this way, a novel eukaryotic gene regulation system responsive to biotin was established and named BS-Biotin-On system. BS-Biotin-On system was further investigated with the enhancing green fluorescent protein (EGFP) as the reporter gene. The results showed that our system was superior to the current similar regulation system in its higher induction ratio, and that the expression of interest gene could be tuned in a rapid and efficient manner by changing the biotin concentrations in the cultures, Our results show that the established system may provide a new alternative for the exogenous gene modulation.
Bacillus subtilis ; Biotin ; chemistry ; Eukaryotic Cells ; metabolism ; Gene Expression Regulation ; Genetic Vectors ; Promoter Regions, Genetic ; Trans-Activators

BACKGROUND:Islet beta cell replacement therapy is one of the most promising approaches for treating type 1 diabetes mellitus. However, its large scale application is hampered by a shortage of islet beta cells for transplantation. Pluripotent stem cells are one of ideal seed cells for islet beta cell replacement therapy, but pancreatic beta-cell differentiation is time-consuming and labor-intensive. OBJECTIVE:To construct a high efficient pancreatic and duodenal homeobox 1 (Pdx1)/insulin dual-reporter vector and to monitor the key genes expression during pancreatic beta-cell differentiation from pluripotent stem cells. METHODS:In order to construct a high efficient Pdx1/insulin dual-reporter vector, puromycin resistance gene was firstly introduced into pTiger vector, and then the original 410 bp mouse Ins1 promoter of the vector was replaced by 646 bp mouse Ins1 promoter. Finally, the dual-reporter vector was transduced into INS-1 and human induced pluripotent stem cells to testify its function. RESULTS AND CONCLUSION:The high efficient Pdx1/insulin dual-reporter vector was constructed successfully. The vector successfully acquired puromycin resistance gene and high gene expression efficacy of insulin in INS-1 cells. The specific gene expression pattern of Pdx1/insulin was first found in INS-1 cells. To conclude, the real-time monitoring function of Pdx1/insulin expression is preliminarily confirmed during pancreatic beta-cell differentiation.

By using the cell density, cell viability, Pro-UK activity, specific consumption rate of glucose (q(glc)), specific production rate of lactate (q(lac)), yield of lactate to glucose (Y(lac/glc)) and as the evaluation indexes, the growth and metabolism characteristics of pro-urokinase (Pro-UK) expressing CHO cells in serum-free suspension batch culture were examined and compared to those in serum-containing suspension batch culture. We observed hardly differences in growth and metabolism characteristics between the CHO cell populations grown in serum-free suspension batch culture and serum-containing suspension batch culture. The optimal mathematical model parameters for the CHO cells grown in suspension batch culture were obtained by non-linear programming of data representing the growth, substrate consumption and product formation of the CHO cells during logarithmic growth phase using MATLAB software, and the kinetic model of the cell growth and metabolism in serum-free culture were established.
Animals ; Bioreactors ; CHO Cells ; Cricetinae ; Cricetulus ; Culture Media, Serum-Free ; Culture Techniques ; methods ; Kinetics ; Models, Theoretical ; Recombinant Proteins ; biosynthesis ; genetics ; metabolism ; Urokinase-Type Plasminogen Activator ; biosynthesis ; genetics ; metabolism

Currently, exogenous gene expression system based on retroviral vector has been widely used as efficient gene expression system in both gene therapeutic research and RNA interference. In this study, we evaluated the efficiency of exogenous gene expression mediated by the retroviral vector in mammalian cells. First, we constructed EGFP (enhanced green fluorescent protein) vector using pcDNA3.1(+) and retroviral vector pQCXIN as backbone vector respectively. Then, we transfected or infected HEK293 cells and CHO-K1 cells with above vector or corresponding retroviral virus, and measured the relative fluorescence intensity (RFI) of EGFP. The results showed that the RFI of the retroviral virus-infected cells was two times higher than that of the plasmid-transfected cells. Further experiments revealed repeated virus infection enhanced the expression of EGFP markedly, with RFI increasing twice after four rounds of virus infection. Furthermore, the EGFP expression in HEK293 cells mediated by the retroviral vector was more stable than transfected with plasmid pcDNA3.1(+). Finally, we further validated the efficiency of exogenous gene expression system based on the retroviral vector by expressing recombinant human activated protein C (rhAPC) in HEK293 cells. We obtained HEK293 cell lines with rhAPC expression between 10 and 15 microg/(10(6) cells d). In conclusion, the exogenous gene expression system based on the retroviral vector is an alternative method for the generation of stable and high-expressing mammalian cell lines.
Animals ; CHO Cells ; Cricetinae ; Genetic Vectors ; genetics ; Green Fluorescent Proteins ; genetics ; HEK293 Cells ; Humans ; Protein C ; biosynthesis ; genetics ; RNA Interference ; Recombinant Proteins ; biosynthesis ; genetics ; Retroviridae ; genetics ; metabolism ; Transfection

In the light of Chinese hamster ovary (CHO) cell line 11G-S expressing human recombinant pro-urokinase, the differences of gene expression levels of the cells in different growth phases in both batch and fed-batch cultures were revealed by using gene chip technology. Then, based on the known cell cycle regulatory networks, the transcriptional profiling of the cell cycle regulatory networks of the cells in batch and fed-batch cultures was analyzed by using Genmapp software. Among the approximate 19 191 target genes in gene chip, the number of down-regulated genes was more than those of up-regulated genes of the cells in both batch and fed-batch cultures. The number of down-regulated genes of the cells in the recession phase in fed-batch culture was much more than that of the cells in batch culture. Comparative transcriptional analysis of the key cell cycle regulatory genes of the cells in both culture modes indicated that the cell proliferation and cell viability of the cells in both batch and fed-batch cultures were mainly regulated through down-regulating Cdk6, Cdk2, Cdc2a, Ccne1, Ccne2 genes of CDKs, Cyclin and CKI family and up-regulating Smad4 gene.
Animals ; Batch Cell Culture Techniques ; CHO Cells ; Cell Cycle Proteins ; genetics ; Cell Line ; Cricetinae ; Cyclin-Dependent Kinase 2 ; genetics ; Cyclin-Dependent Kinase 6 ; genetics ; Gene Expression Profiling ; Gene Expression Regulation ; Humans ; Recombinant Proteins ; biosynthesis ; genetics ; Smad4 Protein ; genetics ; Urokinase-Type Plasminogen Activator ; biosynthesis ; genetics

With suspension adapted recombinant Chinese hamster ovary (CHO) cell lines 11G-S expressing human pro-urokinase (pro-UK) as the object of study, a serum-free medium for the cultivation of recombinant CHO cells in suspension was formulated by using Plackett-Burman design and response surface methodology. The two-level Plackett-Burman design was used to evaluate the effect of 10 medium supplements on the growth of the 11G-S cells in suspension culture. Among the 10 medium supplements, insulin, transferrin, and putrescine were identified as the most significant factors (P < 0.05). The response surface methodology with three factors and three levels was used to determine the optimal levels of these factors. And a serum-free medium, SFM-CHO-S for recombinant CHO cells suspension culture was formulated. The maximum cell density of 11G-S cells in SFM-CHO-S in suspension batch culture reached 4.12 x 10(6) cells/mL with a maximum pro-UK activity at 5614 IU/mL, which was superior to the commercial serum-free medium for recombinant CHO cells.
Animals ; CHO Cells ; Cell Culture Techniques ; methods ; Cricetinae ; Cricetulus ; Culture Media, Serum-Free ; Genetic Engineering ; Insulin ; pharmacology ; Recombinant Proteins ; biosynthesis ; genetics ; Transferrin ; pharmacology ; Urokinase-Type Plasminogen Activator ; biosynthesis ; genetics

We constructed and identified cardiac-specific a-myosin heavy chain (alpha-MHC) promoter-driven expression vector. alpha-MHC promoter was amplified by PCR by using mouse genomic DNA as template and inserted into pGEM-T Easy vector. The inserted fragment was released by enzyme digestion, and then the cytomegalovirus (CMV) promoter in pcDNA3.1(+)-EGFP-hygro vector was replaced by the alpha-MHC promoter to construct alpha-MHC-EGFP expression vector. After identification with enzyme digestion, alpha-MHC-EGFP was transfected into mouse primary cardiomyocytes by electroporation. Green fluorescence could be observed in transfected cardiomyocytes, but not in transfected non-cardiomyocytes. Alpha-MHC-EGFP expression vector was specifically expressed in cardiomyocytes, and could be used to purify embryonic stem cell-derived cardiomyocytes.
Animals ; Cell Differentiation ; Cytomegalovirus ; genetics ; metabolism ; DNA, Complementary ; genetics ; Electroporation ; Embryonic Stem Cells ; cytology ; Genetic Vectors ; genetics ; Green Fluorescent Proteins ; biosynthesis ; genetics ; Mice ; Myocardium ; cytology ; metabolism ; Myosin Heavy Chains ; biosynthesis ; genetics ; Promoter Regions, Genetic ; genetics ; Transfection