Science.gov

Sample records for serum-free cho cell

  1. [Metabolic characteristics and kinetic model of recombinant CHO cells in serum-free suspension batch culture].

    PubMed

    Liu, Xingmao; Liu, Hong; Ye, Lingling; Li, Shichong; Wu, Benchuan; Wang, Haitao; Xie, Jing; Chen, Zhaolie

    2010-01-01

    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. PMID:20353097

  2. Serum-free transfection of CHO-cells with tailor-made unilamellar vesicles

    PubMed Central

    Sevcsik, Eva; Vorauer-Uhl, Karola; Lohner, Karl; Katinger, Hermann; Kunert, Renate

    2007-01-01

    At present, a number of transfection techniques are available to introduce foreign DNA into cells, but still minimal intrusion or interference with normal cell physiology, low toxicity, reproducibility, cost efficiency and successful creation of stable transfectants are highly desirable properties for improved transfection techniques. For all previous transfection experiments done in our labs, using serum-free cultivated host cell lines, an efficiency value of ∼0.1% for selection of stable cell lines has not been exceeded, consequently we developed and improved a transfection system based on defined liposomes, so-called large unilamellar vesicles, consisting of different lipid compositions to facilitate clone selection and increase the probability for creation of recombinant high-production clones. DNA and DOTAP/DOPE or CHEMS/DOPE interact by electrostatic means forming so-called lipoplexes (Even-Chen and Barenholz 2000) and the lipofection efficiency of those lipoplexes has been determined via confocal microscopy. In addition, the expression of the EGFP was determined by FACS to investigate transient as well as stable transfection and the transfection efficiency of a selection of different commercially available transfection reagents and kits has been compared to our tailor-made liposomes. PMID:19003008

  3. Overexpression and purification of HSV-2 glycoprotein D in suspension CHO cells with serum-free medium and immunogenicity analysis.

    PubMed

    Qi, Yong; Xu, Yueyue; Pan, Ying; Li, Suqin; Li, Bingjun; Pan, Mingjie; Zhang, Shumin; Li, Yuexi

    2016-05-01

    Glycoprotein D (gD2) is the most important candidate antigen for herpes simplex virus type 2 (HSV-2) vaccine development. Establishment of a stable eukaryotic cell line to overexpress gD2 and an efficient purification process to purify is essential for the development of subunit vaccine against HSV-2. The DNA sequence of the extracellular epitope-rich fragment of gD2 was optimized, chemically synthesized, and cloned into plasmid pMD902. The recombinant plasmid pMD902-gD was stably transfected into CHO-DG44 cells, and cell lines with high levels of expression of gD2 were established. The recombinant gD2 was purified efficiently using an anion exchange column and a Sephadex G-25 desalting column. The yield of the purified gD2 was 57 mg/L of serum-free culture medium, and its purity was determined to be about 95% by HPLC analysis. Finally, the immunogenicity of the purified gD2 was measured and it induced strong and specific humoral immunity and higher level of cellular immune response than gD2 expressed in prokaryotic cells. We established a stable, secretory, and high-yield gD2-expression cell line and an easy and efficient gD2-purification process, which lays the foundation for preparation of large amount of gD2 that is essential for HSV-2 subunit vaccine development. PMID:25906680

  4. Novel Cell-Ess ® supplement used as a feed or as an initial boost to CHO serum free media results in a significant increase in protein yield and production.

    PubMed

    Elhofy, Adam

    2016-01-01

    Many metrics, including metabolic profiles, have been used to analyze cell health and optimize productivity. In this study, we investigated the ability of a lipid supplement to increase protein yield. At a concentration of 1% (v/v) the lipid supplement caused a significant increase in protein titer (1118 ± 65.4 ng 10(5) cells(- 1) days(- 1)) when compared to cultures grown in the absence of supplementation (819.3 ± 38.1 ng 10(5) cells(- 1) days(- 1); p < 0.05). This equated to a 37% increase in productivity. Furthermore, metabolic profiles of ammonia, glutamate, lactate, and glucose were not significantly altered by the polar lipid supplement. In a separate set of experiments, using the supplement as a feed resulted in 2 notable effects. The first was a 25% increase in protein titer. The second was an extension of peak protein production from 1 day to 2 days. These results suggest that lipid supplementation is a promising avenue for enhancing protein production. In addition, our results also suggest that an increase in protein production may not necessarily require a change in the metabolic state of the cells. PMID:27594979

  5. Rakkyo fructan as a cryoprotectant for serum-free cryopreservation of mammalian cells.

    PubMed

    Ogawa, Akiko; Mizui, Shinya; Chida, Yasuhito; Shimizu, Masafumi; Terada, Satoshi; Ohura, Takeshi; Kobayashi, Kyo-Ichi; Yasukawa, Saori; Moriyama, Nobuyuki

    2014-07-01

    Cryopreservation refers to the long-term storage of mammalian cells. Mammalian serum is generally used as a cryoprotectant, but is associated with problems including the risk of contamination by pathogens and quality control issues. Therefore, a serum-free cryopreservation method needs to be established. In this study, we focused on rakkyo fructan, a fructose polymer, derived from the Japanese shallot as an alternative factor to serum. Fructan contributes to tolerance to frost and dehydration in plants by stabilizing the plant membrane. However, whether fructan protects mammalian cells against freezing stress remains unknown. The ability of rakkyo fructan to be an alternative cryoprotectant to fetal bovine serum (FBS) was examined in the present study. 2E3-O, a mouse hybridoma, was preserved in rakkyo fructan, was highly viable after being defrosted, and then proliferated rapidly. When rakkyo fructan was combined with dimethylsulfoxide (DMSO), its ability to protect the hybridoma against freezing stress was improved. The rakkyo fructan and DMSO mixture was used in the cryopreservation of the mammalian cell lines CHO-DP12, a producer of recombinant antibodies, and HepG2, human hepatoma cells frequently tested in bio-artificial livers. Following the freezing and thawing processes, CHO-DP12 cells retained their ability to produce recombinant antibodies and as did HepG2 cells for albumin and mRNA expression of cytochrome P450 enzymes. These results indicate that rakkyo fructan is a promising cryoprotectant that prevents mammalian cells from freezing stress similar to FBS. PMID:24485744

  6. Serum-Free Suspension Culture of MDCK Cells for Production of Influenza H1N1 Vaccines

    PubMed Central

    Huang, Ding; Peng, Wen-Juan; Ye, Qian; Liu, Xu-Ping; Zhao, Liang; Fan, Li; Xia-Hou, Kang; Jia, Han-Jing; Luo, Jian; Zhou, Lin-Ting; Li, Bei-Bei; Wang, Shi-Lei; Xu, Wen-Ting; Chen, Ze; Tan, Wen-Song

    2015-01-01

    Development of serum-free suspension cell culture processes is very important for influenza vaccine production. Previously, we developed a MDCK suspension cell line in a serum-free medium. In the present study, the growth kinetics of suspension MDCK cells and influenza virus production in the serum-free medium were investigated, in comparison with those of adherent MDCK cells in both serum-containing and serum-free medium. It was found that the serum-free medium supported the stable subculture and growth of both adherent and suspension cells. In batch culture, for both cell lines, the growth kinetics in the serum-free medium was comparable with those in the serum-containing medium and a commercialized serum-free medium. In the serum-free medium, peak viable cell density (VCD), haemagglutinin (HA) and median tissue culture infective dose (TCID50) titers of the two cell lines reached 4.51×106 cells/mL, 2.94Log10(HAU/50 μL) and 8.49Log10(virions/mL), and 5.97×106 cells/mL, 3.88Log10(HAU/50 μL), and 10.34Log10(virions/mL), respectively. While virus yield of adherent cells in the serum-free medium was similar to that in the serum-containing medium, suspension culture in the serum-free medium showed a higher virus yield than adherent cells in the serum-containing medium and suspension cells in the commercialized serum-free medium. However, the percentage of infectious viruses was lower for suspension culture in the serum-free medium. These results demonstrate the great potential of this suspension MDCK cell line in serum-free medium for influenza vaccine production and further improvements are warranted. PMID:26540170

  7. Culture of porcine hepatocytes or bile duct epithelial cells by inductive serum-free media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A serum-free, feeder-cell-dependent, selective culture system for the long-term culture of porcine hepatocytes or cholangiocytes was developed. Liver cells were isolated from 1 wk old pigs or young adult pigs (25 and 63 kg live weight) and were placed in primary culture on feeder-cell layers of mit...

  8. Differentiation of human embryonic stem cells to dopaminergic neurons in serum-free suspension culture.

    PubMed

    Schulz, Thomas C; Noggle, Scott A; Palmarini, Gail M; Weiler, Deb A; Lyons, Ian G; Pensa, Kate A; Meedeniya, Adrian C B; Davidson, Bruce P; Lambert, Nevin A; Condie, Brian G

    2004-01-01

    The use of human embryonic stem cells (hESCs) as a source of dopaminergic neurons for Parkinson's disease cell therapy will require the development of simple and reliable cell differentiation protocols. The use of cell cocultures, added extracellular signaling factors, or transgenic approaches to drive hESC differentiation could lead to additional regulatory as well as cell production delays for these therapies. Because the neuronal cell lineage seems to require limited or no signaling for its formation, we tested the ability of hESCs to differentiate to form dopamine-producing neurons in a simple serum-free suspension culture system. BG01 and BG03 hESCs were differentiated as suspension aggregates, and neural progenitors and neurons were detectable after 2-4 weeks. Plated neurons responded appropriately to electrophysiological cues. This differentiation was inhibited by early exposure to bone morphogenic protein (BMP)-4, but a pulse of BMP-4 from days 5 to 9 caused induction of peripheral neuronal differentiation. Real-time polymerase chain reaction and whole-mount immunocytochemistry demonstrated the expression of multiple markers of the midbrain dopaminergic phenotype in serum-free differentiations. Neurons expressing tyrosine hydroxylase (TH) were killed by 6-hydroxydopamine (6-OHDA), a neurotoxic catecholamine. Upon plating, these cells released dopamine and other catecholamines in response to K+ depolarization. Surviving TH+ neurons, derived from the cells differentiated in serum-free suspension cultures, were detected 8 weeks after transplantation into 6-OHDA-lesioned rat brains. This work suggests that hESCs can differentiate in simple serum-free suspension cultures to produce the large number of cells required for transplantation studies. PMID:15579641

  9. Sorafenib suppresses the cell cycle and induces the apoptosis of hepatocellular carcinoma cell lines in serum-free media

    PubMed Central

    TOMIZAWA, MINORU; SHINOZAKI, FUMINOBU; SUGIYAMA, TAKAO; YAMAMOTO, SHIGENORI; SUEISHI, MAKOTO; YOSHIDA, TAKANOBU

    2010-01-01

    To suppress the invasion of hepatocellular carcinoma (HCC) cells into surrounding connective tissues during metastasis, we investigated the usefulness of sorafenib. In order to search for model cell lines, cell numbers were counted to reveal cell lines with the potential to proliferate in serum-free media. Cell proliferation and cell motility were analyzed with the MTS and wound assay, respectively. 5-Bromo-2′-deoxyuridine (BrdU) labeling and mitotic and apoptotic indices were analyzed to assess the cell cycle and apoptosis. The expression levels of cyclin D1 and the cleavage of caspase-3 were analyzed by Western blotting. HLF cells exhibited growth in the serum-free medium, while the other cell lines examined did not. Sorafenib suppressed the cell proliferation and motility of the HLF cells in the serum-free media. Both indices of BrdU and mitotic potential decreased and the apoptotic index was increased in the serum-free media with sorafenib, suggesting that the cell cycle was suppressed and apoptosis was induced. The expression levels of cyclin D1 decreased and the cleavage of caspase-3 was noted in the serum-free media with sorafenib. Sorafenib may be suitable for molecular therapy to suppress the metastasis of HCC. PMID:22993610

  10. Yeast hydrolysate as a low-cost additive to serum-free medium for the production of human thrombopoietin in suspension cultures of Chinese hamster ovary cells.

    PubMed

    Sung, Y H; Lim, S W; Chung, J Y; Lee, G M

    2004-02-01

    To enhance the performance of a serum-free medium (SFM) for human thrombopoietin (hTPO) production in suspension cultures of recombinant Chinese hamster ovary (rCHO) cells, several low-cost hydrolysates such as yeast hydrolysate (YH), soy hydrolysate, wheat gluten hydrolysate and rice hydrolysate were tested as medium additives. Among various hydrolysates tested, the positive effect of YH on hTPO production was most significant. When 5 g l(-1) YH was added to SFM, the maximum hTPO concentration in batch culture was 40.41 microg ml(-1), which is 11.5 times higher than that in SFM without YH supplementation. This enhanced hTPO production in YH-supplemented SFM was obtained by the combined effect of enhanced q(hTPO) (the specific rate of hTPO production). The supplementation of YH in SFM increased q(hTPO) by 294% and extended culture longevity by >2 days if the culture was terminated at a cell viability of 50%. Furthermore, cell viability throughout the culture using YH-supplemented SFM was higher than that using any other hydrolysate-supplemented SFM tested, thereby minimizing degradation of hTPO susceptible to proteolytic degradation. In addition, YH supplementation did not affect in vivo biological activity of hTPO. Taken together, the results obtained demonstrate the potential of YH as a medium additive for hTPO production in serum-free suspension cultures of rCHO cells. PMID:12856163

  11. Survival and neurite growth of chick embryo spinal cord cells in serum-free culture.

    PubMed

    Tanaka, H; Obata, K

    1982-07-01

    Cell survival and neurite growth were investigated in serum-free spinal cord cell cultures on polyornithine coating (PORN). Cells were obtained from 6- or 7-day-old chick embryos. Isolated spinal cord cells required promoting factors for their survival and neurite growth. The survival-promoting factors were initially present in spinal cord cells. High density cultures, co-cultures with spinal cord explants, and spinal cord extract promoted survival of isolated spinal cord cells in MEM with no additives. Other tissue extracts (brain, liver, heart and skeletal muscle), serum, and serum-free conditioned medium (SF-CM) of muscle or glioma C6 cells also promoted survival. The active substances in the brain extract and SF-CM were shown to be protein and were separated into 3 fractions (approximately molecular weight 150,000, 70,000, 40,000) by gel filtration chromatography. Survival and neurite growth were suggested to be promoted by different factors because: (1) survival was promoted by both tissue extract and SF-CM, but neurite growth was promoted only by SF-CM; (2) the neurite growth-stimulating activity of SF-CM was lost following dialysis and heat (100 degrees C, 2 min) treatment; however, the survival-promoting activity was not. It was also suggested that spinal cord cells produce neurite growth promoting factors, but did not initially contain these factors. PMID:7104764

  12. Development of a chemically defined serum-free medium for differentiation of rat adipose precursor cells

    SciTech Connect

    Deslex, S.; Negrel, R.; Ailhaud, G.

    1987-01-01

    Stromal-vascular cells from the epididymal fat pad of 4-week-old rats, when cultured in a medium containing insulin or insulin-like growth factor, IFG-I, triiodothyronine and transferrin, were able to undergo adipose conversion. Over ninety percent of the cells accumulated lipid droplets and this proportion was reduced in serum-supplemented medium. The adipose conversion was assessed by the development of lipoprotein lipase (LPL) and glycerol-3-phosphate dehydrogenase (GPDH) activities, (/sup 14/)glucose incorporation into polar and neutral lipids, triacylglycerol accumulation and lipolysis in response to isoproterenol. Similar results were obtained with stromal-vascular cells from rat subcutaneous and retroperitoneal adipose tissues. Stromal-vascular cells required no adipogenic factors in addition to the components of the serum-free medium. Insulin was required within a physiological range of concentrations for the emergence of LPL and at higher concentrations for that of GPDH. When present at concentrations ranging from 2 to 50 nM, IGF-I was able to replace insulin for the expression of both LPL and and GPDH. The development of a serum free, chemically defined medium for the differentiation of diploid adiopose precursor cells opens up the possibility of characterizing inhibitors or activators of the adipose conversion process.

  13. Development of Serum-Free Media for Lepidopteran Insect Cell Lines.

    PubMed

    Chan, Leslie C L; Reid, Steven

    2016-01-01

    Baculovirus-based Insect Cell Technology (ICT) is widely used for the expression of recombinant heterologous proteins and baculovirus bioinsecticides, and has recently gained momentum as a commercial manufacturing platform for human and veterinary vaccines. The three key components of ICT are the Lepidopteran insect cell line, the baculovirus vector, and the growth medium. Insect cell growth media have evolved significantly in the past five decades, from basal media supplemented with hemolymph or animal serum, to highly optimized serum-free media and feeds (SFM and SFF) capable of supporting very high cell densities and recombinant protein yields. The substitution of animal sera with protein hydrolysates in SFM results in greatly reduced medium costs and much improved process scalability. However, both sera and hydrolysates share the disadvantage of lot-to-lot variability, which is detrimental to process reproducibility. Hence, the industrialization of ICT would benefit greatly from chemically defined media (CDM) for insect cells, which are not yet commercially available. On the other hand, applications such as baculovirus bioinsecticides would need truly low cost serum-free media and feeds (LC-SFM and LC-SFF) for economic viability, which require the substitution of a majority of expensive added amino acids with even higher levels of hydrolysates, hence increasing the risk of a variable process. CDM developments are anticipated to benefit both conventional and low cost ICT applications, by identifying key growth factors in hydrolysates for more targeted media and feed design. PMID:26820858

  14. The serial cultivation of suspended BHK-21/13 cells in serum-free Waymouth medium.

    PubMed

    Guskey, L E; Jenkin, H M

    1976-01-01

    A simple medium system was developed to obtain growth of BHK-21 cells in shaker cultures in the absence of serum. These cells have now undergone over 80 serial passages in serum-free Waymouth medium and have been recovered from the frozen state after storage for over 1 month in medium containing 10% dimethyl sulfoxide (DMSO) and 1% bovine serum albumin (BSA). Various amounts of exogenous lipid in the form of sodium oleate were added to cultures of cells growing in serum-free Waymouth medium. Concentrations of 10-50 mug of sodium oleate/ml had no detrimental effects on the cells as measured by trypan blue uptake. Furthermore, the cells were serially passed ten times in the presence of 10 mug sodium oleate/ml. Depletion of calf serum from the growth medium and addition of known quantities of lipids to the system provides a means of revealing subtle changes in lipid synthesis and lipid turnover during cellular growth. PMID:1250851

  15. Production of canine adenovirus type 2 in serum-free suspension cultures of MDCK cells.

    PubMed

    Castro, R; Fernandes, P; Laske, T; Sousa, M F Q; Genzel, Y; Scharfenberg, K; Alves, P M; Coroadinha, A S

    2015-09-01

    The potential of adherent Madin Darby Canine Kidney (MDCK) cells for the production of influenza viruses and canine adenovirus type 2 (CAV-2) for vaccines or gene therapy approaches has been shown. Recently, a new MDCK cell line (MDCK.SUS2) that was able to grow in suspension in a fully defined system was established. In this work, we investigated whether the new MDCK.SUS2 suspension cell line is suitable for the amplification of CAV-2 under serum-free culture conditions. Cell growth performance and CAV-2 production were evaluated in three serum-free media: AEM, SMIF8, and EXCELL MDCK. CAV-2 production in shake flasks was maximal when AEM medium was used, resulting in an amplification ratio of infectious particles (IP) of 142 IP out/IP in and volumetric and cell-specific productivities of 2.1 × 10(8) IP/mL and 482 IP/cell, respectively. CAV-2 production was further improved when cells were cultivated in a 0.5-L stirred tank bioreactor. To monitor infection and virus production, cells were analyzed by flow cytometry. A correlation between the side scatter measurement and CAV-2 productivity was found, which represents a key feature to determine the best harvesting time during process development of gene therapy vectors that do not express reporter genes. This work demonstrates that MDCK.SUS2 is a suitable cell substrate for CAV-2 production, constituting a step forward in developing a production process transferable to industrial scales. This could allow for the production of high CAV-2 titers either for vaccination or for gene therapy purposes. PMID:25994255

  16. Growth of hybridoma cells in serum-free medium: ethanolamine is an essential component.

    PubMed Central

    Murakami, H; Masui, H; Sato, G H; Sueoka, N; Chow, T P; Kano-Sueoka, T

    1982-01-01

    A serum-free medium supplemented with a few growth factors was devised to grow lymphocyte hybridomas. The medium was developed with the hybridoma line MPC11-BL, a fusion product between a mouse plasmacytoma cell line (MPC11TG70na3) and mouse (BALB/c) spleen cells. In the process of developing the medium, ethanolamine was found to be an essential growth factor for the hybridoma. Phosphoethanolamine at 10-fold higher concentration could substitute for ethanolamine. Long-term cultivation of the cells was achieved in the defined medium supplemented with insulin, transferrin, ethanolamine, and selenium. The defined medium supported the growth of various other mouse hybridoma cell lines, mostly at a rate comparable to that observed in a serum-containing medium. After one-step ammonium sulfate precipitation of the spent medium, more than 95% of the protein recovered was immunoglobulin as shown by NaDodSO4/polyacrylamide gel electrophoresis. Images PMID:7041116

  17. Ex Vivo Expansion of Human Mesenchymal Stem Cells in Defined Serum-Free Media

    PubMed Central

    Jung, Sunghoon; Panchalingam, Krishna M.; Rosenberg, Lawrence; Behie, Leo A.

    2012-01-01

    Human mesenchymal stem cells (hMSCs) are presently being evaluated for their therapeutic potential in clinical studies to treat various diseases, disorders, and injuries. To date, early-phase studies have indicated that the use of both autologous and allogeneic hMSCs appear to be safe; however, efficacy has not been demonstrated in recent late-stage clinical trials. Optimized cell bioprocessing protocols may enhance the efficacy as well as safety of hMSC therapeutics. Classical media used for generating hMSCs are typically supplemented with ill-defined supplements such as fetal bovine serum (FBS) or human-sourced alternatives. Ideally, culture media are desired to have well-defined serum-free formulations that support the efficient production of hMSCs while maintaining their therapeutic and differentiation capacity. Towards this objective, we review here current cell culture media for hMSCs and discuss medium development strategies. PMID:22645619

  18. Functional Myotube Formation from Adult Rat Satellite Cells in a Defined Serum-free System

    PubMed Central

    McAleer, Christopher W.; Rumsey, John W.; Stancescu, Maria; Hickman, James J.

    2016-01-01

    This manuscript describes the development of a culture system whereby mature contracting myotubes were formed from adult rat derived satellite cells. Satellite cells, extracted from the Tibialis Anterior (TA) of adult rats, were grown in defined serum-free growth and differentiation media, on a non-biological substrate, N-1[3-trimethoxysilyl propyl] diethylenetriamine. Myotubes were evaluated morphologically and immunocytochemically, using MyHC specific antibodies, as well as functionally using patch clamp electrophysiology to measure ion channel activity. Results indicated the establishment of the rapid expression of adult myosin isoforms that contrasts to their slow development in embryonic cultures. This culture system has applications in the understanding and treatment of age related muscle myopathy, muscular dystrophy, and for skeletal muscle engineering by providing a more relevant phenotype for both in vitro and in vivo applications. PMID:25683642

  19. Expansion, harvest and cryopreservation of human mesenchymal stem cells in a serum-free microcarrier process.

    PubMed

    Heathman, Thomas R J; Glyn, Veronica A M; Picken, Andrew; Rafiq, Qasim A; Coopman, Karen; Nienow, Alvin W; Kara, Bo; Hewitt, Christopher J

    2015-08-01

    Human mesenchymal stem cell (hMSC) therapies are currently progressing through clinical development, driving the need for consistent, and cost effective manufacturing processes to meet the lot-sizes required for commercial production. The use of animal-derived serum is common in hMSC culture but has many drawbacks such as limited supply, lot-to-lot variability, increased regulatory burden, possibility of pathogen transmission, and reduced scope for process optimization. These constraints may impact the development of a consistent large-scale process and therefore must be addressed. The aim of this work was therefore to run a pilot study in the systematic development of serum-free hMSC manufacturing process. Human bone-marrow derived hMSCs were expanded on fibronectin-coated, non-porous plastic microcarriers in 100 mL stirred spinner flasks at a density of 3 × 10(5) cells.mL(-1) in serum-free medium. The hMSCs were successfully harvested by our recently-developed technique using animal-free enzymatic cell detachment accompanied by agitation followed by filtration to separate the hMSCs from microcarriers, with a post-harvest viability of 99.63 ± 0.03%. The hMSCs were found to be in accordance with the ISCT characterization criteria and maintained hMSC outgrowth and colony-forming potential. The hMSCs were held in suspension post-harvest to simulate a typical pooling time for a scaled expansion process and cryopreserved in a serum-free vehicle solution using a controlled-rate freezing process. Post-thaw viability was 75.8 ± 1.4% with a similar 3 h attachment efficiency also observed, indicating successful hMSC recovery, and attachment. This approach therefore demonstrates that once an hMSC line and appropriate medium have been selected for production, multiple unit operations can be integrated to generate an animal component-free hMSC production process from expansion through to cryopreservation. PMID:25727395

  20. Establishment of human ovarian serous carcinomas cell lines in serum free media.

    PubMed

    Pan, Zhuangyu; Hooley, Jeffrey; Smith, Douglas H; Young, Peter; Roberts, Penelope E; Mather, Jennie P

    2012-03-01

    Ovarian cancers are the fifth leading cause of cancer death among US woman. The majority of ovarian cancers belong to a category of serous adenocarcinomas. This type of cancer is often diagnosed at a late stage of the disease. Surgical debulking, followed by chemotherapy is the current treatment. Half of all patients will die within 5 years of diagnosis of the disease. Poor survival may be due to disease progression as a consequence of development of drug resistance, cancer cell heterogeneity within the tumor, or the persistence of cancer stem cells. Cancer stem cells (CSC) are defined as a minority cell type in the tumor, which retains the capacity, through asymmetric division, for self-renewal as well as differentiation into multiple cell types. Through this process, CSC can regenerate the entire tumor phenotype and subsequent metastases. Initial in vitro work in the area of solid tumor CSC biology has focused on the isolation and propagation of cells with CSC-like properties from breast and colon tumors. Breast and colon cell lines with CSC-like properties have been isolated and maintained in vitro for extended periods of time. The in vitro maintenance of these CSC requires growth in hormone-supplemented serum-free media and the use of matrix or growth as tumor spheres (Roberts, Ricci-Vitiani et al., Cammareri et al.). Based on the pioneering work generating breast and colon CSC, our lab has begun to develop methods for the establishment cell lines with CSC-like properties from additional solid tumors. In this article, we describe methods, using defined medium, which allow for the successful establishment of continuous cell cultures from a minority cell type within serous ovarian cancers. The cell lines established using these methods grow in serum-free hormone-supplemented medium either as a monolayer on a matrix, or as tumor spheres in suspension. These cells express markers previously reported for tumor stem cells, including CD44 and CD133, and form tumors

  1. Proliferation and responsiveness to estrogen of human endometrial cancer cells under serum-free culture conditions.

    PubMed

    Holinka, C F; Anzai, Y; Hata, H; Kimmel, N; Kuramoto, H; Gurpide, E

    1989-06-15

    Studies of hormonal growth regulation in cultured human endometrial cancer cells are limited by the requirement of exogenous growth factors, usually supplied by addition of serum. The present report provides evidence that estradiol can stimulate proliferation of endometrial cancer cells of the Ishikawa line in the absence of serum or added growth factors. Mitogenic effects of estrogen were demonstrated in two different experimental systems, in cells attached to the substratum of mammalian tissue culture dishes, and in cells forming colonies in soft agar under anchorage-independent conditions. Addition of estradiol to a mixture of serum-free, phenol red-free Dulbecco's minimal essential medium and Ham's F-12 medium, supplemented with L-glutamine and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid [basal medium: (BM)] significantly increased the proliferation of cells attached to culture dishes. Dose-response experiments revealed maximal estradiol stimulation at 10 nM; significant responses were also observed at 1 nM and at 100 nM concentrations. The mitogenic effect of 10 nM estradiol was comparable to that of 1% charcoal-treated fetal bovine serum and the two effects were additive. The presence of estradiol in serum-free BM resulted in a shortening of the doubling time of exponentially proliferating cells from 38 to 29 h. From the labeling index, measured after exposure to a pulse of [3H]thymidine, and from the mitotic index, both determined in exponentially proliferating cells, the lengths of the S and M phases were calculated to be 11 and 1 h, respectively. From these data it was estimated that estradiol shortened the G1 phase by approximately 40%, from 22 to 13 h. Estradiol doubled the colony formation efficiency of cells plated in BM containing 0.3% agar in the absence of serum as well as in the presence of 1% charcoal-treated fetal bovine serum. The stimulation of colony formation by estradiol was influenced by medium components, since no effects were

  2. Differential requirements of two insect cell lines for growth in serum-free medium.

    PubMed

    Vaughn, J L; Fan, F

    1997-06-01

    The development of a serum-free medium that supports the growth of cells from a Spodoptera frugiperda and a Lymantria dispar cell line is reported. A yeast hydrolysate provided the B-vitamin complex, and a combination of a meat hydrolysate and tryptose provided most of the free amino acids required for cell growth. Supplemental cystine and methionine were required to achieve maximum cell growth. The serum or serum replacements used in earlier formulations were replaced with commercial lipid preparations and increased levels of iron salts. Although the cell growth cycle had a somewhat extended lag phase and the population doubling time of the S. frugiperda cells was longer than on serum-containing medium, the saturation densities were much higher. Spodoptera cells grown in this medium replicated the Autographa californica nuclear polyhedrosis virus well, producing 8.71 x 10(6) TCID50 extracellular virus and 4.4 x 10(6) polyhedra/ml culture. The specific activity of the polyhedra was somewhat less than that of polyhedra produced in insects. PMID:9201517

  3. Human dental pulp stem cells cultured in serum-free supplemented medium

    PubMed Central

    Bonnamain, Virginie; Thinard, Reynald; Sergent-Tanguy, Solène; Huet, Pascal; Bienvenu, Géraldine; Naveilhan, Philippe; Farges, Jean-Christophe; Alliot-Licht, Brigitte

    2013-01-01

    Growing evidence show that human dental pulp stem cells (DPSCs) could provide a source of adult stem cells for the treatment of neurodegenerative pathologies. In this study, DPSCs were expanded and cultured with a protocol generally used for the culture of neural stem/progenitor cells. Methodology: DPSC cultures were established from third molars. The pulp tissue was enzymatically digested and cultured in serum-supplemented basal medium for 12 h. Adherent (ADH) and non-adherent (non-ADH) cell populations were separated according to their differential adhesion to plastic and then cultured in serum-free defined N2 medium with epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). Both ADH and non-ADH populations were analyzed by FACS and/or PCR. Results: FACS analysis of ADH-DPSCs revealed the expression of the mesenchymal cell marker CD90, the neuronal marker CD56, the transferrin receptor CD71, and the chemokine receptor CXCR3, whereas hematopoietic stem cells markers CD45, CD133, and CD34 were not expressed. ADH-DPSCs expressed transcripts coding for the Nestin gene, whereas expression levels of genes coding for the neuronal markers β-III tubulin and NF-M, and the oligodendrocyte marker PLP-1 were donor dependent. ADH-DPSCs did not express the transcripts for GFAP, an astrocyte marker. Cells of the non-ADH population that grew as spheroids expressed Nestin, β-III tubulin, NF-M and PLP-1 transcripts. DPSCs that migrated out of the spheroids exhibited an odontoblast-like morphology and expressed a higher level of DSPP and osteocalcin transcripts than ADH-DPSCs. Conclusion: Collectively, these data indicate that human DPSCs can be expanded and cultured in serum-free supplemented medium with EGF and bFGF. ADH-DPSCs and non-ADH populations contained neuronal and/or oligodendrocyte progenitors at different stages of commitment and, interestingly, cells from spheroid structures seem to be more engaged into the odontoblastic lineage than the ADH

  4. Serum-Free and Xenobiotic-Free Preservation of Cultured Human Limbal Epithelial Cells

    PubMed Central

    Utheim, Oeygunn; Islam, Rakibul; Lyberg, Torstein; Roald, Borghild; Eidet, Jon Roger; de la Paz, Maria Fideliz; Dartt, Darlene A.; Raeder, Sten; Utheim, Tor Paaske

    2015-01-01

    Aim/Purpose of the Study To develop a one-week storage method, without serum and xenobiotics, that would maintain cell viability, morphology, and phenotype of cultured human limbal epithelial sheets. Materials and Methods Human limbal explants were cultured on intact human amniotic membranes for two weeks. The sheets were stored in a hermetically sealed container at 23°C in either a serum-free medium with selected animal serum-derived compounds (Quantum 286) or a xenobiotic-free medium (Minimal Essential Medium) for 4 and 7 days. Stored and non-stored cultures were analyzed for cell viability, amniotic membrane and epithelial sheet thickness, and a panel of immunohistochemical markers for immature cells (ΔNp63α, p63, Bmi-1, C/EBP∂, ABCG2 and K19), differentiated cells (K3 and Cx43), proliferation (PCNA), and apoptosis (Caspase-3). Results The cell viability of the cultures was 98 ± 1% and remained high after storage. Mean central thickness of non-stored limbal epithelial sheets was 23 ± 3 μm, and no substantial loss of cells was observed after storage. The non-stored epithelial sheets expressed a predominantly immature phenotype with ΔNp63α positivity of more than 3% in 9 of 13 cultures. After storage, the expression of ABCG2 and C/EBP∂ was reduced for the 7 day Quantum 286-storage group; (P = 0.04), and Bmi-1 was reduced after 4 day Quantum 286-storage; (P = 0.02). No other markers varied significantly. The expression of differentiation markers was unrelated to the thickness of the epithelia and amniotic membrane, apart from ABCG2, which correlated negatively with thickness of limbal epithelia (R = -0.69, P = 0.01) and ΔNp63α, which correlated negatively with amniotic membrane thickness (R = -0.59, P = 0.03). Conclusion Limbal epithelial cells cultured from explants on amniotic membrane can be stored at 23°C in both serum-free and xenobiotic-free media, with sustained cell viability, ultrastructure, and ΔNp63α-positivity after both 4 and 7 days

  5. Culture of fetal alveolar epithelial type II cells in serum-free medium.

    PubMed

    Fraslon, C; Rolland, G; Bourbon, J R; Rieutort, M; Valenza, C

    1991-11-01

    A serum-free culture medium (defined medium = DM) was elaborated by adding to Eagle's minimum essential medium (MEM), non-essential amino acids, transferrin, putrescine, tripeptide glycyl-histidyl-lysine, somatostatin, sodium selenite, ethanolamine, phosphoethanolamine, sodium pyruvate, and metal trace elements. This medium was tested for its ability to support sustained surfactant biosynthesis in fetal alveolar epithelial type II cells. For up to 8 days, ultrastructure was maintained with persistence of lamellar inclusion bodies. Thymidine incorporation into DNA was enhanced about 50% in DM as compared with MEM, whereas it was enhanced 300% in 10% fetal bovine serum. With DM, the incorporation of tritiated choline into phosphatidylcholine (PC) of isolated surfactant material was about twice that with MEM. Deletion experiments evidenced the prominent role of pyruvate, transferrin, and selenium in the stimulation of surfactant PC biosynthesis. The addition of biotin to DM enhanced surfactant PC biosynthesis slightly and nonsurfactant PC biosynthesis markedly. The presence of nucleosides seemed unfavorable to the synthesis of surfactant PC. Type II cells responded to the addition of epidermal growth factor and insulinlike growth factor-I both by increased thymidine incorporation into DNA and choline incorporation into PC. It is concluded that DM represents a useful tool for cultivating type II cells without loss of their specialized properties and for studying the regulation of cell proliferation and surfactant biosynthesis in a controlled environment. PMID:1748624

  6. Cytotoxicity and mutagenicity of the fungicides captan and folpet in cultured mammalian cells (CHO/HGPRT system)

    SciTech Connect

    O'Neill, J.P.; Forbes, N.L; Hsie, A.W.

    1981-01-01

    The cytotoxicity and mutagenicity of the fungicides captan and folpet were determined in the CHO/HGPRT system which utilizes Chinese hamster ovary cells and resistance to 6-thioguanine to estimate mutation induction at the hypoxanthine-guanine phosphoribosyl transferase locus. Treatment of cultures with each compound for 5 hr in serum-free medium resulted in reproducible, significant, concentration-dependent increases in the frequency of 6-thioguanine-resistant mutants.

  7. A critical synopsis: Continuous growth of proximal tubular kidney epithelial cells in hormone-supplemented serum-free medium

    NASA Technical Reports Server (NTRS)

    Chuman, L. M.; FINE; COHEN; Saier, M. H.

    1985-01-01

    The kidney forms urine and reabsorbs electrolytes and water. Kidney cell lines and hormone supplemented serum free medium were used for growth. The hormones were insulin, transferrin, vasopressin, cholesterol, prostaglandins, hydrocortisone, and triidothyronine. Epithelial cell lines are polar and form hemicysts. The Madin-Darby canine kidney(MDCK) cell line used is distal tubulelike. LLC-PK sub 1 cells are derived from pig kidneys and have the properties of different kidney segments. The LLC-PK sub 1 cells with proximal tubule properties were maintained in hormone-supplemented serum free medium. Seven factors (the aforementioned homrones and selenium) were needed for growth. Hormone-defined medium supported LLC-PK sub 1 cell growth, allowed transport (as seen by hemicyst formation), and influenced cell morphology. Vasopressin (used for growth and morphology) could be partially replaced by isobutylmethylxanthine or dibutyryl cAMP. The defined medium was used to isolate rabbit proximal tubule kidney epithelial cells free of fibroblasts.

  8. Canine and Equine Mesenchymal Stem Cells Grown in Serum Free Media Have Altered Immunophenotype.

    PubMed

    Clark, Kaitlin C; Kol, Amir; Shahbenderian, Salpi; Granick, Jennifer L; Walker, Naomi J; Borjesson, Dori L

    2016-04-01

    Mesenchymal stem cell (MSC) therapy is being increasingly used to treat dogs and horses with naturally-occurring diseases. However these animals also serve as critical large animal models for ongoing translation of cell therapy products to the human market. MSC manufacture for clinical use mandates improvement in cell culture systems to meet demands for higher MSC numbers and removal of xeno-proteins (i.e. fetal bovine serum, FBS). While serum-free media (SFM) is commercially available, its affects on MSC phenotype and immunomodulatory functions are not fully known. The objective of this study was to determine if specific MSC culture conditions, MSC expansion in HYPERFlasks® or MSC expansion in a commercially available SFM, would alter MSC proliferation, phenotype or immunomodulatory properties in vitro. MSCs cultured in HYPERFlasks® were similar in phenotype, proliferative capacity and immunomodulatory functions to MSCs grown in standard flasks however MSC yield was markedly increased. HYPERFlasks® therefore provide a viable option to generate greater cell numbers in a streamlined manner. Canine and equine MSCs expanded in SFM displayed similar proliferation, surface phenotype and inhibitory effect on lymphocyte proliferation in vitro. However, MSCs cultured in the absence of FBS secreted significantly less PGE2, and were significantly less able to inhibit IFNγ secretion by activated T-cells. Immunomodulatory functions altered by expansion in SFM were species dependent. Unlike equine MSCs, in canine adipose-derived MSCs, the inhibition of lymphocyte proliferation was not principally modulated by PGE2. The removal of FBS from both canine and equine MSC culture systems resulted in altered immunomodulatory properties in vitro and warrants further investigation prior to moving towards FBS-free culture conditions. PMID:26638159

  9. Growth, differentiation capacity, and function of mesenchymal stem cells expanded in serum-free medium developed via combinatorial screening.

    PubMed

    Crapnell, Kirsten; Blaesius, Rainer; Hastings, Abel; Lennon, Donald P; Caplan, Arnold I; Bruder, Scott P

    2013-06-10

    The presence of serum in cell culture medium presents an obstacle to safe and efficient production of hMSCs for therapeutic purposes. Availability of defined medium will be crucial to elucidating the mechanism of action of hMSCs in many indications as well as a prerequisite to consistently produce cells with predictable performance characteristics. Using a bioinformatics driven approach, which we call the BD Discovery Platform, we have developed a novel serum-free medium that supports highly efficient growth while maintaining the surface markers and functional characteristics defining hMSCs. In a comparison with serum-containing and other commercially available serum-free formulations, all conditions led to expansion of cells that meet the minimal criteria for hMSCs as set by the International Society for Cellular Therapy (ISCT). However, differences in growth characteristics and gene expression patterns suggest that expansion in serum-free growth conditions can provide greater yields in a shorter time. The mRNA expression profile observed in cells grown without serum suggests upregulation of several genes implicated in hMSC function as well as downregulation of the proinflammatory cytokine IL6. PMID:23597555

  10. Collagen nanofibres are a biomimetic substrate for the serum-free osteogenic differentiation of human adipose stem cells

    PubMed Central

    Sefcik, Lauren S.; Neal, Rebekah A.; Kaszuba, Stephanie N.; Parker, Anna M.; Katz, Adam J.; Ogle, Roy C.; Botchwey, Edward A.

    2011-01-01

    Electrospinning has recently gained widespread attention as a process capable of producing nanoscale fibres that mimic native extracellular matrix. In this study, we compared the osteogenic differentiation behaviour of human adipose stem cells (ASCs) on a 3D nanofibre matrix of type I rat tail collagen (RTC) and a 2D RTC collagen-coated substrate, using a novel serum-free osteogenic medium. The serum-free medium significantly enhanced the numbers of proliferating cells in culture, compared to ASCs in traditional basal medium containing 10% animal serum, highlighting a potential clinical role for in vitro stem cell expansion. Osteogenic differentiation behaviour was assessed at days 7, 14 and 21 using quantitative real-time RT–PCR analysis of the osteogenic genes collagen I (Coll I), alkaline phosphatase (ALP), osteopontin (OP), osteonectin (ON), osteocalcin (OC) and core-binding factor-α (cbfa1). All genes were upregulated (>one-fold) in ASCs cultured on nanofibre scaffolds over 2D collagen coatings by day 21. Synthesis of mineralized extracellular matrix on the scaffolds was assessed on day 21 with Alizarin red staining. These studies demonstrate that 3D nanoscale morphology plays a critical role in regulating cell fate processes and in vitro osteogenic differentiation of ASCs under serum-free conditions. PMID:18493910

  11. Serum free hemoglobin test

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003677.htm Serum free hemoglobin test To use the sharing features on this page, please enable JavaScript. Serum free hemoglobin is a blood test that measures the ...

  12. Large-scale expansion of pre-isolated bone marrow mesenchymal stromal cells in serum-free conditions.

    PubMed

    Gottipamula, Sanjay; Muttigi, Manjunatha S; Chaansa, S; Ashwin, K M; Priya, Nancy; Kolkundkar, Udaykumar; SundarRaj, Swathi; Majumdar, Anish Sen; Seetharam, Raviraja N

    2016-02-01

    The regenerative potential of mesenchymal stromal or stem cells (MSCs) has generated tremendous interest for treating various degenerative diseases. Regulatory preference is to use a culture medium that is devoid of bovine components for stem cell expansion intended for therapeutic applications. However, a clear choice an alternative to fetal bovine serum (FBS) has not yet emerged. We have screened five different commercially available serum-free media (SFM) for their ability to support the growth and expansion of pre-isolated undifferentiated bone marrow-derived MSCs (BM-MSCs) and compared the results with cells grown in standard FBS-containing medium as control. In addition, based on initial screening results, BD Mosaic™ Mesenchymal Stem Cell Serum-free (BD-SFM) medium was evaluated in large-scale cultures for the performance and culture characteristics of BM-MSCs. Of the five different serum-free media, BD-SFM enhanced BM-MSCs growth and expansion in Cell STACK (CS), but the cell yield per CS-10 was less when compared to the control medium. The characteristics of MSCs were measured in terms of population doubling time (PDT), cell yield and expression of MSC-specific markers. Significant differences were observed between BD-SFM and control medium in terms of population doublings (PDs), cell yield, CFU-F and morphological features, whereas surface phenotype and differentiation potentials were comparable. The BD-SFM-cultured MSCs were also found to retain the differentiation potential, immune-privileged status and immunosuppressive properties inherent to MSCs. Our results suggest that BD-SFM supports large-scale expansion of BM-MSCs for therapeutic use. PMID:23495227

  13. The growth factor inhibitor suramin reduces apoptosis and cell aggregation in protein-free CHO cell batch cultures.

    PubMed

    Zanghi, J A; Renner, W A; Bailey, J E; Fussenegger, M

    2000-01-01

    We have previously shown that Chinese hamster ovary (CHO) cells capable of growing in medium free of exogenous proteins die by apoptosis during all stages of a batch culture (Zanghi et al., 1999). On the basis of the hypothesis that extracellular death factors might be important in apoptosis under these conditions, we examined the effect of the growth factor inhibitor and antitumor agent suramin on CHO cell growth and apoptosis in serum-free culture. Suramin protected against apoptosis during exponential growth, as indicated by the absence of DNA laddering and an increase in cell viability from roughly 70% to above 95%. Suramin also effectively dispersed cell aggregates so that single-cell suspension culture was possible. However, suramin did not protect against apoptosis during the death phase, in contrast to serum, suggesting that antiapoptotic factors in the serum remain to be discovered. The increased viable cell yield following suramin supplementation resulted in a 40% increase in product yield, based on results with cells expressing recombinant secreted alkaline phosphatase. Polysulfated compounds dextran sulfate and polyvinyl sulfate worked nearly as well as suramin in dispersing cell clumps and increasing viable cell yield, which implies that suramin's high sulfate group density may be responsible for its effects in cell culture. In addition, suramin was beneficial for long-term adaptation of CHO cells to protein-free media suspension culture, and the compound was synergistic with insulin in accelerating this adaptation time. PMID:10835230

  14. Transient transfection of serum-free suspension HEK 293 cell culture for efficient production of human rFVIII

    PubMed Central

    2011-01-01

    Background Hemophilia A is a bleeding disorder caused by deficiency in coagulation factor VIII. Recombinant factor VIII (rFVIII) is an alternative to plasma-derived FVIII for the treatment of hemophilia A. However, commercial manufacturing of rFVIII products is inefficient and costly and is associated to high prices and product shortage, even in economically privileged countries. This situation may be solved by adopting more efficient production methods. Here, we evaluated the potential of transient transfection in producing rFVIII in serum-free suspension HEK 293 cell cultures and investigated the effects of different DNA concentration (0.4, 0.6 and 0.8 μg/106 cells) and repeated transfections done at 34° and 37°C. Results We observed a decrease in cell growth when high DNA concentrations were used, but no significant differences in transfection efficiency and in the biological activity of the rFVIII were noticed. The best condition for rFVIII production was obtained with repeated transfections at 34°C using 0.4 μg DNA/106 cells through which almost 50 IU of active rFVIII was produced six days post-transfection. Conclusion Serum-free suspension transient transfection is thus a viable option for high-yield-rFVIII production. Work is in progress to further optimize the process and validate its scalability. PMID:22115125

  15. Towards dynamic metabolic flux analysis in CHO cell cultures.

    PubMed

    Ahn, Woo Suk; Antoniewicz, Maciek R

    2012-01-01

    Chinese hamster ovary (CHO) cells are the most widely used mammalian cell line for biopharmaceutical production, with a total global market approaching $100 billion per year. In the pharmaceutical industry CHO cells are grown in fed-batch culture, where cellular metabolism is characterized by high glucose and glutamine uptake rates combined with high rates of ammonium and lactate secretion. The metabolism of CHO cells changes dramatically during a fed-batch culture as the cells adapt to a changing environment and transition from exponential growth phase to stationary phase. Thus far, it has been challenging to study metabolic flux dynamics in CHO cell cultures using conventional metabolic flux analysis techniques that were developed for systems at metabolic steady state. In this paper we review progress on flux analysis in CHO cells and techniques for dynamic metabolic flux analysis. Application of these new tools may allow identification of intracellular metabolic bottlenecks at specific stages in CHO cell cultures and eventually lead to novel strategies for improving CHO cell metabolism and optimizing biopharmaceutical process performance. PMID:22102428

  16. Growth control of prostatic carcinoma cells in serum-free media: interrelationship of hormone response, cell density, and nutrient media.

    PubMed Central

    Kaighn, M E; Kirk, D; Szalay, M; Lechner, J F

    1981-01-01

    Two established prostatic carcinoma cell lines have been grown in long-term culture in a defined medium (PFMR-4) free of serum, hormones, or growth factors. Growth of both lines in serum-free medium was population dependent. This cell-density requirement could be replaced by mitomycin C-inactivated feeder cells, homologous conditioned medium, or fetal bovine serum, but not by hormones or growth factors. The cells responded to these factors only at high density. The nature of this hormonal response was dependent on the kind of basal nutrient medium used. Growth in PFMR-4 with added insulin was more rapid than that in DME/F12 medium with any combination of hormones or growth factors and was substantially greater than growth in DME/F12 medium with insulin alone. The results demonstrate that whereas these two prostatic carcinoma lines (PC-3 and DU 145) do not require hormones for survival or growth, they do respond to certain hormones under appropriate conditions. These conditions include both the type of basal nutrient medium used and the population density. PMID:7029542

  17. Inducible packaging cells for large-scale production of lentiviral vectors in serum-free suspension culture.

    PubMed

    Broussau, Sophie; Jabbour, Nadine; Lachapelle, Guillaume; Durocher, Yves; Tom, Rosanne; Transfiguracion, Julia; Gilbert, Rénald; Massie, Bernard

    2008-03-01

    We have developed new packaging cell lines (293SF-PacLV) that can produce lentiviral vectors (LVs) in serum-free suspension cultures. A cell line derived from 293SF cells, expressing the repressor (CymR) of the cumate switch and the reverse transactivator (rtTA2(S)-M2) of the tetracycline (Tet) switch, was established first. We next generated clones stably expressing the Gag/Pol and Rev genes of human immunodeficiency virus-1, and the glycoprotein of vesicular stomatitis virus (VSV-G). Expression of Rev and VSV-G was tightly regulated by the cumate and Tet switches. Our best packaging cells produced up to 2.6 x 10(7) transducing units (TU)/ml after transfection with the transfer vector. Up to 3.4 x 10(7) TU/ml were obtained using stable producers generated by transducing the packaging cells with conditional-SIN-LV. The 293SF-PacLV was stable, as shown by the fact that some producers maintained high-level LV production for 18 weeks without selective pressure. The utility of the 293SF-PacLV for scaling up production in serum-free medium was demonstrated in suspension cultures and in a 3.5-L bioreactor. In shake flasks, the best packaging cells produced between 3.0 and 8.0 x 10(6) TU/ml/day for 3 days, and the best producer cells, between 1.0 and 3.4 x 10(7) TU/ml/day for 5 days. In the bioreactor, 2.8 liters containing 2.0 x 10(6) TU/ml was obtained after 3 days of batch culture following the transfection of packaging cells. In summary, the 293SF-PacLV possesses all the attributes necessary to become a valuable tool for scaling up LV production for preclinical and clinical applications. PMID:18180776

  18. Label-retaining assay enriches tumor-initiating cells in glioblastoma spheres cultivated in serum-free medium

    PubMed Central

    Zeng, Lingcheng; Zhao, Yiqing; Ouyang, Taohui; Zhao, Tianyuan; Zhang, Suojun; Chen, Jian; Yu, Jiasheng; Lei, Ting

    2016-01-01

    Label-retaining cells, which are characterized by dormancy or slow cycling, may be identified in a number of human normal and cancer tissues, and these cells demonstrate stem cell potential. In glioblastoma, label-retaining assays to enrich glioma stem cells remain to be fully investigated. In the present study, glioblastoma sphere cells cultured in serum-free medium were initially stained with the cell membrane fluorescent marker DiI. The fluorescence intensity during cell proliferation and sphere reformation was observed. At 2 weeks, the DiI-retaining cells were screened by fluorescence-activated cell sorting and compared phenotypically with the DiI-negative cells in terms of in vitro proliferation, clonogenicity and multipotency and for in vivo tumorigenicity, as well as sensitivity to irradiation and temozolomide treatment. It was observed that DiI-retaining cells accounted for a small proportion, <10%, within the glioblastoma spheres and that DiI-retaining cells proliferated significantly more slowly compared with DiI-negative cells (P=0.011, P=0.035 and P=0.023 in the of NCH421k, NCH441 and NCH644 glioblastoma sphere cell lines). Significantly increased clonogenicity (P=0.002, P=0.034 and P=0.016 in the NCH441, NCH644 and NCH421k glioblastoma sphere cell lines) and three-lineage multipotency were observed in DiI-retaining cells in vitro compared with DiI-negative cells. As few as 100 DiI-retaining cells were able to effectively generate tumors in the immunocompromised mouse brain, whereas the same number of DiI-negative cells possessed no such ability, indicating the increased tumorigenicity of DiI-retaining cells compared with DiI-negative cells. Furthermore, DiI-retaining cells demonstrated significant resistance following irradiation (P=0.012, P=0.024 and P=0.036) and temozolomide (P=0.003, P=0.005 and P=0.029) compared with DiI-negative cells in the NCH421k, NCH441 and NCH644 glioblastoma sphere cell lines, respectively. It was concluded that label

  19. Benefits and Limitations of Protein Hydrolysates as Components of Serum-Free Media for Animal Cell Culture Applications

    NASA Astrophysics Data System (ADS)

    Lobo-Alfonso, Juliet; Price, Paul; Jayme, David

    Increased understanding of influential factors for the cultivation of animal cells, combined with heightened regulatory concern over potential transmission of adventitious contaminants associated with serum and other animal-derived components, has elevated interest in using protein hydrolysates as serum replacements or nutrient supplements. This paper reviews the chemistry and biology of various hydrolysates derived from animal, plant and microbial sources. It provides specific examples of a beneficial selection of plant and yeast hydrolysates as ingredients of serum-free nutrient formulations for bioproduction applications of cultured mammalian and insect cells. Strategies for customizing and optimizing nutrients for specialized applications and general benefits and limitations of protein hydrolysates for biopharmaceutical production are also discussed.

  20. Serum-free, chemically defined medium with TGF-beta(3) enhances functional properties of nucleus pulposus cell-laden carboxymethylcellulose hydrogel constructs.

    PubMed

    Reza, Anna T; Nicoll, Steven B

    2010-02-01

    Degeneration of the nucleus pulposus (NP) has been implicated as a major cause of low back pain. Tissue engineering strategies may provide a viable NP replacement therapy; however, culture conditions must be optimized to promote functional tissue development. In this study, a standard serum-containing medium formulation was compared to a chemically defined, serum-free medium to determine the effect on matrix elaboration and functional properties of NP cell-laden carboxymethylcellulose (CMC) hydrogels. Additionally, both media were further supplemented with transforming growth factor-beta 3 (TGF-beta(3)). Glycosaminoglycan (GAG) content increased in both TGF-beta(3)-treated groups and was highest for treated, serum-free constructs (9.46 +/- 1.51 microg GAG/mg wet weight), while there were no quantifiable GAGs in untreated serum-containing samples. Histology revealed uniform, interterritorial staining for chondroitin sulfate proteoglycan throughout the treated, serum-free constructs. Type II collagen content was greater in both serum-free groups and highest in treated, serum-free constructs. The equilibrium Young's modulus was highest in serum-free samples supplemented with TGF-beta(3) (18.54 +/- 1.92 kPa), and the equilibrium weight swelling ratio of these constructs approached that of the native NP tissue (22.19 +/- 0.46 vs. 19.94 +/- 3.09, respectively). Taken together, these results demonstrate enhanced functional matrix development by NP cells when cultured in CMC hydrogels maintained in serum-free, TGF-beta(3) supplemented medium, indicating the importance of medium formulation in NP construct development. PMID:19777586

  1. Norepinephrine stimulates progesterone production in highly estrogenic bovine granulosa cells cultured under serum-free, chemically defined conditions

    PubMed Central

    2012-01-01

    Background Since noradrenergic innervation was described in the ovarian follicle, the actions of the intraovarian catecholaminergic system have been the focus of a variety of studies. We aimed to determine the gonadotropin-independent effects of the catecholamine norepinephrine (NE) in the steroid hormone profile of a serum-free granulosa cell (GC) culture system in the context of follicular development and dominance. Methods Primary bovine GCs were cultivated in a serum-free, chemically defined culture system supplemented with 0.1% polyvinyl alcohol. The culture features were assessed by hormone measurements and ultrastructural characteristics of GCs. Results GCs produced increasing amounts of estradiol and pregnenolone for 144h and maintained ultrastructural features of healthy steroidogenic cells. Progesterone production was also detected, although it significantly increased only after 96h of culture. There was a highly significant positive correlation between estradiol and pregnenolone production in high E2-producing cultures. The effects of NE were further evaluated in a dose–response study. The highest tested concentration of NE (10 (−7) M) resulted in a significant increase in progesterone production, but not in estradiol or pregnenolone production. The specificity of NE effects on progesterone productio n was further investigated by incubating GCs with propranolol (10 (−8) M), a non-selective beta-adrenergic antagonist. Conclusions The present culture system represents a robust model to study the impact of intrafollicular factors, such as catecholamines, in ovarian steroidogenesis and follicular development. The results of noradrenergic effects in the steroidogenesis of GC have implications on physiological follicular fate and on certain pathological ovarian conditions such as cyst formation and anovulation. PMID:23171052

  2. Ameloblasts serum-free conditioned medium: bone morphogenic protein 4-induced odontogenic differentiation of mouse induced pluripotent stem cells.

    PubMed

    Liu, Li; Liu, Ying-Feng; Zhang, Jing; Duan, Yin-Zhong; Jin, Yan

    2016-06-01

    Induced pluripotent stem (iPS) cells possess the ability of self-renewal and can differentiate into cells of the three germ layers, both in vitro and in vivo. Here we report a new method to efficiently induce differentiation of mouse iPS cells into the odontogenic lineage. Using ameloblasts serum-free conditioned medium (ASF-CM), we successfully generated ameloblast-like cells from mouse iPS cells. Importantly, culturing mouse iPS cells in ASF-CM supplemented with BMP4 (ASF-BMP4) promoted odontogenic differentiation, which was evident by the upregulation of ameloblast-specific as well as odontoblast-specific genes. On the other hand, culturing mouse iPS cells in ASF-CM supplemented with noggin (ASF-noggin), an inhibitor of BMP4, abrogated this effect. These results suggest that mouse iPS cells can be induced by ASF-BMP4 to differentiate into ameloblast-like and odontoblast-like cells. The results of our study raise the possibility of using patient-specific iPS cells for tooth regeneration in the future. Copyright © 2016 John Wiley & Sons, Ltd. PMID:23606575

  3. Characterization of Vero cell growth and death in bioreactor with serum-containing and serum-free media.

    PubMed

    Quesney, S; Marvel, J; Marc, A; Gerdil, C; Meignier, B

    2001-03-01

    The density of viable cells in a culture results from a balance between cell proliferation and cell death. The aim of this study was to characterize and compare these two phenomena in Vero cell cultures in one serum containing medium (ScA) and one serum free medium (SfB) in bioreactors. Cell growth was evaluated by cell counting(after crystal violet staining) and cell cycle analysis. Necrosis and apoptosis were characterized and quantified by measuring the release of LDH, trypan blue exclusion,annex in V-FITC/PI staining and TUNEL assay. ScA supported a higher maximal viable-cell density(2.3 x 10(6) vs. 1.8 x 10(6) cells ml(-1)). However, cell cycle analysis showed that cell division was more active in SfB than in ScA. LDH release in the supernatant increased much earlier in SfB than in ScA (one vs. five days), but trypan blue counts showed no apparent difference in the viability of the cultures. Apoptosis, evidenced by annexin V-FITC/PI staining, could be detected in the population of suspension cells detached from microcarriers, but not among adherent cells; positivity of the TUNEL assay occurred later than that of the annexin V-FITC/PI staining. Our data indicate that the lower cell yield in SfB,compared with that in ScA, results from a higher cell death rate. Apparently, cells die from apoptosis followed by secondary necrosis. PMID:19003288

  4. Application of a serum-free medium for the growth of Vero cells and the production of reovirus.

    PubMed

    Butler, M; Burgener, A; Patrick, M; Berry, M; Moffatt, D; Huzel, N; Barnabé, N; Coombs, K

    2000-01-01

    Two strains of reovirus (serotype 1 Lang/TIL and serotype 3 Dearing/T3D) were propagated in Vero cells grown in stationary or agitated cultures in a serum-free medium, M-VSFM. Solid microcarriers (Cytodex-1) were used to support cell growth in agitated cultures with a normal doubling time of 25 h. Cell yields of 1 x 10(6) cells/mL were obtained from an inoculum of 2 x 10(5) cells/mL in 4 days in microcarrier cultures. The growth profile and cell yield was not significantly different from serum-supplemented cultures. The virus titer increased by 3-4 orders of magnitude over a culture period of 150 h. The maximum virus titer in stationary cultures reached >1 x 10(9) pfu/mL for both strains of reovirus in M-VSFM. M-VSFM also supported high viral yields in microcarrier cultures. Both the specific productivity and final viral yield was higher in M-VSFM than serum-supplemented cultures. The high viral productivity suggests that this is a suitable system for the production of reovirus as an oncolytic agent for human therapeutic use. PMID:11027181

  5. Use of a stationary bed reactor and serum-free medium for the production of recombinant proteins in insect cells.

    PubMed

    Kompier, R; Kislev, N; Segal, I; Kadouri, A

    1991-10-01

    Insect cells (Spodoptera frugiperda) have been cultured in a stationary bed reactor, packed with a fibrous polyester carrier. When the bioreactor was perfused with serum-supplemented medium, a cell density of 6 x 10(6) cells ml-1 packed carrier was reached. Scanning electron microscopy investigations have shown that the insect cells grew along the three-dimensionally oriented fibers of the Fibra-cel carrier. After infection of the logarithmically growing cells with a recombinant baculovirus (Autographa californica) containing the gene coding for beta-galactosidase, the medium in the bioreactor was changed to serum-free medium. At day 13 postinfection (p.i.), a beta-galactosidase level of 320 microgram ml-1 and, at day 17 p.i., a virus titer of 2.1 x 10(8) TCID50 units ml-1 (day 17 p.i.) were reached. In another bioreactor, operated in a similar way but with serum-containing medium, a beta-galactosidase concentration of 360 microgram ml-1 and a virus titer of 2.3 x 10(8) TCID50 units ml-1 were obtained. These results indicate the potential use of this production system for the production of recombinant protein and baculovirus in insect cells. PMID:1367637

  6. Purified human pancreatic duct cell culture conditions defined by serum-free high-content growth factor screening.

    PubMed

    Hoesli, Corinne A; Johnson, James D; Piret, James M

    2012-01-01

    The proliferation of pancreatic duct-like CK19+ cells has implications for multiple disease states including pancreatic cancer and diabetes mellitus. The in vitro study of this important cell type has been hampered by their limited expansion compared to fibroblast-like vimentin+ cells that overgrow primary cultures. We aimed to develop a screening platform for duct cell mitogens after depletion of the vimentin+ population. The CD90 cell surface marker was used to remove the vimentin+ cells from islet-depleted human pancreas cell cultures by magnetic-activated cell sorting. Cell sorting decreased CD90+ cell contamination of the cultures from 34±20% to 1.3±0.6%, yielding purified CK19+ cultures with epithelial morphology. A full-factorial experimental design was then applied to test the mitogenic effects of bFGF, EGF, HGF, KGF and VEGF. After 6 days in test conditions, the cells were labelled with BrdU, stained and analyzed by high-throughput imaging. This screening assay confirmed the expected mitogenic effects of bFGF, EGF, HGF and KGF on CK19+ cells and additionally revealed interactions between these factors and VEGF. A serum-free medium containing bFGF, EGF, HGF and KGF led to CK19+ cell expansion comparable to the addition of 10% serum. The methods developed in this work should advance pancreatic cancer and diabetes research by providing effective cell culture and high-throughput screening platforms to study purified primary pancreatic CK19+ cells. PMID:22442738

  7. Derivation of embryonic stem cells from Kunming mice IVF blastocyst in feeder- and serum-free condition.

    PubMed

    Liu, Xiaokun; Wei, Qiang; Zhang, Junhong; Yang, Wanli; Zhao, Xiaoe; Ma, Baohua

    2015-06-01

    Kunming mice are widely used in China; however, it is difficult to isolate embryonic stem cells (ESCs) in conventional derivation condition containing feeder cells and serum. 6-Bromoindirubin-3'-oxime (BIO), a glycogen synthase kinase 3 (GSK3) inhibitor, could facilitate the maintenance of pluripotency of ESCs. Therefore, BIO could be considered as a candidate to replace feeder cells and serum. On the other hand, in vitro fertilization (IVF) is an important technology in assisted reproduction. It is reported that there was some difference in gene expression between IVF and in vivo developed blastocyst. ESCs derived from IVF blastocyst could provide a valuable tool to research the effect of IVF on differentiation and development. In the present study, we established two novel ESC lines from IVF blastocyst of Kunming mice in a feeder- and serum-free condition containing 2.5 μM BIO. In this condition, expanded IVF blastocyst could spontaneously hatch from zonae pellucidae and attached to the gelatin-coated bottom of dishes. ESC-like outgrowth could be observed without overfull trophoblast cells. After further propagation, two Kunming mice ESC lines, designated as KMES1 and KMES2, were obtained. These two novel ESCs shared common morphological characteristics with other rodent ESCs, showed strong alkaline phosphatase activity, and expressed pluripotent markers, including Oct-4, Nanog, and SSEA-1. Embryoid body (EB) and teratoma test indicated that these ESCs could spontaneously differentiate into cells representative of all three embryonic germ layers. PMID:25592083

  8. Tetramer-organizing polyproline-rich peptides differ in CHO cell-expressed and plasma-derived human butyrylcholinesterase tetramers.

    PubMed

    Schopfer, Lawrence M; Lockridge, Oksana

    2016-06-01

    Tetrameric butyrylcholinesterase (BChE) in human plasma is the product of multiple genes, namely one BCHE gene on chromosome 3q26.1 and multiple genes that encode polyproline-rich peptides. The function of the polyproline-rich peptides is to assemble BChE into tetramers. CHO cells transfected with human BChE cDNA express BChE monomers and dimers, but only low quantities of tetramers. Our goal was to identify the polyproline-rich peptides in CHO-cell derived human BChE tetramers. CHO cell-produced human BChE tetramers were purified from serum-free culture medium. Peptides embedded in the tetramerization domain were released from BChE tetramers by boiling and identified by liquid chromatography-tandem mass spectrometry. A total of 270 proline-rich peptides were sequenced, ranging in size from 6-41 residues. The peptides originated from 60 different proteins that reside in multiple cell compartments including the nucleus, cytoplasm, and endoplasmic reticulum. No single protein was the source of the polyproline-rich peptides in CHO cell-expressed human BChE tetramers. In contrast, 70% of the tetramer-organizing peptides in plasma-derived BChE tetramers originate from lamellipodin. No protein source was identified for polyproline peptides containing up to 41 consecutive proline residues. In conclusion, the use of polyproline-rich peptides as a tetramerization motif is documented only for the cholinesterases, but is expected to serve other tetrameric proteins as well. The CHO cell data suggest that the BChE tetramer-organizing peptide can arise from a variety of proteins. PMID:26947244

  9. Performance goals for immunoglobulins and serum free light chain measurements in plasma cell dyscrasias can be based on biological variation.

    PubMed

    Hansen, Charlotte Toftmann

    2016-06-01

    Measurements of immunoglobulins and serum free light chains (sFLC) are frequently used in patients with monoclonal plasma cell dyscrasia (PCD). For optimum patient care, well-defined performance standards or goals for the measured concentrations of immunoglobulins and sFLC are required. Generally, data based on biological variation is a good and reliable method for setting desirable performance standards; this also applies for the measurements of paraprotein and sFLC. The benefits of this approach are several. Among others, it is independent of the clinician, and it provides us with information about reference change value and index of individuality. Several studies on biological variation of both immunoglobulins and sFLC have been published, and mostly the studies are well performed. The studies normally show small within-subject biological variation resulting in strict analytical goals, which in most cases are difficult to meet. Nevertheless, we still need further information on biological variation of immunoglobulins and sFLC in patients with PCD and in the elderly, which are the main target populations for the two measurands. Furthermore, to improve data on biological variation of immunoglobulins and sFLC, studies accounting for number of individuals, samples, and replicates, as well as time length of the studies are needed. PMID:26824979

  10. Enhanced expression of codon optimized interferon gamma in CHO cells.

    PubMed

    Chung, Bevan Kai-Sheng; Yusufi, Faraaz N K; Mariati; Yang, Yuansheng; Lee, Dong-Yup

    2013-09-10

    The human interferon-gamma (IFN-γ) is a potential drug candidate for treating various diseases due to its immunomodulatory properties. The efficient production of this protein can be achieved through a popular industrial host, Chinese hamster ovary (CHO) cells. However, recombinant expression of foreign proteins is typically suboptimal possibly due to the usage of non-native codon patterns within the coding sequence. Therefore, we demonstrated the application of a recently developed codon optimization approach to design synthetic IFN-γ coding sequences for enhanced heterologous expression in CHO cells. For codon optimization, earlier studies suggested to establish the target usage distribution pattern in terms of selected design parameters such as individual codon usage (ICU) and codon context (CC), mainly based on the host's highly expressed genes. However, our RNA-Seq based transcriptome profiling indicated that the ICU and CC distribution patterns of different gene expression classes in CHO cell are relatively similar, unlike other microbial expression hosts, Escherichia coli and Saccharomyces cerevisiae. This finding was further corroborated through the in vivo expression of various ICU and CC optimized IFN-γ in CHO cells. Interestingly, the CC-optimized genes exhibited at least 13-fold increase in expression level compared to the wild-type IFN-γ while a maximum of 10-fold increase was observed for the ICU-optimized genes. Although design criteria based on individual codons, such as ICU, have been widely used for gene optimization, our experimental results suggested that codon context is relatively more effective parameter for improving recombinant IFN-γ expression in CHO cells. PMID:23876479

  11. Production of Inactivated Influenza H5N1 Vaccines from MDCK Cells in Serum-Free Medium

    PubMed Central

    Hu, Alan Yung-Chih; Tseng, Yu-Fen; Weng, Tsai-Chuan; Liao, Chien-Chun; Wu, Johnson; Chou, Ai-Hsiang; Chao, Hsin-Ju; Gu, Anna; Chen, Janice; Lin, Su-Chen; Hsiao, Chia-Hsin; Wu, Suh-Chin; Chong, Pele

    2011-01-01

    Background Highly pathogenic influenza viruses pose a constant threat which could lead to a global pandemic. Vaccination remains the principal measure to reduce morbidity and mortality from such pandemics. The availability and surging demand for pandemic vaccines needs to be addressed in the preparedness plans. This study presents an improved high-yield manufacturing process for the inactivated influenza H5N1 vaccines using Madin-Darby canine kidney (MDCK) cells grown in a serum-free (SF) medium microcarrier cell culture system. Principal Finding The current study has evaluated the performance of cell adaptation switched from serum-containing (SC) medium to several commercial SF media. The selected SF medium was further evaluated in various bioreactor culture systems for process scale-up evaluation. No significant difference was found in the cell growth in different sizes of bioreactors studied. In the 7.5 L bioreactor runs, the cell concentration reached to 2.3×106 cells/mL after 5 days. The maximum virus titers of 1024 Hemagglutinin (HA) units/50 µL and 7.1±0.3×108 pfu/mL were obtained after 3 days infection. The concentration of HA antigen as determined by SRID was found to be 14.1 µg/mL which was higher than those obtained from the SC medium. A mouse immunogenicity study showed that the formalin-inactivated purified SF vaccine candidate formulated with alum adjuvant could induce protective level of virus neutralization titers similar to those obtained from the SC medium. In addition, the H5N1 viruses produced from either SC or SF media showed the same antigenic reactivity with the NIBRG14 standard antisera. Conclusions The advantages of this SF cell-based manufacturing process could reduce the animal serum contamination, the cost and lot-to-lot variation of SC medium production. This study provides useful information to manufacturers that are planning to use SF medium for cell-based influenza vaccine production. PMID:21283675

  12. Comparative study of polyethylenimines for transient gene expression in mammalian HEK293 and CHO cells.

    PubMed

    Delafosse, Laurence; Xu, Ping; Durocher, Yves

    2016-06-10

    Three commercially available linear polyethylenimines (25kDa LPEI, 40kDa PEI"Max" and PEIpro™) were compared regarding their potency to transfect serum-free growing and suspension-adapted HEK293 and CHO cells. We determined the optimal DNA:PEI ratios for maximal expression of the reporter gene SEAP while monitoring cytotoxicity following transfection. PEIs acylation was determined by (1)H NMR and their apparent size and polydispersity assessed by size-exclusion chromatography. The propensity of PEIs to condense plasmid DNA was evaluated by agarose-gel electrophoresis. The zeta potentials and particle sizes at optimal DNA:PEI ratio were analyzed. Polyplex attachment to the cells and internalization kinetics were monitored. The quantity of PEIpro™ needed to efficiently transfect the cells was significantly lower than with LPEI and PEI"Max" and, interestingly, the maximal amount of internalized PEIpro™-based polyplexes was approximately half of that observed with its counterparts. PEIpro™ was the largest and least polydisperse polymer, but also the most cytotoxic. The optimal transfection conditions were subsequently used to express three monoclonal antibodies at larger-scale. The use of the deacylated PEI"Max" and PEIpro™ resulted in a significant increase of recombinant protein expression compared to LPEI. These findings demonstrate the importance of properly choosing the most suitable polymers to obtain optimal recombinant protein transient expression. PMID:27085888

  13. Metabolite profiling of CHO cells: Molecular reflections of bioprocessing effectiveness.

    PubMed

    Sellick, Christopher A; Croxford, Alexandra S; Maqsood, Arfa R; Stephens, Gill M; Westerhoff, Hans V; Goodacre, Royston; Dickson, Alan J

    2015-09-01

    Whilst development of medium and feeds has provided major advances in recombinant protein production in CHO cells, the fundamental understanding is limited. We have applied metabolite profiling with established robust (GC-MS) analytics to define the molecular loci by which two yield-enhancing feeds improve recombinant antibody yields from a model GS-CHO cell line. With data across core metabolic pathways, that report on metabolism within several cellular compartments, these data identify key metabolites and events associated with increased cell survival and specific productivity of cells. Of particular importance, increased process efficiency was linked to the functional activity of the mitochondria, with the amount and time course of use/production of intermediates of the citric acid cycle, for uses such as lipid biosynthesis, precursor generation and energy production, providing direct indicators of cellular status with respect to productivity. The data provide clear association between specific cellular metabolic indicators and cell process efficiency, extending from prior indications of the relevance of lactate metabolic balance to other redox sinks (glycerol, sorbitol and threitol). The information, and its interpretation, identifies targets for engineering cell culture efficiency, either from genetic or environmental perspectives, and greater understanding of the significance of specific medium components towards overall CHO cell bioprocessing. PMID:26198903

  14. Alpha-amanitin resistance: a dominant mutation in CHO cells.

    PubMed

    Lobban, P E; Siminovitch, L

    1975-02-01

    Hybrids of CHO cells were constructed consisting of either a 1:1 or 1:2 ratio of alpha-amanitin-resistant and sensitive cells, respectively. The resistance of such hybrids to killing by the drug was similar but slightly less than that of the resistant parent. The hybrids contained both resistant and wild-type RNA polymerase II, in amounts related to the expected gene dosage. The alpha-amanitin marker therefore is expressed codominantly. PMID:1168545

  15. Isolation and identification of cancer stem cells from human osteosarcom by serum-free three-dimensional culture combined with anticancer drugs.

    PubMed

    Zhou, Song; Li, Feng; Xiao, Jun; Xiong, Wei; Fang, Zhong; Chen, Wenjian; Niu, Pengyan

    2010-02-01

    The cancer stem cells (CSCs) from human osteosarcoma by serum-free three-dimensional culture combined with anticancer drugs were isolated and identified. The primary cells derived from human osteosarcoma were digested by trypsin to prepare a single-cell suspension, and mixed homogeneously into 1.2% alginate gel. Single-cell alginate gel was cultured with serum-free DMEM/F12 medium. Epirubicin (0.8 microg/mL) was added to the medium to enrich CSCs. After cultured conventionally for 7 to 10 days, most of cells suspended in alginate gel were killed by epirubicin. But few cells survived and some single-cell cloning spheres formed. Immunofluorescent staining for Oct3/4 and Nanog was implemented to find cells with properties of self-renewal and multi-potential differentiation. Cells from cloning spheres were transplanted into BALB/c mice to detect the tumorigenicity in vivo. The results showed that some cells positive for Oct3/4 (TRITC) and Nanog (TRITC) were found in single-cell cloning spheres, and most of positive cells were concentrated in the core of sphere. Cells from spheres could form osteosarcoma in the body of mice. It was concluded that cells from single-cell cloning spheres had the properties of the expression of parts of stem cell genes (Oct3/4 and Nanog), resisting anti-cancer drugs, and tumorigenicity in vivo. To sum up, it is believed that cells obtained from osteosarcoma by serum-free three-dimensional culture combined with anticancer drugs are cancer stem cells. PMID:20155460

  16. Label-free quantitative proteomic analysis of benzo(a)pyrene-transformed 16HBE cells serum-free culture supernatant and xenografted nude mice sera.

    PubMed

    Zhao, Peng; Fu, Juanling; Yao, Biyun; Jia, Yongrui; Zhang, Hongtao; Li, Xuehui; Dong, Lisha; Gao, Ya; Liu, Wenli; Chen, Wen; Zhou, Zongcan

    2016-02-01

    To screen potential biomarkers of benzo(a)pyrene (BaP)-induced lung cancer, the proteomic profiles of BaP-transformed 16HBE cell line T-16HBE-C1 cells serum-free culture supernatant and xenografted nude mice sera were compared with those of 16HBE group by utilizing label-free quantitative proteomic strategy. By employing nano-LC-MS/MS technology followed by MaxQuant and Perseus processing, 489 differentially expressed proteins were identified between T-16HBE-C1 and 16HBE cells serum-free culture supernatant, and 49 significantly up-regulated proteins were identified in T-16HBE-C1 xenografted nude mice sera. Three proteins neuropilin-2 (NRP2), clusterin (CLU) and A-kinase anchor protein 12 (AKAP12) were up-regulated in the serum-free culture supernatant of T-16HBE-C1 cells. These 3 human proteins were present in the sera of nude mice xenografted with T-16HBE-C1 cells, but were undetectable in mice xenografted with 16HBE cells. The proteomic results of NRP2 and AKAP12 were confirmed by Western blotting and enzyme-linked immunosorbent assays, respectively. Moreover, the serum NRP2 levels were significantly elevated at the 4th day after tumor cell implantation and showed good positive correlation with tumor growth characterized by tumor volume. In conclusion, serum NRP2, CLU and AKAP12 could be potential biomarkers of BaP-induced lung cancer. The proteomic results will gain deeper insights into the mechanisms of BaP-induced carcinogenesis. PMID:26748308

  17. Genotoxicity of complex mixtures: CHO cell mutagenicity assay

    SciTech Connect

    Frazier, M.E.; Samuel, J.E.

    1985-02-01

    A Chinese hamster ovary (CHO) mammalian cell assay was used to evaluate the genotoxicity of complex mixtures (synthetic fuels). The genotoxicity (mutagenic potency) of the mixtures increased as the temperature of their boiling range increased. Most of the genotoxicity in the 750/sup 0/F+ boiling-range materials was associated with the neutral polycyclic aromatic hydrocarbon (PAH) fractions. Chemical analysis data indicate that the PAH fractions of high-boiling coal liquids contain a number of known chemical carcinogens, including five- and six-ring polyaromatics (e.g., benzo(a)pyrene) as well as four- and five-ring alkyl-substituted PAH (e.g., methylchrysene and dimethylbenzanthracenes); concentrations are a function of boiling point (bp). In vitro genotoxicity was also detected in fractions of nitrogen-containing polyaromatic compounds, as well as in those with aliphatics of hydroxy-containing PAH. Mutagenic activity of some fractions was detectable in the CHO assay in the absence of an exogenous metabolic activation system; in some instances, addition of exogenous enzymes and cofactors inhibited expression of the direct-acting mutagenic potential of the fraction. These data indicate that the organic matrix of the chemical fraction determines whether, and to what degree, various mutagens are expressed in the CHO assay. Therefore, the results of biological assays of these mixtures must be correlated with chemical analyses for proper interpretation of these data. 29 references, 16 figures, 4 tables.

  18. What Kind of Signaling Maintains Pluripotency and Viability in Human-Induced Pluripotent Stem Cells Cultured on Laminin-511 with Serum-Free Medium?

    PubMed Central

    Nakashima, Yoshiki; Omasa, Takeshi

    2016-01-01

    Abstract Xeno-free medium contains no animal-derived components, but is composed of minimal growth factors and is serum free; the medium may be supplemented with insulin, transferrin, and selenium (ITS medium). Serum-free and xeno-free culture of human-induced pluripotent stem cells (hiPSCs) uses a variety of components based on ITS medium and Dulbecco's modified Eagle's medium/Ham's nutrient mixture F12 (DMEM/F12) that contain high levels of iron salt and glucose. Culture of hiPSCs also requires scaffolding materials, such as extracellular matrix, collagen, fibronectin, laminin, proteoglycan, and vitronectin. The scaffolding component laminin-511, which is composed of α5, β1, and γ1 chains, binds to α3β1, α6β1, and α6β4 integrins on the cell membrane to induce activation of the PI3K/AKT- and Ras/MAPK-dependent signaling pathways. In hiPSCs, the interaction of laminin-511/α6β1 integrin with the cell–cell adhesion molecule E-cadherin confers protection against apoptosis through the Ras homolog gene family member A (RhoA)/Rho kinase (ROCK) signaling pathway (the major pathways for cell death) and the proto-oncogene tyrosine-protein kinase Fyn (Fyn)-RhoA-ROCK signaling pathway. The expression levels of α6β1 integrin and E-cadherin on cell membranes are controlled through the activation of insulin receptor/insulin, FGF receptor/FGF2, or activin-like kinase 5 (ALK5)-dependent TGF-β signaling. A combination of growth factors, medium constituents, cell membrane-located E-cadherin, and α6β1 integrin-induced signaling is required for pluripotent cell proliferation and for optimal cell survival on a laminin-511 scaffold. In this review, we discuss and explore the influence of growth factors on the cadherin and integrin signaling pathways in serum-free and xeno-free cultures of hiPSCs during the preparation of products for regenerative medicinal therapies. In addition, we suggest the optimum serum-free medium components for use with laminin-511, a new

  19. An improved method for western blotting when extracting proteins from mammalian cells cultured on a collagen gel under serum-free conditions.

    PubMed

    Ishihara, Seiichiro; Mizutani, Takeomi; Kawabata, Kazushige; Haga, Hisashi

    2016-01-01

    Western blotting is a widely used method for detection and quantification of specific proteins extracted from mammalian cells. In the conventional method of protein extraction, we found that collagen-containing gels interfered with detection of the p65 protein (one of the subunits in the NF-κB family of proteins) in human lung adenocarcinoma A549 cells cultured on a collagen gel containing serum. In contrast, the collagen gels did not affect detection of the GAPDH protein. Then, we established an improved method for preparation of protein extracts (using trichloroacetic acid fixation and collagenase treatment) from the cells cultured on the collagen gel. Using the improved method, we were able to detect p65 proteins without loss in A549 cells cultured on a collagen gel under serum-free conditions, but we could not detect the proteins if serum was present in cell culture. Thus, using western blotting and serum-free culture conditions, we succeeded in comparing the p65 expression between the cells grown in a plastic dish and cells grown on a collagen gel. PMID:25005915

  20. Newly-derived neuroblastoma cell lines propagated in serum-free media recapitulate the genotype and phenotype of primary neuroblastoma tumours.

    PubMed

    Bate-Eya, Laurel T; Ebus, Marli E; Koster, Jan; den Hartog, Ilona J M; Zwijnenburg, Danny A; Schild, Linda; van der Ploeg, Ida; Dolman, M Emmy M; Caron, Huib N; Versteeg, Rogier; Molenaar, Jan J

    2014-02-01

    Recently protocols have been devised for the culturing of cell lines from fresh tumours under serum-free conditions in defined neural stem cell medium. These cells, frequently called tumour initiating cells (TICs) closely retained characteristics of the tumours of origin. We report the isolation of eight newly-derived neuroblastoma TICs from six primary neuroblastoma tumours and two bone marrow metastases. The primary tumours from which these TICs were generated have previously been fully typed by whole genome sequencing (WGS). Array comparative genomic hybridisation (aCGH) analysis showed that TIC lines retained essential characteristics of the primary tumours and exhibited typical neuroblastoma chromosomal aberrations such as MYCN amplification, gain of chromosome 17q and deletion of 1p36. Protein analysis showed expression for neuroblastoma markers MYCN, NCAM, CHGA, DBH and TH while haematopoietic markers CD19 and CD11b were absent. We analysed the growth characteristics and confirmed tumour-forming potential using sphere-forming assays, subcutaneous and orthotopic injection of these cells into immune-compromised mice. Affymetrix mRNA expression profiling of TIC line xenografts showed an expression pattern more closely mimicking primary tumours compared to xenografts from classical cell lines. This establishes that these neuroblastoma TICs cultured under serum-free conditions are relevant and useful neuroblastoma tumour models. PMID:24321263

  1. Differential regulation of pig theca cell steroidogenesis by LH, insulin-like growth factor I and granulosa cells in serum-free culture.

    PubMed

    Shores, E M; Picton, H M; Hunter, M G

    2000-03-01

    The regulation of pig theca cell steroidogenesis was studied by the development of a physiological serum-free culture system, which was subsequently extended to investigate potential theca-granulosa cell interactions. Theca cells were isolated from antral follicles 6-9 mm in diameter and the effects of plating density (50-150x10(3) viable cells per well), LH (0.01-1.0 ng ml(-1)), Long R3 insulin-like growth factor I (IGF-I) (10, 100 ng ml(-1)) and insulin (1, 10 ng ml(-1)) on the number of cells and steroidogenesis were examined. The purity of the theca cell preparation was verified biochemically and histologically. Co-cultures contained 50x10(3) viable cells per well in granulosa to theca cell ratio of 4:1. Wells containing granulosa cells only were supplemented with 'physiological' doses of androstenedione or 100 ng ml(-1). Oestradiol production by co-cultures was compared with the sum of the oestradiol synthesized by granulosa and theca cells cultured separately. Oestradiol and androstenedione production continued throughout culture. High plating density decreased steroid production (P < 0.01). LH increased androstenedione (P < 0.001) and oestradiol (P < 0.05) synthesis and the sensitivity of the cells increased with time in culture. Oestradiol production was increased by 10 ng IGF-I ml(-1) (P < 0.001) but androstenedione required 100 ng ml(-1) (P < 0.001). Co-cultures produced more oestradiol than the sum of oestradiol synthesized by theca and granulosa cells cultured separately (P < 0. 001), irrespective of the androstenedione dose. This serum-free culture system for pig theca cells maintained in vivo steroidogenesis and gonadotrophin responsiveness. Thecal androstenedione and oestradiol production were differentially regulated and were primarily stimulated by LH and IGF-I, respectively. Theca-granulosa cell interactions stimulated oestradiol synthesis and this interaction was mediated by factors additional to the provision of thecal androgen substrate to

  2. A new mammalian host cell with enhanced survival enables completely serum-free development of high-level protein production cell lines.

    PubMed

    Rossi, Diane L; Rossi, Edmund A; Goldenberg, David M; Chang, Chien-Hsing

    2011-01-01

    With over 25 monoclonal antibodies (mAbs) currently approved and many more in development, there is considerable interest in gaining improved productivity by increasing cell density and enhancing cell survival of production cell lines. In addition, high costs and growing safety concerns with use of animal products have made the availability of serum-free cell lines more appealing. We elected to transfect the myeloma cell line Sp2/0-Ag14 with Bcl2-EEE, the constitutively active phosphomimetic mutant of Bcl2, for extended cell survival. After adaptation of the initial transfectants to serum-independent growth, a clone with superior growth properties, referred to as SpESF, was isolated and further subjected to iterative rounds of stressful growth over a period of 4 months. The effort resulted in the selection of a promising clone, designated SpESFX-10, which was shown to exhibit robust growth and resist apoptosis induced by sodium butyrate or glutamine deprivation. The advantage of SpESFX-10 as a host for generating mAb-production cell lines was demonstrated by its increased transfection efficiency, culture longevity, and mAb productivity, as well as by the feasibility of accomplishing the entire cell line development process, including transfection, subcloning, and cryopreservation, in the complete absence of serum. PMID:21473000

  3. Maintenance of oestradiol production and expression of cytochrome P450 aromatase enzyme mRNA in long-term serum-free cultures of pig granulosa cells.

    PubMed

    Picton, H M; Campbell, B K; Hunter, M G

    1999-01-01

    Studies were carried out to investigate the conditions required for maintenance of aromatase activity and expression in long-term cultures of pig granulosa cells. Cells from large (> 2 mm) and small (< or = 2 mm) follicles were cultured at 37 degrees C with 5% CO2 in McCoys 5a medium supplemented with 0.1% (w/v) BSA, testosterone (100 micrograms l-1), insulin (10 micrograms l-1) and long R3 insulin-like growth factor I (IGF-I) (100 micrograms l-1). Cells were cultured with five concentrations of USDA pFSH-I-2 (0-100 micrograms l-1) for 48, 96 or 144 h with or without fetal calf serum (FCS). The number of cells and oestradiol, progesterone and inhibin production were measured. In marked contrast to oestradiol production from cells cultured in plates precoated with FCS, 1 microgram FSH l-1 was optimal for the maintenance of high oestradiol production by granulosa cells from large follicles after 144 h of serum-free culture. Culture with FCS promoted cell proliferation, reduced oestradiol production, and supported FSH-dependent (P < 0.01) increased progesterone and inhibin production indicating cellular luteinization. Northern blot analysis of total RNA from cells cultured with 1 microgram FSH l-1 detected 2.5 and 1.8 kb transcripts encoding aromatase cytochrome P450 (P450arom) and cholesterol side-chain cleavage cytochrome P450 (P450scc), respectively. Transcript expression was hormone sensitive, irrespective of the presence of FCS. High concentrations of FSH (100 micrograms l-1) stimulated expression of P450scc, but inhibited P450arom expression as the cells luteinized after 144 h of culture. This serum-free system, which maintains the aromatase enzyme complex, is fundamental if physiologically relevant observations are to be made of the mechanisms regulating follicle hierarchy development from long-term cultures of pig cells. PMID:10341724

  4. Use of cycloheximide to study independent lipid metabolism of Chlamydia trachomatis cultivated in mouse L cells grown in serum-free medium.

    PubMed Central

    Reed, S I; Anderson, L E; Jenkin, H M

    1981-01-01

    A system for measuring chlamydial lipid synthesis was developed with mouse L cells grown in serum-free modified Waymouth 752/l medium in a shaker culture. Host lipid synthesis was reduced approximately 90% when cells were incubated for 24 h in medium containing cycloheximide (2 micrograms/ml). Lipid metabolism was monitored by measuring the incorporation of [3H]isoleucine into the total lipid of normal and infected cells. The results suggested that lipid synthesis of Chlamydia trachomatis lymphogranuloma venereum (LGV-404L) was not inhibited by cycloheximide treatment when the chlamydiae were grown in L cells, whereas host lipid synthesis was inhibited. Chlamydial lipid metabolism began about 6 to 12 h after infection when the noninfectious reticulate body was found and continually increased until the beginning of the appearance of intracellular infectious elementary bodies at 24 to 30 h. PMID:7216466

  5. Monitoring the biology stability of human umbilical cord-derived mesenchymal stem cells during long-term culture in serum-free medium.

    PubMed

    Chen, Gecai; Yue, Aihuan; Ruan, Zhongbao; Yin, Yigang; Wang, Ruzhu; Ren, Yin; Zhu, Li

    2014-12-01

    Mesenchymal stem cells (MSCs) are multipotent adult stem cells that have an immunosuppressive effect. The biological stability of MSCs in serum-free medium during long-term culture in vitro has not been elucidated clearly. The morphology, immunophenotype and multi-lineage potential were analyzed at passages 3, 5, 10, 15, 20, and 25 (P3, P5, P10, P15, P20, and P25, respectively). The cell cycle distribution, apoptosis, and karyotype of human umbilical cord-derived (hUC)-MSCs were analyzed at P3, P5, P10, P15, P20, and P25. From P3 to P25, the three defining biological properties of hUC-MSCs [adherence to plastic, specific surface antigen expression, multipotent differentiation potential] met the standards proposed by the International Society for Cellular Therapy for definition of MSCs. The cell cycle distribution analysis at the P25 showed that the percentage of cells at G0/G1 was increased, compared with the cells at P3 (P < 0.05). Cells at P25 displayed an increase in the apoptosis rate (to 183 %), compared to those at P3 (P < 0.01). Within subculture generations 3-20 (P3-P20), the differences between the cell apoptotic rates were not statistically significant (P > 0.05). There were no detectable chromosome eliminations, displacements, or chromosomal imbalances, as assessed by the karyotyping guidelines of the International System for Human Cytogenetic Nomenclature (ISCN, 2009). Long-term culture affects the biological stability of MSCs in serum-free MesenCult-XF medium. MSCs can be expanded up to the 25th passage without chromosomal changes by G-band. The best biological activity period and stability appeared between the third to 20th generations. PMID:24407613

  6. Improving expression of recombinant human IGF-1 using IGF-1R knockout CHO cell lines.

    PubMed

    Romand, Sandrine; Jostock, Thomas; Fornaro, Mara; Schmidt, Joerg; Ritter, Anett; Wilms, Burkhard; Laux, Holger

    2016-05-01

    Chinese Hamster Ovary (CHO) cells are widely used for the large-scale production of recombinant biopharmaceuticals. However, attempts to express IGF-1 (a mutated human Insulin-like growth factor 1 Ea peptide (hIGF-1Ea mut)) in CHO cells resulted in poor cell growth and low productivity (0.1-0.2 g/L). Human IGF-1 variants negatively impacted CHO cell growth via the IGF-1 receptor (IGF-1R). Therefore knockout (KO) of the IGF-1R gene in two different CHO cell lines as well as knockdown (KD) of IGF-1R in one CHO cell line were performed. These cell line engineering approaches decreased significantly the hIGF-1 mediated cell growth inhibition and increased productivity of both KO CHO cell lines as well as of the KD CHO cell line. A productivity increase of 10-fold at pool level and sevenfold at clone level was achieved, resulting in a titer of 1.3 g/L. This data illustrate that cell line engineering approaches are powerful tools to improve the yields of recombinant proteins which are difficult to produce in CHO cells. Biotechnol. Bioeng. 2016;113: 1094-1101. © 2015 Wiley Periodicals, Inc. PMID:26523469

  7. [Stable expression of recombinant human podoplanin in Chinese hamster ovary (CHO) cells].

    PubMed

    Qu, Le; Zhao, Xingpeng; Fu, Jianxin; Xia, Lijun; Dai, Lan; Ruan, Changgeng; Zhao, Yiming

    2016-01-01

    Objective To construct podoplanin (PDPN) eukaryotic expression plasmid PDPN-pEGFP-N1, establish Chinese hamster ovary (CHO) cell line stably expressing recombinant human PDPN and investigate its biological activity. Methods PDPN cDNA was cloned from HEK293 cells by reverse transcription PCR and recombinant DNA technology and inserted into plasmid pEGFP-N1 labeled by enhanced green fluorescent protein (EGFP). The recombinant vector was identified by PCR, restriction enzyme digestion and DNA sequencing, and then transfected into CHO cells. Recombinant PDPN-EGFP was observed by fluorescent microscopy and CHO cell line with the high expression of PDPN-EGFP was selected by flow cytometry. Recombinant PDPN was detected by Western blotting and the biological activity of the cell line was determined by platelet aggregation assay. Results DNA sequencing and restriction enzyme digestion proved that the gene of PDPN was inserted successfully into pEGFP-N1 plasmid. After stable transfection of the recombinant plasmid into CHO cells, CHO with EGFP could be seen under a fluorescent microscope. The CHO cell line with the high expression of recombinant PDPN-EGFP was obtained after sorting by flow cytometry. Western blotting showed that the recombinant PDPN was expressed on the cell surface. The over-expressing PDPN-EGFP CHO cells were able to induce human platelet aggregation. Conclusion The CHO cell line with the stable and high expression of recombinant PDPN-EGFP has been constructed successfully, and it could induce platelet aggregation. PMID:26728373

  8. Iron absorption by intestinal epithelial cells: 1. CaCo2 cells cultivated in serum-free medium, on polyethyleneterephthalate microporous membranes, as an in vitro model.

    PubMed

    Halleux, C; Schneider, Y J

    1991-04-01

    Iron absorption by intestinal epithelial cells, passage onto plasmatic apotransferrin, and regulation of the process remain largely misunderstood. To investigate this problem, we have set up an in vitro model, consisting in CaCo2 cells (a human colon adenocarcinoma line, which upon cultivation displays numerous differentiation criteria of small intestine epithelial cells). Cells are cultivated in a serum-free medium, containing 1 microgram/ml insulin, 1 ng/ml epidermal growth factor, 10 micrograms/ml albumin-linoleic acid, 100 nM hydrocortisone, and 2 nM T3 on new, transparent, Cyclopore polyethyleneterephthalate microporous membranes coated with type I collagen. Cells rapidly adhere, grow, and form confluent monolayers; after 15 days, scanning electron microscopy reveals numerous uniform microvilli. Domes, which develop on nonporous substrata, are absent on high porosity membranes. Culture medium from upper and lower compartments of microplate inserts and cell lysates were immunoprecipitated after labeling with [3H]glucosamine and leucine; analysis was done by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), followed by autoradiography. [3H]transferrin is found mainly in the lower compartment and in cells; [3H]apolipoprotein B is released in both compartments, and fibronectin almost entirely recovered in the lower compartment; [3H]transferrin receptors and ferritin are only present in cell lysates. Binding experiments also show that transferrin receptors are accessible from the lower compartment. These results suggest that CaCo2 cells, cultivated in synthetic medium on membranes of appropriate porosity, could provide an in vitro model of the intestinal barrier, with the upper compartment of the culture insert corresponding to the apical pole facing the intestinal lumen and the lower one to the basal pole in contact with blood. PMID:1830303

  9. Serum free hemoglobin test

    MedlinePlus

    Blood hemoglobin; Serum hemoglobin ... Hemoglobin (Hb) is the main component of red blood cells. It is a protein that carries oxygen. ... people may contain up to 5 mg/dL hemoglobin. Normal value ranges may vary slightly among different ...

  10. Serum-free growth of human mammary epithelial cells: rapid clonal growth in defined medium and extended serial passage with pituitary extract

    SciTech Connect

    Hammond, S.L.; Ham, R.G.; Stampfer, M.R.

    1984-09-01

    A serum-free medium with bovine pituitary extract as the only undefined supplement has been developed for long-term culture of human mammary epithelial cells. This medium supports serial subculture of normal cells for 10-20 passages (1:10 splits) without conditioning or special substrates, and it supports rapid clonal growth with plating efficiencies up to 35%. It consists of an optimized basal nutrient medium, (MCDB 170, supplemented with insulin, hydrocortisone, epidermal growth factor, ethanolamine, phosphoethanolamine, and bovine pituitary extract. Replacement of pituitary extract with prostaglandin E/sub 1/ and ovine prolactin yields a defined medium that supports rapid clonal growth and serial subculture for three of four passages. Cultures initiated in these media from normal reduction mammoplasty tissue remain diploid and maintain normal epithelia morphology, distribution of cell-associated fibronectin, expression of keratin fibrils, and a low level of expression of milk fat globule antigen. Large cell populations can now be generated and stored frozen, permitting multiple experiments over a period of time with cells from a single donor. These media greatly extend the range of experiments that can be performed both conveniently and reproducibly with cultured normal and tumor-derived human mammary epithelial cells. 31 references, 3 figures, 4 tables.

  11. Increasing Vero viable cell densities for yellow fever virus production in stirred-tank bioreactors using serum-free medium.

    PubMed

    Mattos, Diogo A; Silva, Marlon V; Gaspar, Luciane P; Castilho, Leda R

    2015-08-20

    In this work, changes in Vero cell cultivation methods have been employed in order to improve cell growth conditions to obtain higher viable cell densities and to increase viral titers. The propagation of the 17DD yellow fever virus (YFV) in Vero cells grown on Cytodex I microcarriers was evaluated in 3-L bioreactor vessels. Prior to the current changes, Vero cells were repeatedly displaying insufficient microcarrier colonization. A modified cultivation process with four changes has resulted in higher cell densities and higher virus titers than previously observed for 17DD YFV. PMID:25930117

  12. Stepwise differentiation of pluripotent stem cells into osteoblasts using four small molecules under serum-free and feeder-free conditions.

    PubMed

    Kanke, Kosuke; Masaki, Hideki; Saito, Taku; Komiyama, Yuske; Hojo, Hironori; Nakauchi, Hiromitsu; Lichtler, Alexander C; Takato, Tsuyoshi; Chung, Ung-Il; Ohba, Shinsuke

    2014-06-01

    Pluripotent stem cells are a promising tool for mechanistic studies of tissue development, drug screening, and cell-based therapies. Here, we report an effective and mass-producing strategy for the stepwise differentiation of mouse embryonic stem cells (mESCs) and mouse and human induced pluripotent stem cells (miPSCs and hiPSCs, respectively) into osteoblasts using four small molecules (CHIR99021 [CHIR], cyclopamine [Cyc], smoothened agonist [SAG], and a helioxanthin-derivative 4-(4-methoxyphenyl)pyrido[4',3':4,5]thieno[2,3-b]pyridine-2-carboxamide [TH]) under serum-free and feeder-free conditions. The strategy, which consists of mesoderm induction, osteoblast induction, and osteoblast maturation phases, significantly induced expressions of osteoblast-related genes and proteins in mESCs, miPSCs, and hiPSCs. In addition, when mESCs defective in runt-related transcription factor 2 (Runx2), a master regulator of osteogenesis, were cultured by the strategy, they molecularly recapitulated osteoblast phenotypes of Runx2 null mice. The present strategy will be a platform for biological and pathological studies of osteoblast development, screening of bone-augmentation drugs, and skeletal regeneration. PMID:24936463

  13. Wnt3a Protein Reduces Growth Factor-Driven Expansion of Human Hematopoietic Stem and Progenitor Cells in Serum-Free Cultures

    PubMed Central

    Duinhouwer, Lucia E.; Tüysüz, Nesrin; Rombouts, Elwin W. J. C.; ter Borg, Mariette N. D.; Mastrobattista, Enrico; Spanholtz, Jan; Cornelissen, Jan J.; ten Berge, Derk; Braakman, Eric

    2015-01-01

    Ex vivo expansion of hematopoietic stem and progenitor cells (HSPC) is a promising approach to improve insufficient engraftment after umbilical cord blood stem cell transplantation (UCB-SCT). Although culturing HSPC with hematopoietic cytokines results in robust proliferation, it is accompanied with extensive differentiation and loss of self-renewal capacity. Wnt signaling has been implicated in regulating HSPC fate decisions in vivo and in promoting HSPC self-renewal by inhibition of differentiation, but the effects of Wnt on the ex vivo expansion of HSPC are controversial. Here, we demonstrate that exogenous Wnt3a protein suppresses rather than promotes the expansion of UCB-derived CD34+ cells in serum free expansion cultures. The reduced expansion was also observed in cultures initiated with Lin-CD34+CD38lowCD45RA-CD90+ cells which are highly enriched in HSC and was also observed in response to activation of beta-catenin signaling by GSK3 inhibition. The presence of Wnt3a protein during the culture reduced the frequency of multilineage CFU-GEMM and the long-term repopulation ability of the expanded HSPC. These data suggest that Wnt signaling reduces expansion of human HSPC in growth factor-driven expansion cultures by promoting differentiation of HSPC. PMID:25807521

  14. A novel Vero cell line for use as a mammalian host-vector system in serum-free medium.

    PubMed

    Ohno, T; Wang, X; Kurashima, J; Saijo-Kurita, K; Hirono, M

    1991-11-01

    We have established a novel cell line from a Vero cell derivative that is useful for expression of exogenous genes and protein production. Parental Vero-317 cells can grow in biotin-containing Eagle's MEM without supplements. By transforming this cell line with replication origin-defective SV40 DNA, which contains a temperature-sensitive tsA58 large T antigen gene, we established the Verots S3 cell line that amplified a SV40-origin containing plasmid. The cell line expressed a human growth hormone (hGH) gene insert with higher efficiency than COS-7 cells in 5% serum-containing MEM and could grow and continue hGH expression in protein-free MEM. However, temperature-sensitive shut down of hGH production was observed not immediately but 3 days after the temperature shift from 33 degrees C to 39.5 degrees C. PMID:1368119

  15. CRISPR/Cas9-mediated genome engineering of CHO cell factories: Application and perspectives.

    PubMed

    Lee, Jae Seong; Grav, Lise Marie; Lewis, Nathan E; Faustrup Kildegaard, Helene

    2015-07-01

    Chinese hamster ovary (CHO) cells are the most widely used production host for therapeutic proteins. With the recent emergence of CHO genome sequences, CHO cell line engineering has taken on a new aspect through targeted genome editing. The bacterial clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system enables rapid, easy and efficient engineering of mammalian genomes. It has a wide range of applications from modification of individual genes to genome-wide screening or regulation of genes. Facile genome editing using CRISPR/Cas9 empowers researchers in the CHO community to elucidate the mechanistic basis behind high level production of proteins and product quality attributes of interest. In this review, we describe the basis of CRISPR/Cas9-mediated genome editing and its application for development of next generation CHO cell factories while highlighting both future perspectives and challenges. As one of the main drivers for the CHO systems biology era, genome engineering with CRISPR/Cas9 will pave the way for rational design of CHO cell factories. PMID:26058577

  16. Cell-free protein expression based on extracts from CHO cells.

    PubMed

    Brödel, Andreas K; Sonnabend, Andrei; Kubick, Stefan

    2014-01-01

    Protein expression systems are widely used in biotechnology and medicine for the efficient and economic production of therapeutic proteins. Today, cultivated Chinese hamster ovary (CHO) cells are the market dominating mammalian cell-line for the production of complex therapeutic proteins. Despite this outstanding potential of CHO cells, no high-yield cell-free system based on translationally active lysates from these cells has been reported so far. To date, CHO cell extracts have only been used as a foundational research tool for understanding mRNA translation (Lodish et al., 1974; McDowell et al., 1972). In the present study, we address this fact by establishing a novel cell-free protein expression system based on extracts from cultured CHO cells. Lysate preparation, adaptation of in vitro reaction conditions and the construction of particular expression vectors are considered for high-yield protein production. A specific in vitro expression vector, which includes an internal ribosome entry site (IRES) from the intergenic region (IGR) of the Cricket paralysis virus (CrPV), has been constructed in order to obtain optimal performance. The IGR IRES is supposed to bind directly to the eukaryotic 40S ribosomal subunit thereby bypassing the process of translation initiation, which is often a major bottleneck in cell-free systems. The combination of expression vector and optimized CHO cell extracts enables the production of approximately 50 µg/mL active firefly luciferase within 4 h. The batch-type cell-free coupled transcription-translation system has the potential to perform post-translational modifications, as shown by the glycosylation of erythropoietin. Accordingly, the system contains translocationally active endogenous microsomes, enabling the co-translational incorporation of membrane proteins into biological membranes. Hence, the presented in vitro translation system is a powerful tool for the fast and convenient optimization of expression constructs, the

  17. Functional Langerinhigh-Expressing Langerhans-like Cells Can Arise from CD14highCD16- Human Blood Monocytes in Serum-Free Condition.

    PubMed

    Picarda, Gaëlle; Chéneau, Coraline; Humbert, Jean-Marc; Bériou, Gaëlle; Pilet, Paul; Martin, Jérôme; Duteille, Franck; Perrot, Pierre; Bellier-Waast, Frédérique; Heslan, Michèle; Haspot, Fabienne; Guillon, Fabien; Josien, Regis; Halary, Franck Albert

    2016-05-01

    Langerhans cells (LCs) are epithelial APCs that sense danger signals and in turn trigger specific immune responses. In steady-state, they participate in the maintenance of peripheral tolerance to self-antigens whereas under inflammation LCs efficiently trigger immune responses in secondary lymphoid organs. It has been demonstrated in mice that LC-deprived epithelia are rapidly replenished by short half-life langerin-expressing monocyte-derived LCs (MDLCs). These surrogate LCs are thought to be progressively replaced by langerin(high) LCs arising from self-renewing epithelial precursors of hematopoietic origin. How LCs arise from blood monocytes is not fully understood. Hence, we sought to characterize key factors that induce differentiation of langerin(high)-expressing monocyte-derived Langerhans-like cells. We identified GM-CSF and TGF-β1 as key cytokines to generate langerin(high)-expressing cells but only in serum-free conditions. These cells were shown to express the LC-specific TROP-2 and Axl surface markers and contained Birbeck granules. Surprisingly, E-cadherin was not spontaneously expressed by these cells but required a direct contact with keratinocytes to be stably induced. MDLCs induced stronger allogeneic T cell proliferations but released low amounts of inflammatory cytokines upon TLR stimulation compared with donor-paired monocyte-derived dendritic cells. Immature langerin(high) MDLCs were responsive to MIP-3β/CCL20 and CTAC/CCL27 chemokine stimulations. Finally, we demonstrated that those cells behaved as bona fide LCs when inserted in a three-dimensional rebuilt epithelium by becoming activated upon TLR or UV light stimulations. Collectively, these results prompt us to propose these langerin(high) MDLCs as a relevant model to address LC biology-related questions. PMID:27016604

  18. Transient Gene Expression in Serum-Free Suspension-Growing Mammalian Cells for the Production of Foot-and-Mouth Disease Virus Empty Capsids

    PubMed Central

    Mignaqui, Ana Clara; Ruiz, Vanesa; Perret, Sylvie; St-Laurent, Gilles; Singh Chahal, Parminder; Transfiguracion, Julia; Sammarruco, Ayelén; Gnazzo, Victoria; Durocher, Yves; Wigdorovitz, Andrés

    2013-01-01

    Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals. It produces severe economic losses in the livestock industry. Currently available vaccines are based on inactivated FMD virus (FMDV). The use of empty capsids as a subunit vaccine has been reported to be a promising candidate because it avoids the use of virus in the vaccine production and conserves the conformational epitopes of the virus. In this report, we explored transient gene expression (TGE) in serum-free suspension-growing mammalian cells for the production of FMDV recombinant empty capsids as a subunit vaccine. The recombinant proteins produced, assembled into empty capsids and induced protective immune response against viral challenge in mice. Furthermore, they were recognized by anti-FMDV bovine sera. By using this technology, we were able to achieve expression levels that are compatible with the development of a vaccine. Thus, TGE of mammalian cells is an easy to perform, scalable and cost-effective technology for the production of a recombinant subunit vaccine against FMDV. PMID:23977353

  19. Comparison of growth and drug response of human tumor cells in serum-free and serum-supplemented media in human tumor-clonogenic assay.

    PubMed

    Zirvi, K A; Hill, G J

    1988-06-01

    A comparison was made of growth and drug-response of five human tumor cell lines (HT-29, colon carcinoma; TWI, melanoma; A-549, lung carcinoma; Panc-1, pancreatic carcinoma; and EJ, bladder carcinoma) in serum-free media (SFM) and in serum-supplemented media (SSM) using the human tumor-clonogenic assay (HTCA) system. HT-29 cells, which had the highest plating efficiency in both SFM and SSM, were used to obtain dose-response curves for four drugs (adriamycin, 5-fluorouracil, cisplatin, and BCNU) in the HTCA. Three of the drugs (adriamycin, 5-fluorouracil, and cisplatin) produced identical drug-response curves in both SFM and SSM. These results suggest that, for some chemotherapeutic agents, results comparable to those obtained with SSM in the HTCA can be achieved using SFM. Step-by-step addition of growth factors and hormones to SFM may be a useful technique to improve some of the technical and logistic problems associated with the HTCA. PMID:3379971

  20. An Enzyme- and Serum-free Neural Stem Cell Culture Model for EMT Investigation Suited for Drug Discovery.

    PubMed

    Sailer, Martin H M; Sarvepalli, Durga; Brégère, Catherine; Fisch, Urs; Guentchev, Marin; Weller, Michael; Guzman, Raphael; Bettler, Bernhard; Ghosh, Arkasubhra; Hutter, Gregor

    2016-01-01

    Epithelial to mesenchymal transition (EMT) describes the process of epithelium transdifferentiating into mesenchyme. EMT is a fundamental process during embryonic development that also commonly occurs in glioblastoma, the most frequent malignant brain tumor. EMT has also been observed in multiple carcinomas outside the brain including breast cancer, lung cancer, colon cancer, gastric cancer. EMT is centrally linked to malignancy by promoting migration, invasion and metastasis formation. The mechanisms of EMT induction are not fully understood. Here we describe an in vitro system for standardized isolation of cortical neural stem cells (NSCs) and subsequent EMT-induction. This system provides the flexibility to use either single cells or explant culture. In this system, rat or mouse embryonic forebrain NSCs are cultured in a defined medium, devoid of serum and enzymes. The NSCs expressed Olig2 and Sox10, two transcription factors observed in oligodendrocyte precursor cells (OPCs). Using this system, interactions between FGF-, BMP- and TGFβ-signaling involving Zeb1, Zeb2, and Twist2 were observed where TGFβ-activation significantly enhanced cell migration, suggesting a synergistic BMP-/TGFβ-interaction. The results point to a network of FGF-, BMP- and TGFβ-signaling to be involved in EMT induction and maintenance. This model system is relevant to investigate EMT in vitro. It is cost-efficient and shows high reproducibility. It also allows for the comparison of different compounds with respect to their migration responses (quantitative distance measurement), and high-throughput screening of compounds to inhibit or enhance EMT (qualitative measurement). The model is therefore well suited to test drug libraries for substances affecting EMT. PMID:27583933

  1. Effects of Peptone Supplementation in Different Culture Media on Growth, Metabolic Pathway and Productivity of CHO DG44 Cells; a New Insight into Amino Acid Profiles

    PubMed Central

    Davami, Fatemeh; Eghbalpour, Farnaz; Nematollahi, Leila; Barkhordari, Farzaneh; Mahboudi, Fereidoun

    2015-01-01

    Background: The optimization of bioprocess conditions towards improved growth profile and productivity yield is considered of great importance in biopharmaceutical manufacturing. Peptones as efficient sources of nutrients have been studied for their effect on media development; however, their role on metabolic pathway is not well understood. Methods: In the present study, the effect of different concentration of peptones on a recombinant Chinese hamster ovary (CHO) cell line grown in three serum-free suspension cultures was determined. Six peptones of different origins and available amino acid profiles were investigated regarding their impact on cell growth, productivity, and metabolic pathways changes. Results: In optimized feeding strategies, increases of 136% and 159% in volumetric productivity (for a low-nutrient culture media) and 55% (for a high-nutrient culture media) were achieved. Furthermore, particular sources of peptones with specific amino acid profile developed preferential results for each different culture medium. Two peptones, SoyA2SC and SoyE-110, were the only hydrolysates that showed production improvement in all three media. Casein Peptone plus Tryptone N1 and SoyA3SC showed different improved results based on their implemented concentration for each individual basal medium. Conclusion: The amino acid profile of peptones may provide clues to identify the most effective feeding strategies for recombinant CHO cells. PMID:26232332

  2. Culturing in serum-free culture medium on collagen type-I-coated plate increases expression of CD133 and retains original phenotype of HT-29 cancer stem cell

    PubMed Central

    Arab-Bafrani, Zahra; Shahbazi-Gahrouei, Daryoush; Abbasian, Mehdi; Saberi, Alihossein; Fesharaki, Mehrafarin; Hejazi, Seyed Hossein; Manshaee, Samira

    2016-01-01

    Background: A sub-population of tumor cells termed cancer stem cells (CSCs) has an important role in tumor initiation, progression, and recurrence. Selecting a suitable procedure for isolation and enrichment of CSCs is the biggest challenge in the study of CSCs. In the present study, the role of the combination of stem cell culture medium and collagen type-I was evaluated for successful isolation and enrichment of HT-29 CSCs. Materials and Methods: HT-29 cells were cultured in serum-containing medium (parental culture medium: Medium + 10% fetal bovine serum) and serum-free medium (stem cell culture medium); both on collagen-coated plates. Spheres forming ability and CD133 expression, as a potential marker of colorectal CSCs, were evaluated in two culture mediums. Results: The results show spheroids usually give rise completely within 15 days in the stem cell culture medium on the collagen-coated plate. CD133 expression in spheroid cells (84%) is extensively higher than in parental cells (25%). Moreover, relative to parental cells, spheroid cells were more radioresistance. Conclusion: Finding of this study suggested that CSCs derived from colon cancer cell line (HT-29) can be propagated and form colonospheres in serum-free culture medium on collagen type-I. According to maintenance of their original phenotype in these conditions, it seems serum-free culture medium on collagen type-I is a suitable way to drug screening of HT-29 CSCs. PMID:27135028

  3. A defined synthetic substrate for serum-free culture of human stem cell derived cardiomyocytes with improved functional maturity identified using combinatorial materials microarrays

    PubMed Central

    Patel, Asha K.; Celiz, Adam D.; Rajamohan, Divya; Anderson, Daniel G.; Langer, Robert; Davies, Martyn C.

    2016-01-01

    Cardiomyocytes from human stem cells have applications in regenerative medicine and can provide models for heart disease and toxicity screening. Soluble components of the culture system such as growth factors within serum and insoluble components such as the substrate on which cells adhere to are important variables controlling the biological activity of cells. Using a combinatorial materials approach we develop a synthetic, chemically defined cellular niche for the support of functional cardiomyocytes derived from human embryonic stem cells (hESC-CMs) in a serum-free fully defined culture system. Almost 700 polymers were synthesized and evaluated for their utility as growth substrates. From this group, 20 polymers were identified that supported cardiomyocyte adhesion and spreading. The most promising 3 polymers were scaled up for extended culture of hESC-CMs for 15 days and were characterized using patch clamp electrophysiology and myofibril analysis to find that functional and structural phenotype was maintained on these synthetic substrates without the need for coating with extracellular matrix protein. In addition, we found that hESC-CMs cultured on a co-polymer of isobornyl methacrylate and tert-butylamino-ethyl methacrylate exhibited significantly longer sarcomeres relative to gelatin control. The potential utility of increased structural integrity was demonstrated in an in vitro toxicity assay that found an increase in detection sensitivity of myofibril disruption by the anti-cancer drug doxorubicin at a concentration of 0.05 µM in cardiomyocytes cultured on the co-polymer compared to 0.5 µM on gelatin. The chemical moieties identified in this large-scale screen provide chemically defined conditions for the culture and manipulation of hESC-CMs, as well as a framework for the rational design of superior biomaterials. PMID:26005764

  4. A robust and reproducible animal serum-free culture method for clinical-grade bone marrow-derived mesenchymal stromal cells.

    PubMed

    Laitinen, Anita; Oja, Sofia; Kilpinen, Lotta; Kaartinen, Tanja; Möller, Johanna; Laitinen, Saara; Korhonen, Matti; Nystedt, Johanna

    2016-08-01

    Efficient xenofree expansion methods to replace fetal bovine serum (FBS)-based culture methods are strongly encouraged by the regulators and are needed to facilitate the adoption of mesenchymal stromal cell (MSC)-based therapies. In the current study we established a clinically-compliant and reproducible animal serum-free culture protocol for bone marrow-(BM-) MSCs based on an optimized platelet-derived supplement. Our study compared two different platelet-derived supplements, platelet lysate PL1 versus PL2, produced by two different methods and lysed with different amounts of freeze-thaw cycles. Our study also explored the effect of a low oxygen concentration on BM-MSCs. FBS-supplemented BM-MSC culture served as control. Growth kinetics, differentiation and immunomodulatory potential, morphology, karyotype and immunophenotype was analysed. Growth kinetics in long-term culture was also studied. Based on the initial results, we chose to further process develop the PL1-supplemented culture protocol at 20 % oxygen. The results from 11 individual BM-MSC batches expanded in the chosen condition were consistent, yielding 6.60 × 10(9) ± 4.74 × 10(9) cells from only 20 ml of bone marrow. The cells suppressed T-cell proliferation, displayed normal karyotype and typical MSC differentiation potential and phenotype. The BM-MSCs were, however, consistently HLA-DR positive when cultured in platelet lysate (7.5-66.1 %). We additionally show that culture media antibiotics and sterile filtration of the platelet lysate can be successfully omitted. We present a robust and reproducible clinically-compliant culture method for BM-MSCs based on platelet lysate, which enables high quantities of HLA-DR positive MSCs at a low passage number (p2) and suitable for clinical use. PMID:25777046

  5. The GalNAc-type O-Glycoproteome of CHO Cells Characterized by the SimpleCell Strategy*

    PubMed Central

    Yang, Zhang; Halim, Adnan; Narimatsu, Yoshiki; Jitendra Joshi, Hiren; Steentoft, Catharina; Gram Schjoldager, Katrine Ter-Borch; Alder Schulz, Morten; Sealover, Natalie R.; Kayser, Kevin J.; Paul Bennett, Eric; Levery, Steven B.; Vakhrushev, Sergey Y.; Clausen, Henrik

    2014-01-01

    The Chinese hamster ovary cell (CHO) is the major host cell factory for recombinant production of biological therapeutics primarily because of its “human-like” glycosylation features. CHO is used for production of several O-glycoprotein therapeutics including erythropoietin, coagulation factors, and chimeric receptor IgG1-Fc-fusion proteins, however, some O-glycoproteins are not produced efficiently in CHO. We have previously shown that the capacity for O-glycosylation of proteins can be one limiting parameter for production of active proteins in CHO. Although the capacity of CHO for biosynthesis of glycan structures (glycostructures) on glycoproteins are well established, our knowledge of the capacity of CHO cells for attaching GalNAc-type O-glycans to proteins (glycosites) is minimal. This type of O-glycosylation is one of the most abundant forms of glycosylation, and it is differentially regulated in cells by expression of a subset of homologous polypeptide GalNAc-transferases. Here, we have genetically engineered CHO cells to produce homogeneous truncated O-glycans, so-called SimpleCells, which enabled lectin enrichment of O-glycoproteins and characterization of the O-glycoproteome. We identified 738 O-glycoproteins (1548 O-glycosites) in cell lysates and secretomes providing the first comprehensive insight into the O-glycosylation capacity of CHO (http://glycomics.ku.dk/o-glycoproteome_db/). PMID:25092905

  6. Importance of Interaction between Integrin and Actin Cytoskeleton in Suspension Adaptation of CHO cells.

    PubMed

    Walther, Christa G; Whitfield, Robert; James, David C

    2016-04-01

    The biopharmaceutical production process relies upon mammalian cell technology where single cells proliferate in suspension in a chemically defined synthetic environment. This environment lacks exogenous growth factors, usually contributing to proliferation of fibroblastic cell types such as Chinese hamster ovary (CHO) cells. Use of CHO cells for production hence requires a lengthy 'adaptation' process to select clones capable of proliferation as single cells in suspension. The underlying molecular changes permitting proliferation in suspension are not known. Comparison of the non-suspension-adapted clone CHO-AD and a suspension-adapted propriety cell line CHO-SA by flow cytometric analysis revealed a highly variable bi-modal expression pattern for cell-to-cell contact proteins in contrast to the expression pattern seen for integrins. Those have a uni-modal expression on suspension and adherent cells. Integrins showed a conformation distinguished by regularly distributed clusters forming a sphere on the cell membrane of suspension-adapted cells. Actin cytoskeleton analysis revealed reorganisation from the typical fibrillar morphology found in adherent cells to an enforced spherical subcortical actin sheath in suspension cells. The uni-modal expression and specific clustering of integrins could be confirmed for CHO-S, another suspension cell line. Cytochalasin D treatment resulted in breakdown of the actin sheath and the sphere-like integrin conformation demonstrating the link between integrins and actin in suspension-adapted CHO cells. The data demonstrates the importance of signalling changes, leading to an integrin rearrangement on the cell surface, and the necessity of the reinforcement of the actin cytoskeleton for proliferation in suspension conditions. PMID:26679704

  7. The art of CHO cell engineering: A comprehensive retrospect and future perspectives.

    PubMed

    Fischer, Simon; Handrick, René; Otte, Kerstin

    2015-12-01

    Chinese hamster ovary (CHO) cells represent the most frequently applied host cell system for industrial manufacturing of recombinant protein therapeutics. CHO cells are capable of producing high quality biologics exhibiting human-like post-translational modifications in gram quantities. However, production processes for biopharmaceuticals using mammalian cells still suffer from cellular limitations such as limited growth, low productivity and stress resistance as well as higher expenses compared to bacterial or yeast based expression systems. Besides bioprocess, media and vector optimizations, advances in host cell engineering technologies comprising introduction, knock-out or post-transcriptional silencing of engineering genes have paved the way for remarkable achievements in CHO cell line development. Furthermore, thorough analysis of cellular pathways and mechanisms important for bioprocessing steadily unravels novel target molecules which might be addressed by functional genomic tools in order to establish superior production cell factories. This review provides a comprehensive summary of the most fundamental achievements in CHO cell engineering over the past three decades. Finally, the authors discuss the potential of novel and innovative methodologies that might contribute to further enhancement of existing CHO based production platforms for biopharmaceutical manufacturing in the future. PMID:26523782

  8. Decreased tumorigenicity correlates with expression of altered cell surface carbohydrates in Lec9 CHO cells.

    PubMed Central

    Ripka, J; Shin, S; Stanley, P

    1986-01-01

    To investigate a role for surface carbohydrates in cellular malignancy, 15 different glycosylation-defective CHO cell mutants were examined for their tumorigenic and metastatic capacities after subcutaneous injection into nude mice. Most of the glycosylation mutants displayed similar or slightly decreased tumorigenicity compared with parental CHO cells. Neither parental CHO cells nor any of the mutants were observed to metastasize. However, independent isolates of one mutant type, Lec9, showed a dramatic reduction in tumor formation. The altered carbohydrates expressed at the surface of Lec9 cells appeared to be responsible for their loss of tumorigenicity, because revertants for lectin resistance were able to form tumors, and a double mutant (Lec9.Lec1) that expressed a Lec1 glycosylation phenotype also formed tumors. Finally, Lec9 cells were able to form tumors in gamma-irradiated nude mice, suggesting that recognition by an irradiation-sensitive host cell(s) was responsible for their reduced tumorigenicity in untreated nude mice. PMID:3785164

  9. Serum-free primary human fibroblast and keratinocyte coculture.

    PubMed

    Mujaj, Sally; Manton, Kerry; Upton, Zee; Richards, Sean

    2010-04-01

    Research has shown that the inclusion of a fibroblast cell support layer is required for the isolation and expansion of primary keratinocytes. Recent advances have provided keratinocyte culture with fibroblast-free alternatives. However, these technologies are often undefined and rely on the incorporation of purified proteins/components. To address this problem we developed a medium that used recombinant proteins to support the serum-free isolation and expansion of human dermal fibroblasts and keratinocytes. The human dermal fibroblasts were able to be isolated serum free by adding recombinant human albumin to a collagenase solution. These fibroblasts were then expanded using a serum-free medium containing recombinant proteins: epidermal growth factor, basic fibroblast growth factor, chimeric vitronectin:insulin-like growth factor-I protein, and recombinant human albumin. These fibroblasts maintained a typical morphology and expressed fibroblast markers during their serum-free isolation, expansion, and freezing. Moreover, these fibroblasts were able to support the serum-free isolation and expansion of primary keratinocytes using these recombinant proteins. Real-time polymerase chain reaction and immunofluorescence analysis confirmed that there were no differences in expression levels of p63 or keratins 1, 6, and 10 when keratinocytes were grown in either serum-supplemented or serum-free medium. Using a three-dimensional human skin equivalent model we demonstrated that these keratinocytes also maintained their ability to reform an epidermal layer. In summary, the techniques described provide a valuable alternative for culturing fibroblasts and keratinocytes using recombinant proteins. PMID:19929322

  10. Construction of a public CHO cell line transcript database using versatile bioinformatics analysis pipelines.

    PubMed

    Rupp, Oliver; Becker, Jennifer; Brinkrolf, Karina; Timmermann, Christina; Borth, Nicole; Pühler, Alfred; Noll, Thomas; Goesmann, Alexander

    2014-01-01

    Chinese hamster ovary (CHO) cell lines represent the most commonly used mammalian expression system for the production of therapeutic proteins. In this context, detailed knowledge of the CHO cell transcriptome might help to improve biotechnological processes conducted by specific cell lines. Nevertheless, very few assembled cDNA sequences of CHO cells were publicly released until recently, which puts a severe limitation on biotechnological research. Two extended annotation systems and web-based tools, one for browsing eukaryotic genomes (GenDBE) and one for viewing eukaryotic transcriptomes (SAMS), were established as the first step towards a publicly usable CHO cell genome/transcriptome analysis platform. This is complemented by the development of a new strategy to assemble the ca. 100 million reads, sequenced from a broad range of diverse transcripts, to a high quality CHO cell transcript set. The cDNA libraries were constructed from different CHO cell lines grown under various culture conditions and sequenced using Roche/454 and Illumina sequencing technologies in addition to sequencing reads from a previous study. Two pipelines to extend and improve the CHO cell line transcripts were established. First, de novo assemblies were carried out with the Trinity and Oases assemblers, using varying k-mer sizes. The resulting contigs were screened for potential CDS using ESTScan. Redundant contigs were filtered out using cd-hit-est. The remaining CDS contigs were re-assembled with CAP3. Second, a reference-based assembly with the TopHat/Cufflinks pipeline was performed, using the recently published draft genome sequence of CHO-K1 as reference. Additionally, the de novo contigs were mapped to the reference genome using GMAP and merged with the Cufflinks assembly using the cuffmerge software. With this approach 28,874 transcripts located on 16,492 gene loci could be assembled. Combining the results of both approaches, 65,561 transcripts were identified for CHO cell lines

  11. Monoclonal and polyclonal gammopathy measured by serum free light chain and immunofixation subdivide the clinical outcomes of diffuse large B-cell lymphoma according to molecular classification.

    PubMed

    Kim, Yu Ri; Kim, Soo-Jeong; Cheong, June-Won; Kim, Yundeok; Jang, Ji Eun; Lee, Jung Yeon; Min, Yoo Hong; Song, Jae-Woo; Yang, Woo Ick; Kim, Jin Seok

    2014-11-01

    Elevated serum free light chain (FLC) is known to be an adverse prognostic factor for diffuse large B-cell lymphoma (DLBCL). We hypothesized that monoclonal gammopathy (MG; elevated kappa [κ] or lambda [λ] FLC with an abnormal κ/λ ratio or a positive IF [immunofixation]) and polyclonal gammopathy (PG; elevated κ and/or λ FLC with a normal κ/λ ratio and a negative IF) would have different clinical outcome according to the molecular classification of DLBCL. In addition, MG would be a poor prognostic factor in patients with activated B-cell like type of DLBCL. Molecular classification of DLBCL, such as germinal center B-cell (GCB) type and non-GCB type, was performed according to the Hans algorithm. Among 175 newly diagnosed DLBCL patients, 96 (54.9 %) patients had an elevated FLC. MG and PG were observed in 34 and 68 patients, respectively. The 2-year overall survival (OS) and event-free survival (EFS) rates were 79.0 % and 71.6 %, respectively. In multivariate analysis, high-intermediate/high International Prognostic Index score and elevated FLC were significant for the OS (P = 0.002, P = 0.005, respectively) and EFS (P < 0.002, P = 0.010, respectively). MG and PG were also associated with inferior OS (P = 0.002, P = 0.011, respectively) and EFS (P = 0.002, P = 0.013, respectively). Ninety-six patients from a total 133 evaluable patients were classified to the non-GCB type. Patients with PG showed inferior clinical outcome for OS and EFS in patients with the GCB type (P = 0.006, P = 0.035, respectively). MG was a significant poor prognostic factor for OS and EFS in patients with the non-GCB type (P = 0.017, P = 0.004, respectively). MG was a poor prognostic maker in patients with the non-GCB type and PG was a poor prognostic indicator for the GCB type of DLBCL who were treated with R-CHOP. PMID:24947797

  12. Proteomic differences in recombinant CHO cells producing two similar antibody fragments.

    PubMed

    Sommeregger, Wolfgang; Mayrhofer, Patrick; Steinfellner, Willibald; Reinhart, David; Henry, Michael; Clynes, Martin; Meleady, Paula; Kunert, Renate

    2016-09-01

    Chinese hamster ovary (CHO) cells are the most commonly used mammalian hosts for the production of biopharmaceuticals. To overcome unfavorable features of CHO cells, a lot of effort is put into cell engineering to improve phenotype. "Omics" studies investigating elevated growth rate and specific productivities as well as extracellular stimulus have already revealed many interesting engineering targets. However, it remains largely unknown how physicochemical properties of the recombinant product itself influence the host cell. In this study, we used quantitative label-free LC-MS proteomic analyses to investigate product-specific proteome differences in CHO cells producing two similar antibody fragments. We established recombinant CHO cells producing the two antibodies, 3D6 and 2F5, both as single-chain Fv-Fc homodimeric antibody fragments (scFv-Fc). We applied three different vector strategies for transgene delivery (i.e., plasmid, bacterial artificial chromosome, recombinase-mediated cassette exchange), selected two best performing clones from transgene variants and transgene delivery methods and investigated three consecutively passaged cell samples by label-free proteomic analysis. LC-MS-MS profiles were compared in several sample combinations to gain insights into different aspects of proteomic changes caused by overexpression of two different heterologous proteins. This study suggests that not only the levels of specific product secretion but the product itself has a large impact on the proteome of the cell. Biotechnol. Bioeng. 2016;113: 1902-1912. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:26913574

  13. GENOTOXICITY OF 2-AMINO-6-N-HYDROXYADENINE (AHA) TO MOUSE LYMPHOMA AND CHO CELLS

    EPA Science Inventory

    2-Amino-6-hydroxyadenine (AHA) was evaluated in L5178Y/TK+/--3.7.2C mouse lymphoma cells for mutation at tk, hgprt, and the Ouabain r loci, as well as for gross aberrations and induction of micronuclei. n addition, AMA was evaluated for its ability to induce mutants in CHO cells....

  14. More similar than different: Host cell protein production using three null CHO cell lines.

    PubMed

    Yuk, Inn H; Nishihara, Julie; Walker, Donald; Huang, Eric; Gunawan, Feny; Subramanian, Jayashree; Pynn, Abigail F J; Yu, X Christopher; Zhu-Shimoni, Judith; Vanderlaan, Martin; Krawitz, Denise C

    2015-10-01

    To understand the diversity in the cell culture harvest (i.e., feedstock) provided for downstream processing, we compared host cell protein (HCP) profiles using three Chinese Hamster Ovary (CHO) cell lines in null runs which did not generate any recombinant product. Despite differences in CHO lineage, upstream process, and culture performance, the cell lines yielded similar cell-specific productivities for immunogenic HCPs. To compare the dynamics of HCP production, we searched for correlations between the time-course profiles of HCP (as measured by multi-analyte ELISA) and those of two intracellular HCP species, phospholipase B-like 2 (PLBL2) and lactate dehydrogenase (LDH). Across the cell lines, proteins in the day 14 supernatants analyzed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) showed different spot patterns. However, subsequent analysis by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) indicated otherwise: the total number of peptides and proteins identified were comparable, and 80% of the top 1,000 proteins identified were common to all three lines. Finally, to assess the impact of culture viability on extracellular HCP profiles, we analyzed supernatants from a cell line whose viability dropped after day 10. The amounts of HCP and PLBL2 (quantified by their respective ELISAs) as well as the numbers and major populations of HCPs (identified by LC-MS/MS) were similar across days 10, 14, and 17, during which viabilities declined from ∼80% to <20% and extracellular LDH levels increased several-fold. Our findings indicate that the CHO-derived HCPs in the feedstock for downstream processing may not be as diverse across cell lines and upstream processes, or change as dramatically upon viability decline as originally expected. In addition, our findings show that high density CHO cultures (>10(7) cells/mL)-operated in fed-batch mode and exhibiting high viabilities (>70%) throughout the culture duration-can accumulate a

  15. Mannose metabolism in recombinant CHO cells and its effect on IgG glycosylation.

    PubMed

    Slade, Peter G; Caspary, R Guy; Nargund, Shilpa; Huang, Chung-Jr

    2016-07-01

    Understanding the causes of high-mannose (HM) glycosylation of recombinant IgG in CHO cells would facilitate the production of therapeutics. CHO cells grown with mannose as the major carbon source demonstrated a dramatic increase in total HM glycosylation in recombinant IgG, with no effect on cell growth, viability, or titer. Quantitative metabolomics and (13) C flux analysis were used to explore the mechanism for increased HM glycosylation and understand the metabolism of mannose in CHO cells. It was demonstrated that mannose was a good carbon source for CHO cell growth and IgG production, readily entering both glycolysis and the TCA Cycle. Previous mechanisms for increased HM glycosylation during antibody production have been attributed to changes in pH, osmolality, increased specific productivity, and nutrient limitation. The results from this study propose a novel mechanism where an increased carbon flux in the GDP-mannose synthetic pathway increased the intracellular concentration of mannose-containing metabolites. The abnormally high concentration of mannose and mannose-metabolites were shown to inhibit α-mannosidase activity and it was proposed that this inhibition in the ER and Golgi caused the production of IgG with increased high-mannose glycosylation. Biotechnol. Bioeng. 2016;113: 1468-1480. © 2016 Wiley Periodicals, Inc. PMID:26724786

  16. Annotation of additional evolutionary conserved microRNAs in CHO cells from updated genomic data

    PubMed Central

    Hackl, Matthias; Klanert, Gerald; Jadhav, Vaibhav; Reithofer, Manuel; Stiefel, Fabian; Hesse, Friedemann; Grillari, Johannes; Borth, Nicole

    2015-01-01

    ABSTRACT MicroRNAs are small non‐coding RNAs that play a critical role in post‐transcriptional control of gene expression. Recent publications of genomic sequencing data from the Chinese Hamster (CGR) and Chinese hamster ovary (CHO) cells provide new tools for the discovery of novel miRNAs in this important production system. Version 20 of the miRNA registry miRBase contains 307 mature miRNAs and 200 precursor sequences for CGR/CHO. We searched for evolutionary conserved miRNAs from miRBase v20 in recently published genomic data, derived from Chinese hamster and CHO cells, to further extend the list of known miRNAs. With our approach we could identify several hundred miRNA sequences in the genome. For several of these, the expression in CHO cells could be verified from multiple next‐generation sequencing experiments. In addition, several hundred unexpressed miRNAs are awaiting further confirmation by testing for their transcription in different Chinese hamster tissues. Biotechnol. Bioeng. 2015;112: 1488–1493. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:25689160

  17. Characterisation of hepcidin response to holotransferrin treatment in CHO TRVb-1 cells.

    PubMed

    Mehta, Kosha; Greenwell, Pamela; Renshaw, Derek; Busbridge, Mark; Garcia, Mitla; Farnaud, Sebastien; Patel, Vinood B

    2015-08-01

    Iron overload coupled with low hepcidin levels are characteristics of hereditary haemochromatosis. To understand the role of transferrin receptor (TFR) and intracellular iron in hepcidin secretion, Chinese hamster ovary transferrin receptor variant (CHO TRVb-1) cells were used that express iron-response-element-depleted human TFRC mRNA (TFRC∆IRE). Results showed that CHO TRVb-1 cells expressed higher basal levels of cell-surface TFR1 than HepG2 cells (2.2-fold; p < 0.01) and following 5 g/L holotransferrin treatment maintained constitutive over-expression at 24h and 48 h, contrasting the HepG2 cells where the receptor levels significantly declined. Despite this, the intracellular iron content was neither higher than HepG2 cells nor increased over time under basal or holotransferrin-treated conditions. Interestingly, hepcidin secretion in CHO TRVb-1 cells exceeded basal levels at all time-points (p < 0.02) and matched levels in HepG2 cells following treatment. While TFRC mRNA expression showed expected elevation (2h, p < 0.03; 4h; p < 0.05), slc40a1 mRNA expression was also elevated (2 h, p < 0.05; 4 h, p < 0.03), unlike the HepG2 cells. In conclusion, the CHO TRVb-1 cells prevented cellular iron-overload by elevating slc40a1 expression, thereby highlighting its significance in the absence of iron-regulated TFRC mRNA. Furthermore, hepcidin response to holotransferrin treatment was similar to HepG2 cells and resembled the human physiological response. PMID:26142326

  18. In what time scale proton transfer takes place in a live CHO cell?

    NASA Astrophysics Data System (ADS)

    Mojumdar, Supratik Sen; Chowdhury, Rajdeep; Mandal, Amit Kumar; Bhattacharyya, Kankan

    2013-06-01

    Excited state proton transfer (ESPT) of pyranine (8-hydroxypyrene-1,3,6-trisulfonate, HPTS) in a live Chinese hamster ovary (CHO) cell is studied by time resolved confocal microscopy. The cytoplasm region of the cell is stained by a photoacid, HPTS (HA). The time constant of initial proton transfer (τPT) in the cell is found to be ˜10 times longer than that in bulk water, while the time constants of recombination (τrec) and dissociation (τdiss) in the cell are ˜3 times and ˜2 times longer, respectively. The slower rate of proton transfer (˜10 times) inside the CHO cell compared to that in bulk water is ascribed to slower solvation dynamics, lower availability of free water molecules, and disruption of hydrogen-bond network inside the cell. Translational and rotational diffusion of HPTS inside a single CHO cell have been investigated by fluorescence correlation spectroscopy (FCS) and picosecond anisotropy measurement, respectively. Both the translational and rotational diffusion slow down inside the live cell. FCS studies indicate that HPTS remains tightly bound to a macromolecule inside the cell.

  19. Designing media for animal cell culture: CHO cells, the industrial standard.

    PubMed

    Landauer, Karlheinz

    2014-01-01

    The success of culturing CHO cells solely depends on functionality of the used media. Cell culture technology is more than 50 years old, and the knowledge of cell requirements increased steadily. In the beginning, animal-sourced components were the key to growth. Nowadays state-of-the-art media do not contain any animal or naturally sourced components. The compositions are based on scientific awareness of the needs of the cells. The result is high lot-to-lot consistency and high performance.In this book section, a method for the development of a synthetic, animal component-free medium is described. The composition is based on public available formulations and information based on the work of many scientists printed in numerous papers and manuscripts. The method shall help beginners to design their own medium, although some knowledge of biochemistry and animal cells is still required. PMID:24297411

  20. MULTIPLE-ENDPOINT MUTAGENESIS WITH CHINESE HAMSTER OVARY (CHO) CELLS: EVALUATION WITH EIGHT CARCINOGENIC AND NON-CARCINOGENIC COMPOUNDS

    EPA Science Inventory

    Using Chinese hamster ovary (CHO) cells in culture, the authors have defined an assay, CHO/HGPRT, to quantify mutagen-induced cytotoxicity and mutations at the hypoxanthine-guanine phosphoribosyltransferase (hgprt) locus. This assay permits elucidation of the structure-activity r...

  1. Quantitative analysis of the supernatant from host and transfected CHO cells using iTRAQ 8-plex technique.

    PubMed

    Zhu, Guijie; Sun, Liangliang; Albanetti, Thomas; Linkous, Travis; Larkin, Christopher; Schoner, Ronald; McGivney, James B; Dovichi, Norman J

    2016-10-01

    We employed UPLC-MS/MS with iTRAQ 8-plex labeling to quantitatively analyze the supernatant produced by two Chinese hamster ovary (CHO) cell lines (CHO K1SV and CHO CAT-S). In each case, the supernatant from the host and three transfected clones were analyzed at days 5, 7, and 10 of culture. A total of eight iTRAQ 8-plex experiments were performed. For each cell line, the overlap of supernatant protein identifications between transfected clones is over 60%. Over 70% of the supernatant proteins in the CHO K1SV host cell line are present in the CHO CAT-S cell line. For the CHO K1SV cell line, the overlap in supernatant protein identifications between the host cell line and the transfected clones is >59%. For the CHO CAT-S cell line, the overlap between supernatant protein identifications for the transfected clone and host cell is >45%. These differences in the supernatant protein identifications between transfected clones in each cell line and between the two host cell lines are not significant. We used cluster analysis to characterize the change in supernatant protein expression as a function of cell culture time. Roughly <60% of the supernatant proteins show significant change across the three time points (ratio >1.3 or <0.7). We also used cluster analysis to compare changes in supernatant protein expression between the host and three transfected clones at each time point. Greater than 65% of the common proteins in the CHO K1SV cell line supernatant and over 54% in the CHO CAT-S cell line supernatant show no significant expression difference between host and the three transfected clones. Data are available via ProteomeXchange with identifier PXD003462. Biotechnol. Bioeng. 2016;113: 2140-2148. © 2016 Wiley Periodicals, Inc. PMID:27070921

  2. Genetic damage in CHO cells exposed to enzymically generated active oxygen species.

    PubMed

    Phillips, B J; James, T E; Anderson, D

    1984-05-01

    The genetic toxicity of active oxygen species produced during the enzymic oxidation of xanthine has been investigated using Chinese hamster ovary (CHO) cells. Incubation of cells with xanthine plus xanthine oxidase resulted in extensive chromosome breakage and sister-chromatid exchange and gave a small increase in frequency of thioguanine-resistant cells (HGPRT test). Inclusion of superoxide dismutase or catalase in the xanthine/xanthine oxidase system inhibited chromosome breakage, whereas only catalase prevented SCE and mutant induction. It is concluded that hydrogen peroxide is responsible for most of the genetic effects observed in CHO cells exposed to xanthine/xanthine oxidase but that superoxide plays a key role in chromosome breakage. PMID:6325900

  3. Fetal bovine serum and human constitutive androstane receptor: Evidence for activation of the SV23 splice variant by artemisinin, artemether, and arteether in a serum-free cell culture system

    SciTech Connect

    Lau, Aik Jiang; Chang, Thomas K.H.

    2014-06-01

    The naturally occurring SV23 splice variant of human constitutive androstane receptor (hCAR-SV23) is activated by di-(2-ethylhexyl)phthalate (DEHP), which is detected as a contaminant in fetal bovine serum (FBS). In our initial experiment, we compared the effect of dialyzed FBS, charcoal-stripped, dextran-treated FBS (CS-FBS), and regular FBS on the basal activity and ligand-activation of hCAR-SV23 in a cell-based reporter gene assay. In transfected HepG2 cells cultured in medium supplemented with 10% FBS, basal hCAR-SV23 activity varied with the type of FBS (regular > dialyzed > CS). DEHP increased hCAR-SV23 activity when 10% CS-FBS, but not regular FBS or dialyzed FBS, was used. With increasing concentrations (1–10%) of regular FBS or CS-FBS, hCAR-SV23 basal activity increased, whereas in DEHP-treated cells, hCAR-SV23 activity remained similar (regular FBS) or slightly increased (CS-FBS). Subsequent experiments identified a serum-free culture condition to detect DEHP activation of hCAR-SV23. Under this condition, artemisinin, artemether, and arteether increased hCAR-SV23 activity, whereas they decreased it in cells cultured in medium supplemented with 10% regular FBS. By comparison, FBS increased the basal activity of the wild-type isoform of hCAR (hCAR-WT), whereas it did not affect the basal activity of the SV24 splice variant (hCAR-SV24) or ligand activation of hCAR-SV24 and hCAR-WT by 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime (CITCO). The use of serum-free culture condition was suitable for detecting CITCO activation of hCAR-WT and hCAR-SV24. In conclusion, FBS leads to erroneous classification of pharmacological ligands of hCAR-SV23 in cell-based assays, but investigations on functional ligands of hCAR isoforms can be conducted in serum-free culture condition. - Highlights: • FBS leads to erroneous pharmacological classification of hCAR-SV23 ligands. • Artemisinin, artemether, and arteether activate h

  4. Metabolic engineering of CHO cells to alter lactate metabolism during fed-batch cultures.

    PubMed

    Toussaint, Cécile; Henry, Olivier; Durocher, Yves

    2016-01-10

    Recombinant yeast pyruvate carboxylase (PYC2) expression was previously shown to be an effective metabolic engineering strategy for reducing lactate formation in a number of relevant mammalian cell lines, but, in the case of CHO cells, did not consistently lead to significant improvement in terms of cell growth, product titer and energy metabolism efficiency. In the present study, we report on the establishment of a PYC2-expressing CHO cell line producing a monoclonal antibody and displaying a significantly altered lactate metabolism compared to its parental line. All clones exhibiting strong PYC2 expression were shown to experience a significant and systematic metabolic shift toward lactate consumption, as well as a prolonged exponential growth phase leading to an increased maximum cell concentration and volumetric product titer. Of salient interest, PYC2-expressing CHO cells were shown to maintain a highly efficient metabolism in fed-batch cultures, even when exposed to high glucose levels, thereby alleviating the need of controlling nutrient at low levels and the potential negative impact of such strategy on product glycosylation. In bioreactor operated in fed-batch mode, the higher maximum cell density achieved with the PYC2 clone led to a net gain (20%) in final volumetric productivity. PMID:26603123

  5. Precision control of recombinant gene transcription for CHO cell synthetic biology.

    PubMed

    Brown, Adam J; James, David C

    2016-01-01

    The next generation of mammalian cell factories for biopharmaceutical production will be genetically engineered to possess both generic and product-specific manufacturing capabilities that may not exist naturally. Introduction of entirely new combinations of synthetic functions (e.g. novel metabolic or stress-response pathways), and retro-engineering of existing functional cell modules will drive disruptive change in cellular manufacturing performance. However, before we can apply the core concepts underpinning synthetic biology (design, build, test) to CHO cell engineering we must first develop practical and robust enabling technologies. Fundamentally, we will require the ability to precisely control the relative stoichiometry of numerous functional components we simultaneously introduce into the host cell factory. In this review we discuss how this can be achieved by design of engineered promoters that enable concerted control of recombinant gene transcription. We describe the specific mechanisms of transcriptional regulation that affect promoter function during bioproduction processes, and detail the highly-specific promoter design criteria that are required in the context of CHO cell engineering. The relative applicability of diverse promoter development strategies are discussed, including re-engineering of natural sequences, design of synthetic transcription factor-based systems, and construction of synthetic promoters. This review highlights the potential of promoter engineering to achieve precision transcriptional control for CHO cell synthetic biology. PMID:26721629

  6. Endocytosis of a Functionally Enhanced GFP-Tagged Transferrin Receptor in CHO Cells

    PubMed Central

    Chu, Chong; Jiang, Qing; Zhu, Huifen; He, Yong; Yue, Tingting; Wang, Ruibo; Lei, Ping; Shen, Guanxin

    2015-01-01

    The endocytosis of transferrin receptor (TfR) has served as a model to study the receptor-targeted cargo delivery system for cancer therapy for many years. To accurately evaluate and optically measure this TfR targeting delivery in vitro, a CHO cell line with enhanced green fluorescent protein (EGFP)-tagged human TfR was established. A chimera of the hTfR and EGFP was engineered by fusing EGFP to the amino terminus of hTfR. Data were provided to demonstrate that hTfR-EGFP chimera was predominantly localized on the plasma membrane with some intracellular fluorescent structures on CHO cells and the EGFP moiety did not affect the endocytosis property of hTfR. Receptor internalization occurred similarly to that of HepG2 cells expressing wild-type hTfR. The internalization percentage of this chimeric receptor was about 81±3% of wild type. Time-dependent co-localization of hTfR-EGFP and PE-conjugated anti-hTfR mAb in living cells demonstrated the trafficking of mAb-receptor complexes through the endosomes followed by segregation of part of the mAb and receptor at the late stages of endocytosis. The CHO-hTfR cells preferentially took up anti-hTfR mAb conjugated nanoparticles. This CHO-hTfR cell line makes it feasible for accurate evaluation and visualization of intracellular trafficking of therapeutic agents conjugated with transferrin or Abs targeting the hTfRs. PMID:25803700

  7. Expression of GPI anchored human recombinant erythropoietin in CHO cells is devoid of glycosylation heterogeneity.

    PubMed

    Singh, Pankaj Kumar; Devasahayam, Mercy; Devi, Sobita

    2015-04-01

    Erythropoietin is a glycohormone involved in the regulation of the blood cell levels. It is a 166 amino acid protein having 3 N-glycosylation and one O-linked glycosylation sites, and is used to treat anaemia related illness. Though human recombinant erythropoietin (rEPO) is produced in CHO cells, the loss in quality control is 80% due to incomplete glycosylation of the rEPO with low levels of fully glycosylated active rEPO. Here, we describe the expression from CHO cells of fully glycosylated human rEPO when expressed as a GPI anchored molecule (rEPO-g). The results demonstrated the production of a homogenous completely glycosylated human rEPO-g as a 42 kD band without any low molecular weight glycoform variants as shown by affinity chromatography followed by SDS-PAGE and anti-human EPO specific western blot. The western blot using specific monoclonal antibody is the available biochemical technique to prove the presence of homogeneity in the expressed recombinant protein. The GPI anchor can be removed during the purification process to yield a therapeutically relevant recombinant erythropoietin molecule cells with a higher in vivo biological activity due to its high molecular weight of 40 kD. This is possibly the first report on the production of a homogenous and completely glycosylated human rEPO from CHO cells for efficient therapy. PMID:26011979

  8. Effects of nanosecond pulsed electrical fields (nsPEFs) on the cell cycle of CHO and Jurkat cells

    NASA Astrophysics Data System (ADS)

    Mahlke, Megan A.; Navara, Christopher; Ibey, Bennett L.

    2014-03-01

    Exposure to nano-second pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. Variations between cell lines in membrane and cytoskeletal structure as well as in survival of nsPEF exposure should correspond to unique line-dependent cell cycle effects. Additionally, phase of cell cycle during exposure may be linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate role of cell cycle phase in survival of nsPEFs. CHO populations recovered similarly to sham populations postnsPEF exposure and did not exhibit a phase-specific change in response. Jurkat cells exhibited considerable apoptosis/necrosis in response to nsPEF exposure and were unable to recover and proliferate in a manner similar to sham exposed cells. Additionally, Jurkat cells appear to be more sensitive to nsPEFs in G2/M phases than in G1/S phases. Recovery of CHO populations suggests that nsPEFs do not inhibit proliferation in CHO cells; however, inhibition of Jurkat cells post-nsPEF exposure coupled with preferential cell death in G2/M phases suggest that cell cycle phase during exposure may be an important factor in determining nsPEF toxicity in certain cell lines. Interestingly, CHO cells have a more robust and rigid cytoskeleton than Jurkat cells which is thought to contribute to their ability to

  9. Quantification of cell lysis during CHO bioprocesses: Impact on cell count, growth kinetics and productivity.

    PubMed

    Klein, Tobias; Heinzel, Nicole; Kroll, Paul; Brunner, Matthias; Herwig, Christoph; Neutsch, Lukas

    2015-08-10

    High cell densities and high viability are critical quality attributes for mammalian bioprocesses. Determination of living and dead cell numbers is nowadays routinely performed by automated image-based cell analyzers or flow cytometry. However, complete lysis of cells is usually neglected by these devices. We present a novel method for robust quantification of lysed cell populations over the course of a CHO bioprocess. The release of lactate dehydrogenase (LDH) and double stranded genomic DNA in culture supernatants were used as markers for cell lysis. We considered the degradation of both markers over cultivation time, which significantly increased the amount of released LDH and DNA. For correct and robust estimation of lysed cell fractions, degradation of both markers over cultivation time was considered, where redundancy of markers allowed data reconciliation. Calculating the number of cells which were subject to complete cell lysis, we could show that this fraction makes up as much as 30% of the total produced biomass and is not described by measurements of image-based analyzers. Finally, we demonstrate that disregarding cell lysis heavily affects the calculation of biomass yields and growth rates and that increasing levels of cell lysis are related to decreased productivity. PMID:25956245

  10. Endogenous TRPM4-like channel in Chinese hamster ovary (CHO) cells

    SciTech Connect

    Yarishkin, Oleg V.; Hwang, Eun-Mi; Park, Jae-Yong; Kang, Dawon; Han, Jaehee; Hong, Seong-Geun

    2008-05-02

    Chinese hamster ovary (CHO) cells used in many transfection studies have been found to endogenously express channels permeable to monovalent cations, but not to divalent cations. In the presence of intracellular Ca{sup 2+}, 23-pS channel with a linear current-voltage (I-V) relationship could be frequently observed in inside-out patches but not in cell-attached patches. The open probability was voltage-dependent, which is higher at positive potentials. The channel was dose-dependently activated by relatively high level of Ca{sup 2+} (EC{sub 50} = 1.04 {+-} 0.08 mM), and sensitively inhibited by 100 {mu}M ATP, ADP, AMP, and 1 mM spermine. However, ruthenium red (2 {mu}M) had no effect. Reverse transcript polymerase chain reaction (RT-PCR) supported the presence of mRNA encoding TRPM4b channel protein. Western blot assay finally confirmed the presence of this channel protein in membrane fraction of CHO cells. These results provide evidence that CHO cells express an endogenous TRPM4b-like channel, and thereby can be used as a tool to study de novo regulation/modulation of TRPM4 channel.

  11. The PiggyBac transposon enhances the frequency of CHO stable cell line generation and yields recombinant lines with superior productivity and stability.

    PubMed

    Matasci, Mattia; Baldi, Lucia; Hacker, David L; Wurm, Florian M

    2011-09-01

    Generating stable, high-producing mammalian cell lines is a major bottleneck in the manufacture of recombinant therapeutic proteins. Conventional gene transfer methods for cell line generation rely on random plasmid integration, resulting in unpredictable and highly variable levels of transgene expression. As a consequence, a large number of stably transfected cells must be analyzed to recover a few high-producing clones. Here we present an alternative gene transfer method for cell line generation based on transgene integration mediated by the piggyBac (PB) transposon. Recombinant Chinese hamster ovary (CHO) cell lines expressing a tumor necrosis factor receptor:Fc fusion protein were generated either by PB transposition or by conventional transfection. Polyclonal populations and isolated clonal cell lines were characterized for the level and stability of transgene expression for up to 3 months in serum-free suspension culture. Pools of transposed cells produced up to fourfold more recombinant protein than did the pools generated by standard transfection. For clonal cell lines, the frequency of high-producers was greater following transposition as compared to standard transfection, and these clones had a higher volumetric productivity and a greater number of integrated transgenes than did those generated by standard transfection. In general, the volumetric productivity of the cell pools and individual cell lines generated by transposition was stable for up to 3 months in the absence of selection. Our results indicate that the PB transposon supports the generation of cell lines with high and stable transgene expression at an elevated frequency relative to conventional transfection. Thus, PB-mediated gene delivery is expected to reduce the extent of recombinant cell line screening. PMID:21495018

  12. Flt3/Flk-2-ligand in synergy with thrombopoietin delays megakaryocyte development and increases the numbers of megakaryocyte progenitor cells in serum-free cultures initiated with CD34+ cells.

    PubMed

    Sigurjónsson, Olafur Eysteinn; Gudmundsson, Kristbjörn Orri; Haraldsdóttir, Vilhelmína; Rafnar, Thorunn; Gudmundsson, Sveinn; Guomundsson, Kristbjörn Orri; Guomundsson, Sveinn

    2002-04-01

    Megakaryocytopoiesis involves proliferation and maturation of committed precursors that increase their size by polyploidy, a process that is believed to be critical for the efficient production and release of platelets. Thrombopoietin has been shown to act on proliferation, maturation, and survival pathways in megakaryocytopoiesis. Less is known about the role of Flt3/Flk-2-ligand in this development. Apoptosis has an important role in hematopoiesis in general. It has been shown to have an effect on senescent megakaryocytes but not megakaryocyte progenitor cells. In this study, a serum-free culture model was developed, differentiating bone marrow CD34(+) hematopoietic stem cells into megakaryocytes, using thrombopoietin and Flt3/Flk-2-ligand. The model was used to study the effect of these growth factors on expansion of megakaryocyte progenitor cells, differentiation of megakaryocytes, and ploidy. Our results demonstrate that bone marrow CD34(+) cells cultured with thrombopoietin and Flt3/Flk-2-ligand show a lower developmental rate into MK cells compared to cells cultured with thrombopoietin alone. Cells cultured with thrombopoietin and Flt3/Flk-2-ligand expressed less CD41, the ploidy level was lower, and they appeared less mature. On the other hand, the cells showed up to 10-fold increase in cell numbers compared to five-fold increase when cultured with thrombopoietin alone. These results suggest that Flt3/Flk-2-ligand in synergy with thrombopoietin may slow down megakaryocyte development by causing increased proliferation of megakaryocyte progenitor cells. PMID:11983110

  13. Dynamics of unfolded protein response in recombinant CHO cells.

    PubMed

    Prashad, Kamal; Mehra, Sarika

    2015-03-01

    Genes in the protein secretion pathway have been targeted to increase productivity of monoclonal antibodies in Chinese hamster ovary cells. The results have been highly variable depending on the cell type and the relative amount of recombinant and target proteins. This paper presents a comprehensive study encompassing major components of the protein processing pathway in the endoplasmic reticulum (ER) to elucidate its role in recombinant cells. mRNA profiles of all major ER chaperones and unfolded protein response (UPR) pathway genes are measured at a series of time points in a high-producing cell line under the dynamic environment of a batch culture. An initial increase in IgG heavy chain mRNA levels correlates with an increase in productivity. We observe a parallel increase in the expression levels of majority of chaperones. The chaperone levels continue to increase until the end of the batch culture. In contrast, calreticulin and ERO1-L alpha, two of the lowest expressed genes exhibit transient time profiles, with peak induction on day 3. In response to increased ER stress, both the GCN2/PKR-like ER kinase and inositol-requiring enzyme-1alpha (Ire1α) signalling branch of the UPR are upregulated. Interestingly, spliced X-Box binding protein 1 (XBP1s) transcription factor from Ire1α pathway is detected from the beginning of the batch culture. Comparison with the expression levels in a low producer, show much lower induction at the end of the exponential growth phase. Thus, the unfolded protein response strongly correlates with the magnitude and timing of stress in the course of the batch culture. PMID:24504562

  14. Rapid recombinant protein production from piggyBac transposon-mediated stable CHO cell pools.

    PubMed

    Balasubramanian, Sowmya; Matasci, Mattia; Kadlecova, Zuzana; Baldi, Lucia; Hacker, David L; Wurm, Florian M

    2015-04-20

    Heterogeneous populations of stably transfected cells (cell pools) can serve for the rapid production of moderate amounts of recombinant proteins. Here, we propose the use of the piggyBac (PB) transposon system to improve the productivity and long-term stability of cell pools derived from Chinese hamster ovary (CHO) cells. PB is a naturally occurring genetic element that has been engineered to facilitate the integration of a transgene into the genome of the host cell. In this report PB-derived cell pools were generated after 10 days of selection with puromycin. The resulting cell pools had volumetric productivities that were 3-4 times higher than those achieved with cell pools generated by conventional plasmid transfection even though the number of integrated transgene copies per cell was similar in the two populations. In 14-day batch cultures, protein levels up to 600 and 800 mg/L were obtained for an Fc-fusion protein and a monoclonal antibody, respectively, at volumetric scales up to 1L. In general, the volumetric protein yield from cell pools remained constant for up to 3 months in the absence of selection. In conclusion, transfection of CHO cells with the PB transposon system is a simple, efficient, and reproducible approach to the generation of cell pools for the rapid production of recombinant proteins. PMID:25758242

  15. Rapid amplification system for recombinant protein production in Chinese Hamster Ovary (CHO) Cells.

    PubMed

    Metta, M K; Kunaparaju, R K; Tantravahi, S

    2016-01-01

    Recombinant therapeutic proteins have changed the face of modern medicine in the present trend and they continue to provide innovative therapies for deadly diseases. This study describes the development of a novel stable expression system for rapid amplification of genes in Chinese Hamster Ovary (CHO) cells. The expression system consists of a host CHO cell line and an expression vector (pUB-PyOri-D-C) which encodes for Polyomavirus (Py) Origin of Replication (PyOri) for amplification of integrated genes in the presence of Py Large T Antigen (PyLT) and Dihydrofolate Reductase (DHFR) selectable marker gene for selection in the presence of Methotrexate (MTX). Use of both PyOri/PyLT and DHFR can reduce the number of rounds of selection and amplification required for isolation of high producing clones. The efficiency of pUB-PyOri-D-C was compared with that of pUB-D-C plasmid using Green fluorescent protein (GFP) and Erythropoietin (EPO) as reporter proteins. Our results showed that pUB-PyOri-D-C-EPO can help development of high expressing clone in one round of selection/amplification as compared to multiple rounds of selection/amplification with pUB-D-C-EPO plasmid. CHO-DG44/EPO clone generated using pUB-PyOri-D-C-EPO gave a productivity of 119 mg/L in shake flask. PMID:26950459

  16. Effects of selenocystine on lead-exposed Chinese hamster ovary (CHO) and PC-12 cells

    SciTech Connect

    Aykin-Burns, Nukhet; Ercal, Nuran . E-mail: nercal@umr.edu

    2006-07-15

    Lead is a pervasive environmental toxin that affects multiple organ systems, including the nervous, renal, reproductive, and hematological systems. Even though it is probably the most studied toxic metal, some of the symptoms of lead toxicity still cannot be explained by known molecular mechanisms. Therefore, lead-induced oxidative stress has recently started to gain attention. This in vitro study confirms the existence of oxidative stress due to lead exposure. Administration of lead acetate (PbA) to cultures of Chinese hamster ovary cells (CHO) had a concentration-dependent inhibitory effect on colony formation and cell proliferation. This inhibition was eliminated by 5 {mu}M selenocystine (SeCys). In order to evaluate the nature of SeCys's effect, we measured glutathione (GSH), its oxidized form glutathione disulfide (GSSG), malondialdehyde (MDA), catalase, and GSH peroxidase (GPx) activities in lead-exposed CHO cells both in the presence and absence of SeCys. Increases in MDA, catalase, and GPx activities were observed in cultures that received only PbA, but supplementation with SeCys returned these measures to pretreatment levels. The ratio of GSH to GSSG increased in lead-exposed cells incubated in SeCys-enhanced media but declined in cultures treated with PbA only. In order to determine whether SeCys also reverses lead-induced neurotoxicity, a neuronal cell line, PC-12 cells, was used. Lead's inhibition on neurite formation was significantly eliminated by SeCys in PC-12 cells. Our results suggest that SeCys can confer protection against lead-induced toxicity in CHO cells and neurotoxicity in PC-12 cells.

  17. Effect of 5-aminolevulinic acid on kinetics of protoporphyrin IX production in CHO cells.

    PubMed

    Wołuń-Cholewa, M; Warchoł, W

    2004-01-01

    5-aminolevulinic acid (ALA) is utilized in a photodynamic therapy as a compound capable of augmenting intracellular pool of protoporphyrin IX (PpIX), which exhibits properties of a photosensitizer. The studies were aimed at monitoring accumulation of endogenous protoporphyrin IX in CHO cells under effect of various concentrations of ALA in culture medium and following removal of the compound from the culture medium. Cell content of PpIX was determined following incubation of the cells for 72 h in a culture medium containing different concentration of ALA. Moreover, the cells were preincubated for 2 h in ALA at various concentrations and separated from the compound by medium change and their PpIX content was monitored following incubation. PpIX content was defined by a fluorescent technique under the confocal microscope. In the course of continuous incubation of cells with ALA, biphasic alterations were noted in cellular PpIX concentration. Removal of ALA from the incubation medium resulted at first in a decrease in PpIX content in cells, which was followed by an evidently augmented accumulation of the compound in the cells. The results suggested that in the case of CHO cells, exogenous ALA was not an exclusive source of PpIX synthesis and that alterations in enzyme activities were responsible for production of PpIX. PMID:15253138

  18. Influence of the rapeseed protein hydrolysis process on CHO cell growth.

    PubMed

    Chabanon, G; Alves da Costa, L; Farges, B; Harscoat, C; Chenu, S; Goergen, J-L; Marc, A; Marc, I; Chevalot, I

    2008-10-01

    Different protein hydrolysates were prepared from enzymatic hydrolyses of a rapeseed isolate (>90% protein content) using different commercial enzymes of non-animal origin. The extent of hydrolysis was controlled to produce hydrolysates corresponding to various degrees of hydrolysis (DH) from 5 to 30. These hydrolysates were characterized according to their solubility and size peptide pattern. Different growth behaviours of Chinese Hamster Ovary cells were observed when these various hydrolysates were added in serum-free medium containing transferrin, albumin and insulin. Hydrolysates from low degree of hydrolysis generally did not exhibit significant positive effect on cell growth; conversely hydrolysates from extensive hydrolysis, corresponding to a major low molecular size peptides content, usually allowed an increase of the maximal cell density. However, depending on the enzyme used, the supplementation with hydrolysates corresponding to a high degree of hydrolysis and composed of at least 70% peptides with a molecular size under 1kDa, led to different maximal cell density values, indicating the importance of enzyme specificity and consequently the nature of the released peptides. This result showed that the positive influence of the rapeseed hydrolysates on cell growth was not only due to a nutritional support tied to the addition of small peptides but may be related to the presence of peptides exhibiting growth or survival factor effects. Furthermore, total substitution of proteins (transferrin, albumin and insulin) in the cell culture medium by some rapeseed hydrolysates appeared to be a promising alternative to improve the cell growth in protein-free media. PMID:18296044

  19. Impact of apoptosis on the on-line measured dielectric properties of CHO cells.

    PubMed

    Zalai, Dénes; Tobak, Teodóra; Putics, Ákos

    2015-12-01

    Apoptosis is a common type of cell death in biopharmaceutical cell culture processes which causes decrease in viable cell density and product yield. The progression of apoptosis has been reported to influence the dielectric properties of mammalian cells; however, the on-line detection of these effects has been rarely described. This study provides a comprehensive analysis of the on-line detectability of dielectric changes upon apoptosis induction in an industrial fed-batch process of CHO cells expressing a recombinant monoclonal antibody. Using capacitance signals, measured at 25 frequencies, the impact of apoptosis on the dielectric spectra was investigated in eight bioreactor cultivations in which various process conditions were combined with two different apoptosis induction strategies (camptothecin treatment and glucose starvation). To differentiate the apoptosis-related information from the cell concentration-associated variance in the multivariate capacitance datasets, principal component analysis (PCA) was used. A second principal component, explaining an explicit proportion (>20%) of the variance, was identified to be related to dielectric changes induced by apoptosis. Furthermore, the analysis of caspase-3 and -7 activation and DNA fragmentation showed that the detected dielectric change occurred in the early phase of apoptosis. The presented results verify that apoptosis has a considerable impact on the dielectric features of CHO cells and it can be monitored on-line with the introduced tool-set combining capacitance measurement with multivariate data analysis. PMID:26440966

  20. Genetically modified CHO cells for studying the genotoxicity of heterocyclic amines from cooked foods

    SciTech Connect

    Thompson, L.H.; Wu, R.W.; Felton, J.S.

    1995-07-01

    We have developed metabolically competent CHO cells to evaluate the genotoxicity associated with heterocyclic amines, such as those that are present in cooked foods. Into repair-deficient UV5 cells we introduced cDNAs for expressing cytochrome P450IA2 and acetyltransferases. We then genetically reverted these transformed lines to obtain matched metabolically competent repair-deficient/proficient lines. For a high mutagenic response, we find a requirement for acetyltransferase with IQ but not with PhIP. This system allows for both quantifying mutagenesis and analyzing the mutational spectra produced by heterocyclic amines.

  1. Analysis and metabolic engineering of lipid-linked oligosaccharides in glycosylation-deficient CHO cells

    SciTech Connect

    Jones, Meredith B.; Tomiya, Noboru; Betenbaugh, Michael J.; Krag, Sharon S.

    2010-04-23

    Glycosylation-deficient Chinese Hamster Ovary (CHO) cell lines can be used to expand our understanding of N-glycosylation pathways and to study Congenital Disorders of Glycosylation, diseases caused by defects in the synthesis of N-glycans. The mammalian N-glycosylation pathway involves the step-wise assembly of sugars onto a dolichol phosphate (P-Dol) carrier, forming a lipid-linked oligosaccharide (LLO), followed by the transfer of the completed oligosaccharide onto the protein of interest. In order to better understand how deficiencies in this pathway affect the availability of the completed LLO donor for use in N-glycosylation, we used a non-radioactive, HPLC-based assay to examine the intermediates in the LLO synthesis pathway for CHO-K1 cells and for three different glycosylation-deficient CHO cell lines. B4-2-1 cells, which have a mutation in the dolichol phosphate-mannose synthase (DPM2) gene, accumulated LLO with the structure Man{sub 5}GlcNAc{sub 2}-P-P-Dol, while MI8-5 cells, which lack glucosyltransferase I (ALG6) activity, accumulated Man{sub 9}GlcNAc{sub 2}-P-P-Dol. CHO-K1 and MI5-4 cells both produced primarily the complete LLO, Glc{sub 3}Man{sub 9}GlcNAc{sub 2}-P-P-Dol, though the relative quantity was lower in MI5-4. MI5-4 cells have reduced hexokinase activity which could affect the availability of many of the substrates required for LLO synthesis and, consequently, impair production of the final LLO donor. Increasing hexokinase activity by overexpressing hexokinase II in MI5-4 caused a decrease in the relative quantities of the incomplete LLO intermediates from Man{sub 5}GlcNAc{sub 2}-PP-Dol through Glc{sub 1}Man{sub 9}GlcNAc{sub 2}-PP-Dol, and an increase in the relative quantity of the final LLO donor, Glc{sub 3}Man{sub 9}GlcNAc{sub 2}-P-P-Dol. This study suggests that metabolic engineering may be a useful strategy for improving LLO availability for use in N-glycosylation.

  2. Cytoprotective effect of resveratrol diastereomers in CHO-K1 cells exposed to beauvericin.

    PubMed

    Mallebrera, B; Brandolini, V; Font, G; Ruiz, M J

    2015-06-01

    Beauvericin (BEA) causes cytotoxicity, lipid peroxidation and reactive oxygen species in CHO-K1 cells. Resveratrol (RSV) is a polyphenol with multiple biological properties, including antioxidant effects. RSV has two forms: trans and cis. The aims of this study were to determine the cytoprotective effect of trans-RSV and diastereomers mixtures (50:50 trans/cis-RSV and 70:30 trans/cis-RSV) incubated alone and in combination with BEA in ovarian (CHO-K1) cells. The results demonstrated that cell viability increases (from 9% to 77%) when they were exposed to low concentration of RSV. Moreover, when the cells were pre-treated with RSV and then exposed to BEA, a cytoprotective effect (from 25% to 76%) and a ROS production diminution (from 27% to 92%) were observed, with respect to cells exposed to BEA without previous RSV exposure. RSV pre-treatment decreased the MDA levels (from 15% to 37%) when it is compared with cells exposed only to BEA. Therefore, it can be concluded that RSV could reduce the toxicological risk produced by BEA when they are in combination. PMID:25843362

  3. Potential of 5-azacytidine induction decidual stromal cells from maternal human term placenta towards cardiomyocyte-like cells in serum-free medium.

    PubMed

    Chen, Gecai; Yue, Aihuan; Ruan, Zhongbao; Yin, Yigang; Wang, Ruzhu; Ren, Yin; Zhu, Li

    2015-09-01

    Decidual stromal cells (DSCs) from maternal term placenta represent a potential source of cells for the treatment of cardiovascular and graft-versus-host diseases. However, it is not clear whether DSCs could be induced towards cardiomyocyte-like differentiation. We chose the placentas which should bred male new-baby. We isolated DSCs from placenta by tissue adherence. The morphology, immunophenotype, and multi-lineage potential were analyzed. Karyotype analysis (G-band) was performed to determine the source and karyotype stability of DSCs. DSCs were induced by 5-azacytidine. Expression of Myf5, α-cardiac actin, Cardiac troponin T (cTnT) and GAPDH was assessed by PCR, and cTnT expression was also analyzed by immunofluorescence. Karyotype analyses indicated that cells were derived from the maternal matrix. After induction with 5-azacytidine, DSCs expressed the cardiac-specific markers Myf5, myogenin and cTnT, indicating differentiation towards cardiomyocyte-like cells. PMID:25589450

  4. Cleavage efficient 2A peptides for high level monoclonal antibody expression in CHO cells

    PubMed Central

    Chng, Jake; Wang, Tianhua; Nian, Rui; Lau, Ally; Hoi, Kong Meng; Ho, Steven CL; Gagnon, Peter; Bi, Xuezhi; Yang, Yuansheng

    2015-01-01

    Linking the heavy chain (HC) and light chain (LC) genes required for monoclonal antibodies (mAb) production on a single cassette using 2A peptides allows control of LC and HC ratio and reduces non-expressing cells. Four 2A peptides derived from the foot-and-mouth disease virus (F2A), equine rhinitis A virus (E2A), porcine teschovirus-1 (P2A) and Thosea asigna virus (T2A), respectively, were compared for expression of 3 biosimilar IgG1 mAbs in Chinese hamster ovary (CHO) cell lines. HC and LC were linked by different 2A peptides both in the absence and presence of GSG linkers. Insertion of a furin recognition site upstream of 2A allowed removal of 2A residues that would otherwise be attached to the HC. Different 2A peptides exhibited different cleavage efficiencies that correlated to the mAb expression level. The relative cleavage efficiency of each 2A peptide remains similar for expression of different IgG1 mAbs in different CHO cells. While complete cleavage was not observed for any of the 2A peptides, GSG linkers did enhance the cleavage efficiency and thus the mAb expression level. T2A with the GSG linker (GT2A) exhibited the highest cleavage efficiency and mAb expression level. Stably amplified CHO DG44 pools generated using GT2A had titers 357, 416 and 600 mg/L for the 3 mAbs in shake flask batch cultures. Incomplete cleavage likely resulted in incorrectly processed mAb species and aggregates, which were removed with a chromatin-directed clarification method and protein A purification. The vector and methods presented provide an easy process beneficial for both mAb development and manufacturing. PMID:25621616

  5. Cleavage efficient 2A peptides for high level monoclonal antibody expression in CHO cells.

    PubMed

    Chng, Jake; Wang, Tianhua; Nian, Rui; Lau, Ally; Hoi, Kong Meng; Ho, Steven C L; Gagnon, Peter; Bi, Xuezhi; Yang, Yuansheng

    2015-01-01

    Linking the heavy chain (HC) and light chain (LC) genes required for monoclonal antibodies (mAb) production on a single cassette using 2A peptides allows control of LC and HC ratio and reduces non-expressing cells. Four 2A peptides derived from the foot-and-mouth disease virus (F2A), equine rhinitis A virus (E2A), porcine teschovirus-1 (P2A) and Thosea asigna virus (T2A), respectively, were compared for expression of 3 biosimilar IgG1 mAbs in Chinese hamster ovary (CHO) cell lines. HC and LC were linked by different 2A peptides both in the absence and presence of GSG linkers. Insertion of a furin recognition site upstream of 2A allowed removal of 2A residues that would otherwise be attached to the HC. Different 2A peptides exhibited different cleavage efficiencies that correlated to the mAb expression level. The relative cleavage efficiency of each 2A peptide remains similar for expression of different IgG1 mAbs in different CHO cells. While complete cleavage was not observed for any of the 2A peptides, GSG linkers did enhance the cleavage efficiency and thus the mAb expression level. T2A with the GSG linker (GT2A) exhibited the highest cleavage efficiency and mAb expression level. Stably amplified CHO DG44 pools generated using GT2A had titers 357, 416 and 600 mg/L for the 3 mAbs in shake flask batch cultures. Incomplete cleavage likely resulted in incorrectly processed mAb species and aggregates, which were removed with a chromatin-directed clarification method and protein A purification. The vector and methods presented provide an easy process beneficial for both mAb development and manufacturing. PMID:25621616

  6. The characterization and quantitation of glycomic changes in CHO cells during a bioreactor campaign.

    PubMed

    Tep, Samnang; Hincapie, Marina; Hancock, William S

    2012-12-01

    Within the biotechnology industry there is a continuous drive to better and more fully understand the biopharmaceutical process in order to achieve better process control. A method to monitor and quantitate glycomic changes that occur in CHO cells during a bioreactor campaign could help to address this. The goal of the method presented here is to provide data that may help to understand the changes in glycosylation that are occurring, within the cell, to proteins other than the expressed biotherapeutic. The method involves the lysing of cells to gain access to intracellular proteins. The expressed biotherapeutic is specifically removed by affinity chromatography, while the remaining proteins are subjected to deglycosylation by treatment with PNGase F. The released glycans are derivatized with isotopic tags, and quantitative analysis by MALDI-TOF MS is performed. The MALDI-TOF MS method allows for the simultaneous analysis of both neutral and sialylated glycans, displays a linear dynamic range over two orders of magnitude for both neutral and sialylated glycans and achieves sub-picomolar sensitivity. This method may yield valuable information that gives further insight into the inner-workings of CHO cells, potentially taking another step towards fully understanding and controlling the biopharmaceutical process. PMID:22752974

  7. Benchmarking of commercially available CHO cell culture media for antibody production.

    PubMed

    Reinhart, David; Damjanovic, Lukas; Kaisermayer, Christian; Kunert, Renate

    2015-06-01

    In this study, eight commercially available, chemically defined Chinese hamster ovary (CHO) cell culture media from different vendors were evaluated in batch culture using an IgG-producing CHO DG44 cell line as a model. Medium adaptation revealed that the occurrence of even small aggregates might be a good indicator of cell growth performance in subsequent high cell density cultures. Batch experiments confirmed that the culture medium has a significant impact on bioprocess performance, but high amino acid concentrations alone were not sufficient to ensure superior cell growth and high antibody production. However, some key amino acids that were limiting in most media could be identified. Unbalanced glucose and amino acids led to high cell-specific lactate and ammonium production rates. In some media, persistently high glucose concentrations probably induced the suppression of respiration and oxidative phosphorylation, known as Crabtree effect, which resulted in high cell-specific glycolysis rates along with a continuous and high lactate production. In additional experiments, two of the eight basal media were supplemented with feeds from two different manufacturers in six combinations, in order to understand the combined impact of media and feeds on cell metabolism in a CHO fed-batch process. Cell growth, nutrient consumption and metabolite production rates, antibody production, and IgG quality were evaluated in detail. Concentrated feed supplements boosted cell concentrations almost threefold and antibody titers up to sevenfold. Depending on the fed-batch strategy, fourfold higher peak cell concentrations and eightfold increased IgG titers (up to 5.8 g/L) were achieved. The glycolytic flux was remarkably similar among the fed-batches; however, substantially different specific lactate production rates were observed in the different media and feed combinations. Further analysis revealed that in addition to the feed additives, the basal medium can make a considerable

  8. CHO cell enlargement oscillates with a temperature-compensated period of 24 min

    NASA Technical Reports Server (NTRS)

    Pogue, R.; Morre, D. M.; Morre, D. J.

    2000-01-01

    The rate of increase in cell area of CHO cells when measured at intervals of 1 min using a light microscope equipped with a video measurement system, oscillated with a minimum period of about 24 min. The pattern of oscillations paralleled those of the 24 min period observed with the oxidation of NADH by an external cell surface or plasma membrane NADH oxidase. The increase in cell area was non-linear. Intervals of rapid increase in area alternated with intervals of rapid decrease in area. The length of the 24 min period was temperature-compensated (approximately the same when measured at 14 degrees C, 24 degrees C or 34 degrees C) while the rate of cell enlargement increased with temperature over this same range of temperatures.

  9. PER.C6(®) cells as a serum-free suspension cell platform for the production of high titer poliovirus: a potential low cost of goods option for world supply of inactivated poliovirus vaccine.

    PubMed

    Sanders, Barbara P; Edo-Matas, Diana; Custers, Jerome H H V; Koldijk, Martin H; Klaren, Vincent; Turk, Marije; Luitjens, Alfred; Bakker, Wilfried A M; Uytdehaag, Fons; Goudsmit, Jaap; Lewis, John A; Schuitemaker, Hanneke

    2013-01-21

    There are two highly efficacious poliovirus vaccines: Sabin's live-attenuated oral polio vaccine (OPV) and Salk's inactivated polio vaccine (IPV). OPV can be made at low costs per dose and is easily administrated. However, the major drawback is the frequent reversion of the OPV vaccine strains to virulent poliovirus strains which can result in Vaccine Associated Paralytic Poliomyelitis (VAPP) in vaccinees. Furthermore, some OPV revertants with high transmissibility can circulate in the population as circulating Vaccine Derived Polioviruses (cVDPVs). IPV does not convey VAPP and cVDPVs but the high costs per dose and insufficient supply have rendered IPV an unfavorable option for low and middle-income countries. Here, we explored whether the human PER.C6(®) cell-line, which has the unique capability to grow at high density in suspension, under serum-free conditions, could be used as a platform for high yield production of poliovirus. PER.C6(®) cells supported replication of all three poliovirus serotypes with virus titers ranging from 9.4 log(10) to 11.1 log(10)TCID(50)/ml irrespective of the volume scale (10 ml in shaker flasks to 2 L in bioreactors). This production yield was 10-30 fold higher than in Vero cell cultures performed here, and even 100-fold higher than what has been reported for Vero cell cultures in literature [38]. In agreement, the D-antigen content per volume PER.C6(®)-derived poliovirus was on average 30-fold higher than Vero-derived poliovirus. Interestingly, PER.C6(®) cells produced on average 2.5-fold more D-antigen units per cell than Vero cells. Based on our findings, we are exploring PER.C6(®) as an interesting platform for large-scale production of poliovirus at low costs, potentially providing the basis for global supply of an affordable IPV. PMID:23123018

  10. Comprehensive genome and epigenome characterization of CHO cells in response to evolutionary pressures and over time.

    PubMed

    Feichtinger, Julia; Hernández, Inmaculada; Fischer, Christoph; Hanscho, Michael; Auer, Norbert; Hackl, Matthias; Jadhav, Vaibhav; Baumann, Martina; Krempl, Peter M; Schmidl, Christian; Farlik, Matthias; Schuster, Michael; Merkel, Angelika; Sommer, Andreas; Heath, Simon; Rico, Daniel; Bock, Christoph; Thallinger, Gerhard G; Borth, Nicole

    2016-10-01

    The most striking characteristic of CHO cells is their adaptability, which enables efficient production of proteins as well as growth under a variety of culture conditions, but also results in genomic and phenotypic instability. To investigate the relative contribution of genomic and epigenetic modifications towards phenotype evolution, comprehensive genome and epigenome data are presented for six related CHO cell lines, both in response to perturbations (different culture conditions and media as well as selection of a specific phenotype with increased transient productivity) and in steady state (prolonged time in culture under constant conditions). Clear transitions were observed in DNA-methylation patterns upon each perturbation, while few changes occurred over time under constant conditions. Only minor DNA-methylation changes were observed between exponential and stationary growth phase; however, throughout a batch culture the histone modification pattern underwent continuous adaptation. Variation in genome sequence between the six cell lines on the level of SNPs, InDels, and structural variants is high, both upon perturbation and under constant conditions over time. The here presented comprehensive resource may open the door to improved control and manipulation of gene expression during industrial bioprocesses based on epigenetic mechanisms. Biotechnol. Bioeng. 2016;113: 2241-2253. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:27072894

  11. IRES-mediated Tricistronic vectors for enhancing generation of high monoclonal antibody expressing CHO cell lines.

    PubMed

    Ho, Steven C L; Bardor, Muriel; Feng, Huatao; Mariati; Tong, Yen Wah; Song, Zhiwei; Yap, Miranda G S; Yang, Yuansheng

    2012-01-01

    A Tricistronic vector utilizing internal ribosome entry site (IRES) elements to express the light chain (LC), heavy chain (HC), and a neomycin phosphotransferase (NPT) selection marker from one transcript is designed for generation of mAb expressing CHO cell lines. As compared to the commonly used vectors, benefits of this design include: (1) minimized non-expressing clones, (2) enhanced stable mAb productivity without gene amplification, (3) control of LC and HC expression at defined ratios, and (4) consistent product quality. After optimization of the LC and HC arrangement and increasing selection stringency by weakening the NPT selection marker, this Tricistronic vector is able to generate stably transfected pools with specific productivity (qmAb) greater than 5pg/cell/day (pcd) and titers over 150mg/L. 5% of clones from these pools have qmAb greater than 20pcd and titers ranging from 300 to more than 500mg/L under non-optimized shake flask batch cultures using commercially available protein-free medium. The mAb produced by these clones have low aggregation and consistent glycosylation profiles. The entire process of transfection to high-expressing clones requires only 6 months. The IRES-mediated Tricistronic vector provides an attractive alternative to commonly used vectors for fast generation of mAb CHO cell lines with high productivity. PMID:22024589

  12. Accelerating Genome Editing in CHO Cells Using CRISPR Cas9 and CRISPy, a Web-Based Target Finding Tool

    PubMed Central

    Ronda, Carlotta; Pedersen, Lasse Ebdrup; Hansen, Henning Gram; Kallehauge, Thomas Beuchert; Betenbaugh, Michael J; Nielsen, Alex Toftgaard; Kildegaard, Helene Faustrup

    2014-01-01

    Chinese hamster ovary (CHO) cells are widely used in the biopharmaceutical industry as a host for the production of complex pharmaceutical proteins. Thus genome engineering of CHO cells for improved product quality and yield is of great interest. Here, we demonstrate for the first time the efficacy of the CRISPR Cas9 technology in CHO cells by generating site-specific gene disruptions in COSMC and FUT8, both of which encode proteins involved in glycosylation. The tested single guide RNAs (sgRNAs) created an indel frequency up to 47.3% in COSMC, while an indel frequency up to 99.7% in FUT8 was achieved by applying lectin selection. All eight sgRNAs examined in this study resulted in relatively high indel frequencies, demonstrating that the Cas9 system is a robust and efficient genome-editing methodology in CHO cells. Deep sequencing revealed that 85% of the indels created by Cas9 resulted in frameshift mutations at the target sites, with a strong preference for single base indels. Finally, we have developed a user-friendly bioinformatics tool, named “CRISPy” for rapid identification of sgRNA target sequences in the CHO-K1 genome. The CRISPy tool identified 1,970,449 CRISPR targets divided into 27,553 genes and lists the number of off-target sites in the genome. In conclusion, the proven functionality of Cas9 to edit CHO genomes combined with our CRISPy database have the potential to accelerate genome editing and synthetic biology efforts in CHO cells. Biotechnol. Bioeng. 2014; 111: 1604–1616. © 2014 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:24827782

  13. Components of yeast (Sacchromyces cervisiae) extract as defined media additives that support the growth and productivity of CHO cells.

    PubMed

    Spearman, Maureen; Chan, Sarah; Jung, Vince; Kowbel, Vanessa; Mendoza, Meg; Miranda, Vivian; Butler, Michael

    2016-09-10

    Yeast and plant hydrolysates are used as media supplements to support the growth and productivity of CHO cultures for biopharmaceutical production. Through fractionation of a yeast lysate and metabolic analysis of a fraction that had bioactivity equivalent to commercial yeast extract (YE), bioactive components were identified that promoted growth and productivity of two recombinant CHO cell lines (CHO-Luc and CHO-hFcEG2) equivalent to or greater than YE-supplemented media. Autolysis of the yeast lysate was not necessary for full activity, suggesting that the active components are present in untreated yeast cells. A bioactive fraction (3KF) of the yeast lysate was isolated from the permeate using a 3kDa molecular weight cut-off (MWCO) filter. Supplementation of this 3KF fraction into the base media supported growth of CHO-Luc cells over eight passages equivalent to YE-supplemented media. The 3KF fraction was fractionated further by a cation exchange spin column using a stepwise pH elution. Metabolomic analysis of a bioactive fraction isolated at high pH identified several arginine and lysine-containing peptides as well as two polyamines, spermine and spermidine, with 3.5× and 4.5× higher levels compared to a fraction showing no bioactivity. The addition of a mixture of polyamines and their precursors (putrescine, spermine, spermidine, ornithine and citrulline) as well as increasing the concentration of some of the components of the original base medium resulted in a chemically-defined (CD) formulation that produced an equivalent viable cell density (VCD) and productivity of the CHO-Luc cells as the YE-supplemented medium. The VCD of the CHO-hFcEG2 culture in the CD medium was 1.9× greater and with equivalent productivity to the YE-supplemented media. PMID:27165505

  14. Accelerating genome editing in CHO cells using CRISPR Cas9 and CRISPy, a web-based target finding tool.

    PubMed

    Ronda, Carlotta; Pedersen, Lasse Ebdrup; Hansen, Henning Gram; Kallehauge, Thomas Beuchert; Betenbaugh, Michael J; Nielsen, Alex Toftgaard; Kildegaard, Helene Faustrup

    2014-08-01

    Chinese hamster ovary (CHO) cells are widely used in the biopharmaceutical industry as a host for the production of complex pharmaceutical proteins. Thus genome engineering of CHO cells for improved product quality and yield is of great interest. Here, we demonstrate for the first time the efficacy of the CRISPR Cas9 technology in CHO cells by generating site-specific gene disruptions in COSMC and FUT8, both of which encode proteins involved in glycosylation. The tested single guide RNAs (sgRNAs) created an indel frequency up to 47.3% in COSMC, while an indel frequency up to 99.7% in FUT8 was achieved by applying lectin selection. All eight sgRNAs examined in this study resulted in relatively high indel frequencies, demonstrating that the Cas9 system is a robust and efficient genome-editing methodology in CHO cells. Deep sequencing revealed that 85% of the indels created by Cas9 resulted in frameshift mutations at the target sites, with a strong preference for single base indels. Finally, we have developed a user-friendly bioinformatics tool, named "CRISPy" for rapid identification of sgRNA target sequences in the CHO-K1 genome. The CRISPy tool identified 1,970,449 CRISPR targets divided into 27,553 genes and lists the number of off-target sites in the genome. In conclusion, the proven functionality of Cas9 to edit CHO genomes combined with our CRISPy database have the potential to accelerate genome editing and synthetic biology efforts in CHO cells. PMID:24827782

  15. Cytotoxic effects of zearalenone and its metabolites and antioxidant cell defense in CHO-K1 cells.

    PubMed

    Tatay, Elena; Font, Guillermina; Ruiz, Maria-Jose

    2016-10-01

    Zearalenone (ZEA) and its metabolites (α-zearalenol; α-ZOL, β-zearalenol; β-ZOL) are secondary metabolites of Fusarium fungi that produce cell injury. The present study explores mycotoxin-induced cell damage and cellular protection mechanisms in CHO-K1 cells. Cytotoxicity has been determined by reactive oxygen species (ROS) production and DNA damage. ROS production was determined using the fluorescein assay and DNA strand breakage by comet assay. Intracellular protection systems were glutathione (GSH), glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD). The results demonstrated that all mycotoxins increased the ROS levels up to 5.3-fold the control levels in CHO-K1 cells. Zearalenone metabolites, but not ZEA, increased DNA damage 43% (α-ZOL) and 28% (β-ZOL) compared to control cells. The GSH levels decreased from 18% to 36%. The GPx and SOD activities respectively increased from 26% to 62% and from 23% to 69% in CHO-K1 cells, whereas CAT activity decreased from 14% to 52%. In addition, intracellular ROS production was induced by ZEA and its metabolites. The endogenous antioxidant system components GSH, GPx and SOD were activated against ZEA and its metabolites. These antioxidant system components thus could contribute to decrease cell injury by ZEA and its metabolites. PMID:27465603

  16. Heat Shock Response in CHO Mammalian Cells Is Controlled by a Nonlinear Stochastic Process

    PubMed Central

    Lipan, Ovidiu; Navenot, Jean-Marc; Wang, Zixuan; Huang, Lei; Peiper, Stephen C

    2007-01-01

    In many biological systems, the interactions that describe the coupling between different units in a genetic network are nonlinear and stochastic. We study the interplay between stochasticity and nonlinearity using the responses of Chinese hamster ovary (CHO) mammalian cells to different temperature shocks. The experimental data show that the mean value response of a cell population can be described by a mathematical expression (empirical law) which is valid for a large range of heat shock conditions. A nonlinear stochastic theoretical model was developed that explains the empirical law for the mean response. Moreover, the theoretical model predicts a specific biological probability distribution of responses for a cell population. The prediction was experimentally confirmed by measurements at the single-cell level. The computational approach can be used to study other nonlinear stochastic biological phenomena. PMID:17922567

  17. The relationship between mTOR signalling pathway and recombinant antibody productivity in CHO cell lines

    PubMed Central

    2014-01-01

    Background High recombinant protein productivity in mammalian cell lines is often associated with phenotypic changes in protein content, energy metabolism, and cell growth, but the key determinants that regulate productivity are still not clearly understood. The mammalian target of rapamycin (mTOR) signalling pathway has emerged as a central regulator for many cellular processes including cell growth, apoptosis, metabolism, and protein synthesis. This role of this pathway changes in response to diverse environmental cues and allows the upstream proteins that respond directly to extracellular signals (such as nutrient availability, energy status, and physical stresses) to communicate with downstream effectors which, in turn, regulate various essential cellular processes. Results In this study, we have performed a transcriptomic analysis using a pathway-focused polymerase chain reaction (PCR) array to compare the expression of 84 target genes related to the mTOR signalling in two recombinant CHO cell lines with a 17.4-fold difference in specific monoclonal antibody productivity (q p ). Eight differentially expressed genes that exhibited more than a 1.5-fold change were identified. Pik3cd (encoding the Class 1A catalytic subunit of phosphatidylinositol 3-kinase [PI3K]) was the most differentially expressed gene having a 71.3-fold higher level of expression in the high producer cell line than in the low producer. The difference in the gene’s transcription levels was confirmed at the protein level by examining expression of p110δ. Conclusion Expression of p110δ correlated with specific productivity (q p ) across six different CHO cell lines, with a range of expression levels from 3 to 51 pg/cell/day, suggesting that p110δ may be a key factor in regulating productivity in recombinant cell lines. PMID:24533650

  18. Optimization of cell line development in the GS-CHO expression system using a high-throughput, single cell-based clone selection system.

    PubMed

    Nakamura, Tsuyoshi; Omasa, Takeshi

    2015-09-01

    Therapeutic antibodies are commonly produced by high-expressing, clonal and recombinant Chinese hamster ovary (CHO) cell lines. Currently, CHO cells dominate as a commercial production host because of their ease of use, established regulatory track record, and safety profile. CHO-K1SV is a suspension, protein-free-adapted CHO-K1-derived cell line employing the glutamine synthetase (GS) gene expression system (GS-CHO expression system). The selection of high-producing mammalian cell lines is a crucial step in process development for the production of therapeutic antibodies. In general, cloning by the limiting dilution method is used to isolate high-producing monoclonal CHO cells. However, the limiting dilution method is time consuming and has a low probability of monoclonality. To minimize the duration and increase the probability of obtaining high-producing clones with high monoclonality, an automated single cell-based clone selector, the ClonePix FL system, is available. In this study, we applied the high-throughput ClonePix FL system for cell line development using CHO-K1SV cells and investigated efficient conditions for single cell-based clone selection. CHO-K1SV cell growth at the pre-picking stage was improved by optimizing the formulation of semi-solid medium. The efficiency of picking and cell growth at the post-picking stage was improved by optimization of the plating time without decreasing the diversity of clones. The conditions for selection, including the medium formulation, were the most important factors for the single cell-based clone selection system to construct a high-producing CHO cell line. PMID:25792187

  19. One-step generation of triple knockout CHO cell lines using CRISPR/Cas9 and fluorescent enrichment.

    PubMed

    Grav, Lise Marie; Lee, Jae Seong; Gerling, Signe; Kallehauge, Thomas Beuchert; Hansen, Anders Holmgaard; Kol, Stefan; Lee, Gyun Min; Pedersen, Lasse Ebdrup; Kildegaard, Helene Faustrup

    2015-09-01

    The CRISPR/Cas9 genome editing technology has previously been shown to be a highly efficient tool for generating gene disruptions in CHO cells. In this study we further demonstrate the applicability and efficiency of CRISPR/Cas9 genome editing by disrupting FUT8, BAK and BAX simultaneously in a multiplexing setup in CHO cells. To isolate Cas9-expressing cells from transfected cell pools, GFP was linked to the Cas9 nuclease via a 2A peptide. With this method, the average indel frequencies generated at the three genomic loci were increased from 11% before enrichment to 68% after enrichment. Despite the high number of genome editing events in the enriched cell pools, no significant off-target effects were observed from off-target prediction followed by deep sequencing. Single cell sorting of enriched multiplexed cells and deep sequencing of 97 clones revealed the presence of four single, 23 double and 34 triple gene-disrupted cell lines. Further characterization of selected potential triple knockout clones confirmed the removal of Bak and Bax protein and disrupted fucosylation activity as expected. The knockout cell lines showed improved resistance to apoptosis compared to wild-type CHO-S cells. Taken together, multiplexing with CRISPR/Cas9 can accelerate genome engineering efforts in CHO cells even further. PMID:25864574

  20. Homologous desensitization of human histamine H₃ receptors expressed in CHO-K1 cells.

    PubMed

    Osorio-Espinoza, Angélica; Escamilla-Sánchez, Juan; Aquino-Jarquin, Guillermo; Arias-Montaño, José-Antonio

    2014-02-01

    Histamine H₃ receptors (H₃Rs) modulate the function of the nervous system at the pre- and post-synaptic levels. In this work we aimed to determine whether, as other G protein-coupled receptors (GPCRs), H₃Rs desensitize in response to agonist exposure. By using CHO-K1 cells stably transfected with the human H₃R (hH3R) we show that functional responses (inhibition of forskolin-induced cAMP accumulation in intact cells and stimulation of [(35)S]-GTPγS binding to cell membranes) were markedly reduced after agonist exposure. For cAMP accumulation assays the effect was significant at 60 min with a maximum at 90 min. Agonist exposure resulted in decreased binding sites for the radioligand [(3)H]-N-methyl-histamine ([(3)H]-NMHA) to intact cells and modified the sub-cellular distribution of H₃Rs, as detected by sucrose density gradients and [(3)H]-NMHA binding to cell membranes, suggesting receptor internalization. The reduction in the inhibition of forskolin-stimulated cAMP formation observed after agonist pre-incubation was prevented by incubation in hypertonic medium or in ice-cold medium. Agonist-induced loss in binding sites was also prevented by hypertonic medium or incubation at 4 °C, but not by filipin III, indicating clathrin-dependent endocytosis. Immunodetection showed that CHO-K1 cells express GPCR kinases (GRKs) 2/3, and both the GRK general inhibitor ZnCl₂ and a small interfering RNA against GRK-2 reduced receptor desensitization. Taken together these results indicate that hH₃Rs experience homologous desensitization upon prolonged exposure to agonists, and that this process involves the action of GRK-2 and internalization via clathrin-coated vesicles. PMID:24161268

  1. Chemical inhibition of autophagy: Examining its potential to increase the specific productivity of recombinant CHO cell lines.

    PubMed

    Baek, Eric; Kim, Che Lin; Kim, Mi Gyeom; Lee, Jae Seong; Lee, Gyun Min

    2016-09-01

    Chinese hamster ovary (CHO) cells activate and undergo apoptosis and autophagy for various environmental stresses. Unlike apoptosis, studies on increasing the production of therapeutic proteins in CHO cells by targeting the autophagy pathway are limited. In order to identify the effects of chemical autophagy inhibitors on the specific productivity (qp ), nine chemical inhibitors that had been reported to target three different phases of autophagy (metformin, dorsomorphin, resveratrol, and SP600125 against initiation and nucleation; 3-MA, wortmannin, and LY294002 against elongation, and chloroquine and bafilomycin A1 against autophagosome fusion) were used to treat three recombinant CHO (rCHO) cell lines: the Fc-fusion protein-producing DG44 (DG44-Fc) and DUKX-B11 (DUKX-Fc) and antibody-producing DG44 (DG44-Ab) cell lines. Among the nine chemical inhibitors tested, 3-MA, dorsomorphin, and SP600125 significantly increased the qp of DG44-Fc and DUKX-Fc. In contrast, for DG44-Ab, only 3-MA significantly increased the qp . The autophagy-inhibiting activity of the nine chemical inhibitors on the rCHO cell lines was evaluated through Western blot analysis and flow cytometry. Unexpectedly, some chemical inhibitors did not exhibit any apparent inhibition activity on autophagy. The chemical inhibitors that enhanced the qp , 3-MA, dorsomorphin, and SP600125, exhibited instead an increased autophagic flux. Taken all together, the chemical inhibition of autophagy was not effective in increasing the qp in rCHO cell lines and the positive effect of 3-MA, dorsomorphin, and SP600125 on the qp was not due to the inhibition of autophagy. Biotechnol. Bioeng. 2016;113: 1953-1961. © 2016 Wiley Periodicals, Inc. PMID:26914152

  2. Comparison between the cultures of human induced pluripotent stem cells (hiPSCs) on feeder-and serum-free system (Matrigel matrix), MEF and HDF feeder cell lines.

    PubMed

    Ghasemi-Dehkordi, Payam; Allahbakhshian-Farsani, Mehdi; Abdian, Narges; Mirzaeian, Amin; Saffari-Chaleshtori, Javad; Heybati, Fatemeh; Mardani, Gashtasb; Karimi-Taghanaki, Alireza; Doosti, Abbas; Jami, Mohammad-Saeid; Abolhasani, Marziyeh; Hashemzadeh-Chaleshtori, Morteza

    2015-09-01

    Human induced pluripotent stem cells (hiPSCs) are a type of pluripotent stem cells artificially derived from an adult somatic cell (typically human fibroblast) by forced expression of specific genes. In recent years, different feeders like inactivated mouse embryonic fibroblasts (MEFs), human dermal fibroblasts (HDFs), and feeder free system have commonly been used for supporting the culture of stem cells in undifferentiated state. In the present work, the culture of hiPSCs and their characterizations on BD Matrigel (feeder-and serum-free system), MEF and HDF feeders using cell culture methods and molecular techniques were evaluated and compared. The isolated HDFs from foreskin samples were reprogrammed to hiPSCs using gene delivery system. Then, the pluripotency ability of hiPSCs cultured on each layer was determined by teratoma formation and immunohistochemical staining. After EBs generation the expression level of three germ layers genes were evaluated by Q-real-time PCR. Also, the cytogenetic stability of hiPSCs cultured on each condition was analyzed by karyotyping and comet assay. Then, the presence of pluripotency antigens were confirmed by Immunocytochemistry (ICC) test and alkaline phosphatase staining. This study were showed culturing of hiPSCs on BD Matrigel, MEF and HDF feeders had normal morphology and could maintain in undifferentiated state for prolonged expansion. The hiPSCs cultured in each system had normal karyotype without any chromosomal abnormalities and the DNA lesions were not observed by comet assay. Moreover, up-regulation in three germ layers genes in cultured hiPSCs on each layer (same to ESCs) compare to normal HDFs were observed (p < 0.05). The findings of the present work were showed in stem cells culturing especially hiPSCs both MEF and HDF feeders as well as feeder free system like Matrigel are proper despite benefits and disadvantages. Although, MEFs is suitable for supporting of stem cell culturing but it can animal pathogens

  3. Valeric acid induces cell cycle arrest at G1 phase in CHO cell cultures and improves recombinant antibody productivity.

    PubMed

    Park, Jin Hyoung; Noh, Soo Min; Woo, Ju Rang; Kim, Jong Won; Lee, Gyun Min

    2016-03-01

    To find a more effective chemical reagent for improved monoclonal antibody (mAb) production, eight chemical reagents (curcumin, quercein, DL-sulforaphane, thymidine, valeric acid, phenyl butyrate, valproic acid, and lithium chloride) known to induce cell cycle arrest were examined individually as chemical additives to recombinant CHO (rCHO) cell cultures producing mAb. Among these chemical additives, valeric acid showed the best production performance. Valeric acid decreased specific growth rate (μ), but increased culture longevity and specific mAb productivity (qmAb ) in a dose-dependent manner. The beneficial effect of valeric acid on culture longevity and qmAb outweighed its detrimental effect on μ, resulting in 2.9-fold increase in the maximum mAb concentration when 1.5 mM valeric acid was added to the cultures. Furthermore, valeric acid did not negatively affect the mAb quality attributes with regard to aggregation, charge variation, and galactosylation. Unexpectedly, galactosylation of the mAb increased by the 1.5 mM valeric acid addition. Taken together, the results obtained here demonstrate that valeric acid is an effective chemical reagent to increase mAb production in rCHO cells. PMID:26663903

  4. Ionizing radiation-induced 6-thioguanine-resistant clones in synchronous CHO cells

    SciTech Connect

    Burki, J.

    1980-01-01

    When cultured Chinese hamster ovary (CHO) cells are exposed to acute doses of ionizing radiation at different times during the cell division cycle, there is a characteristic cell-cycle response for radiation-induced cell killing and induced resistance to 6-thio-guanine (6TG). For cell killing the sensitive periods of the cell cycle are the G1, G2, M, and early S periods, as others have reported. For mutation induction the sensitive stage is the G1 period with the maximum sensitivity near the boundary between the G1 and the S period. Cells appear to be very refractile to induction of 6TG resistance in other periods of the cell cycle. These results suggest that chromosomal rearrangements of the X chromosome are most likely to occur in the G1 period before the gene for hypoxanthine-guanine-phosphoribosyl-transferase replicates, most likely due to genetic recombination. Clones resistant to 6TG after exposure to x rays are most likely induced by a different mutagenic pathway than ones stimulated by ultraviolet (uv) or ethylnitrosourea treatments, since the mutation induction patterns in the cell cycle are quite different.

  5. CHO cells knocked out for TSC2 display an improved productivity of antibodies under fed batch conditions.

    PubMed

    McVey, Duncan; Aronov, Michael; Rizzi, Giovanni; Cowan, Alexis; Scott, Charo; Megill, John; Russell, Reb; Tirosh, Boaz

    2016-09-01

    The kinase mTOR operates in two cellular complexes, mTORC1 and mTORC2. mTORC1 adjusts metabolic activity according to external growth conditions and nutrients availability. When conditions are prosperous, mTOR facilitates protein and lipid biosyntheses and inhibits autophagy, while under metabolic constraints, however, its attenuation induces a catabolic program, energy preservation and autophagy. CHO is a key cell line for manufacturing of biologics owing to its remarkable ability to grow to high densities and maintain protein production and secretion for extended times. While high mTOR activity has been associated with high productivity in CHO cells, its inhibition by rapamycin has also been documented to augment productivity via promotion of viability. Here using CRISPR/Cas9 editing we engineered CHO cells to enforce high mTORC1 activity by knocking-out TSC2, a major mTOR inhibitory protein, or PTEN, a phosphatase that attenuates the PI3K/AKT/mTOR pathway. Only TSC2-deleted cells exhibited a constitutive activation of mTORC1 under fed batch conditions. Cells grew larger in size, synthesized more proteins and displayed an over twofold elevation in their specific productivity. While peak viable cell density was compromised, overall titers increased to an extent dependent upon the parental clone. Our data underscore manipulation of TSC as a strategy to improve performance of CHO cell in bioreactors. Biotechnol. Bioeng. 2016;113: 1942-1952. © 2016 Wiley Periodicals, Inc. PMID:26888596

  6. Molecular characterization of a human matrix attachment region that improves transgene expression in CHO cells.

    PubMed

    Sun, Qiu-Li; Zhao, Chun-Peng; Chen, Shao-Nan; Wang, Li; Wang, Tian-Yun

    2016-05-15

    Chinese hamster ovary (CHO) cells offer many advantages for recombinant gene expression, including proper folding and post-translational modification of the recombinant protein. However, due to positional effects resulting from the neighboring chromatin, transgenes are often expressed at low levels in these cells. While previous studies demonstrated that matrix attachment regions (MARs) can be utilized to increase transgene expression by buffering transgene silencing, the mechanism by which this occurs is poorly understood. We therefore performed a deletion analysis of the human β-globin MAR sequence to characterize the regions that are necessary to enhance transgene expression in CHO cells. Our results indicate that of the six β-globin MAR fragments tested (MAR-1-6; nucleotides 1-540, 420-1020, 900-1500, 1380-1980, 1860-2460, and 2340-2999, respectively), MAR-2, followed by MAR-3, was the most effective region for promoting stable and elevated transgene expression. Meanwhile, bioinformatic analyses demonstrated that these fragments encode a MAR-like motif and several transcription factor binding sites, including special AT-rich binding protein 1 (SATB1), CCAAT-enhancer-binding proteins (C/EBP), CCCTC-binding factor (CTCF), and Glutathione (GSH) binding motifs, indicating that these elements may contribute to the MAR-mediated enhancement of transgene expression. In addition, we found that truncated MAR derivatives yield more stable transgene expression levels than transgenes lacking the MAR. We concluded that the MAR-mediated transcriptional activation of transgenes requires a specific AT-rich sequence, as well as specific transcription factor-binding motifs. PMID:26869318

  7. Sulfonate groups grafted on Ti6Al4V favor MC3T3-E1 cell performance in serum free medium conditions.

    PubMed

    Felgueiras, Helena; Migonney, Véronique

    2014-06-01

    Ten years ago, we synthesized "bioactive model polymers" bearing sulfonate groups and proposed a mechanism of their modulation effect at different steps of the cell response. Then, we set up the grafting of polymers bearing sulfonate on Ti6Al4V surfaces by a grafting "from" technique making sure of the creation of covalent bonds between the grafted polymer and the Ti6Al4V surface. We have checked and confirmed the positive effect of grafted sulfonate groups on the osteoblastic cell response in vivo and in vitro but we did not elucidate the mechanism. The aim of this basic work consists first in investigating the role of sulfonate groups in the presence and in the absence of proteins at early stages of the osteointegration process on poly(sodium styrene sulfonate) poly(NaSS) grafted and ungrafted Ti6Al4V surfaces, in vitro. To understand the role of poly(NaSS) grafted chains on osteoblast-like cell response and to confirm/elucidate the importance of fetal bovine serum (FBS) proteins in the culture medium, MC3T3-E1 cells were seeded onto poly(NaSS) grafted and non-grafted Ti6Al4V surfaces. Cultures were carried out in a complete (10% FBS) and in a non-complete medium (without FBS). Cell viability assay, cell attachment number and cell adhesion strength were followed up to 3days of culture. The presence of proteins enhanced cell growth and development whatever the surface and the presence of sulfonate groups enhanced the cell attachment even in the absence of proteins, which suggests and confirms that the sulfonate groups can modify the activity of cells such as the secretion of binding proteins. Statistical differences were found in the attachment strength tests on poly(NaSS) grafted and ungrafted surfaces and showed that the sulfonate groups play an important role in the cell resistance to shear stress. PMID:24863216

  8. Molecular recombination and the repair of DNA double-strand breaks in CHO cells.

    PubMed Central

    Resnick, M A; Moore, P D

    1979-01-01

    Molecular recombination and the repair of DNA double-strand breaks (DSB) have been examined in the G-0 and S phase of the cell cycle using a temperature-sensitive CHO cell line to test i) if there are cell cycle restrictions on the repair of DSB's' ii) the extent to which molecular recombination can be induced between either sister chromatids or homologous chromosomes and iii) whether repair of DSB's involves recombination (3). Mitomycin C (1-2 micrograms/ml) or ionizing radiation (50 krad) followed by incubation resulted in molecular recombination (hybrid DNA) in S phase cells. Approximately 0.03 to 0.10% of the molecules (number average molecular weight: 5.6 x 10(6) Daltons after shearing) had hybrid regions for more than 75% of their length. However, no recombination was detected in G-0 cells. Since the repair of DSB was observed in both stages with more than 50% of the breaks repaired in 5 hours, it appears that DSB repair in G-0 cells does not involve recombination between homologous chromosomes. The possibility is not excluded that repair in G-0 cells involves only small regions (less than 4 x 10(6) Daltons). PMID:493136

  9. GLUT4 and transferrin receptor are differentially sorted along the endocytic pathway in CHO cells.

    PubMed

    Wei, M L; Bonzelius, F; Scully, R M; Kelly, R B; Herman, G A

    1998-02-01

    The trafficking of GLUT4, a facilitative glucose transporter, is examined in transfected CHO cells. In previous work, we expressed GLUT4 in neuroendocrine cells and fibroblasts and found that it was targeted to a population of small vesicles slightly larger than synaptic vesicles (Herman, G.A, F. Bonzelius, A.M. Cieutat, and R.B. Kelly. 1994. Proc. Natl. Acad. Sci. USA. 91: 12750-12754.). In this study, we demonstrate that at 37 degrees C, GLUT4-containing small vesicles (GSVs) are detected after cell surface radiolabeling of GLUT4 whereas uptake of radioiodinated human transferrin does not show appreciable accumulation within these small vesicles. Immunofluorescence microscopy experiments show that at 37 degrees C, cell surface-labeled GLUT4 as well as transferrin is internalized into peripheral and perinuclear structures. At 15 degrees C, endocytosis of GLUT4 continues to occur at a slowed rate, but whereas fluorescently labeled GLUT4 is seen to accumulate within large peripheral endosomes, no perinuclear structures are labeled, and no radiolabeled GSVs are detectable. Shifting cells to 37 degrees C after accumulating labeled GLUT4 at 15 degrees C results in the reappearance of GLUT4 in perinuclear structures and GSV reformation. Cytosol acidification or treatment with hypertonic media containing sucrose prevents the exit of GLUT4 from peripheral endosomes as well as GSV formation, suggesting that coat proteins may be involved in the endocytic trafficking of GLUT4. In contrast, at 15 degrees C, transferrin continues to traffic to perinuclear structures and overall labels structures similar in distribution to those observed at 37 degrees C. Furthermore, treatment with hypertonic media has no apparent effect on transferrin trafficking from peripheral endosomes. Double-labeling experiments after the internalization of both transferrin and surface-labeled GLUT4 show that GLUT4 accumulates within peripheral compartments that exclude the transferrin receptor (TfR) at

  10. The human XRCC9 gene corrects chromosomal instability and mutagen sensitivities in CHO UV40 cells.

    PubMed

    Liu, N; Lamerdin, J E; Tucker, J D; Zhou, Z Q; Walter, C A; Albala, J S; Busch, D B; Thompson, L H

    1997-08-19

    The Chinese hamster ovary (CHO) mutant UV40 cell line is hypersensitive to UV and ionizing radiation, simple alkylating agents, and DNA cross-linking agents. The mutant cells also have a high level of spontaneous chromosomal aberrations and 3-fold elevated sister chromatid exchange. We cloned and sequenced a human cDNA, designated XRCC9, that partially corrected the hypersensitivity of UV40 to mitomycin C, cisplatin, ethyl methanesulfonate, UV, and gamma-radiation. The spontaneous chromosomal aberrations in XRCC9 cDNA transformants were almost fully corrected whereas sister chromatid exchanges were unchanged. The XRCC9 genomic sequence was cloned and mapped to chromosome 9p13. The translated XRCC9 sequence of 622 amino acids has no similarity with known proteins. The 2.5-kb XRCC9 mRNA seen in the parental cells was undetectable in UV40 cells. The mRNA levels in testis were up to 10-fold higher compared with other human tissues and up to 100-fold higher compared with other baboon tissues. XRCC9 is a candidate tumor suppressor gene that might operate in a postreplication repair or a cell cycle checkpoint function. PMID:9256465

  11. Deletion of a telomeric region on chromosome 8 correlates with higher productivity and stability of CHO cell lines.

    PubMed

    Ritter, Anett; Voedisch, Bernd; Wienberg, Johannes; Wilms, Burkhard; Geisse, Sabine; Jostock, Thomas; Laux, Holger

    2016-05-01

    Chinese Hamster Ovary (CHO) cells are widely used for large scale production of recombinant biopharmaceuticals. Although these cells have been extensively used, a demand to further increase the performance, for example, to facilitate the process of clone selection to isolate the highest producing cell lines that maintain stability of production over time is still existing. We compared gene expression profiles of high versus low producing CHO clones to identify regulated genes which can be used as biomarkers during clone selection or for cell line engineering. We present evidence that increased production rates and cell line stability are correlated with the loss of the telomeric region of the chromosome 8. A new parental CHO cell line lacking this region was generated and its capability for protein production was assessed. The average volumetric productivity of cells after gene transfer and selection was found to be several fold improved, facilitating the supply of early drug substance material to determine for example, quality. In addition, significantly more cell clones with a higher average productivity and higher protein production stability were obtained with the new host cell line after single cell cloning. This allows reduced efforts in single cell sorting, screening of fewer clones and raises the opportunity to circumvent time and labor-intensive stability studies. Biotechnol. Bioeng. 2016;113: 1084-1093. © 2015 Wiley Periodicals, Inc. PMID:26523402

  12. CHO-S Antibody Titers >1 Gram/Liter Using Flow Electroporation-Mediated Transient Gene Expression followed by Rapid Migration to High-Yield Stable Cell Lines

    PubMed Central

    Brady, James; Wang, Weili; Duskin, Meg; Donato, Karen; Peshwa, Madhusudan

    2015-01-01

    In recent years, researchers have turned to transient gene expression (TGE) as an alternative to CHO stable cell line generation for early-stage antibody development. Despite advances in transfection methods and culture optimization, the majority of CHO-based TGE systems produce insufficient antibody titers for extensive use within biotherapeutic development pipelines. Flow electroporation using the MaxCyte STX Scalable Transfection System is a highly efficient, scalable means of CHO-based TGE for gram-level production of antibodies without the need for specialized expression vectors or genetically engineered CHO cell lines. CHO cell flow electroporation is easily scaled from milligram to multigram quantities without protocol reoptimization while maintaining transfection performance and antibody productivity. In this article, data are presented that demonstrate the reproducibility, scalability, and antibody production capabilities of CHO-based TGE using the MaxCyte STX. Data show optimization of posttransfection parameters such as cell density, media composition, and feed strategy that result in secreted antibody titers >1 g/L and production of multiple grams of antibody within 2 weeks of a single CHO-S cell transfection. In addition, data are presented to demonstrate the application of scalable electroporation for the rapid generation of high-yield stable CHO cell lines to bridge the gap between early- and late-stage antibody development activities. PMID:25520372

  13. A kinetic-metabolic model based on cell energetic state: study of CHO cell behavior under Na-butyrate stimulation.

    PubMed

    Ghorbaniaghdam, Atefeh; Henry, Olivier; Jolicoeur, Mario

    2013-04-01

    A kinetic-metabolic model approach describing and simulating Chinese hamster ovary (CHO) cell behavior is presented. The model includes glycolysis, pentose phosphate pathway, TCA cycle, respiratory chain, redox state and energetic metabolism. Growth kinetic is defined as a function of the major precursors for the synthesis of cell building blocks. Michaelis-Menten type kinetic is used for metabolic intermediates as well as for regulatory functions from energy shuttles (ATP/ADP) and cofactors (NAD/H and NADP/H). Model structure and parameters were first calibrated using results from bioreactor cultures of CHO cells expressing recombinant t-PA. It is shown that the model can simulate experimental data for all available experimental data, such as extracellular glucose, glutamine, lactate and ammonium concentration time profiles, as well as cell energetic state. A sensitivity analysis allowed identifying the most sensitive parameters. The model was then shown to be readily adaptable for studying the effect of sodium butyrate on CHO cells metabolism, where it was applied to the cases with sodium butyrate addition either at mid-exponential growth phase (48 h) or at the early plateau phase (74 h). In both cases, a global optimization routine was used for the simultaneous estimation of the most sensitive parameters, while the insensitive parameters were considered as constants. Finally, confidence intervals for the estimated parameters were calculated. Results presented here further substantiate our previous findings that butyrate treatment at mid-exponential phase may cause a shift in cellular metabolism toward a sustained and increased efficiency of glucose utilization channeled through the TCA cycle. PMID:22976819

  14. Highly inducible expression from vectors containing multiple GRE's in CHO cells overexpressing the glucocorticoid receptor.

    PubMed Central

    Israel, D I; Kaufman, R J

    1989-01-01

    A conditional glucocorticoid-responsive expression vector system is described for highly inducible expression of heterologous genes in mammalian cells. This host-vector system requires high level expression of the glucocorticoid receptor (GR) protein in the host cell and multiple copies of the receptor binding site within the expression vector. Transfection and selection of Chinese hamster ovary cells with expression vectors encoding the rat GR yielded cell lines which express functional receptor at high levels. Insertion of multiple copies of the MMTV enhancer (glucocorticoid responsive element, GRE) into an Adenovirus major late promoter (AdMLP) based expression vector yielded greater than 1000-fold inducible expression by dexamethasone (dex) in transient DNA transfection assays. The induced expression level was 7-fold greater than that obtained with an AdMLP based vector containing an SV40 enhancer, but lacking GRE's. Vectors containing the SV40 enhancer in combination with multiple GRE's exhibited elevated basal expression in the absence of dex, but retained inducibility in both transient assays and after integration and amplification in the CHO genome. This expression system should be of general utility for studying gene regulation and for expressing heterologous genes in a regulatable fashion. Images PMID:2546123

  15. Characterization of recombinant human diamine oxidase (rhDAO) produced in Chinese Hamster Ovary (CHO) cells.

    PubMed

    Gludovacz, Elisabeth; Maresch, Daniel; Bonta, Maximilian; Szöllösi, Helen; Furtmüller, Paul G; Weik, Robert; Altmann, Friedrich; Limbeck, Andreas; Borth, Nicole; Jilma, Bernd; Boehm, Thomas

    2016-06-10

    Human diamine oxidase (hDAO) efficiently degrades polyamines and histamine. Reduced enzyme activities might cause complications during pregnancy and be involved in histamine intolerance. So far hDAO has been characterized after isolation from either native sources or the heterologous production in insect cells. Accessibility to human enzyme is limited and insect cells produce non-human glycosylation patterns that may alter its biochemical properties. We present the heterologous expression of hDAO in Chinese Hamster Ovary (CHO) cells and a three step purification protocol. Analysis of metal content using ICP-MS revealed that 93% of the active sites were occupied by copper. Topaquinone (TPQ) cofactor content was determined using phenylhydrazine titration. Ninety-four percent of DAO molecules contained TPQ and therefore the copper content at the active site was indirectly confirmed. Mass spectrometric analysis was conducted to verify sequence integrity of the protein and to assess the glycosylation profile. Electronic circular dichroism and UV-vis spectra data were used to characterize structural properties. The substrate preference and kinetic parameters were in accordance with previous publications. The establishment of a recombinant production system for hDAO enables us to generate decent amounts of protein with negligible impurities to address new scientific questions. PMID:27063138

  16. Microparticle-Mediated Transfer of the Viral Receptors CAR and CD46, and the CFTR Channel in a CHO Cell Model Confers New Functions to Target Cells

    PubMed Central

    Gonzalez, Gaëlle; Vituret, Cyrielle; Di Pietro, Attilio; Chanson, Marc; Boulanger, Pierre; Hong, Saw-See

    2012-01-01

    Cell microparticles (MPs) released in the extracellular milieu can embark plasma membrane and intracellular components which are specific of their cellular origin, and transfer them to target cells. The MP-mediated, cell-to-cell transfer of three human membrane glycoproteins of different degrees of complexity was investigated in the present study, using a CHO cell model system. We first tested the delivery of CAR and CD46, two monospanins which act as adenovirus receptors, to target CHO cells. CHO cells lack CAR and CD46, high affinity receptors for human adenovirus serotype 5 (HAdV5), and serotype 35 (HAdV35), respectively. We found that MPs derived from CHO cells (MP-donor cells) constitutively expressing CAR (MP-CAR) or CD46 (MP-CD46) were able to transfer CAR and CD46 to target CHO cells, and conferred selective permissiveness to HAdV5 and HAdV35. In addition, target CHO cells incubated with MP-CD46 acquired the CD46-associated function in complement regulation. We also explored the MP-mediated delivery of a dodecaspanin membrane glycoprotein, the CFTR to target CHO cells. CFTR functions as a chloride channel in human cells and is implicated in the genetic disease cystic fibrosis. Target CHO cells incubated with MPs produced by CHO cells constitutively expressing GFP-tagged CFTR (MP-GFP-CFTR) were found to gain a new cellular function, the chloride channel activity associated to CFTR. Time-course analysis of the appearance of GFP-CFTR in target cells suggested that MPs could achieve the delivery of CFTR to target cells via two mechanisms: the transfer of mature, membrane-inserted CFTR glycoprotein, and the transfer of CFTR-encoding mRNA. These results confirmed that cell-derived MPs represent a new class of promising therapeutic vehicles for the delivery of bioactive macromolecules, proteins or mRNAs, the latter exerting the desired therapeutic effect in target cells via de novo synthesis of their encoded proteins. PMID:23284987

  17. In search of expression bottlenecks in recombinant CHO cell lines--a case study.

    PubMed

    Reinhart, David; Sommeregger, Wolfgang; Debreczeny, Monika; Gludovacz, Elisabeth; Kunert, Renate

    2014-07-01

    The efficient production of recombinant proteins such as antibodies typically involves the screening of an extravagant number of clones in order to finally select a stable and high-producing cell line. Thereby, the underlying principles of a powerful protein machinery, but also potential expression limitations, often remain poorly understood. To shed more light on this topic, we applied several different techniques to investigate a previously generated cell line (4B3-IgA), which expressed recombinant immunoglobulin A (IgA) with an unusually low specific productivity. Results were compared to the host cell line and to another recombinant CHO cell line (3D6-IgA) expressing another IgA that binds to an overlapping epitope. The low specific productivity of clone 4B3-IgA could not be explained by GCN or mRNA levels, but insufficiencies in protein maturation and/or secretion were determined. Despite the presence of free light chain polypeptides, they occasionally failed to associate with their heavy chain partners. Consequently, heavy chains were misassembled and accumulated to form intracellular aggregates, so-called Russell bodies. These protein deposits evoked the expression of increased amounts of ER-resident chaperones to combat the induced stress. Despite bottlenecks in protein processing, the cells' quality checkpoints remained intact, and predominantly correctly processed IgA was exported into the culture medium. The results of our study demonstrated that recombinant protein expression was impaired by heavy chain aggregation despite the presence of a disposable light chain and revealed elevated chaperone formation in combination with limited antibody assembly. Our studies suggest that the primary amino acid sequence and consequently the resulting structure of an expressed protein need to be considered as a factor influencing a cell's productivity. PMID:24557570

  18. Stable Expression of Recombinant Factor VIII in CHO Cells Using Methotrexate-Driven Transgene Amplification.

    PubMed

    Orlova, N A; Kovnir, S V; Vorobiev, I I; Yuriev, A S; Gabibov, A G; Vorobiev, A I

    2012-01-01

    Prophylaxis and treatment of inherited clotting disorder hemophilia A requires regular administration of factor VIII. Recombinant factor VIII, which is produced in CHO or BHK cells, is equivalent to the plasma-derived one and is prevalent in current clinical practice in developed countries. Development of a biosimilar recombinant FVIII requires the creation of a highly productive clonal cell line and generation of monoclonal antibodies suitable for affinity purification of the product. Methotrexate-driven transgene amplification of genetic cassettes that code full-length and truncated variants of FVIII under the control of the CMV promoter was studied. It was shown that the expression level of the truncated variant of FVIII is 6.5 times higher than that of the full-length molecule. The transgene amplification procedure was sufficient for a twofold increase of the expression level in the transfected cells pool and subsequent selection of the clonal line, stably producing truncated FVIII at the level of 0.52 IU/ml during cultivation in a chemically defined protein-free culture medium. Four generated mouse monoclonal antibodies toward the heavy chain of FVIII were found suitable for binding the truncated variant of FVIII directly from the conditioned medium and elution of the FVIII with a more than 85% yield and normal pro-coagulant activity. The producer cell line and monoclonal antibodies obtained are sufficient for the development of upstream and downstream processes of biosimilar FVIII production. Generation of more productive cell lines by the use of stronger, nonviral promoters and shorter cDNA of FVIII will be the subject of further studies. PMID:22708069

  19. Protective effects of antioxidants on micronuclei induced by irradiated 9-fluorenone/N,N-dimethyl-p-toluidine in CHO cells.

    PubMed

    Li, Yi-Ching; Huang, Fu-Mei; Lee, Shiuan-Shinn; Lin, Ruey-Hseng; Chou, Ming-Yung; Chang, Yu-Chao

    2008-01-01

    9-Fluorenone (9F), the aromatic photosensitizer, is widely used as an initiator in visible-light (VL) cured resin systems. There is growing concern that 9F may produce genetic damage by inducing mutation. In this study, 9F in the presence or absence of reducing agent N,N-dimethyl-p-toluidine (DMT) with or without VL irradiation was analyzed for the induction of chromosomal aberrations indicated by micronuclei (MN) induced in CHO cells. Our data demonstrated that a dose-related increase in the frequency of MN and prolonged cell cycles in 9F with or without DMT in the presence or absence of VL irradiation (p < 0.05). The rank orders with respect to genotoxicity and cytotoxicity were found to be as follows: 9F/DMT +VL > 9F/DMT = 9F + VL > 9F. To determine whether oxidative stress could modulate MN induced by 9F/DMT with or without VL irradiation in CHO cells, cells were pretreated with N-acetyl-L-cysteine (NAC), ascorbic acid, and alpha-tocopherol. The pretreatment with antioxidants could diminish not only the prolonged cell cycle but also the decreased frequency of MN which is induced by 9F with or without DMT in the presence or absence of VL irradiation in CHO cells (p < 0.05). Our findings provide the evidences for the induction of MN by 9F in the presence or absence of DMT with or without VL irradiation in CHO cells, indicating clastogenic activity of 9F/DMT in vitro. These antioxidants act as the antagonists against the genotoxicity and cytotoxicity of 9F/DMT. Thus, leaching photoinitiator and reducing agent might be contributing the sources of oxidative stress. PMID:17455275

  20. Cytotoxic effects induced by patulin, sterigmatocystin and beauvericin on CHO-K1 cells.

    PubMed

    Zouaoui, Nidhal; Mallebrera, Beatriz; Berrada, Houda; Abid-Essefi, Salwa; Bacha, Hassen; Ruiz, Maria-Jose

    2016-03-01

    Mycotoxins are produced by different genera of fungi; mainly Aspergillus, Penicillium and Fusarium. The natural co-occurrence of beauvericin (BEA), patulin (PAT) and sterigmatocystin (STE) has been proved in feed and food commodities. This study investigates the cytotoxicity of individual and combined mycotoxins BEA, PAT and STE. The cytotoxicity on immortalized ovarian cells (CHO-K1) was evaluated using the MTT assay. After 24, 48 and 72 h, the IC50 values were 2.9 μM for PAT and ranged from 10.7 to 2.2 μM and from 25.0 to 12.5 μM for BEA and STE, respectively. Cytotoxic interactions were assayed by the isobologram method, which provides a combination index (CI) value as a quantitative measure of the three mycotoxin interaction's degree. Binary and tertiary combinations showed a dose dependent effect. At low fraction affected, mycotoxin combinations were synergetic; whereas, at higher fraction affected, the combinations showed additive effect. Our results indicate that the co-occurrence of low concentrations of mycotoxin in food may increase their toxic effects. PMID:26802678

  1. Comparison of three transposons for the generation of highly productive recombinant CHO cell pools and cell lines.

    PubMed

    Balasubramanian, Sowmya; Rajendra, Yashas; Baldi, Lucia; Hacker, David L; Wurm, Florian M

    2016-06-01

    Several naturally occurring vertebrate transposable elements have been genetically modified to enable the transposition of recombinant genes in mammalian cells. We compared three transposons-piggyBac, Tol2, and Sleeping Beauty-for their ability to generate cell pools (polyclonal cultures of recombinant cells) and clonal cell lines for the large-scale production of recombinant proteins using Chinese hamster ovary cells (CHO-DG44) as the host. Transfection with each of the dual-vector transposon systems resulted in cell pools with volumetric yields of tumor necrosis factor receptor-Fc fusion protein (TNFR:Fc) that were about ninefold higher than those from cell pools generated by conventional plasmid transfection. On average, the cell pools had 10-12 integrated copies of the transgene per cell. In the absence of selection, the volumetric productivity of the cell pools decreased by 50% over a 2-month cultivation period and then remained constant. The average volumetric TNFR:Fc productivity of clonal cell lines recovered from cell pools was about 25 times higher than that of cell lines generated by conventional transfection. In 14-day fed-batch cultures, TNFR:Fc levels up to 900 mg/L were obtained from polyclonal cell pools and up to 1.5 g/L from clonal cell lines using any of the three transposons. Biotechnol. Bioeng. 2016;113: 1234-1243. © 2015 Wiley Periodicals, Inc. PMID:26616356

  2. Verhulst and stochastic models for comparing mechanisms of MAb productivity in six CHO cell lines.

    PubMed

    Shirsat, Nishikant; Avesh, Mohd; English, Niall J; Glennon, Brian; Al-Rubeai, Mohamed

    2016-08-01

    The present study validates previously published methodologies-stochastic and Verhulst-for modelling the growth and MAb productivity of six CHO cell lines grown in batch cultures. Cytometric and biochemical data were used to model growth and productivity. The stochastic explanatory models were developed to improve our understanding of the underlying mechanisms of growth and productivity, whereas the Verhulst mechanistic models were developed for their predictability. The parameters of the two sets of models were compared for their biological significance. The stochastic models, based on the cytometric data, indicated that the productivity mechanism is cell specific. However, as shown before, the modelling results indicated that G2 + ER indicate high productivity, while G1 + ER indicate low productivity, where G1 and G2 are the cell cycle phases and ER is Endoplasmic Reticulum. In all cell lines, growth proved to be inversely proportional to the cumulative G1 time (CG1T) for the G1 phase, whereas productivity was directly proportional to ER. Verhulst's rule, "the lower the intrinsic growth factor (r), the higher the growth (K)," did not hold for growth across all cell lines but held good for the cell lines with the same growth mechanism-i.e., r is cell specific. However, the Verhulst productivity rule, that productivity is inversely proportional to the intrinsic productivity factor (r x ), held well across all cell lines in spite of differences in their mechanisms for productivity-that is, r x is not cell specific. The productivity profile, as described by Verhulst's logistic model, is very similar to the Michaelis-Menten enzyme kinetic equation, suggesting that productivity is more likely enzymatic in nature. Comparison of the stochastic and Verhulst models indicated that CG1T in the cytometric data has the same significance as r, the intrinsic growth factor in the Verhulst models. The stochastic explanatory and the Verhulst logistic models can explain the

  3. Optimization of the medium perfusion rate in a packed-bed bioreactor charged with CHO cells.

    PubMed

    Meuwly, F; von Stockar, U; Kadouri, A

    2004-09-01

    In the present study, the optimal medium perfusion rate to be used for the continuous culture of a recombinant CHO cell line in a packed-bed bioreactor made of Fibra-Cel((R)) disk carriers was determined. A first-generation process had originally been designed with a high perfusion rate, in order to rapidly produce material for pre-clinical and early clinical trials. It was originally operated with a perfusion of 2.6 vvd during production phase in order to supply the high cell density (2.5x10(7) cell ml(-1) of packed-bed) with sufficient fresh medium. In order to improve the economics of this process, a reduction of the medium perfusion rate by -25% and -50% was investigated at small-scale. The best option was then implemented at pilot scale in order to further produce material for clinical trials with an improved second-generation process. With a -25% reduction of the perfusion rate, the volumetric productivity was maintained compared to the first-generation process, but a -30% loss of productivity was obtained when the medium perfusion rate was further reduced to -50% of its original level. The protein quality under reduced perfusion rate conditions was analyzed for purity, N-glycan sialylation level, abundance of dimers or aggregates, and showed that the quality of the final drug substance was comparable to that obtained in reference conditions. Finally, a reduction of -25% medium perfusion was implemented at pilot scale in the second-generation process, which enabled to maintain the same productivity and the same quality of the molecule, while reducing costs of media, material and manpower of the production process. For industrial applications, it is recommended to test whether and how far the perfusion rate can be decreased during the production phase - provided that the product is not sensitive to residence time - with the benefits of reduced cost of goods and to simplify manufacturing operations. PMID:19003257

  4. DNA and chromosome breaks induced by {sup 123}I-estrogen in CHO cells

    SciTech Connect

    Schwartz, J.L. |; Mustafi, R.; Hughes, A.; DeSombre, E.R.

    1997-07-01

    The effects of the Auger electron-emitting isotope I-123, covalently bound to estrogen, on DNA single- and double-strand breakage and on chromosome breakage was determined in estrogen positive Chinese hamster ovary (CHO-ER) cells. Exposure to the {sup 123}I-estrogen induced both single- and double-strand breaks with a ratio of single- to double-strand breaks of 2.2. The corresponding ratio with {sup 60}Co gamma rays was 15.6. The dose-response was biphasic suggesting that either receptor sites are saturated at high does, or that there is a nonrandom distribution of breaks induced by the {sup 123}I-estrogen. The {sup 123}I-estrogen treatment induced chromosome aberrations with an efficiency of about 1 aberration for each 1,000 disintegrations per cell. This corresponds to the mean lethal dose of {sup 123}I-estrogen for these cells suggesting that the lethal event induced by the Auger electron emitter bound to estrogen is a chromosome aberration. Most of the chromosome-type aberrations were dicentrics and rings, suggesting that {sup 123}I-estrogen-induced chromosome breaks are rejoined. The F-ratio, the ratio of dicentrics to centric rings, was 5.8 {plus_minus} 1.7, which is similar to that seen with high LET radiations. Their results suggest that I-123 bound to estrogen is an efficient clastogenic agent, that the cytotoxic damage produced by I-123 bound to estrogen is very like high LET-induced damage, and the I-123 in the estrogen-receptor-DNA complex is probably in close proximity to the sugar-phosphate backbone of the DNA.

  5. Genotoxic effects of environmental estrogen-like compounds in CHO-K1 cells.

    PubMed

    Tayama, Sumiko; Nakagawa, Yoshio; Tayama, Kuniaki

    2008-01-01

    Some environmental estrogen-like compounds, such as bisphenol A (BPA), 4-nonylphenol (NP), 4-octylphenol (OP), propyl p-hydroxybenzoate (P-PHBA), and butyl p-hydroxybenzoate (B-PHBA), synthetic estrogen, diethylstilbestrol (DES), and natural estrogen, 17beta-estradiol (E2), were studied for their genotoxicity in CHO-K1 cells using sister-chromatid exchange (SCE), chromosome aberration (CA), and DNA strand break (comet) assays. Six of the chemicals, excluding E2, caused DNA migration in the comet assay and induced SCEs at one or more of the highest doses. Among the chemicals, OP produced an especially high incidence of SCEs. Structural CA was induced by five of the chemicals, excluding OP and NP, and BPA, E2, and DES also induced aneuploid cells. E2 and DES particularly increased the rate of polyploidy at high doses. The incidence of colchicine-mitosis-like (c-mitotic) figures suggesting spindle disrupting effects was also detected with five of the chemicals, excluding OP and NP, and six of the chemicals, excluding E2, caused endoreduplication (ERD), a form of nuclear polyploidization induced by block of cell cycle at G2 phase, at one or more high doses. Our present results suggest that OP and NP cause repairable DNA damage, including SCEs, and do not result in CA, while the damage caused by DES, BPA, P-PHBA, and B-PHBA results in the induction of CAs together with SCEs probably because of imperfect repair. We are unable to explain the observation that the DNA damage caused by E2 resulted in CA induction but not DNA migration or SCE induction, except for speculating that the DNA damage is different from that caused by DES and the estrogen-like chemicals. Our findings also suggest that E2, DES and BPA have aneuploidogenic properties, and that the former two of chemicals also are polyploidy-inducing agents. PMID:17913570

  6. Growth, productivity and protein glycosylation in a CHO EpoFc producer cell line adapted to glutamine-free growth.

    PubMed

    Taschwer, Michael; Hackl, Matthias; Hernández Bort, Juan A; Leitner, Christian; Kumar, Niraj; Puc, Urszula; Grass, Josephine; Papst, Martin; Kunert, Renate; Altmann, Friedrich; Borth, Nicole

    2012-01-20

    A primary objective of cell line development and process optimisation in animal cell culture is the improvement of culture performance as indicated by desirable properties such as high cell concentration, viability, productivity and product quality. The inefficient energy metabolism of mammalian cells in culture is still a major limiting factor for improvements in process performance. It results in high uptake rates of glucose and glutamine and the concomitant accumulation of waste products which in turn limits final cell concentrations and growth. To avoid these negative side effects, a CHO host cell line was established recently which is able to grow in completely glutamine free medium (Hernandez Bort et al., 2010). To determine the influence of this adaptation on productivity and product quality, the same procedure was repeated with a recombinant CHO cell line producing an erythropoietin-Fc fusion protein (CHO-EpoFc) for this publication. After adaptation to higher cell densities and glutamine free medium, culture performance was monitored in batch bioprocesses and revealed comparable growth properties and EpoFc product formation in both cell lines. The level of reactive oxygen species was elevated in the adapted cells, reflecting a higher level of oxidative stress, however, at the same time the level of the oxido-protective glutathione was also higher, so that cells seem adequately protected against cellular damage. Analysis of nucleotides and nucleotide sugars revealed elevated UDP-sugars in cells grown in the absence of glutamine. Furthermore, the antennarity of N-glycans was moderately higher on the Epo part of the protein produced by the adapted cell line compared to the parental cell line. Except for this, the glycosylation, with respect to site occupancy, degree of sialylation and glycoform structure, was highly comparable, both for the Epo and the Fc part of the protein. PMID:22178781

  7. Very high cell density perfusion of CHO cells anchored in a non-woven matrix-based bioreactor.

    PubMed

    Zhang, Ye; Stobbe, Per; Silvander, Christian Orrego; Chotteau, Véronique

    2015-11-10

    Recombinant Chinese Hamster Ovary (CHO) cells producing IgG monoclonal antibody were cultivated in a novel perfusion culture system CellTank, integrating the bioreactor and the cell retention function. In this system, the cells were harbored in a non-woven polyester matrix perfused by the culture medium and immersed in a reservoir. Although adapted to suspension, the CHO cells stayed entrapped in the matrix. The cell-free medium was efficiently circulated from the reservoir into- and through the matrix by a centrifugal pump placed at the bottom of the bioreactor resulting in highly homogenous concentrations of the nutrients and metabolites in the whole system as confirmed by measurements from different sampling locations. A real-time biomass sensor using the dielectric properties of living cells was used to measure the cell density. The performances of the CellTank were studied in three perfusion runs. A very high cell density measured as 200 pF/cm (where 1 pF/cm is equivalent to 1 × 10(6)viable cells/mL) was achieved at a perfusion rate of 10 reactor volumes per day (RV/day) in the first run. In the second run, the effect of cell growth arrest by hypothermia at temperatures lowered gradually from 37 °C to 29 °C was studied during 13 days at cell densities above 100 pF/cm. Finally a production run was performed at high cell densities, where a temperature shift to 31 °C was applied at cell density 100 pF/cm during a production period of 14 days in minimized feeding conditions. The IgG concentrations were comparable in the matrix and in the harvest line in all the runs, indicating no retention of the product of interest. The cell specific productivity was comparable or higher than in Erlenmeyer flask batch culture. During the production run, the final harvested IgG production was 35 times higher in the CellTank compared to a repeated batch culture in the same vessel volume during the same time period. PMID:26211737

  8. Using Gene Essentiality and Synthetic Lethality Information to Correct Yeast and CHO Cell Genome-Scale Models

    PubMed Central

    Chowdhury, Ratul; Chowdhury, Anupam; Maranas, Costas D.

    2015-01-01

    Essentiality (ES) and Synthetic Lethality (SL) information identify combination of genes whose deletion inhibits cell growth. This information is important for both identifying drug targets for tumor and pathogenic bacteria suppression and for flagging and avoiding gene deletions that are non-viable in biotechnology. In this study, we performed a comprehensive ES and SL analysis of two important eukaryotic models (S. cerevisiae and CHO cells) using a bilevel optimization approach introduced earlier. Information gleaned from this study is used to propose specific model changes to remedy inconsistent with data model predictions. Even for the highly curated Yeast 7.11 model we identified 50 changes (metabolic and GPR) leading to the correct prediction of an additional 28% of essential genes and 36% of synthetic lethals along with a 53% reduction in the erroneous identification of essential genes. Due to the paucity of mutant growth phenotype data only 12 changes were made for the CHO 1.2 model leading to an additional correctly predicted 11 essential and eight non-essential genes. Overall, we find that CHO 1.2 was 76% less accurate than the Yeast 7.11 metabolic model in predicting essential genes. Based on this analysis, 14 (single and double deletion) maximally informative experiments are suggested to improve the CHO cell model by using information from a mouse metabolic model. This analysis demonstrates the importance of single and multiple knockout phenotypes in assessing and improving model reconstructions. The advent of techniques such as CRISPR opens the door for the global assessment of eukaryotic models. PMID:26426067

  9. Using Gene Essentiality and Synthetic Lethality Information to Correct Yeast and CHO Cell Genome-Scale Models.

    PubMed

    Chowdhury, Ratul; Chowdhury, Anupam; Maranas, Costas D

    2015-01-01

    Essentiality (ES) and Synthetic Lethality (SL) information identify combination of genes whose deletion inhibits cell growth. This information is important for both identifying drug targets for tumor and pathogenic bacteria suppression and for flagging and avoiding gene deletions that are non-viable in biotechnology. In this study, we performed a comprehensive ES and SL analysis of two important eukaryotic models (S. cerevisiae and CHO cells) using a bilevel optimization approach introduced earlier. Information gleaned from this study is used to propose specific model changes to remedy inconsistent with data model predictions. Even for the highly curated Yeast 7.11 model we identified 50 changes (metabolic and GPR) leading to the correct prediction of an additional 28% of essential genes and 36% of synthetic lethals along with a 53% reduction in the erroneous identification of essential genes. Due to the paucity of mutant growth phenotype data only 12 changes were made for the CHO 1.2 model leading to an additional correctly predicted 11 essential and eight non-essential genes. Overall, we find that CHO 1.2 was 76% less accurate than the Yeast 7.11 metabolic model in predicting essential genes. Based on this analysis, 14 (single and double deletion) maximally informative experiments are suggested to improve the CHO cell model by using information from a mouse metabolic model. This analysis demonstrates the importance of single and multiple knockout phenotypes in assessing and improving model reconstructions. The advent of techniques such as CRISPR opens the door for the global assessment of eukaryotic models. PMID:26426067

  10. The inhibition of CHO-K1-BH4 cell proliferation and induction of chromosomal aberrations by brevetoxins in vitro.

    PubMed

    Sayer, A N; Hu, Q; Bourdelais, A J; Baden, D G; Gibson, J E

    2006-07-01

    Brevetoxins (PbTxs) are highly potent trans-syn polyether neurotoxins produced during blooms of several species of marine dinoflagellates, most notably Karenia brevis. These neurotoxins act on voltage-sensitive sodium channels prolonging the active state. During red tides, the commercial fishing and tourism industries experience millions of dollars of lost revenue. Human consumption of shellfish contaminated with PbTxs results in neurotoxic shellfish poisoning (NSP). Additionally, blooms of K. brevis are potentially responsible for adverse human health effects such as respiratory irritation and airway constriction in coastal residents. There is little information regarding the full range of potential toxic effects caused by PbTxs. Recent evidence suggests that PbTxs are genotoxic substances. The purpose of this study was to determine if PbTxs could induce chromosomal aberrations and inhibit cellular proliferation in CHO-K1-BH4 cells, and if so, could the damage be negated or reduced by the PbTx antagonist brevenal. Results from the chromosomal aberrations assay demonstrated that PbTxs are potent inducers of CHO-K1-BH4 chromosome damage. Results from the inhibition of cellular proliferation assays demonstrated that PbTxs inhibit the ability of CHO-K1-BH4 cells to proliferate, an effect which can be reduced with brevenal. PMID:16487644

  11. The inhibition of CHO-K1-BH4 cell proliferation and induction of chromosomal aberrations by brevetoxins in vitro

    PubMed Central

    Sayer, A.N.; Hu, Q.; Bourdelais, A.J.; Baden, D.G.; Gibson, J.E.

    2009-01-01

    Brevetoxins (PbTxs) are highly potent trans-syn polyether neurotoxins produced during blooms of several species of marine dinoflagellates, most notably Karenia brevis. These neurotoxins act on voltage-sensitive sodium channels prolonging the active state. During red tides, the commercial fishing and tourism industries experience millions of dollars of lost revenue. Human consumption of shellfish contaminated with PbTxs results in neurotoxic shellfish poisoning (NSP). Additionally, blooms of K. brevis are potentially responsible for adverse human health effects such as respiratory irritation and airway constriction in coastal residents. There is little information regarding the full range of potential toxic effects caused by PbTxs. Recent evidence suggests that PbTxs are genotoxic substances. The purpose of this study was to determine if PbTxs could induce chromosomal aberrations and inhibit cellular proliferation in CHO-K1-BH4 cells, and if so, could the damage be negated or reduced by the PbTx antagonist brevenal. Results from the chromosomal aberrations assay demonstrated that PbTxs are potent inducers of CHO-K1-BH4 chromosome damage. Results from the inhibition of cellular proliferation assays demonstrated that PbTxs inhibit the ability of CHO-K1-BH4 cells to proliferate, an effect which can be reduced with brevenal. PMID:16487644

  12. A novel regulatory element (E77) isolated from CHO-K1 genomic DNA enhances stable gene expression in Chinese hamster ovary cells.

    PubMed

    Kang, Shin-Young; Kim, Yeon-Gu; Kang, Seunghee; Lee, Hong Weon; Lee, Eun Gyo

    2016-05-01

    Vectors flanked by regulatory DNA elements have been used to generate stable cell lines with high productivity and transgene stability; however, regulatory elements in Chinese hamster ovary (CHO) cells, which are the most widely used mammalian cells in biopharmaceutical production, are still poorly understood. We isolated a novel gene regulatory element from CHO-K1 cells, designated E77, which was found to enhance the stable expression of a transgene. A genomic library was constructed by combining CHO-K1 genomic DNA fragments with a CMV promoter-driven GFP expression vector, and the E77 element was isolated by screening. The incorporation of the E77 regulatory element resulted in the generation of an increased number of clones with high expression, thereby enhancing the expression level of the transgene in the stable transfectant cell pool. Interestingly, the E77 element was found to consist of two distinct fragments derived from different locations in the CHO genome shotgun sequence. High and stable transgene expression was obtained in transfected CHO cells by combining these fragments. Additionally, the function of E77 was found to be dependent on its site of insertion and specific orientation in the vector construct. Our findings demonstrate that stable gene expression mediated by the CMV promoter in CHO cells may be improved by the isolated novel gene regulatory element E77 identified in the present study. PMID:26762773

  13. Effects of ammonia on CHO cell growth, erythropoietin production, and glycosylation.

    PubMed

    Yang, M; Butler, M

    2000-05-20

    The effect of ammonium chloride was determined on a culture of CHO cells transfected with the human erythropoietin (EPO) gene. Cell growth was inhibited above a culture concentration of 5 mM NH(4)Cl with an IC-50 determined to be 33 mM. The specific production of EPO increased with the addition of NH(4)Cl above 5 mM. At 10 mM NH(4)Cl, the final cell density after 4 days in culture was significantly lower but the final yield of EPO was significantly higher. This appeared to be due to continued protein production after cell growth had ceased. The metabolic effects of added NH(4)Cl included higher specific consumption rates of glucose and glutamine and an increased rate of production of alanine, glycine, and glutamate. The EPO analyzed from control cultures had a molecular weight range of 33-39 kDa and an isoelectric point range of 4.06-4.67. Seven distinct isoforms of the molecule were identified by two-dimensional electrophoresis. This molecular heterogeneity was ascribed to variable glycosylation. Complete enzymatic de-glycosylation resulted in a single molecular form with a molecular mass of 18 kDa. Addition of NH(4)Cl to the cultures caused a significant increase in the heterogeneity of the glycoforms as shown by an increased molecular weight and pI range. Enzymatic de-sialylation of the EPO from the ammonia-treated and control cultures resulted in identical electrophoretic patterns. This indicated that the effect of ammonia was in the reduction of terminal sialylation of the glycan structures which accounted for the increased pI. Selective removal of the N-glycan structures by PNGase F resulted in two bands identified as the O-glycan linked structure (19 kDa) and the completely de-glycosylated structure (18 kDa). The proportion of the O-linked glycan structure was reduced, and its pI increased in cultures to which ammonia was added. Thus, the glycosylation pattern altered by the presence of ammonia included a reduction in terminal sialylation of all the glycans

  14. Carboxypeptidase D is the only enzyme responsible for antibody C-terminal lysine cleavage in Chinese hamster ovary (CHO) cells.

    PubMed

    Hu, Zhilan; Zhang, Henry; Haley, Benjamin; Macchi, Frank; Yang, Feng; Misaghi, Shahram; Elich, Joseph; Yang, Renee; Tang, Yun; Joly, John C; Snedecor, Bradley R; Shen, Amy

    2016-10-01

    Heterogeneity of C-terminal lysine levels often observed in therapeutic monoclonal antibodies is believed to result from the proteolysis by endogenous carboxypeptidase(s) during cell culture production. Identifying the responsible carboxypeptidase(s) for C-terminal lysine cleavage in CHO cells would provide valuable insights for antibody production cell culture processes development and optimization. In this study, five carboxypeptidases, CpD, CpM, CpN, CpB, and CpE, were studied for message RNA (mRNA) expression by qRT-PCR analysis in two most commonly used blank hosts (DUXB-11 derived DHFR-deficient DP12 host and DHFR-positive CHOK1 host), used for therapeutic antibody production, as well an antibody-expressing cell line derived from each host. Our results showed that CpD had the highest mRNA expression. When CpD mRNA levels were reduced by RNAi (RNA interference) technology, C-terminal lysine levels increased, whereas there was no obvious change in C-terminal lysine levels when a different carboxypeptidase mRNA level was knocked down suggesting that carboxypeptidase D is the main contributor for C-terminal lysine processing. Most importantly, when CpD expression was knocked out by CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) technology, C-terminal lysine cleavage was completely abolished in CpD knockout cells based on mass spectrometry analysis, demonstrating that CpD is the only endogenous carboxypeptidase that cleaves antibody heavy chain C-terminal lysine in CHO cells. Hence, our work showed for the first time that the cleavage of antibody heavy chain C-terminal lysine is solely mediated by the carboxypeptidase D in CHO cells and our finding provides one solution to eliminating C-terminal lysine heterogeneity for therapeutic antibody production by knocking out CpD gene expression. Biotechnol. Bioeng. 2016;113: 2100-2106. © 2016 Wiley Periodicals, Inc. PMID:26989081

  15. Cytogenetic analyses of Azadirachtin reveal absence of genotoxicity but marked antiproliferative effects in human lymphocytes and CHO cells in vitro.

    PubMed

    Mosesso, Pasquale; Bohm, Lothar; Pepe, Gaetano; Fiore, Mario; Carpinelli, Alice; Gäde, Gerd; Nagini, Siddavaram; Ottavianelli, Alessandro; Degrassi, Francesca

    2012-09-18

    In this work we have examined the genotoxic potential of the bioinsecticide Azadirachtin A (AZA) and its influence on cell proliferation on human lymphocytes and Chinese Hamster ovary (CHO) cells. AZA genotoxicity was assessed by the analysis of chromosomal aberrations and sister chromatid exchanges (SCEs) in the absence and presence of rat liver S9 metabolism. Primary DNA damage was also investigated by means of the comet assay. The results obtained clearly indicate that AZA is not genotoxic in mammalian cells. On the other hand, AZA proved to interfere with cell cycle progression as shown by modulation of frequencies of first (M1) and second division (M2) metaphases detected by 5-Bromo-2'-deoxyuridine labeling. Accumulation of M1 metaphases were more pronounced in human lymphocytes. In the transformed CHO cell line, however, significant increases of multinucleated interphases and polyploid cells were observed at long treatment time. At higher dose-levels, the incidence of polyploidy was close to 100%. Identification of spindle structure and number of centrosomes by fluorescent immunostaining with α- and γ-tubulin antibodies revealed aberrant mitoses exhibiting multipolar spindles with several centrosomal signals. These findings suggest that AZA can act either through a stabilizing activity of microtubules or by inhibition of Aurora A, since both mechanisms are able to generate genetically unstable polyploid cells with multipolar spindles and multinucleated interphases. PMID:22885097

  16. Enhanced plasmid DNA utilization in transiently transfected CHO-DG44 cells in the presence of polar solvents.

    PubMed

    Rajendra, Yashas; Balasubramanian, Sowmya; Kiseljak, Divor; Baldi, Lucia; Wurm, Florian M; Hacker, David L

    2015-01-01

    Although the protein yields from transient gene expression (TGE) with Chinese hamster ovary (CHO) cells have recently improved, the amount of plasmid DNA (pDNA) needed for transfection remains relatively high. We describe a strategy to reduce the pDNA amount by transfecting CHO-DG44 cells with 0.06 μg pDNA/10(6) cells (10% of the optimal amount) in the presence of nonspecific (filler) DNA and various polar solvents including dimethylsufoxide, dimethyl formamide, acetonitrile, dimethyl acetamide (DMA), and hexamethyl phosphoramide (HMP). All of the polar solvents with the exception of HMP increased the production of a recombinant antibody in comparison to the untreated control transfection. In the presence of 0.25% DMA, the antibody yield in a 7-day batch culture was 500 mg/L. This was fourfold higher than the yield from the untreated control transfection. Mechanistic studies revealed that the polar solvents did not affect polyethylenimine-mediated pDNA delivery into cells or nuclei. The steady-state transgene mRNA level was elevated in the presence of each of the polar solvents tested, while the transgene mRNA half-life remained the same. These results indicated that the polar solvents enhanced transgene transcription. When screening a panel of recombinant antibodies and Fc-fusion proteins for production in the presence of the polar solvents, the highest increase in yield was observed following DMA addition for 11 of the 12 proteins. These results are expected to enhance the applicability of high-yielding TGE processes with CHO-DG44 cells by decreasing the amount of pDNA required for transfection. PMID:26260195

  17. Transferability study of CHO cell clustering assays for monitoring of pertussis toxin activity in acellular pertussis vaccines.

    PubMed

    Isbrucker, R; Daas, A; Wagner, L; Costanzo, A

    2016-01-01

    Current regulations for acellular pertussis (aP) vaccines require that they are tested for the presence of residual or reversion-derived pertussis toxin (PTx) activity using the mouse histamine sensitisation test (HIST). Although a CHO cell clustering assay can be used by manufacturers to verify if sufficient inactivation of the substance has occurred in-process, this assay cannot be used at present for the final product due to the presence of aluminium adjuvants which interfere with mammalian cell cultures. Recently, 2 modified CHO cell clustering assays which accommodate for the adjuvant effects have been proposed as alternatives to the HIST. These modified assays eliminate the adjuvant-induced cytotoxicity either through dilution of the vaccine (called the Direct Method) or by introducing a porous barrier between the adjuvant and the cells (the Indirect Method). Transferability and suitability of these methods for testing of products present on the European market were investigated during a collaborative study organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM). Thirteen laboratories participated in this study which included 4 aP-containing vaccines spiked by addition of PTx. This study also assessed the transferability of a standardised CHO cell clustering assay protocol for use with non-adjuvanted PTx preparations. Results showed that the majority of laboratories were able to detect the PTx spike in all 4 vaccines at concentrations of 4 IU/mL or lower using the Indirect Method. This sensitivity is in the range of the theoretical sensitivity of the HIST. The Direct Method however did not show the expected results and would need additional development work. PMID:27506252

  18. Effects of Iron-Oxide Nanoparticle Surface Chemistry on Uptake Kinetics and Cytotoxicity in CHO-K1 Cells

    PubMed Central

    Hanot, Camille C.; Choi, Young Suk; Anani, Tareq B.; Soundarrajan, Dharsan; David, Allan E.

    2015-01-01

    Superparamagnetic iron-oxide nanoparticles (SPIONs) show great promise for multiple applications in biomedicine. While a number of studies have examined their safety profile, the toxicity of these particles on reproductive organs remains uncertain. The goal of this study was to evaluate the cytotoxicity of starch-coated, aminated, and PEGylated SPIONs on a cell line derived from Chinese Hamster ovaries (CHO-K1 cells). We evaluated the effect of particle diameter (50 and 100 nm) and polyethylene glycol (PEG) chain length (2k, 5k and 20k Da) on the cytotoxicity of SPIONs by investigating cell viability using the tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and sulforhodamine B (SRB) assays. The kinetics and extent of SPION uptake by CHO-K1 cells was also studied, as well as the resulting generation of intracellular reactive oxygen species (ROS). Cell toxicity profiles of SPIONs correlated strongly with their cellular uptake kinetics, which was strongly dependent on surface properties of the particles. PEGylation caused a decrease in both uptake and cytotoxicity compared to aminated SPIONs. Interestingly, 2k Da PEG-modifed SPIONs displayed the lowest cellular uptake and cytotoxicity among all studied particles. These results emphasize the importance of surface coatings when engineering nanoparticles for biomedical applications. PMID:26729108

  19. Chromosome breakage at a major fragile site associated with P-glycoprotein gene amplification in multidrug-resistant CHO cells.

    PubMed Central

    Kuo, M T; Vyas, R C; Jiang, L X; Hittelman, W N

    1994-01-01

    Recent studies of several drug-resistant Chinese hamster cell lines suggested that a breakage-fusion-bridge mechanism is frequently involved in the amplification of drug resistance genes. These observations underscore the importance of chromosome breakage in the initiation of DNA amplification in mammalian cells. However, the mechanism of this breakage is unknown. Here, we propose that the site of chromosome breakage consistent with the initial event of P-glycoprotein (P-gp) gene amplification via the breakage-fusion-bridge cycle in three independently established multidrug-resistant CHO cells was located at 1q31. This site is a major chromosome fragile site that can be induced by methotrexate and aphidicolin treatments. Pretreatments of CHO cells with methotrexate or aphidicolin enhanced the frequencies of resistance to vinca alkaloid and amplification of the P-gp gene. These observations suggest that chromosome fragile sites play a pivotal role in DNA amplification in mammalian cells. Our data are also consistent with the hypothesis that gene amplification can be initiated by stress-induced chromosome breakage that is independent of modes of action of cytotoxic agents. Drug-resistant variants may arise by their growth advantage due to overproduction of cellular target molecules via gene amplification. Images PMID:7913517

  20. Chromosome breakage at a major fragile site associated with P-glycoprotein gene amplification in multidrug-resistant CHO cells.

    PubMed

    Kuo, M T; Vyas, R C; Jiang, L X; Hittelman, W N

    1994-08-01

    Recent studies of several drug-resistant Chinese hamster cell lines suggested that a breakage-fusion-bridge mechanism is frequently involved in the amplification of drug resistance genes. These observations underscore the importance of chromosome breakage in the initiation of DNA amplification in mammalian cells. However, the mechanism of this breakage is unknown. Here, we propose that the site of chromosome breakage consistent with the initial event of P-glycoprotein (P-gp) gene amplification via the breakage-fusion-bridge cycle in three independently established multidrug-resistant CHO cells was located at 1q31. This site is a major chromosome fragile site that can be induced by methotrexate and aphidicolin treatments. Pretreatments of CHO cells with methotrexate or aphidicolin enhanced the frequencies of resistance to vinca alkaloid and amplification of the P-gp gene. These observations suggest that chromosome fragile sites play a pivotal role in DNA amplification in mammalian cells. Our data are also consistent with the hypothesis that gene amplification can be initiated by stress-induced chromosome breakage that is independent of modes of action of cytotoxic agents. Drug-resistant variants may arise by their growth advantage due to overproduction of cellular target molecules via gene amplification. PMID:7913517

  1. Inhibition of glutamine-dependent autophagy increases t-PA production in CHO cell fed-batch processes.

    PubMed

    Jardon, Mario A; Sattha, Beheroze; Braasch, Katrin; Leung, Amy O; Côté, Hélène C F; Butler, Michael; Gorski, Sharon M; Piret, James M

    2012-05-01

    Understanding the cellular responses caused by metabolic stress is crucial for the design of robust fed-batch bioprocesses that maximize the expression of recombinant proteins. Chinese hamster ovary cells were investigated in chemically defined, serum-free cultures yielding 10(7) cells/mL and up to 500 mg/L recombinant tissue-plasminogen activator (t-PA). Upon glutamine depletion increased autophagosome formation and autophagic flux were observed, along with decreased proliferation and high viability. Higher lysosomal levels correlated with decreased productivity. Chemical inhibition of autophagy with 3-methyl adenine (3-MA) increased the t-PA yield by 2.8-fold. Autophagy-related MAP1LC3 and LAMP2 mRNA levels increased continuously in all cultures. Analysis of protein quality revealed that 3-MA treatment did not alter glycan antennarity while increasing fucosylation, galactosylation, and sialylation. Taken together, these findings indicate that inhibition of autophagy can considerably increase the yield of biotechnology fed-batch processes, without compromising the glycosylation capacity of cells. Monitoring or genetic engineering of autophagy provides novel avenues to improve the performance of cell culture-based recombinant protein production. PMID:22125188

  2. Antioxidant and DNA Repair Stimulating Effect of Extracts from Transformed and Normal Roots of Rhaponticum carthamoides against Induced Oxidative Stress and DNA Damage in CHO Cells.

    PubMed

    Skała, Ewa; Sitarek, Przemysław; Różalski, Marek; Krajewska, Urszula; Szemraj, Janusz; Wysokińska, Halina; Śliwiński, Tomasz

    2016-01-01

    Rhaponticum carthamoides has a long tradition of use in Siberian folk medicine. The roots and rhizomes of this species are used in various dietary supplements or nutraceutical preparations to increase energy level or eliminate physical weakness. This is the first report to reveal the protective and DNA repair stimulating abilities of R. carthamoides root extracts in Chinese hamster ovary (CHO) cells exposed to an oxidative agent. Both transformed root extract (TR extract) and extract of soil-grown plant roots (NR extract) may be responsible for stimulating CHO cells to repair oxidatively induced DNA damage, but CHO cells stimulated with extract from the transformed roots demonstrated significantly stronger properties than cells treated with the soil-grown plant root extract. These differences in biological activity may be attributed to the differences in the content of phenolic compounds in these root extracts. Preincubation of the CHO cells with TR and NR extracts showed an increase in gene expression and protein levels of catalase (CAT) and superoxide dismutase (SOD2). R. carthamoides may possess antioxidant properties that protect CHO cells against oxidative stress. PMID:27034736

  3. Antioxidant and DNA Repair Stimulating Effect of Extracts from Transformed and Normal Roots of Rhaponticum carthamoides against Induced Oxidative Stress and DNA Damage in CHO Cells

    PubMed Central

    Skała, Ewa; Sitarek, Przemysław; Różalski, Marek; Krajewska, Urszula; Szemraj, Janusz; Wysokińska, Halina; Śliwiński, Tomasz

    2016-01-01

    Rhaponticum carthamoides has a long tradition of use in Siberian folk medicine. The roots and rhizomes of this species are used in various dietary supplements or nutraceutical preparations to increase energy level or eliminate physical weakness. This is the first report to reveal the protective and DNA repair stimulating abilities of R. carthamoides root extracts in Chinese hamster ovary (CHO) cells exposed to an oxidative agent. Both transformed root extract (TR extract) and extract of soil-grown plant roots (NR extract) may be responsible for stimulating CHO cells to repair oxidatively induced DNA damage, but CHO cells stimulated with extract from the transformed roots demonstrated significantly stronger properties than cells treated with the soil-grown plant root extract. These differences in biological activity may be attributed to the differences in the content of phenolic compounds in these root extracts. Preincubation of the CHO cells with TR and NR extracts showed an increase in gene expression and protein levels of catalase (CAT) and superoxide dismutase (SOD2). R. carthamoides may possess antioxidant properties that protect CHO cells against oxidative stress. PMID:27034736

  4. Control of culture environment for improved polyethylenimine-mediated transient production of recombinant monoclonal antibodies by CHO cells.

    PubMed

    Galbraith, Douglas J; Tait, Andrew S; Racher, Andrew J; Birch, John R; James, David C

    2006-01-01

    In this study we describe optimization of polyethylenimine (PEI)-mediated transient production of recombinant protein by CHO cells by facile manipulation of a chemically defined culture environment to limit accumulation of nonproductive cell biomass, increase the duration of recombinant protein production from transfected plasmid DNA, and increase cell-specific production. The optimal conditions for transient transfection of suspension-adapted CHO cells using branched, 25 kDa PEI as a gene delivery vehicle were experimentally determined by production of secreted alkaline phosphatase reporter in static cultures and recombinant IgG4 monoclonal antibody (Mab) production in agitated shake flask cultures to be a DNA concentration of 1.25 microg 10(6) cells(-1) mL(-1) at a PEI nitrogen:DNA phosphate ratio of 20:1. These conditions represented the optimal compromise between PEI cytotoxicity and product yield with most efficient recombinant DNA utilization. Separately, both addition of recombinant insulin-like growth factor (LR3-IGF) and a reduction in culture temperature to 32 degrees C were found to increase product titer 2- and 3-fold, respectively. However, mild hypothermia and LR3-IGF acted synergistically to increase product titer 11-fold. Although increased product titer in the presence of LR3-IGF alone was solely a consequence of increased culture duration, a reduction in culture temperature post-transfection increased both the integral of viable cell concentration (IVC) and cell-specific Mab production rate. For cultures maintained at 32 degrees C in the presence of LR3-IGF, IVC and qMab were increased 4- and 2.5-fold, respectively. To further increase product yield from transfected DNA, the duration of transgene expression in cell populations maintained at 32 degrees C in the presence of LR3-IGF was doubled by periodic resuspension of transfected cells in fresh media, leading to a 3-fold increase in accumulated Mab titer from approximately 13 to approximately 39

  5. Chinese Hamster Ovary (CHO) Host Cell Engineering to Increase Sialylation of Recombinant Therapeutic Proteins by Modulating Sialyltransferase Expression

    PubMed Central

    Lin, Nan; Mascarenhas, Joaquina; Sealover, Natalie R.; George, Henry J.; Brooks, Jeanne; Kayser, Kevin J.; Gau, Brian; Yasa, Isil; Azadi, Parastoo; Archer-Hartmann, Stephanie

    2015-01-01

    N-Glycans of human proteins possess both α2,6- and α2,3-linked terminal sialic acid (SA). Recombinant glycoproteins produced in Chinese hamster overy (CHO) only have α2,3-linkage due to the absence of α2,6-sialyltransferase (St6gal1) expression. The Chinese hamster ST6GAL1 was successfully overexpressed using a plasmid expression vector in three recombinant immunoglobulin G (IgG)-producing CHO cell lines. The stably transfected cell lines were enriched for ST6GAL1 overexpression using FITC-Sambucus nigra (SNA) lectin that preferentially binds α2,6-linked SA. The presence of α2,6-linked SA was confirmed using a novel LTQ Linear Ion Trap Mass Spectrometry (LTQ MS) method including MSn fragmentation in the enriched ST6GAL1 Clone 27. Furthermore, the total SA (mol/mol) in IgG produced by the enriched ST6GAL1 Clone 27 increased by 2-fold compared to the control. For host cell engineering, the CHOZN® GS host cell line was transfected and enriched for ST6GAL1 overexpression. Single-cell clones were derived from the enriched population and selected based on FITC-SNA staining and St6gal1 expression. Two clones (“ST6GAL1 OE Clone 31 and 32”) were confirmed for the presence of α2,6-linked SA in total host cell protein extracts. ST6GAL1 OE Clone 32 was subsequently used to express SAFC human IgG1. The recombinant IgG expressed in this host cell line was confirmed to have α2,6-linked SA and increased total SA content. In conclusion, overexpression of St6gal1 is sufficient to produce recombinant proteins with increased sialylation and more human-like glycoprofiles without combinatorial engineering of other sialylation pathway genes. This work represents our ongoing effort of glycoengineering in CHO host cell lines for the development of “bio-better” protein therapeutics and cell culture vaccine production. PMID:25641927

  6. Microbioreactors and scale-down models: growth of CHO cells using the Pall Micro24 MicroReactor system.

    PubMed

    Warr, Steve R C

    2014-01-01

    Microbioreactors are increasingly used within animal cell biotechnology to grow mammalian cells for cell line screening and to facilitate process development. Many such devices have been reported in the literature, but only a small number are available commercially. Microbioreactors range in complexity from simple plate-based systems to complex automated parallel bioreactors designed to enable the meaningful scale-down of conventional bioprocesses. The Micro24 MicroReactor system (Pall Life Sciences) fits between these extremes providing 24× 7 mL parallel "bioreactors" with individual monitoring and control of temperature, pH, and dissolved oxygen. Inoculation, sampling, and feed additions are carried out manually in a Biological Safety Cabinet. In this chapter we describe the use of the Micro24 system to carry out screening or process development experiments with CHO cells. PMID:24297415

  7. Optimization of Heavy Chain and Light Chain Signal Peptides for High Level Expression of Therapeutic Antibodies in CHO Cells

    PubMed Central

    Haryadi, Ryan; Ho, Steven; Kok, Yee Jiun; Pu, Helen X.; Zheng, Lu; Pereira, Natasha A.; Li, Bin; Bi, Xuezhi; Goh, Lin-Tang; Yang, Yuansheng; Song, Zhiwei

    2015-01-01

    Translocation of a nascent protein from the cytosol into the ER mediated by its signal peptide is a critical step in protein secretion. The aim of this work was to develop a platform technology to optimize the signal peptides for high level production of therapeutic antibodies in CHO cells. A database of signal peptides from a large number of human immunoglobulin (Ig) heavy chain (HC) and kappa light chain (LC) was generated. Most of the HC signal peptides contain 19 amino acids which can be divided into three domains and the LC signal peptides contain 22 amino acids. The signal peptides were then clustered according to sequence similarity. Based on the clustering, 8 HC and 2 LC signal peptides were analyzed for their impacts on the production of 5-top selling antibody therapeutics, namely, Herceptin, Avastin, Remicade, Rituxan, and Humira. The best HC and LC signal peptides for producing these 5 antibodies were identified. The optimized signal peptides for Rituxan is 2-fold better compared to its native signal peptides which are available in the public database. Substitution of a single amino acid in the optimized HC signal peptide for Avastin reduced its production significantly. Mass spectrometry analyses revealed that all optimized signal peptides are accurately removed in the mature antibodies. The results presented in this report are particularly important for the production of these 5 antibodies as biosimilar drugs. They also have the potential to be the best signal peptides for the production of new antibodies in CHO cells. PMID:25706993

  8. Optimization of heavy chain and light chain signal peptides for high level expression of therapeutic antibodies in CHO cells.

    PubMed

    Haryadi, Ryan; Ho, Steven; Kok, Yee Jiun; Pu, Helen X; Zheng, Lu; Pereira, Natasha A; Li, Bin; Bi, Xuezhi; Goh, Lin-Tang; Yang, Yuansheng; Song, Zhiwei

    2015-01-01

    Translocation of a nascent protein from the cytosol into the ER mediated by its signal peptide is a critical step in protein secretion. The aim of this work was to develop a platform technology to optimize the signal peptides for high level production of therapeutic antibodies in CHO cells. A database of signal peptides from a large number of human immunoglobulin (Ig) heavy chain (HC) and kappa light chain (LC) was generated. Most of the HC signal peptides contain 19 amino acids which can be divided into three domains and the LC signal peptides contain 22 amino acids. The signal peptides were then clustered according to sequence similarity. Based on the clustering, 8 HC and 2 LC signal peptides were analyzed for their impacts on the production of 5-top selling antibody therapeutics, namely, Herceptin, Avastin, Remicade, Rituxan, and Humira. The best HC and LC signal peptides for producing these 5 antibodies were identified. The optimized signal peptides for Rituxan is 2-fold better compared to its native signal peptides which are available in the public database. Substitution of a single amino acid in the optimized HC signal peptide for Avastin reduced its production significantly. Mass spectrometry analyses revealed that all optimized signal peptides are accurately removed in the mature antibodies. The results presented in this report are particularly important for the production of these 5 antibodies as biosimilar drugs. They also have the potential to be the best signal peptides for the production of new antibodies in CHO cells. PMID:25706993

  9. Targeted transgene insertion into the CHO cell genome using Cre recombinase-incorporating integrase-defective retroviral vectors.

    PubMed

    Kawabe, Yoshinori; Shimomura, Takuya; Huang, Shuohao; Imanishi, Suguru; Ito, Akira; Kamihira, Masamichi

    2016-07-01

    Retroviral vectors have served as efficient gene delivery tools in various biotechnology fields. However, viral DNA is randomly inserted into the genome, which can cause problems, such as insertional mutagenesis and gene silencing. Previously, we reported a site-specific gene integration system, in which a transgene is integrated into a predetermined chromosomal locus of Chinese hamster ovary (CHO) cells using integrase-defective retroviral vectors (IDRVs) and Cre recombinase. In this system, a Cre expression plasmid is transfected into founder cells before retroviral transduction. In practical applications of site-specific gene modification such as for hard-to-transfect cells or for in vivo gene delivery, both the transgene and the Cre protein into retroviral virions should be encapsulate. Here, we generated novel hybrid IDRVs in which viral genome and enzymatically active Cre can be delivered (Cre-IDRVs). Cre-IDRVs encoding marker genes, neomycin resistance and enhanced green fluorescent protein (EGFP), flanked by wild-type and mutated loxP sites were produced using an expression plasmid for a chimeric protein of Cre and retroviral gag-pol. After analyzing the incorporation of the Cre protein into retroviral virions by Western blotting, the Cre-IDRV was infected into founder CHO cells, in which marker genes (hygromycin resistance and red fluorescent protein) flanked with corresponding loxP sites are introduced into the genome. G418-resistant colonies expressing GFP appeared and the site-specific integration of the transgene into the expected chromosomal site was confirmed by PCR and sequencing of amplicons. Moreover, when Cre-IDRV carried a gene expression unit for a recombinant antibody, the recombinant cells in which the antibody expression cassette was integrated in a site-specific manner were generated and the cells produced the recombinant antibody. This method may provide a promising tool to perform site-specific gene modification according to Cre

  10. Enhanced translation initiation factor 4G levels correlate with production levels of monoclonal antibodies in recombinant CHO cell lines.

    PubMed

    Pavitt, Graham D

    2016-03-15

    Using cells to manufacture protein-based therapeutics or biopharmaceuticals is a rapidly expanding industrial activity. Chinese hamster ovary (CHO) cells are the most frequently used mammalian host-expression system for the manufacture of biopharmaceuticals. Over the past ∼30 years academic and industrial researchers have studied cell expression characteristics with aims to improve product yield, quality, scalability and reproducibility. Although many steps in the gene expression and secretion pathways have been optimized, little attention has been paid to optimizing protein synthesis factors and regulators during this process. A new study in Biochemical Journal by Mead et al., provides a first systematic study of several protein synthesis factors and finds that the expression level of eIF4G1 correlates with the level of recombinant protein expressed in cultures. Optimizing levels and activities of protein synthesis factors may help to enhance recombinant protein expression of biopharmaceuticals. PMID:26965386

  11. CHO cell repair of single-strand and double-strand DNA breaks induced by gamma- and alpha-radiations.

    PubMed

    Cole, A; Shonka, F; Corry, P; Cooper, W G

    1975-01-01

    Neutral and alkaline sucrose gradient sedimentation analysis was used to measure double- and single-strand breaks in the DNA of Chinese hamster ovary (CHO) cells exposed to either gamma- or alpha-radiation. After irradiation, cells were incubated for 15-180 min to test the ability of the cell to rejoin the DNA breaks. Essentially complete rejoining was observed for single-strand breaks induced by gamma- or alpha-doses below 20 krad and for double-strand breaks induced by gamma doses below 60 krad. Approximately 80% rejoining was observed for double-strand breaks induced by alpha doses below 40 krad. At higher doses, the repair system appeared to saturate in such a way that essentially no additional breaks were rejoined. PMID:1191188

  12. Is accuracy of serum free light chain measurement achievable?

    PubMed

    Jacobs, Joannes F M; Tate, Jillian R; Merlini, Giampaolo

    2016-06-01

    The serum free light chain (FLC) assay has proven to be an important complementary test in the management of patients with monoclonal gammopathies. The serum FLC assay has value for patients with plasma cell disorders in the context of screening and diagnosis, prognostic stratification, and quantitative monitoring. Nonetheless, serum FLC measurements have analytical limitations which give rise to differences in FLC reporting depending on which FLC assay and analytical platform is used. As the FLC measurements are incorporated in the International Myeloma Working Group guidelines for the evaluation and management of plasma cell dyscrasias, this may directly affect clinical decisions. As new certified methods for serum FLC assays emerge, the need to harmonise patient FLC results becomes increasingly important. In this opinion paper we provide an overview of the current lack of accuracy and harmonisation in serum FLC measurements. The clinical consequence of non-harmonized FLC measurements is that an individual patient may or may not meet certain diagnostic, prognostic, or response criteria, depending on which FLC assay and platform is used. We further discuss whether standardisation of serum FLC measurements is feasible and provide an overview of the steps needed to be taken towards harmonisation of FLC measurements. PMID:26641970

  13. Scalable Production of a Multifunctional Protein (TSG-6) That Aggregates with Itself and the CHO Cells That Synthesize It

    PubMed Central

    Kim, Dong-Ki; Choi, Hosoon; Nishida, Hidetaka; Oh, Joo Youn; Gregory, Carl; Lee, Ryang Hwa; Yu, Ji Min; Watanabe, Jun; An, Su Yeon; Bartosh, Thomas J.; Prockop, Darwin J.

    2016-01-01

    TNF-α stimulated gene/protein 6 (TNFAIP6/TSG-6) is a multifunctional protein that has a number of potential therapeutic applications. Experiments and clinical trials with TSG-6, however, have been limited by the technical difficulties of producing the recombinant protein. We prepared stable clones of CHO cells that expressed recombinant human TSG-6 (rhTSG-6) as a secreted glycoprotein. Paradoxically, both cell number and protein production decreased dramatically when the clones were expanded. The decreases occurred because the protein aggregated the synthesizing CHO cells by binding to the brush border of hyaluronan that is found around many cultured cells. In addition, the rhTSG-6 readily self-aggregated. To address these problems, we added to the medium an inhibitor of hyaluronan synthesis and heparin to compete with the binding of TSG-6 to hyaluronan. Also, we optimized the composition of the culture medium, and transferred the CHO cells from a spinner culture system to a bioreactor that controlled pH and thereby decreased pH-dependent binding properties of the protein. With these and other improvements in the culture conditions, we obtained 57.0 mg ± 9.16 S.D. of rhTSG-6 in 5 or 6 liter of medium. The rhTSG-6 accounted for 18.0% ± 3.76 S.D. of the total protein in the medium. We then purified the protein with a Ni-chelate column that bound the His tag engineered into the C-terminus of the protein followed by an anion exchange column. The yield of the purified monomeric rhTSG-6 was 4.1 mg to 5.6 mg per liter of culture medium. After intravenous injection into mice, the protein had a longer plasma half-life than commercially available rhTSG-6 isolated from a mammalian cell lysate, apparently because it was recovered as a secreted glycoprotein. The bioactivity of the rhTSG-6 in suppressing inflammation was demonstrated in a murine model. PMID:26793973

  14. Scalable Production of a Multifunctional Protein (TSG-6) That Aggregates with Itself and the CHO Cells That Synthesize It.

    PubMed

    Kim, Dong-Ki; Choi, Hosoon; Nishida, Hidetaka; Oh, Joo Youn; Gregory, Carl; Lee, Ryang Hwa; Yu, Ji Min; Watanabe, Jun; An, Su Yeon; Bartosh, Thomas J; Prockop, Darwin J

    2016-01-01

    TNF-α stimulated gene/protein 6 (TNFAIP6/TSG-6) is a multifunctional protein that has a number of potential therapeutic applications. Experiments and clinical trials with TSG-6, however, have been limited by the technical difficulties of producing the recombinant protein. We prepared stable clones of CHO cells that expressed recombinant human TSG-6 (rhTSG-6) as a secreted glycoprotein. Paradoxically, both cell number and protein production decreased dramatically when the clones were expanded. The decreases occurred because the protein aggregated the synthesizing CHO cells by binding to the brush border of hyaluronan that is found around many cultured cells. In addition, the rhTSG-6 readily self-aggregated. To address these problems, we added to the medium an inhibitor of hyaluronan synthesis and heparin to compete with the binding of TSG-6 to hyaluronan. Also, we optimized the composition of the culture medium, and transferred the CHO cells from a spinner culture system to a bioreactor that controlled pH and thereby decreased pH-dependent binding properties of the protein. With these and other improvements in the culture conditions, we obtained 57.0 mg ± 9.16 S.D. of rhTSG-6 in 5 or 6 liter of medium. The rhTSG-6 accounted for 18.0% ± 3.76 S.D. of the total protein in the medium. We then purified the protein with a Ni-chelate column that bound the His tag engineered into the C-terminus of the protein followed by an anion exchange column. The yield of the purified monomeric rhTSG-6 was 4.1 mg to 5.6 mg per liter of culture medium. After intravenous injection into mice, the protein had a longer plasma half-life than commercially available rhTSG-6 isolated from a mammalian cell lysate, apparently because it was recovered as a secreted glycoprotein. The bioactivity of the rhTSG-6 in suppressing inflammation was demonstrated in a murine model. PMID:26793973

  15. Heterologous, PKC-Mediated Desensitization of Human Histamine H3 Receptors Expressed in CHO-K1 Cells.

    PubMed

    Montejo-López, Wilber; Rivera-Ramírez, Nayeli; Escamilla-Sánchez, Juan; García-Hernández, Ubaldo; Arias-Montaño, José-Antonio

    2016-09-01

    Desensitization is a major mechanism to regulate the functional response of G protein-coupled receptors. In this work we studied whether the human histamine H3 receptor of 445 amino acids (hH3R445) experiences heterologous desensitization mediated by PKC activation. Bioinformatic analysis indicated the presence of Serine and Threonine residues susceptible of PKC-mediated phosphorylation on the third intracellular loop and the carboxyl terminus of the hH3R445. In CHO-K1 cells stably transfected with the hH3R445 direct PKC activation by phorbol 12-myristate 13-acetate (TPA, 200 nM) abolished H3R-mediated inhibition of forskolin-stimulated cAMP accumulation. Activation of endogenous purinergic receptors by ATP (adenosine 5'-triphosphate, 10 μM) increased the free calcium intracellular concentration ([Ca(2+)]i) confirming their coupling to phospholipase C stimulation. Incubation with ATP also abolished H3R-mediated inhibition of forskolin-induced cAMP accumulation, and this effect was prevented by the PKC inhibitors Ro-31-8220 and Gö-6976. Pre-incubation with TPA or ATP reduced H3R-mediated stimulation of [(35)S]-GTPγS binding to membranes from CHO-K1-hH3R445 cells by 39.7 and 54.2 %, respectively, with no change in the agonist potency, and the effect was prevented by either Ro-31-8220 or Gö-6976. Exposure to ATP or TPA also resulted in the loss of cell surface H3Rs (-30.4 and -45.1 %) as evaluated by [(3)H]-NMHA binding to intact cells. These results indicate that the hH3R445 undergoes heterologous desensitization upon activation of receptors coupled to PKC stimulation. PMID:27350581

  16. Quantitative and molecular analyses of mutation in a pSV2gpt transformed CHO cell line

    SciTech Connect

    Stankowski, L.F. Jr.; Tindall, K.R.; Hsie, A.W.

    1983-01-01

    Following NDA-mediated gene transfer we have isolated a cell line useful for studying gene mutation at the molecular level. This line, AS52, derived from a hypoxanthine-guanine phosphoribosyl transferase (HGPRT) deficient Chinese hamster ovary (CHO) cell line, carries a single copy of the E. coli xanthine-guanine phosphoribosyl transferase (XGPRT) gene (gpt) and exhibits a spontaneous mutant frequency of 20 TG/sup r/ mutants/10/sup 6/ clonable cells. As with HGPRT/sup -/ mutants, XGPRT/sup -/ mutants can be selected in 6-thioguanine. AS52 (XGPRT/sup +/) and wild type CHO (HGPRT/sup +/) cell exhibit almost identical cytotoxic responses to various agents. We observed significant differences in mutation induction by UV light and ethyl methanesulfonate (EMS). Ratios of XGPRT/sup -/ to HGPRT/sup -/ mutants induced per unit dose (J/m/sup 2/ for UV light and ..mu..g/ml for EMS) are 1.4 and 0.70, respectively. Preliminary Southern blot hybridization analyses has been performed on 30 XGPRT/sup -/ AS52 mutants. A majority of spontaneous mutants have deletions ranging in size from 1 to 4 kilobases (9/19) to complete loss of gpt sequences (4/19); the remainder have no detectable (5/19) or only minor (1/19) alterations. 5/5 UV-induced and 5/6 EMS-induced mutants do not show a detectable change. Similar analyses are underway for mutations induced by x-irradiation and ICR 191 treatment.

  17. A direct qPCR method for residual DNA quantification in monoclonal antibody drugs produced in CHO cells.

    PubMed

    Hussain, Musaddeq

    2015-11-10

    Chinese hamster ovary (CHO) cells are the host cell of choice for manufacturing of monoclonal antibody (mAb) drugs in the biopharmaceutical industry. Host cell DNA is an impurity of such manufacturing process and must be controlled and monitored in order to ensure drug purity and safety. A conventional method for quantification of host residual DNA in drug requires extraction of DNA from the mAb drug substance with subsequent quantification of the extracted DNA using real-time PCR (qPCR). Here we report a method where the DNA extraction step is eliminated prior to qPCR. In this method, which we have named 'direct resDNA qPCR', the mAb drug substance is digested with a protease called KAPA in a 96-well PCR plate, the protease in the digest is then denatured at high temperature, qPCR reagents are added to the resultant reaction wells in the plate along with standards and controls in other wells of the same plate, and the plate subjected to qPCR for analysis of residual host DNA in the samples. This direct resDNA qPCR method for CHO is sensitive to 5.0fg of DNA with high precision and accuracy and has a wide linear range of determination. The method has been successfully tested with four mAbs drug, two IgG1 and two IgG4. Both the purified drug substance as well as a number of process intermediate samples, e.g., bioreactor harvest, Protein A column eluate and ion-exchange column eluates were tested. This method simplifies the residual DNA quantification protocol, reduces time of analysis and leads to increased assay sensitivity and development of automated high-throughput methods. PMID:25850374

  18. Iron dose-dependent differentiation and enucleation of human erythroblasts in serum-free medium.

    PubMed

    Byrnes, Colleen; Lee, Y Terry; Meier, Emily R; Rabel, Antoinette; Sacks, David B; Miller, Jeffery L

    2016-02-01

    Improvements in ex vivo generation of enucleated red blood cells are being sought for erythroid biology research, toward the ultimate goal of erythrocyte engineering for clinical use. Based upon the high levels of iron-saturated transferrin in plasma serum, it was hypothesized that terminal differentiation in serum-free media may be highly dependent on the concentration of iron. Here adult human CD34(+) cells were cultured in a serum-free medium containing dosed levels of iron-saturated transferrin (holo-Tf, 0.1-1.0 mg/ml). Iron in the culture medium was reduced, but not depleted, with erythroblast differentiation into haemoglobinized cells. At the lowest holo-Tf dose (0.1 mg/ml), terminal differentiation was significantly reduced and the majority of the cells underwent apoptotic death. Cell survival, differentiation and enucleation were enhanced as the holo-Tf dose increased. These data suggest that adequate holo-Tf dosing is critical for terminal differentiation and enucleation of human erythroblasts generated ex vivo in serum-free culture conditions. Published 2013. This article is a US Government work and is in the public domain in the USA. PMID:23606586

  19. Cofilin Phosphorylation Decreased by Serum-free Starvation with Low Glucose in the L6 Myoblasts.

    PubMed

    Kim, Mee-Young; Kim, Ju-Hyun; Lee, Jeong-Uk; Lee, Lim-Kyu; Yang, Seung-Min; Park, Byoung-Sun; Jeon, Hye-Joo; Lee, Won-Deok; Noh, Ji-Woong; Kwak, Taek-Yong; Jang, Sung-Ho; Lee, Tae-Hyun; Kim, Ju-Young; Kim, Tae-Whan; Kim, Bokyung; Kim, Junghwan

    2014-10-01

    [Purpose] Many studies have been using cell culture models of muscle cells with exogenous cytokines or glucocorticoids to mimic atrophy in in vivo and in vitro tests. However, the changes in the phosphorylation of atrophy-related cofilin are still poorly understood in starved skeletal muscle cells. In this study, we first examined whether or not phosphorylation of cofilin is altered in L6 myoblasts after 3, 6, 12, 24, 48, and 72 hours of serum-free starvation with low glucose. [Methods] We used Western blotting to exam protein expression and phosphorylation in atrophied L6 myoblasts. [Results] L6 cell sizes and numbers were diminished as a result of serum-free starvation in a time-dependent manner. Serum-free starvation for 3, 6, 12, 24, 48, and 72 hours significantly decreased the phosphorylation of cofilin, respectively. [Conclusion] These results suggest that starvation-induced atrophy may be in part related to changes in the phosphorylation of cofilin in L6 myoblasts. PMID:25364107

  20. Low glucose depletes glycan precursors, reduces site occupancy and galactosylation of a monoclonal antibody in CHO cell culture.

    PubMed

    Villacrés, Carina; Tayi, Venkata S; Lattová, Erika; Perreault, Hélène; Butler, Michael

    2015-07-01

    Controlled feeding of glucose has been employed previously to enhance the productivity of recombinant glycoproteins but there is a concern that low concentrations of glucose could limit the synthesis of precursors of glycosylation. Here we investigate the effect of glucose depletion on the metabolism, productivity and glycosylation of a chimeric human-llama monoclonal antibody secreted by CHO cells. The cells were inoculated into media containing varying concentrations of glucose. Glucose depletion occurred in cultures with an initial glucose ≤5.5 mM and seeded at low density (2.5 × 10(5) cells/mL) or at high cell inoculum (≥2.5 × 10(6) cells/mL) at higher glucose concentration (up to 25 mM). Glucose-depleted cultures produced non-glycosylated Mabs (up to 51%), lower galactosylation index (GI <0.43) and decreased sialylation (by 85%) as measured by mass spectrometry and HPLC. At low glucose a reduced intracellular pool of nucleotides (0.03-0.23 fmoles/cell) was measured as well as a low adenylate energy charge (<0.57). Low glucose also reduced GDP-sugars (by 77%) and UDP-hexosamines (by 90%). The data indicate that under glucose deprivation, low levels of intracellular nucleotides and nucleotide sugars reduced the availability of the immediate precursors of glycosylation. These results are important when applied to the design of fed-batch cultures. PMID:26058832

  1. Mouse retina explants after long-term culture in serum free medium.

    PubMed

    Caffé, A R; Ahuja, P; Holmqvist, B; Azadi, S; Forsell, J; Holmqvist, I; Söderpalm, A K; van Veen, T

    2001-11-01

    The neonatal mouse retina remains viable as an explant in serum-supplemented growth media for more than 4 weeks. Interpretation of drug effects on this tissue is compromised by the enigmatic composition of the serum. We sought to remove this ambiguity by culturing neonatal as well as late postnatal mouse retina in serum-free nutrient medium. In this study three important observations were made, (1) there is histotypic development of neonatal as well as preservation of late postnatal mouse retinal structure during long-term culture in serum-free medium, although the late postnatal tissue tends to show some loss of cells in the outer nuclear layer. (2) Protein expression in explant photoreceptor cells was similar to that in the litter-matched ones, except for green cone opsin and interphotoreceptor retinoid-binding protein, although mRNA of the latter is present at similar amounts as in age-matched in vivo controls. (3) Cells of the inner retina stained by antibodies to calcium-binding proteins display some novel sprouting of processes. The results show that the mouse retina can be cultured as an explant for more than 4 weeks in a serum-free medium. This represents an important step forward because, (1) the possibility of interference of drug effects by unknown serum factors has been eliminated; and (2) the spent culture medium can be analyzed to investigate biomolecules released by the retina in vitro. PMID:11719023

  2. A control strategy to investigate the relationship between specific productivity and high-mannose glycoforms in CHO cells.

    PubMed

    Zalai, Dénes; Hevér, Helga; Lovász, Krisztina; Molnár, Dóra; Wechselberger, Patrick; Hofer, Alexandra; Párta, László; Putics, Ákos; Herwig, Christoph

    2016-08-01

    The integration of physiological knowledge into process control strategies is a cornerstone for the improvement of biopharmaceutical cell culture technologies. The present contribution investigates the applicability of specific productivity as a physiological control parameter in a cell culture process producing a monoclonal antibody (mAb) in CHO cells. In order to characterize cell physiology, the on-line oxygen uptake rate (OUR) was monitored and the time-resolved specific productivity was calculated as physiological parameters. This characterization enabled to identify the tight link between the deprivation of tyrosine and the decrease in cell respiration and in specific productivity. Subsequently, this link was used to control specific productivity by applying different feeding profiles. The maintenance of specific productivity at various levels enabled to identify a correlation between the rate of product formation and the relative abundance of high-mannose glycoforms. An increase in high mannose content was assumed to be the result of high specific productivity. Furthermore, the high mannose content as a function of cultivation pH and specific productivity was investigated in a design of experiment approach. This study demonstrated how physiological parameters could be used to understand interactions between process parameters, physiological parameters, and product quality attributes. PMID:26910040

  3. Interactions between Skeletal Muscle Myoblasts and their Extracellular Matrix Revealed by a Serum Free Culture System

    PubMed Central

    Chaturvedi, Vishal; Dye, Danielle E.; Kinnear, Beverley F.; van Kuppevelt, Toin H.; Grounds, Miranda D.; Coombe, Deirdre R.

    2015-01-01

    Decellularisation of skeletal muscle provides a system to study the interactions of myoblasts with muscle extracellular matrix (ECM). This study describes the efficient decellularisation of quadriceps muscle with the retention of matrix components and the use of this matrix for myoblast proliferation and differentiation under serum free culture conditions. Three decellularisation approaches were examined; the most effective was phospholipase A2 treatment, which removed cellular material while maximizing the retention of ECM components. Decellularised muscle matrices were then solubilized and used as substrates for C2C12 mouse myoblast serum free cultures. The muscle matrix supported myoblast proliferation and differentiation equally as well as collagen and fibronectin. Immunofluorescence analyses revealed that myoblasts seeded on muscle matrix and fibronectin differentiated to form long, well-aligned myotubes, while myoblasts seeded on collagen were less organized. qPCR analyses showed a time dependent increase in genes involved in skeletal muscle differentiation and suggested that muscle-derived matrix may stimulate an increased rate of differentiation compared to collagen and fibronectin. Decellularized whole muscle three-dimensional scaffolds also supported cell adhesion and spreading, with myoblasts aligning along specific tracts of matrix proteins within the scaffolds. Thus, under serum free conditions, intact acellular muscle matrices provided cues to direct myoblast adhesion and migration. In addition, myoblasts were shown to rapidly secrete and organise their own matrix glycoproteins to create a localized ECM microenvironment. This serum free culture system has revealed that the correct muscle ECM facilitates more rapid cell organisation and differentiation than single matrix glycoprotein substrates. PMID:26030912

  4. miRNA profiling of high, low and non-producing CHO cells during biphasic fed-batch cultivation reveals process relevant targets for host cell engineering.

    PubMed

    Stiefel, Fabian; Fischer, Simon; Sczyrba, Alexander; Otte, Kerstin; Hesse, Friedemann

    2016-05-10

    Fed-batch cultivation of recombinant Chinese hamster ovary (CHO) cell lines is one of the most widely used production modes for commercial manufacturing of recombinant protein therapeutics. Furthermore, fed-batch cultivations are often conducted as biphasic processes where the culture temperature is decreased to maximize volumetric product yields. However, it remains to be elucidated which intracellular regulatory elements actually control the observed pro-productive phenotypes. Recently, several studies have revealed microRNAs (miRNAs) to be important molecular switches of cell phenotypes. In this study, we analyzed miRNA profiles of two different recombinant CHO cell lines (high and low producer), and compared them to a non-producing CHO DG44 host cell line during fed-batch cultivation at 37°C versus a temperature shift to 30°C. Taking advantage of next-generation sequencing combined with cluster, correlation and differential expression analyses, we could identify 89 different miRNAs, which were differentially expressed in the different cell lines and cultivation phases. Functional validation experiments using 19 validated target miRNAs confirmed that these miRNAs indeed induced changes in process relevant phenotypes. Furthermore, computational miRNA target prediction combined with functional clustering identified putative target genes and cellular pathways, which might be regulated by these miRNAs. This study systematically identified novel target miRNAs during different phases and conditions of a biphasic fed-batch production process and functionally evaluated their potential for host cell engineering. PMID:27002234

  5. [Stable and efficient expression of hepatitis B virus S antigen and preS1 epitope fusion protein (S/preS1) in CHO cells].

    PubMed

    Yang, Zhenxi; Li, Shichong; Liu, Hong; Zhang, Miao; Ye, Lingling; Wu, Yanzhuo; Xu, Mingbo; Chen, Zhaolie

    2013-12-01

    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. PMID:24660628

  6. Protective activity of Cynara scolymus L. leaf extract against chemically induced complex genomic alterations in CHO cells.

    PubMed

    Jacociunas, Laura Vicedo; de Andrade, Heloisa Helena Rodrigues; Lehmann, Mauricio; Pedersini, Larissa Wölfle; Ferraz, Alexandre de Barros Falcão; da Silva, Juliana; Dihl, Rafael Rodrigues

    2013-09-15

    Cynara scolymus L., popularly known as artichoke, has been widely used in traditional medicine as an herbal medicament for therapeutic purposes. The study aimed at assessing the protective activity of Cynara scolymus leaf extract (LE) against DNA lesions induced by the alkylating agent ethylmethnesulphonate (EMS) in Chinese hamster ovary cells (CHO). The ability of C. scolymus L. LE to modulate the mutagenicity of EMS was examined using the cytokinesis block micronucleus (CBMN) cytome assay in three antigenotoxic protocols, pre- post- and simultaneous treatments. In the pre-treatment, C. scolymus L. LE reduced the frequencies of MNi and NBUDs induced by EMS in the lower concentration. In contrast, at the highest concentration (5 mg/ml) artichoke enhanced the frequency of MNi, potentiating EMS genotoxicity. In the simultaneous treatment only the induction of MNi was repressed by the exposure of cells to C. scolymus L. LE. No modification in genotoxicity was observed in LE post-treatment. The results obtained in this study suggest that lower concentrations of artichoke prevent chemically induced genomic damage in mammalian cells. In this context, the protective activity of C. scolymus L. could be associated to its constitutive antioxidants compounds. PMID:23830816

  7. Limitations in the process of transcription and translation inhibit recombinant human chorionic gonadotropin expression in CHO cells.

    PubMed

    Liu, Yang; Yi, Xiaoping; Zhuang, Yingping; Zhang, Siliang

    2015-06-20

    Human chorionic gonadotropin (hCG) is a glycoprotein hormone that exists as a heterodimer with a α subunit and β subunit assembled together with disulfide bridges. This hormone plays an important role in the detection of ovulation induction and in the treatment of certain diseases that cause female infertility. The effects of transcription, subunit expression, assembling and secretion on recombinant hCG expression in CHO cells were studied using stable high-producing and low-producing cell lines generated by the FLP-In™ system. The results indicated that the mRNA and polypeptide levels of the β subunit were always higher than those of the α subunit. Further study confirmed that the differences were caused by the transcription rate rather than by mRNA stability. In the high-producing cell lines, there was obvious transcription level limitation of the α subunit in contrast to the β subunit. In addition, there was obvious limitation of the synthetic steps from mRNA to polypeptide for both the α subunit and the β subunit, especially the β subunit. Significant limitations of the assembly and secretion levels were not observed in this research. This study presents a research methodology for double subunit protein expression and provides valuable evidence for the enhancement of recombinant hCG productivity. PMID:25529346

  8. Investigation of superparamagnetic (Fe3O4) nanoparticles and magnetic field exposures on CHO-K1 cell line

    NASA Astrophysics Data System (ADS)

    Coker, Zachary; Estlack, Larry; Hussain, Saber; Choi, Tae-Youl; Ibey, Bennett L.

    2016-03-01

    Rapid development in nanomaterial synthesis and functionalization has led to advanced studies in actuation and manipulation of cellular functions for biomedical applications. Often these actuation techniques employ externally applied magnetic fields to manipulate magnetic nanomaterials inside cell bodies in order to drive or trigger desired effects. While cellular interactions with low-frequency magnetic fields and nanoparticles have been extensively studied, the fundamental mechanisms behind these interactions remain poorly understood. Additionally, modern investigations on these concurrent exposure conditions have been limited in scope, and difficult to reproduce. This study presents an easily reproducible method of investigating the biological impact of concurrent magnetic field and nanoparticle exposure conditions using an in-vitro CHO-K1 cell line model, with the purpose of establishing grounds for in-depth fundamental studies of the mechanisms driving cellular-level interactions. Cells were cultured under various nanoparticle and magnetic field exposure conditions from 0 to 500 μg/ml nanoparticle concentrations, and DC, 50 Hz, or 100 Hz magnetic fields with 2.0 mT flux density. Cells were then observed by confocal fluorescence microscopy, and subject to biological assays to determine the effects of concurrent extreme-low frequency magnetic field and nanoparticle exposures on cellnanoparticle interactions, such as particle uptake and cell viability by MTT assay. Current results indicate little to no variation in effect on cell cultures based on magnetic field parameters alone; however, it is clear that deleterious synergistic effects of concurrent exposure conditions exist based on a significant decrease in cell viability when exposed to high concentrations of nanoparticles and concurrent magnetic field.

  9. Assay of SF/sub 6/ and spark-decomposed SF/sub 6/ for mutagenic activity in the CHO/HGPRT (Chinese hamster ovary/hypoxanthine-guanine phosphoribosyl transferase) mammalian cell system

    SciTech Connect

    Kurka, K.; Griffin, G.D.

    1987-01-01

    The potential mutagenic (and cytotoxic) activity of SF/sub 6/ and spark-decomposed SF/sub 6/ was investigated in an in vitro mammalian cell culture system using Chinese Hamster Ovary (CHO) cells. The CHO cells were exposed to the gases in vacutainer tubes which were constantly rotated. After a 4 h exposure the mutagenic and cytotoxic activity was assayed with the CHO/hypoxanthine-guanine phosphoribosyl transferase (CHO/HGPRT) system. Results indicated that SF/sub 6/ was neither cytotoxic nor mutagenic to CHO cells. Spark-decomposed SF/sub 6/ was found to be strongly cytotoxic (-80% cell death following 4 h exposure to 2 kJ spark discharge in 60 cm/sup 3/ at 1000 torr of SF/sub 6/) but not mutagenic. Increasing spark energy increased cytotoxicity but the spark samples remained nonmutagenic. The CHO/HGPRT system was coupled with a metabolic activation (S9 fraction) system used for detecting promutagens. When exposures were carried out in the presence of S9 fraction, SF/sub 6/ was still neither cytotoxic nor mutagenic; spark-decomposed SF/sub 6/ was again strongly cytotoxic but not mutagenic. It appears that SF/sub 6/ and sparked SF/sub 6/ are neither promutagens nor direct acting mutagens in the CHO/HGPRT system. Studies have begun using a more mutagenically sensitive subclone of the CHO cells known as CHO-AS/sub 52/. The results of initial experiments using the CHO-AS/sub 52/ cells remain unchanged. 9 refs., 1 tab.

  10. A Single Dynamic Metabolic Model Can Describe mAb Producing CHO Cell Batch and Fed-Batch Cultures on Different Culture Media

    PubMed Central

    Robitaille, Julien; Chen, Jingkui; Jolicoeur, Mario

    2015-01-01

    CHO cell culture high productivity relies on optimized culture medium management under fed-batch or perfused chemostat strategies enabling high cell densities. In this work, a dynamic metabolic model for CHO cells was further developed, calibrated and challenged using datasets obtained under four different culture conditions, including two batch and two fed-batch cultures comparing two different culture media. The recombinant CHO-DXB11 cell line producing the EG2-hFc monoclonal antibody was studied. Quantification of extracellular substrates and metabolites concentration, viable cell density, monoclonal antibody concentration and intracellular concentration of metabolite intermediates of glycolysis, pentose-phosphate and TCA cycle, as well as of energetic nucleotides, were obtained for model calibration. Results suggest that a single model structure with a single set of kinetic parameter values is efficient at simulating viable cell behavior in all cases under study, estimating the time course of measured and non-measured intracellular and extracellular metabolites. Model simulations also allowed performing dynamic metabolic flux analysis, showing that the culture media and the fed-batch strategies tested had little impact on flux distribution. This work thus paves the way to an in silico platform allowing to assess the performance of different culture media and fed-batch strategies. PMID:26331955

  11. Homologous Recombination-Independent Large Gene Cassette Knock-in in CHO Cells Using TALEN and MMEJ-Directed Donor Plasmids.

    PubMed

    Sakuma, Tetsushi; Takenaga, Mitsumasa; Kawabe, Yoshinori; Nakamura, Takahiro; Kamihira, Masamichi; Yamamoto, Takashi

    2015-01-01

    Gene knock-in techniques have rapidly evolved in recent years, along with the development and maturation of genome editing technology using programmable nucleases. We recently reported a novel strategy for microhomology-mediated end-joining-dependent integration of donor DNA by using TALEN or CRISPR/Cas9 and optimized targeting vectors, named PITCh (Precise Integration into Target Chromosome) vectors. Here we describe TALEN and PITCh vector-mediated integration of long gene cassettes, including a single-chain Fv-Fc (scFv-Fc) gene, in Chinese hamster ovary (CHO) cells, with comparison of targeting and cloning efficiency among several donor design and culture conditions. We achieved 9.6-kb whole plasmid integration and 7.6-kb backbone-free integration into a defined genomic locus in CHO cells. Furthermore, we confirmed the reasonable productivity of recombinant scFv-Fc protein of the knock-in cells. Using our protocol, the knock-in cell clones could be obtained by a single transfection and a single limiting dilution using a 96-well plate, without constructing targeting vectors containing long homology arms. Thus, the study described herein provides a highly practical strategy for gene knock-in of large DNA in CHO cells, which accelerates high-throughput generation of cell lines stably producing any desired biopharmaceuticals, including huge antibody proteins. PMID:26473830

  12. Cross-scale predictive modeling of CHO cell culture growth and metabolites using Raman spectroscopy and multivariate analysis.

    PubMed

    Berry, Brandon; Moretto, Justin; Matthews, Thomas; Smelko, John; Wiltberger, Kelly

    2015-01-01

    Multi-component, multi-scale Raman spectroscopy modeling results from a monoclonal antibody producing CHO cell culture process including data from two development scales (3 L, 200 L) and a clinical manufacturing scale environment (2,000 L) are presented. Multivariate analysis principles are a critical component to partial least squares (PLS) modeling but can quickly turn into an overly iterative process, thus a simplified protocol is proposed for addressing necessary steps including spectral preprocessing, spectral region selection, and outlier removal to create models exclusively from cell culture process data without the inclusion of spectral data from chemically defined nutrient solutions or targeted component spiking studies. An array of single-scale and combination-scale modeling iterations were generated to evaluate technology capabilities and model scalability. Analysis of prediction errors across models suggests that glucose, lactate, and osmolality are well modeled. Model strength was confirmed via predictive validation and by examining performance similarity across single-scale and combination-scale models. Additionally, accurate predictive models were attained in most cases for viable cell density and total cell density; however, these components exhibited some scale-dependencies that hindered model quality in cross-scale predictions where only development data was used in calibration. Glutamate and ammonium models were also able to achieve accurate predictions in most cases. However, there are differences in the absolute concentration ranges of these components across the datasets of individual bioreactor scales. Thus, glutamate and ammonium PLS models were forced to extrapolate in cases where models were derived from small scale data only but used in cross-scale applications predicting against manufacturing scale batches. PMID:25504860

  13. Expression and bioactivity of recombinant human serum albumin and dTMP fusion proteins in CHO cells.

    PubMed

    Ru, Yi; Zhi, Dejuan; Guo, Dingding; Wang, Yong; Li, Yang; Wang, Meizhu; Wei, Suzhen; Wang, Haiqing; Wang, Na; Che, Jingmin; Li, Hongyu

    2016-09-01

    The 14-amino acid (IEGPTLRQWLAARA) thrombopoietin mimetic peptide (TMP) shares no sequence homology with native thrombopoietin (TPO). When dimerized, it displays a high-binding affinity for the TPO receptor and has equipotent bioactivity with recombinant human TPO (rhTPO) in stimulating proliferation and maturation of megakaryocytes in vitro. However, TMP is limited for clinical usage because of its short half-life in vivo. In this study, fusion proteins that composed of tandem dimer of TMP (dTMP) genetically fused at the C- or N-terminus of human serum albumin (HSA) were separately expressed in Chinese hamster ovary (CHO) cells. In vitro bioactivity assays showed that purified fusion proteins promoted the proliferation of megakaryocytes in a dose-dependent manner and activated signal transducer and activator of transcription (STAT) pathway in TPO receptor-dependent manner. Following subcutaneous administration, both HSA-dTMP and dTMP-HSA significantly elevated peripheral platelet counts in normal mice in a dose-dependent manner. In addition, fusion with HSA successfully prolonged dTMP half-life in mice. However, when HSA was fused at the C-terminus of dTMP, the bioactivity of dTMP-HSA was about half of that of HSA-dTMP. In conclusion, these results suggested that HSA/dTMP fusion proteins might be potential drugs for thrombocytopenia and, when HSA was fused at the N-terminus of dTMP, the fusion protein had a higher activity. PMID:27115755

  14. Oxygen supply for CHO cells immobilized on a packed-bed of Fibra-Cel disks.

    PubMed

    Meuwly, F; Loviat, F; Ruffieux, P-A; Bernard, A R; Kadouri, A; von Stockar, U

    2006-03-01

    Packed-bed bioreactors (PBR) have proven to be efficient systems to culture mammalian cells at very high cell density in perfusion mode, thus leading to very high volumetric productivity. However, the immobilized cells must be continuously supplied with all nutrients in sufficient quantities to remain viable and productive over the full duration of the perfusion culture. Among all nutrients, oxygen is the most critical since it is present at very low concentration due to its low solubility in cell culture medium. This work presents the development of a model for oxygenation in a packed-bed bioreactor system. The experimental system used to develop the model was a packed-bed of Fibra-Cel disk carriers used to cultivate Chinese Hamster Ovary cells at high density ( approximately 6.1 x 10(7) cell/mL) in perfusion mode. With the help of this model, it was possible to identify if a PBR system is operated in optimal or sub-optimal conditions. Using the model, two options were proposed, which could improve the performance of the basal system by about twofold, that is, by increasing the density of immobilized cells per carrier volume from 6.1 x 10(7) to 1.2 x 10(8) cell/mL, or by increasing the packed-bed height from 0.2 to 0.4 m. Both strategies would be rather simple to test and implement in the packed-bed bioreactor system used for this study. As a result, it would be possible to achieve a substantial improvement of about twofold higher productivity as compared with the basal conditions. PMID:16358288

  15. Structural Rearrangements in CHO Cells After Disruption of Individual Cytoskeletal Elements and Plasma Membrane.

    PubMed

    Jokhadar, Špela Zemljič; Derganc, Jure

    2015-04-01

    Cellular structural integrity is provided primarily by the cytoskeleton, which comprises microtubules, actin filaments, and intermediate filaments. The plasma membrane has been also recognized as a mediator of physical forces, yet its contribution to the structural integrity of the cell as a whole is less clear. In order to investigate the relationship between the plasma membrane and the cytoskeleton, we selectively disrupted the plasma membrane and each of the cytoskeletal elements in Chinese hamster ovary cells and assessed subsequent changes in cellular structural integrity. Confocal microscopy was used to visualize cytoskeletal rearrangements, and optical tweezers were utilized to quantify membrane tether extraction. We found that cholesterol depletion from the plasma membrane resulted in rearrangements of all cytoskeletal elements. Conversely, the state of the plasma membrane, as assessed by tether extraction, was affected by disruption of any of the cytoskeletal elements, including microtubules and intermediate filaments, which are located mainly in the cell interior. The results demonstrate that, besides the cytoskeleton, the plasma membrane is an important contributor to cellular integrity, possibly by acting as an essential framework for cytoskeletal anchoring. In agreement with the tensegrity model of cell mechanics, our results support the notion of the cell as a prestressed structure. PMID:25395197

  16. Impact of aeration strategy on CHO cell performance during antibody production.

    PubMed

    Velez-Suberbie, M Lourdes; Tarrant, Richard D R; Tait, Andrew S; Spencer, Daniel I R; Bracewell, Daniel G

    2013-01-01

    Stirred tank bioreactors using suspension adapted mammalian cells are typically used for the production of complex therapeutic proteins. The hydrodynamic conditions experienced by cells within this environment have been shown to directly impact growth, productivity, and product quality and therefore an improved understanding of the cellular response is critical. Here we investigate the sub-lethal effects of different aeration strategies on Chinese hamster ovary cells during monoclonal antibody production. Two gas delivery systems were employed to study the presence and absence of the air-liquid interface: bubbled direct gas sparging and a non-bubbled diffusive silicone membrane system. Additionally, the effect of higher gas flow rate in the sparged bioreactor was examined. Both aeration systems were run using chemically defined media with and without the shear protectant Pluronic F-68 (PF-68). Cells were unable to grow with direct gas sparging without PF-68; however, when a silicone membrane aeration system was implemented growth was comparable to the sparged bioreactor with PF-68, indicating the necessity of shear protectants in the presence of bubbles. The cultures exposed to increased hydrodynamic stress were shown by flow cytometry to have decreased F-actin intensity within the cytoskeleton and enter apoptosis earlier. This indicates that these conditions elicit a sub-lethal physiological change in cells that would not be detected by the at-line assays which are normally implemented during cell culture. These physiological changes only result in a difference in continuous centrifugation performance under high flow rate conditions. Product quality was more strongly affected by culture age than the hydrodynamic conditions tested. PMID:23074084

  17. Amorphous Alumina Nanowire Array Efficiently Delivers Ac-DEVD-CHO to Inhibit Apoptosis of Dendritic Cells

    PubMed Central

    Lampert, Lester; Timonen, Brittany; Smith, Sean; Davidge, Brittney; Li, Haiyan; Conley, John F.; Singer, Jeffrey D.; Jiao, Jun

    2014-01-01

    To create an effective well-ordered delivery platform still remains a challenge. Herein we fabricate vertically aligned alumina nanowire arrays via atomic layer deposition templated by carbon nanotubes. Using these arrays, a caspase-3/7 inhibitor was delivered into DC 2.4 cells and blocked apoptosis, as confirmed by fluorescence microscopy. PMID:24336780

  18. Use of a small molecule cell cycle inhibitor to control cell growth and improve specific productivity and product quality of recombinant proteins in CHO cell cultures

    PubMed Central

    Du, Zhimei; Treiber, David; McCarter, John D; Fomina-Yadlin, Dina; Saleem, Ramsey A; McCoy, Rebecca E; Zhang, Yuling; Tharmalingam, Tharmala; Leith, Matthew; Follstad, Brian D; Dell, Brad; Grisim, Brent; Zupke, Craig; Heath, Carole; Morris, Arvia E; Reddy, Pranhitha

    2015-01-01

    The continued need to improve therapeutic recombinant protein productivity has led to ongoing assessment of appropriate strategies in the biopharmaceutical industry to establish robust processes with optimized critical variables, that is, viable cell density (VCD) and specific productivity (product per cell, qP). Even though high VCD is a positive factor for titer, uncontrolled proliferation beyond a certain cell mass is also undesirable. To enable efficient process development to achieve consistent and predictable growth arrest while maintaining VCD, as well as improving qP, without negative impacts on product quality from clone to clone, we identified an approach that directly targets the cell cycle G1-checkpoint by selectively inhibiting the function of cyclin dependent kinases (CDK) 4/6 with a small molecule compound. Results from studies on multiple recombinant Chinese hamster ovary (CHO) cell lines demonstrate that the selective inhibitor can mediate a complete and sustained G0/G1 arrest without impacting G2/M phase. Cell proliferation is consistently and rapidly controlled in all recombinant cell lines at one concentration of this inhibitor throughout the production processes with specific productivities increased up to 110 pg/cell/day. Additionally, the product quality attributes of the mAb, with regard to high molecular weight (HMW) and glycan profile, are not negatively impacted. In fact, high mannose is decreased after treatment, which is in contrast to other established growth control methods such as reducing culture temperature. Microarray analysis showed major differences in expression of regulatory genes of the glycosylation and cell cycle signaling pathways between these different growth control methods. Overall, our observations showed that cell cycle arrest by directly targeting CDK4/6 using selective inhibitor compound can be utilized consistently and rapidly to optimize process parameters, such as cell growth, qP, and glycosylation profile in

  19. Continuous precipitation of IgG from CHO cell culture supernatant in a tubular reactor.

    PubMed

    Hammerschmidt, Nikolaus; Hintersteiner, Beate; Lingg, Nico; Jungbauer, Alois

    2015-08-01

    We successfully transferred a two-stage batch precipitation-based antibody capture step to continuous mode using continuous tubular reactors. The precipitation process solely employs a cheap mineral salt (CaCl2 ) and an organic solvent (ethanol) and could replace the costly protein A capture step in the purification of recombinant antibodies from cell culture supernatant. The time from startup untill attaining steady state conditions was reached in less than 15 minutes and both reactors were operated for several hours at steady state without manual intervention, delivering antibody at a constant yield and purity. An overall yield of > 90 percent, with a host cell protein reduction from 42 777 to 9000 ppm and a DNA reduction from 359 ppm to 7 ppm, could be achieved for the antibody investigated. The precipitated antibody can be dissolved at very high concentrations (> 40 g/L) in numerous buffer systems of various pH and high and low ionic strength, thereby rendering a subsequent concentration or buffer exchange step redundant. This system enables cell culture supernatants with low or high antibody titer to be processed with constant reactor size and without changing any parameters or increasing precipitant consumption. Aggregate levels were below 1% under all conditions tested. Purification by precipitation did not affect binding to CD16a or the isoform distribution of the antibody. PMID:25781580

  20. Concise review: no breakthroughs for human mesenchymal and embryonic stem cell culture: conditioned medium, feeder layer, or feeder-free; medium with fetal calf serum, human serum, or enriched plasma; serum-free, serum replacement nonconditioned medium, or ad hoc formula? All that glitters is not gold!

    PubMed

    Mannello, Ferdinando; Tonti, Gaetana A

    2007-07-01

    The choice of an optimal strategy of stem cell culture is at the moment an impossible task, and the elaboration of a culture medium adapted to the production of embryonic and adult mesenchymal stem cells for the clinical application of cell therapy remains a crucial matter. To make an informed choice, it is crucial to not underestimate the theoretical health risk of using xenogenic compounds, to limit the immunological reactions once stem cells are transplanted, to not overestimate the controversial results obtained with human serum, plasma, and blood derivatives, as well as to carefully examine the pros and cons of serum-free and ad hoc formulation strategies; besides that, to also maintain multipotentiality, self-renewal, and transplantability. The extent to which we are able to achieve effective cell therapies will depend on assimilating a rapidly developing base of scientific knowledge with the practical considerations of design, delivery, and host response. Although clinical studies have already started, many questions remain unsolved, and concomitantly even more evidence on suitable and safe off-the-shelf products (mainly xeno-free) for embryonic and mesenchymal stem cells is cropping up, even though there should be no rush to enter the clinical stage while the underlying basic research is still not so solid; this solely will lead to high-quality translational research, without making blunders stemming from the assumption that all that glitters is not gold. Disclosure of potential conflicts of interest is found at the end of this article. PMID:17395775

  1. Quantitative definition and monitoring of the host cell protein proteome using iTRAQ - a study of an industrial mAb producing CHO-S cell line.

    PubMed

    Chiverton, Lesley M; Evans, Caroline; Pandhal, Jagroop; Landels, Andrew R; Rees, Byron J; Levison, Peter R; Wright, Phillip C; Smales, C Mark

    2016-08-01

    There are few studies defining CHO host cell proteins (HCPs) and the flux of these throughout a downstream purification process. Here we have applied quantitative iTRAQ proteomics to follow the HCP profile of an antibody (mAb) producing CHO-S cell line throughout a standard downstream purification procedure consisting of a Protein A, cation and anion exchange process. We used both 6 sample iTRAQ experiment to analyze technical replicates of three samples, which were culture harvest (HCCF), Protein A flow through and Protein A eluate and an 8 sample format to analyze technical replicates of four sample types; HCCF compared to Protein A eluate and subsequent cation and anion exchange purification. In the 6 sample iTRAQ experiment, 8781 spectra were confidently matched to peptides from 819 proteins (including the mAb chains). Across both the 6 and 8 sample experiments 936 proteins were identified. In the 8 sample comparison, 4187 spectra were confidently matched to peptides from 219 proteins. We then used the iTRAQ data to enable estimation of the relative change of individual proteins across the purification steps. These data provide the basis for application of iTRAQ for process development based upon knowledge of critical HCPs. PMID:27214759

  2. In situ cell retention of a CHO culture by a reverse-flow diafiltration membrane bioreactor.

    PubMed

    Meier, Kristina; Djeljadini, Suzana; Regestein, Lars; Büchs, Jochen; Carstensen, Frederike; Wessling, Matthias; Holland, Tanja; Raven, Nicole

    2014-01-01

    Heterogeneities occur in various bioreactor designs including cell retention devices. Whereas in external devices changing environmental conditions cannot be prevented, cells are retained in their optimal environment in internal devices. Conventional reverse-flow diafiltration utilizes an internal membrane device, but pulsed feeding causes temporal heterogeneities. In this study, the influence of conventional reverse-flow diafiltration on the yeast Hansenula polymorpha is investigated. Alternating 180 s of feeding with 360 s of non-feeding at a dilution rate of 0.2 h(-1) results in an oscillating DOT signal with an amplitude of 60%. Thereby, induced short-term oxygen limitations result in the formation of ethanol and a reduced product concentration of 25%. This effect is enforced at increased dilution rate. To overcome this cyclic problem, sequential operation of three membranes is introduced. Thus, quasi-continuous feeding is achieved reducing the oscillation of the DOT signal to an amplitude of 20% and 40% for a dilution rate of 0.2 h(-1) and 0.5 h(-1) , respectively. Fermentation conditions characterized by complete absence of oxygen limitation and without formation of overflow metabolites could be obtained for dilution rates from 0.1 h(-1) - 0.5 h(-1) . Thus, sequential operation of three membranes minimizes oscillations in the DOT signal providing a nearly homogenous culture over time. PMID:25202924

  3. Effects of dapoxetine on cloned Kv1.5 channels expressed in CHO cells.

    PubMed

    Jeong, Imju; Yoon, Shin Hee; Hahn, Sang June

    2012-07-01

    The effects of dapoxetine were examined on cloned Kv1.5 channels stably expressed in Chinese hamster ovary cells using the whole-cell patch clamp technique. Dapoxetine decreased the peak amplitude of Kv1.5 currents and accelerated the decay rate of current inactivation in a concentration-dependent manner with an IC ( 50 ) of 11.6 μM. Kinetic analysis of the time-dependent effects of dapoxetine on Kv1.5 current decay yielded the apparent association (k (+1 )) and dissociation (k (-1 )) rate constants of 2.8 μM(-1) s(-1) and 34.2 s(-1), respectively. The theoretical K ( D ) value, derived by k (-1 )/k (+1 ), yielded 12.3 μM, which was reasonably similar to the IC ( 50 ) value obtained from the concentration-response curve. Dapoxetine decreased the tail current amplitude and slowed the deactivation process of Kv1.5, which resulted in a tail crossover phenomenon. The block by dapoxetine is voltage-dependent and steeply increased at potentials between -10 and +10 mV, which correspond to the voltage range of channel activation. At more depolarized potentials, a weaker voltage dependence was observed (δ=0.31). Dapoxetine had no effect on the steady-state activation of Kv1.5 but shifted the steady-state inactivation curves in a hyperpolarizing direction. Dapoxetine produced a use-dependent block of Kv1.5 at frequencies of 1 and 2 Hz and slowed the time course for recovery of inactivation. These effects were reversible after washout of the drug. Our results indicate that dapoxetine blocks Kv1.5 currents by interacting with the channel in both the open and inactivated states of the channel. PMID:22538641

  4. Effect of mosapride on Kv4.3 potassium channels expressed in CHO cells.

    PubMed

    Sung, Ki-Wug; Hahn, Sang June

    2013-10-01

    Mosapride and cisapride are gastroprokinetic agents with 5-hydroxytryptamine4 receptor agonist activity and have been widely used in the treatment of a variety of gastrointestinal disorders. The effects of mosapride and cisapride on cloned Kv4.3 channels stably expressed in Chinese hamster ovary cells were investigated using the whole-cell patch-clamp technique. Mosapride and cisapride inhibited Kv4.3 in a concentration-dependent manner with IC50 values of 15.2 and 9.8 μM, respectively. Mosapride accelerated the rate of inactivation and activation of Kv4.3 in a concentration-dependent manner and thereby decreased the time to peak. The rate constants of association (k +1) and dissociation (k -1) for mosapride were 9.9 μM(-1) s(-1) and 151.3 s(-1), respectively. The K D (k -1/k +1) was 16.2 μM, similar to the IC50 value calculated from the concentration-response curve. Voltage-dependent inhibition by mosapride was observed in the voltage range for channel opening but was not observed over a voltage range in which all Kv4.3 channels were open. Both the steady-state activation and inactivation curves of Kv4.3 were shifted in the hyperpolarizing direction in the presence of mosapride. Mosapride also caused a substantial acceleration in closed-state inactivation of Kv4.3. Mosapride produced use-dependent inhibition, which was consistent with a slow recovery from inactivation of Kv4.3. M1 and norcisapride, the major metabolites of mosapride and cisapride, respectively, had little or no effect on Kv4.3. These results indicate that mosapride inhibits Kv4.3 by both preferential binding to the open state of the channels during depolarization and acceleration of the closed-state inactivation at subthreshold potentials. PMID:23793103

  5. Influence of radiofrequency radiation on chromosome aberrations in CHO cells and its interaction with DNA-damaging agents.

    PubMed

    Kerbacher, J J; Meltz, M L; Erwin, D N

    1990-09-01

    A limited number of contradictory reports have appeared in the literature about the ability of radiofrequency (rf) radiation to induce chromosome aberrations in different biological systems. The technical documentation associated with such reports is often absent or deficient. In addition, no information is available as to whether any additional genotoxic hazard would result from a simultaneous exposure of mammalian cells to rf radiation and a chemical which (by itself) induces chromosome aberrations. In the work described, we have therefore tested two hypotheses. The first is that rf radiation by itself, at power densities and exposure conditions which are higher than is consistent with accepted safety guidelines, can induce chromosome aberrations in mammalian cells. The second is that, during a simultaneous exposure to a chemical known to be genotoxic, rf radiation can affect molecules, biochemical processes, or cellular organelles, and thus result in an increase or decrease in chromosome aberrations. Mitomycin C (MMC) and Adriamycin (ADR) were selected because they act by different mechanisms, and because they might put normal cells at risk during combined-modality rf radiation (hyperthermia)-chemotherapy treatment of cancer. The studies were performed with suitable 37 degrees C and equivalent convection heating-temperature controls in a manner designed to discriminate between any thermal and possible nonthermal action. Radiofrequency exposures were conducted for 2 h under conditions resulting in measurable heating (a maximum increase of 3.2 degrees C), with pulsed-wave rf radiation at a frequency of 2450 MHz and an average net forward power of 600 W, resulting in an SAR of 33.8 W/kg. Treatments with MMC or ADR were for a total of 2.5 h and encompassed the 2-h rf radiation exposure period. The CHO cells from each of the conditions were subsequently analyzed for chromosome aberrations. In cells exposed to rf radiation alone, and where a maximum temperature of

  6. Dynamics of immature mAb glycoform secretion during CHO cell culture: An integrated modelling framework.

    PubMed

    Jimenez Del Val, Ioscani; Fan, Yuzhou; Weilguny, Dietmar

    2016-05-01

    Ensuring consistent glycosylation-associated quality of therapeutic monoclonal antibodies (mAbs) has become a priority in pharmaceutical bioprocessing given that the distribution and composition of the carbohydrates (glycans) bound to these molecules determines their therapeutic efficacy and immunogenicity. However, the interaction between bioprocess conditions, cellular metabolism and the intracellular process of glycosylation remains to be fully understood. To gain further insight into these interactions, we present a novel integrated modelling platform that links dynamic variations in mAb glycosylation with cellular secretory capacity. Two alternative mechanistic representations of how mAb specific productivity (qp ) influences glycosylation are compared. In the first, mAb glycosylation is modulated by the linear velocity with which secretory cargo traverses the Golgi apparatus. In the second, glycosylation is influenced by variations in Golgi volume. Within our modelling framework, both mechanisms accurately reproduce experimentally-observed dynamic changes in mAb glycosylation. In addition, an optimisation-based strategy has been developed to estimate the concentration of glycosylation enzymes required to minimise mAb glycoform variability. Our results suggest that the availability of glycosylation machinery relative to cellular secretory capacity may play a crucial role in mAb glycosylation. In the future, the modelling framework presented here may aid in selecting and engineering cell lines that ensure consistent mAb glycosylatio. PMID:26743760

  7. Effects of elevated ammonium on glycosylation gene expression in CHO cells.

    PubMed

    Chen, Peifeng; Harcum, Sarah W

    2006-03-01

    The negative effects of ammonium on recombinant protein productivity and glycosylation have been well documented, but the interaction of ammonium on glycosylation genes has not been completely elucidated. In this study, the effects of elevated ammonium on 12 glycosylation related genes in Chinese hamster ovary cells were evaluated by quantitative real time reverse transcriptase polymerase chain reaction. Numerous cytosol and endoplasmic reticulum (ER) localized genes associated with early glycosylation steps were insensitive to the ammonium condition. The initial expression of uridine diphosphate (UDP)-galactose transporter was higher for the ammonium-treated culture, while the initial expressions of cytosine monophosphate (CMP)-sialic acid transporter, beta(1,4)-galactosyltransferase, and UDP-glucose pyrophosphorylase were higher for the control culture. alpha(2,3)-sialyltransferase was observed to have lower expression level under the elevated ammonium condition compared to the control culture. This study indicates that galactosylation and sialylation inhibition is mainly due to decreased gene expression of galactosyltransferase, sialyltransferase, and CMP-sialic acid transporter and not due to sialidase. These unbalanced initial glycosylation and branching steps can explain the higher molecular heterogeneity under ammonium stress. Moreover, this study indicates that elevated ammonium has limited effects on the glycosylation genes associated with the ER and cytosol compared to the genes associated with the Golgi. PMID:16380282

  8. DNA-DSB in CHO-K1 cells induced by heavy-ions: Break rejoining and residual damage (GSI)

    NASA Technical Reports Server (NTRS)

    Taucher-Scholz, G.; Heilmann, J.; Becher, G.; Kraft, G.

    1994-01-01

    DNA double strand breaks (DSB's) are the critical lesions involved in cellular effects of ionizing radiation. Therefore, the evaluation of DSB induction in mammalian cells after heavy ion irradiation is an essential task for the assessment of high-LET radiation risk in space. Of particular interest has been the question of how the biological efficiency for the cellular inactivation endpoint relates to the initial lesions (DSBs) at varying LETs. For cell killing, an increased Relative Biological Efficiency (RBE) has been determined for highLET radiation around 100-200 keV/mu m. At higher LET, the RBE's decrease again to values below one for the very heavy particles. At GSI, DSB-induction was measured in CHO-K1 cells following irradiation with accelerated particles covering a wide LET range. The electrophoretic elution of fragmented DNA out of agarose plugs in a constant electrical field was applied for the detection of DSB's. The fraction of DNA retained was determined considering the relative intensities of ethidium bromide fluorescence in the well and in the gel lane. Dose-effect curves were established, from which the RBE for DSB induction was calculated at a fraction of 0.7 of DNA retained In summary, these rejoining studies are in line with an enhanced severity of the DNA DSB's at higher LET's, resulting in a decreased repairability of the induced lesions. However, no information concerning the fidelity of strand breaks rejoining is provided in these studies. To assess correct rejoining of DNA fragments an experimental system involving individual DNA hybridization bands has been set up. In preliminary experiments Sal I generated DNA fragments of 0.9 Mbp were irradiated with xrays and incubated for repair However, restitution of the original signals was not observed, probably due to the high radiation dose necessary for breakage of a fragment of this size. A banding pattern with NotI hybridization signals in a higher MW range (3Mbp) has been obtained by varying

  9. Rational vector design and multi-pathway modulation of HEK 293E cells yield recombinant antibody titers exceeding 1 g/l by transient transfection under serum-free conditions

    PubMed Central

    Backliwal, Gaurav; Hildinger, Markus; Chenuet, Sebastien; Wulhfard, Sarah; De Jesus, Maria; Wurm, Florian M.

    2008-01-01

    Transient transfection allows for fast production of recombinant proteins. However, the current bottlenecks in transient transfection are low titers and low specific productivity compared to stable cell lines. Here, we report an improved transient transfection protocol that yields titers exceeding 1 g/l in HEK293E cells. This was achieved by combining a new highly efficient polyethyleneimine (PEI)-based transfection protocol, optimized gene expression vectors, use of cell cycle regulators p18 and p21, acidic Fibroblast Growth Factor, exposure of cells to valproic acid and consequently the maintenance of cells at high cell densities (4 million cells/ml). This protocol was reproducibly scaled-up to a working volume of 2 l, thus delivering >1 g of purified protein just 2 weeks after transfection. This is the fastest approach to gram quantities of protein ever reported from cultivated mammalian cells and could initiate, upon further scale-up, a paradigm shift in industrial production of such proteins for any application in biotechnology. PMID:18617574

  10. Macrophage receptor with collagenous structure (MARCO) is a dynamic adhesive molecule that enhances uptake of carbon nanotubes by CHO-K1 Cells

    SciTech Connect

    Hirano, Seishiro; Fujitani, Yuji; Furuyama, Akiko; Kanno, Sanae

    2012-02-15

    The toxicity of carbon nanotubes (CNTs), a highly promising nanomaterial, is similar to that of asbestos because both types of particles have a fibrous shape and are biopersistent. Here, we investigated the characteristics of macrophage receptor with collagenous structure (MARCO), a membrane receptor expressed on macrophages that recognizes environmental or unopsonized particles, and we assessed whether and how MARCO was involved in cellular uptake of multi-walled CNTs (MWCNTs). MARCO-transfected Chinese hamster ovary (CHO-K1) cells took up polystyrene beads irrespective of the particle size (20 nm–1 μm). In the culture of MARCO-transfected CHO-K1 cells dendritic structures were observed on the bottom of culture dishes, and the edges of these dendritic structures were continually renewed as the cell body migrated along the dendritic structures. MWCNTs were first tethered to the dendritic structures and then taken up by the cell body. MWCNTs appeared to be taken up via membrane ruffling like macropinocytosis, rather than phagocytosis. The cytotoxic EC{sub 50} value of MWCNTs in MARCO-transfected CHO-K1 cells was calculated to be 6.1 μg/mL and transmission electron microscopic observation indicated that the toxicity of MWCNTs may be due to the incomplete inclusion of MWCNTs by the membrane structure. -- Highlights: ►Carbon nanotubes (CNTs) were tethered to MARCO in vitro. ►CNTs were taken up rapidly into the cell body via MARCO by membrane ruffling. ►The incomplete inclusion of CNTs by membranes caused cytotoxicity.

  11. Decreasing lactate level and increasing antibody production in Chinese Hamster Ovary cells (CHO) by reducing the expression of lactate dehydrogenase and pyruvate dehydrogenase kinases.

    PubMed

    Zhou, Meixia; Crawford, Yongping; Ng, Domingos; Tung, Jack; Pynn, Abigail F J; Meier, Angela; Yuk, Inn H; Vijayasankaran, Natarajan; Leach, Kimberly; Joly, John; Snedecor, Bradley; Shen, Amy

    2011-04-20

    Large-scale fed-batch cell culture processes of CHO cells are the standard platform for the clinical and commercial production of monoclonal antibodies. Lactate is one of the major by-products of CHO fed-batch culture. In pH-controlled bioreactors, accumulation of high levels of lactate is accompanied by high osmolality due to the addition of base to control pH of the cell culture medium, potentially leading to lower cell growth and lower therapeutic protein production during manufacturing. Lactate dehydrogenase (LDH) is an enzyme that catalyzes the conversion of the substrate, pyruvate, into lactate and many factors including pyruvate concentration modulate LDH activity. Alternately, pyruvate can be converted to acetyl-CoA by pyruvate dehydrogenases (PDHs), to be metabolized in the TCA cycle. PDH activity is inhibited when phosphorylated by pyruvate dehydrogenase kinases (PDHKs). In this study, we knocked down the gene expression of lactate dehydrogenase A (LDHa) and PDHKs to investigate the effect on lactate metabolism and protein production. We found that LDHa and PDHKs can be successfully downregulated simultaneously using a single targeting vector carrying small inhibitory RNAs (siRNA) for LDHa and PDHKs. Moreover, our fed-batch shake flask evaluation data using siRNA-mediated LDHa/PDHKs knockdown clones showed that downregulating LDHa and PDHKs in CHO cells expressing a therapeutic monoclonal antibody reduced lactate production, increased specific productivity and volumetric antibody production by approximately 90%, 75% and 68%, respectively, without appreciable impact on cell growth. Similar trends of lower lactate level and higher antibody productivity on average in siRNA clones were also observed from evaluations performed in bioreactors. PMID:21392546

  12. Purification of the extracellular domain of the membrane protein GlialCAM expressed in HEK and CHO cells and comparison of the glycosylation.

    PubMed

    Gaudry, Jean-Philippe; Arod, Christian; Sauvage, Christophe; Busso, Stephane; Dupraz, Philippe; Pankiewicz, Renata; Antonsson, Bruno

    2008-03-01

    Adhesion molecules are essential for a wide range of biological and physiological functions, including cell-cell interactions, cell interactions with the extracellular matrix, cell migration, proliferation and survival. Defects in cell adhesion have been associated with pathological conditions such as neoplasia, and neurodegenerative diseases. We have identified a new adhesion molecule of the immunoglobulin family, GlialCAM. The same protein was recently published under the name hepaCAM and was suggested to be associated with hepatocellular carcinoma. Here we have expressed and purified the extracellular domain of this molecule in two mammalian expression systems, HEK and CHO cells. A three step purification protocol gave an over 95% pure protein. The extracellular domain of GlialCAM possesses several potential N- and O-glycosylation sites. Glycosylation is one of the most common post-translational modifications of secreted proteins and of the extracellular domains of membrane bound proteins. It can influence both the activity and the stability of the protein. The glycosylation pattern has been shown to depend on the cell type where the protein is expressed. We examined if differences in the glycosylation of this protein could be detected when it was expressed in the two commonly used mammalian expression systems, HEK and CHO. Differences in the glycosylation were detected. PMID:18082421

  13. Induction of chromosomal damage in CHO-K1 cells and their repair-deficient mutant XRS5 by x-ray and particle irradiation

    NASA Astrophysics Data System (ADS)

    Nasonova, E.; Ritter, S.; Fomenkova, T.; Kraft, G.

    The cytogenetic effects of X-rays and Au ions were investigated in repair-proficient CHO-K1 cells and their radiosensitive mutant strain xrs5, which shows a defect in the rejoining of DNA double-strand breaks. Both cell lines were synchronized by mitotic shake off, irradiated in G_1-phase with either 250 kV X-rays or 780 MeV/u Au ions (LET: 1150 keV/mum) and chromosome aberrations were analyzed in first post-irradiation metaphases. Isoeffective doses of X-rays for the induction of aberrant cells and aberrations per cell were about 14 times lower for xrs5 than for CHO-K1 cells. After high LET radiation the difference in the cytogenetic response of both cell lines was drastically diminished. Furthermore, the analysis of the aberration types induced by sparsely and densely ionizing radiation showed for both cell lines specific changes in the spectrum of aberration types as LET increases. The experimental results are discussed with respect to the different types of lesions induced by sparsely and densely ionizing radiation.

  14. Enhanced transient recombinant protein production in CHO cells through the co-transfection of the product gene with Bcl-xL

    PubMed Central

    Zustiak, Matthew P.; Jose, Lisa; Xie, Yueqing; Zhu, Jianwei; Betenbaugh, Micheal J.

    2014-01-01

    Transient gene expression is gaining popularity as a method to rapidly produce recombinant proteins in mammalian cells. Although significant improvements have been made, in terms of expression, more improvements are needed to compete with the yields achievable in stable gene expression. Much progress has come from optimization of transfection media and parameters, as well as altering culturing conditions to enhance productivity. Recent studies have included using cell lines engineered for apoptosis resistance through the constitutive expression of an anti-apoptotic protein, Bcl-xL. In this study we examine an alternative method of using the benefits of anti-apoptotic gene expression to enhance the transient expression of biotherapeutics, namely, through the co-transfection of bcl-xL and the product-coding gene. CHO-S cells were co-transfected with the product-coding gene and a vector containing Bcl-xL using polyethylenimine. Cells co-transfected with Bcl-xL showed reduced levels of apoptosis, increased specific productivity, and an overall increase in product yield of approximately 100%. Similar results were produced by employing another anti-apoptotic protein, Bcl-2 delta in CHO cells, or through the co-transfection with bcl-xL using HEK-293E cells. This work provides an alternative method for increasing yields of therapeutic proteins in TGE applications without generating a prior stable cell line and subsequent screening which are both time and resource consuming. PMID:24604826

  15. GSI-I (Z-LLNle-CHO) inhibits γ-secretase and the proteosome to trigger cell death in precursor-B acute lymphoblastic leukemia.

    PubMed

    Meng, X; Matlawska-Wasowska, K; Girodon, F; Mazel, T; Willman, C L; Atlas, S; Chen, I-M; Harvey, R C; Hunger, S P; Ness, S A; Winter, S S; Wilson, B S

    2011-07-01

    Gamma secretase inhibitors (GSIs) comprise a growing class of compounds that interfere with the membrane-bound Notch signaling protein and its downstream intra-nuclear transcriptional targets. As GSI-I (Z-LLNle-CHO) is also a derivative of a widely used proteosome inhibitor MG-132, we hypothesized that this compound might be active in precursor-B acute lymphoblastic leukemia (ALL) cell lines and patient samples. We found that GSI-I treatment of precursor-B ALL blasts induced apoptotic cell death within 18-24 h. With confirmation using RNA and protein analyses, GSI-I blocked nuclear accumulation of cleaved Notch1 and Notch2, and inhibited Notch targets Hey2 and Myc. Microarray analyses of 207 children with high-risk precursor-B ALL demonstrate that Notch pathway expression is a common feature of these neoplasms. However, microarray studies also implicated additional transcriptional targets in GSI-I-dependent cell death, including genes in the unfolded protein response, nuclear factor-κB and p53 pathways. Z-LLNle-CHO blocks both γ-secretase and proteosome activity, inducing more robust cell death in precursor-B ALL cells than either proteosome-selective or γ-secretase-selective inhibitors alone. Using Z-LLNle-CHO in a nonobese diabetes/severe combined immunodeficiency (NOD/SCID) precursor-B ALL xenograft model, we found that GSI-I alone delayed or prevented engraftment of B-lymphoblasts in 50% of the animals comprising the experimental group, suggesting that this compound is worthy of additional testing. PMID:21494254

  16. Evidence for transketolase-like TKTL1 flux in CHO cells based on parallel labeling experiments and (13)C-metabolic flux analysis.

    PubMed

    Ahn, Woo Suk; Crown, Scott B; Antoniewicz, Maciek R

    2016-09-01

    The pentose phosphate pathway (PPP) is a fundamental component of cellular metabolism. It provides precursors for the biosynthesis of nucleotides and contributes to the production of reducing power in the form of NADPH. It has been hypothesized that mammalian cells may contain a hidden reaction in PPP catalyzed by transketolase-like protein 1 (TKTL1) that is closely related to the classical transketolase enzyme; however, until now there has been no direct experimental evidence for this reaction. In this work, we have applied state-of-the-art techniques in (13)C metabolic flux analysis ((13)C-MFA) based on parallel labeling experiments and integrated flux fitting to estimate the TKTL1 flux in CHO cells. We identified a set of three parallel labeling experiments with [1-(13)C]glucose+[4,5,6-(13)C]glucose, [2-(13)C]glucose+[4,5,6-(13)C]glucose, and [3-(13)C]glucose+[4,5,6-(13)C]glucose and developed a new method to measure (13)C-labeling of fructose 6-phosphate by GC-MS that allows intuitive interpretation of mass isotopomer distributions to determine key fluxes in the model, including glycolysis, oxidative PPP, non-oxidative PPP, and the TKTL1 flux. Using these tracers we detected a significant TKTL1 flux in CHO cells at the stationary phase. The flux results suggest that the main function of oxidative PPP in CHO cells at the stationary phase is to fuel the TKTL1 reaction. Overall, this study demonstrates for the first time that carbon atoms can be lost in the PPP, by means other than the oxidative PPP, and that this loss of carbon atoms is consistent with the hypothesized TKTL1 reaction in mammalian cells. PMID:27174718

  17. [Stable expression of human anti-IL-33 scFv-IgG1Fc fusion protein in CHO k1 cells].

    PubMed

    Ye, Yingchun; Nian, Siji; Wang, Xu; Wu, Tong; Xu, Wenfeng; Yuan, Qing

    2016-05-01

    Objective To construct two different eukaryotic expression vectors of human anti-interleukin 33 (IL-33) single-chain antibody fragment (scFv-Fc) to transfect Chinese hamster ovary (CHO) k1 cells and select the stably and high-level expressed cell lines to improve the expression level of the fusion protein. Methods The previously constructed recombinant plasmid pcDNA3.1/SP-scFv-Fc was digested to obtain SP-scFv-Fc fragments, and the fragments were inserted into the plasmid PMH3(EN) to construct recombinant plasmid PMH3(EN)/SP-scFv-Fc. The plasmids PMH3(EN)/SP-scFv-Fc and pcDNA3.1/SP-scFv-Fc were separately transfected into CHO k1 cells. The transcription and translation level of the SP-scFv-Fc were detected by reverse transcription PCR (RT-PCR) and Western blotting, respectively. The stably and high-level expressed cell lines were screened by Dot blotting. The expression level and binding activity of the expressed scFv-Fc were measured by ELISA. Results The recombinant plasmid PMH3(EN)/SP-scFv-Fc was successfully constructed and the size of the inserted SP-scFv-Fc was about 1560 bp. The RT-PCR results showed that the SP-scFv-Fc was successfully transfected into CHO k1 cells. The scFv-Fc proteins could be secreted into the cultural supernatant and specifically bind to human IL-33 and anti human IgG1 Fc antibody. The expression level of scFv-Fc in plasmid PMH3(EN) was higher than that in plasmid pcDNA3.1. After four rounds of screening, the stably and high-level expressed cell strains were obtained. The expression level of the scFv-Fc was about 10 mg/L. The competitive ELISA results showed that the expressed scFv-Fc fusion proteins could inhibit the binding of IL-33 to ST2. Conclusion The anti-IL-33 scFv-Fc proteins were highly expressed in CHO k1 cells. PMID:27126936

  18. Conversion of a CHO cell culture process from perfusion to fed-batch technology without altering product quality.

    PubMed

    Meuwly, F; Weber, U; Ziegler, T; Gervais, A; Mastrangeli, R; Crisci, C; Rossi, M; Bernard, A; von Stockar, U; Kadouri, A

    2006-05-01

    During the development of a new drug product, it is a common strategy to develop a first-generation process with the aim to rapidly produce material for pre-clinical and early stage clinical trials. At a later stage of the development, a second-generation process is then introduced with the aim to supply late-stage clinical trials as well as market needs. This work was aimed at comparing the performance of two different CHO cell culture processes (perfusion and fed-batch) used for the production of a therapeutically active recombinant glycoprotein at industrial pilot-scale. The first-generation process was based on the Fibra-Cel packed-bed perfusion technology. It appeared during the development of the candidate drug that high therapeutic doses were required (>100mg per dose), and that future market demand would exceed 100 kg per year. This exceeded by far the production capacity of the first-generation process, and triggered a change of technology from a packed-bed perfusion process with limited scale-up capabilities to a fed-batch process with scale-up potential to typical bioreactor sizes of 15m(3) or more. The productivity per bioreactor unit volume (in product m(-3)year(-1)) of the fed-batch process was about 70% of the level reached with the first-generation perfusion process. However, since the packed-bed perfusion system was limited in scale (0.6m(3) maximum) compared to the volumes reached in suspension cultures (15m(3)), the fed-batch was selected as second-generation process. In fact, the overall process performance (in product year(-1)) was about 18-fold higher for the fed-batch compared to the perfusion mode. Data from perfusion and fed-batch harvests samples indicated that comparable product quality (relative abundance of monomers dimers and aggregates; N-glycan sialylation level; isoforms distribution) was obtained in both processes. To further confirm this observation, purification to homogeneity of the harvest material from both processes, followed

  19. Comparison of five different in vitro assays for assessment of sodium metavanadate cytotoxicity in Chinese hamster ovary cells (CHO-K1 line).

    PubMed

    Zwolak, Iwona

    2015-08-01

    This investigation was undertaken to compare five different in vitro cytotoxicity assays for their power in revealing vanadium-mediated toxicity in Chinese hamster ovary (CHO)-K1 cells. The cells were exposed to sodium metavanadate (NaVO(3)) in the range of 10-1000 µM for 24 h and thereafter the cytotoxic effects of NaVO(3) were measured by colorimetric in vitro assays: the neutral red (NR) test, the 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide inner salt (XTT) assay, the resazurin assay, the sulforhodamine B (SR-B) assay, and by microscopic assessment of cell viability using the trypan blue (TB) staining method. Among the assays used, the NR test was the most sensitive, since it revealed metavanadate cytotoxicity at the lowest NaVO(3) dose (=50 µM). Also, NaVO(3) cytotoxicity expressed as inhibitory concentration (IC) showed the lowest values for the NR test. Three other tests XTT, resazurin, and SR-B assays showed intermediate sensitivity revealing the cytotoxicity of NaVO(3) at 100 µM. The corresponding IC10 and IC50 values calculated for the XTT, resazurin, and SR-B tests were similar. The TB staining method was the least sensitive, since it recorded metavanadate cytotoxicity at the highest NaVO(3) concentration tested (=600 µM). Based on the cytotoxicity end points measured with the above assays, it can be concluded that lysosomal/Golgi apparatus damage (measured by NR assay) may be the primary effect of NaVO(3) on CHO-K1 cells. The disintegration of mitochondria (assessed with the XTT and resazurin assays) probably follows lysosomal impairment. Plasma membrane permeability (staining with TB) occurs at a late stage of NaVO(3)-induced cytotoxicity on CHO-K1 cells. The results obtained in this research work show that the NR test can be recommended as a very sensitive assay for the assessment of NaVO(3) cytotoxicity in the CHO-K1 cell culture model. Considering the convenience of assay performance along with adequate sensitivity

  20. Human adenosine A1 receptor and P2Y2-purinoceptor-mediated activation of the mitogen-activated protein kinase cascade in transfected CHO cells

    PubMed Central

    Dickenson, John M; Blank, Jonathan L; Hill, Stephen J

    1998-01-01

    The mitogen-activated protein (MAP) kinase signalling pathway can be activated by a variety of heterotrimeric Gi/Go protein-coupled and Gq/G11 protein-coupled receptors. The aims of the current study were: (i) to investigate whether the Gi/Go protein-coupled adenosine A1 receptor activates the MAP kinase pathway in transfected Chinese hamster ovary cells (CHO-A1) and (ii) to determine whether adenosine A1 receptor activation would modulate the MAP kinase response elicited by the endogenous P2Y2 purinoceptor.The selective adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) stimulated time and concentration-dependent increases in MAP kinase activity in CHO-A1 cells (EC50 7.1±0.4 nM). CPA-mediated increases in MAP kinase activity were blocked by PD 98059 (50 μM; 89±4% inhibition), an inhibitor of MAP kinase kinase 1 (MEKI) activation, and by pre-treating cells with pertussis toxin (to block Gi/Go-dependent pathways).Adenosine A1 receptor-mediated activation of MAP kinase was abolished by pre-treatment with the protein tyrosine inhibitor, genistein (100 μM; 6±10% of control). In contrast, daidzein (100 μM), the inactive analogue of genistein had no significant effect (96±12 of control). MAP kinase responses to CPA (1 μM) were also sensitive to the phosphatidylinositol 3-kinase inhibitors wortmannin (100 nM; 55±8% inhibition) and LY 294002 (30 μM; 40±5% inhibition) but not to the protein kinase C (PKC) inhibitor Ro 31-8220 (10 μM).Activation of the endogenous P2Y2 purinoceptor with UTP also stimulated time and concentration-dependent increases in MAP kinase activity in CHO-A1 cells (EC50=1.6±0.3 μM). The MAP kinase response to UTP was partially blocked by pertussis toxin (67±3% inhibition) and by the PKC inhibitor Ro 31-8220 (10 μM; 45±5% inhibition), indicating the possible involvement of both Gi/Go protein and Gq protein-dependent pathways in the overall response to UTP.CPA and UTP stimulated concentration

  1. Quantitative modeling of viable cell density, cell size, intracellular conductivity, and membrane capacitance in batch and fed-batch CHO processes using dielectric spectroscopy.

    PubMed

    Opel, Cary F; Li, Jincai; Amanullah, Ashraf

    2010-01-01

    Dielectric spectroscopy was used to analyze typical batch and fed-batch CHO cell culture processes. Three methods of analysis (linear modeling, Cole-Cole modeling, and partial least squares regression), were used to correlate the spectroscopic data with routine biomass measurements [viable packed cell volume, viable cell concentration (VCC), cell size, and oxygen uptake rate (OUR)]. All three models predicted offline biomass measurements accurately during the growth phase of the cultures. However, during the stationary and decline phases of the cultures, the models decreased in accuracy to varying degrees. Offline cell radius measurements were unsuccessfully used to correct for the deviations from the linear model, indicating that physiological changes affecting permittivity were occurring. The beta-dispersion was analyzed using the Cole-Cole distribution parameters Deltaepsilon (magnitude of the permittivity drop), f(c) (critical frequency), and alpha (Cole-Cole parameter). Furthermore, the dielectric parameters static internal conductivity (sigma(i)) and membrane capacitance per area (C(m)) were calculated for the cultures. Finally, the relationship between permittivity, OUR, and VCC was examined, demonstrating how the definition of viability is critical when analyzing biomass online. The results indicate that the common assumptions of constant size and dielectric properties used in dielectric analysis are not always valid during later phases of cell culture processes. The findings also demonstrate that dielectric spectroscopy, while not a substitute for VCC, is a complementary measurement of viable biomass, providing useful auxiliary information about the physiological state of a culture. PMID:20730773

  2. Complete knockout of the lactate dehydrogenase A gene is lethal in pyruvate dehydrogenase kinase 1, 2, 3 down-regulated CHO cells.

    PubMed

    Yip, Shirley S M; Zhou, Meixia; Joly, John; Snedecor, Bradley; Shen, Amy; Crawford, Yongping

    2014-09-01

    Accumulation of high level of lactate can negatively impact cell growth during fed-batch culture process. In this study, we attempted to knockout the lactate dehydrogenase A (LDHA) gene in CHO cells in order to attenuate the lactate level. To prevent the potential deleterious effect of pyruvate accumulation, consequent to LDHA knockout, on cell culture, we chose a pyruvate dehydrogenase kinase 1, 2, and 3 (PDHK1, 2, and 3) knockdown cell line in which to knock out LDHA alleles. Around 3,000 clones were screened to obtain 152 mutants. Only heterozygous mutants were identified. An attempt to knockout the remaining wild-type allele from one such heterozygote yielded only two mutants after screening 567 clones. One had an extra valine. Another evidenced a duplication event, possessing at lease one wild-type and two different frameshifted alleles. Both mutants still retained LDH activity. Together, our data strongly suggest that a complete knockout of LDHA is lethal in CHO cells, despite simultaneous down-regulation of PDHK1, 2, and 3. PMID:24841241

  3. Development of a recombinant CHO cell model for the investigation of CAR and DAF role during early steps of echovirus 6 infection.

    PubMed

    Renois, Fanny; Hong, Saw-See; Le Naour, Richard; Gafa, Valérie; Talmud, Déborah; Andréoletti, Laurent; Lévêque, Nicolas

    2011-06-01

    The early steps of echovirus 6 (E6) infection remain poorly understood and the only described receptor for haemagglutinating E6 strains is the decay accelerating factor (DAF). There is, however, accumulating evidence suggesting that E6 interaction with DAF is necessary but not sufficient for infection. In this report, we investigated the role of the coxsackie-adenovirus-receptor (CAR) as a potential DAF co-receptor during E6 infection. Using stably transfected Chinese Hamster Ovary (CHO) cells expressing CAR and DAF receptors, we found that DAF expression allowed attachment of both haemagglutinating and non-haemagglutinating E6 strains but was not sufficient for promoting E6 cell entry. Interestingly, the co-expression of DAF and CAR rendered 0.1-0.2% of cells permissive to some E6 strains' infection. Although our results did not show a major role of the CAR/DAF cooperation for E6 infection, it nevertheless indicated the use of CAR in the cell entry step of some minor E6 quasispecies. Moreover, the present report validates the use of recombinant CHO cells as valuable cellular model for the further characterisation of E6 receptors. PMID:21420451

  4. Biliary lipids support serum-free growth of Giardia lamblia.

    PubMed Central

    Gillin, F D; Gault, M J; Hofmann, A F; Gurantz, D; Sauch, J F

    1986-01-01

    Giardia lamblia has been grown in vitro only in media containing serum or serum fractions. How this pathogen can grow in the human small intestinal lumen without serum is not known. We found that samples of human hepatic or gall bladder bile maintained G. lamblia survival for 24 to 48 h in medium without serum but did not support growth. By contrast, an artificial biliary lipid dispersion containing six bile salts, phosphatidylcholine (PC), and cholesterol, in the ratios characteristic of human bile, supported parasite growth in medium without serum or serum fractions. To define the requirements, we showed that 1-palmitoyl-2-linoleoyl-PC or 1-palmitoyl-2-oleoyl-PC (which predominate in human bile) satisfied the requirement for PC. Moreover, either glycocholate or glycodeoxycholate could be substituted for the bile salt mixture. The finding that biliary lipids can support serum-free growth of G. lamblia may help explain why this parasite colonizes the upper small intestine. PMID:3744557

  5. Analysis of possible genotoxicity of the herbicide flurochloridone and its commercial formulations: Endo III and Fpg alkaline comet assays in Chinese hamster ovary (CHO-K1) cells.

    PubMed

    Soloneski, Sonia; Nikoloff, Noelia; Larramendy, Marcelo L

    2016-02-01

    Cytotoxic and genotoxic effects of flurochloridone (FLC) and its formulations Twin Pack Gold(®) and Rainbow(®) were evaluated in CHO-K1 cells. Using the alkaline single-cell gel electrophoresis (SCGE) assay, we observed that FLC (15 μg/ml), Twin Pack Gold(®) or Rainbow(®) induced primary DNA damage, increasing the frequency of damaged nucleoids. Vitamin E pretreatment did not modify the effect. Decreased cell viability was observed only in Twin Pack Gold(®)-treated cultures and was significantly ameliorated by vitamin E. Post-treatment of herbicide-damaged CHO-K1 cells with the enzymes Endo III or Fpg did not increase FLC-, Twin Pack Gold(®)-, or Rainbow(®)-induced DNA damage. These results demonstrate that neither FLC nor FLC-based formulations induce DNA damage through hydroxyl radical or lipid alkoxyl radical production, and that the induced DNA lesions were not related to oxidative damage at the purine/pyrimidine level. Our observations strongly suggest that the cytotoxic effects observed after Twin Pack Gold(®) exposure are due to the excipients contained within the technical formulation rather than FLC itself. PMID:26921020

  6. Cyto-genotoxicity assessment of potential radioprotector, 3,3'-diselenodipropionic acid (DSePA) in Chinese Hamster Ovary (CHO) cells and human peripheral blood lymphocytes.

    PubMed

    Chaurasia, Rajesh Kumar; Balakrishnan, Sreedevi; Kunwar, Amit; Yadav, Usha; Bhat, Nagesh; Anjaria, Kshiti; Nairy, Rajesha; Sapra, Balvinder Kaur; Jain, Vimal Kumar; Priyadarsini, K Indira

    2014-11-01

    Our previous study showed that 3,3'-diselenodipropionic acid (DSePA), a simple, stable, and water-soluble organoselenium exhibiting glutathione peroxidase (GPx)-like activity offered good radioprotection under in vitro and in vivo conditions. Herein, we investigated the anti-genotoxic effect of DSePA in model cellular systems such as Chinese Hamster Ovary (CHO) cell line and human peripheral lymphocytes after exposure to γ-radiation. The measurements on the induction of γ-H2AX foci and micronuclei frequency in the cell nuclei indicated that pretreatment with DSePA significantly prevented the radiation induced DNA damage or genotoxicity and subsequent cytotoxicity without exerting its own toxicity. The maximum protective effect of DSePA was seen at a pre-treatment concentration of 3 μg/ml. The mechanistic investigations in CHO cells revealed that DSePA pretreatment prevented the radiation induced ROS generation, lipid peroxidation and subsequent apoptosis in these cells. Further, it was seen to augment the mRNA expressions of GPx2 significantly and GPx4 marginally without causing much change in the total GPx activity after radiation exposure. These results suggested the roles of GPx2 and GPx4 in DSePA mediated radioprotection. In conclusion our results confirm the nongenotoxic nature of the DSePA and validate its radioprotective efficacy and mechanisms of action in model cellular systems. PMID:25440905

  7. Use of a transfected and amplified Drosophila heat shock promoter construction for inducible production of toxic mouse c-myc proteins in CHO cells

    SciTech Connect

    Wurm, F.M.; Gwinn, K.A.; Papoulas, O.; Pallavicini, M.; Kingston, R.E.

    1987-07-24

    After transfection and selection with methotrexate, CHO cell lines were established which contained up to 2000 copies of an expression vector for c-myc protein. The vector contained the Drosophila heat shock protein 70 (hsp70) promoter fused with the coding region of the mouse c-myc gene. Incubation of cells for up to 3 hours at 43/sup 0/C resulted in at least a 100-fold induction of recombinant c-myc mRNA. When cells were shifted back to 37/sup 0/C, within 1 to 4 hours, this RNA was translated into protein to yield about 250 ..mu..g per 10/sup 9/ cells. Cells died a few hours later, suggesting that high concentrations of intracellular c-myc are cytotoxic. 47 refs., 5 figs.

  8. Phenotypic expression time of mutagen-induced 6-thioguanine resistance in Chinese hamster ovary cells (CHO/HGPRT system): expression in division-arrested cell cultures

    SciTech Connect

    O'Neill, J.P.; Machanoff, R.; Hsie, A.W.

    1982-01-01

    The phenotypic expression time of ethyl methanesulfonate (EMS) induced 6-thioguanine-resistant mutants was studied with Chinese hamster ovary cells in culture (CHO/HGPRT system). After mutagen treatment of exponential phase cultures, the cells were maintained either in the exponential phase through subculture in medium containing 5% dialyzed fetal bovine serum (FBS) or in a nondividing viable state by use of medium containing 0-1% dialyzed FBS. The time course of expression of the 6-thioguanine-resistant phenotype was similar with both exponential phase division-arrested cultures showing maximum expression by 9 days after mutagen event is fixed, the expression of the mutant phenotype does not require continued cell division since it occurs in division-arrested cultures. These results also suggest that both dilution of pre-existing hypoxanthine-guanine phosphoribosyl transferase (HGPRT) enzyme by cell division and turnover by protein degradation are involved in the phenotypic expression. These results separate genetic damage and phenotypic expression in a temporal sense, and point out the need to consider the mechanisms responsible for each process involved in the induction and expression of mutations.

  9. Comparison of serum free light chain and urine electrophoresis for the detection of the light chain component of monoclonal immunoglobulins in light chain and intact immunoglobulin multiple myeloma

    PubMed Central

    Dejoie, Thomas; Attal, Michel; Moreau, Philippe; Harousseau, Jean-Luc; Avet-Loiseau, Herve

    2016-01-01

    Response criteria for multiple myeloma are based upon changes in monoclonal protein levels quantified using serum and/or urine protein electrophoresis. The latter lacks sensitivity at low monoclonal protein levels and since 2001, the serum free light chain test has been available and its clinical utility proven, yet guidelines have not recommended it as a replacement for urine assessment. Herein we evaluated responses using serum free light chain measurements and serum and urine electrophoresis after 2 and 4 cycles of therapy and after stem cell transplantation in 25 light chain and 157 intact immunoglobulin myeloma patients enrolled in the IFM 2007-02 MM trial. All 25 light chain patients had measurable disease by serum free light chain and urine methods at presentation. By contrast 98 out of 157 intact immunoglobulin patients had measurable disease by serum free light chain compared to 55 out of 157 by urine electrophoresis. In all patients there was substantial agreement between predicate (serum/urine protein electrophoresis) and test (serum protein electrophoresis and serum free light chain) methods for response assessment (Weighted Kappa=0.83). Urine immunofixation became negative in 47% light chain and 43% intact immunoglobulin patients after 2 cycles of therapy. At this time the serum free light chain ratio normalised in only 11% and 27% patients, respectively. In summary we found good agreement between methods for response assessment, but the serum free light chain test provided greater sensitivity than urine electrophoresis for monitoring. To our knowledge this is the first report comparing both methods for response assignment based on the International Myeloma Working Group guidelines. PMID:26635032

  10. Optimization of gene delivery methods in Xenopus laevis kidney (A6) and Chinese hamster ovary (CHO) cell lines for heterologous expression of Xenopus inner ear genes.

    PubMed

    Ramirez-Gordillo, Daniel; Trujillo-Provencio, Casilda; Knight, V Bleu; Serrano, Elba E

    2011-10-01

    The Xenopus inner ear provides a useful model for studies of hearing and balance because it shares features with the mammalian inner ear, and because amphibians are capable of regenerating damaged mechanosensory hair cells. The structure and function of many proteins necessary for inner ear function have yet to be elucidated and require methods for analysis. To this end, we seek to characterize Xenopus inner ear genes outside of the animal model through heterologous expression in cell lines. As part of this effort, we aimed to optimize physical (electroporation), chemical (lipid-mediated; Lipofectamine™ 2000, Metafectene® Pro), and biological (viral-mediated; BacMam virus Cellular Lights™ Tubulin-RFP) gene delivery methods in amphibian (Xenopus; A6) cells and mammalian (Chinese hamster ovary (CHO)) cells. We successfully introduced the commercially available pEGFP-N3, pmCherry-N1, pEYFP-Tubulin, and Cellular Lights™ Tubulin-RFP fluorescent constructs to cells and evaluated their transfection or transduction efficiencies using the three gene delivery methods. In addition, we analyzed the transfection efficiency of a novel construct synthesized in our laboratory by cloning the Xenopus inner ear calcium-activated potassium channel β1 subunit, then subcloning the subunit into the pmCherry-N1 vector. Every gene delivery method was significantly more effective in CHO cells. Although results for the A6 cell line were not statistically significant, both cell lines illustrate a trend towards more efficient gene delivery using viral-mediated methods; however the cost of viral transduction is also much higher. Our findings demonstrate the need to improve gene delivery methods for amphibian cells and underscore the necessity for a greater understanding of amphibian cell biology. PMID:21959846