Dimethyl sulfoxide restores contact inhibition-induced growth arrest and inhibits cell density-dependent apoptosis in hamster cells

Optimum blue light exposure: a means to increase cell-specific productivity in Chinese hamster ovary cells

Research for biopharmaceutical production processes with mammalian cells steadily aims to enhance the cell-specific productivity as a means for optimizing total productivities of bioreactors. Whereas current technologies such as pH, temperature, and osmolality shift require modifications of the cultivation medium, the use of optogenetic switches in recombinant producer cells might be a promising contact-free alternative. However, the proper application of optogenetically engineered cells requires a detailed understanding of basic cellular responses of cells that do not yet contain the optogenetic switches. The knowhow of ideal light exposure to enable the optimum use of related approaches is missing so far. Consequently, the current study set out to find optimum conditions for IgG1 producing Chinese hamster ovary (CHO) cells which were exposed to blue LED light. Growth characteristics, cell-specific productivity using enzyme-linked immunosorbent assay, as well as cell cycle distribution using flow cytometry were analyzed. Whereas too harsh light exposure causes detrimental growth effects that could be compensated with antioxidants, a surprising boost of cell-specific productivity by 57% occurred at optimum high light doses. The increase coincided with an increased number of cells in the G1 phase of the cell cycle after 72 h of illumination. The results present a promising new approach to boost biopharmaceutical productivity of mammalian cells simply by proper light exposure without any further optogenetic engineering. KEY POINTS: • Blue LED light hinders growth in CHO DP-12 cells • Antioxidants protect to a certain degree from blue light effects • Illumination with blue LED light raises cell-specific productivity.

Factors influencing the success of cryopreserved parathyroid autotransplantation: A systematic review

Permanent hypoparathyroidism is a postoperative complication of thyroid and parathyroid surgery and can be cured by cryopreserved parathyroid autotransplantation (CPAT). However, due to the lack of unified and standardized guidelines, the limited ability of the parathyroid tissue itself to withstand cryopreservation, and some yet-to-be-defined processes or technologies, the success rate of cryopreserved parathyroid autotransplantation varies between institutions; it is low for some institutions and high for others. Due to the sparsity of data, views vary on which factors most influence the success rate of cryopreserved parathyroid autotransplantation. In this review, we analyzed the following probable influencing factors: ischemic period before cryopreservation; processes of cryopreservation and thawing, including freezing medium; freezing and thawing methods; duration of cryopreservation; examination of the graft before transplantation; graft site; mass of transplanted tissue fragments; blood calcium level; and the evaluation criteria for cryopreserved parathyroid autotransplantation success. Although the effects of these factors are debatable, we hypothesized that examining them in the above-given order to determine whether they affect the success rate of cryopreserved parathyroid autotransplantation could be beneficial to maximizing the success rate. Our findings led us to conclude that cryopreserved parathyroid autotransplantation operations should be standardized. Standardized guidelines for cryopreserved parathyroid autotransplantation that include such factors as ischemic period time, freezing and thawing methods, and recipient status should be established based on a comprehensive analysis of these factors.

Recent advances in the production of recombinant factor IX: bioprocessing and cell engineering

Appropriate treatment of Hemophilia B is vital for patients' quality of life. Historically, the treatment used was the administration of coagulation Factor IX derived from human plasma. Advancements in recombinant technologies allowed Factor IX to be produced recombinantly. Successful recombinant production has triggered a gradual shift from the plasma derived origins of Factor IX, as it provides extended half-life and expanded production capacity. However, the complex post-translational modifications of Factor IX have made recombinant production at scale difficult. Considerable research has therefore been invested into understanding and optimizing the recombinant production of Factor IX. Here, we review the evolution of recombinant Factor IX production, focusing on recent developments in bioprocessing and cell engineering to control its post-translational modifications in its expression from Chinese Hamster Ovary (CHO) cells.

Wnt Signaling Inhibits High-Density Cell Sheet Culture Induced Mesenchymal Stromal Cell Aging by Targeting Cell Cycle Inhibitor p27

Mesenchymal stromal cell senescence and apoptosis have been identified as critical molecular hallmarks in aging. In this study, we used stromal cell sheet culture as an in vitro model to study the progressive changes of cellular senescence, apoptosis and underlying mechanism in Wnt3a treated cells. Our results showed fresh bone marrow mesenchymal stromal cells (BMSCs) become senescent and undergo apoptosis with increased inflammatory profile and Reactive Oxygen Species (ROS) in high-density cell sheet cultures. The gene expression level of senescence related proteins and key regulators of apoptosis in cell sheet cultures was significantly increased in older BMSCs at Days 4 and 7 cultures compared with younger cells at Day 1 cultures. More importantly, Wnt signaling activation significantly reduced senescence in cell sheet cultures by direct regulation of cell cycle inhibitor p27. This study not only characterized the cellular and molecular features of aging stromal cells in short-term cell sheet cultures, but also identified the downstream target responsible for Wnt inhibition of cell senescence.

Notch signaling regulates cell density-dependent apoptosis of NIH 3T3 through an IL-6/STAT3 dependent mechanism

Apoptosis is a physiological process that plays a critical maintenance role in cellular homeostasis. Previous reports have demonstrated that cells undergo apoptosis in a cell density-dependent manner, which is regulated, in part, by signal transducers and activators of transcription (STAT) 3. The molecular mechanisms regulating cell density-dependent apoptosis, however, has not been thoroughly investigated to date. Since Notch signaling is activated via direct cell-to-cell contact and plays a pivotal role in cell fate decisions, we examined the role of Notch signaling in cell density-dependent apoptosis of mouse embryonic fibroblasts NIH 3T3 cells. With the increase in cell density, IL-6 expression was induced, which was necessary for STAT3 activation as well as apoptosis regulation. Notch signaling was also activated in a cell-density dependent manner. Blocking Notch signaling either through siRNA-mediated targeting of Jagged1 expression or γ-secretase inhibitor treatment demonstrated that Notch signaling activation was necessary for IL-6 induction. Constitutive activation of Notch signaling via the overexpression of Notch1 intracellular domain was sufficient for the induction of IL-6, which was mediated via direct transcriptional activation. Taken together, our study indicates that Notch signaling regulates cell density-dependent apoptosis through IL-6/STAT3-dependent mechanism. Consequently, Notch signaling might represent a novel therapeutic target in diseases characterized by dysregulated apoptosis.

Dominance of Saccharomyces cerevisiae in alcoholic fermentation processes: role of physiological fitness and microbial interactions

Winemaking, brewing and baking are some of the oldest biotechnological processes. In all of them, alcoholic fermentation is the main biotransformation and Saccharomyces cerevisiae the primary microorganism. Although a wide variety of microbial species may participate in alcoholic fermentation and contribute to the sensory properties of end-products, the yeast S. cerevisiae invariably dominates the final stages of fermentation. The ability of S. cerevisiae to outcompete other microbial species during alcoholic fermentation processes, such as winemaking, has traditionally been ascribed to its high fermentative power and capacity to withstand the harsh environmental conditions, i.e. high levels of ethanol and organic acids, low pH values, scarce oxygen availability and depletion of certain nutrients. However, in recent years, several studies have raised evidence that S. cerevisiae, beyond its remarkable fitness for alcoholic fermentation, also uses defensive strategies mediated by different mechanisms, such as cell-to-cell contact and secretion of antimicrobial peptides, to combat other microorganisms. In this paper, we review the main physiological features underlying the special aptitude of S. cerevisiae for alcoholic fermentation and discuss the role of microbial interactions in its dominance during alcoholic fermentation, as well as its relevance for winemaking.

Hepatitis c virus genotype 4 replication in the hepatocellular carcinoma cell line HepG2/C3A

BACKGROUND/AIMS

The lack of a reliable cell culture system allowing persistent in vitro hepatitis C virus (HCV) propagation is still restraining the search for novel antiviral strategies. HepG2 cells transfection with HCV allows for viral replication. However, the replication is weak presumably because of HepG2 lack of miRNA-122, which is essential for viral replication. Other agents such as polyethylene glycol (PEG) and dimethyl sulfoxide (DMSO) have been shown to increase the efficiency of infection with other viruses. This study included comparison of HCV genotype 4 5'UTR and core RNA levels and HCV core protein expression at different time intervals in the absence or presence of PEG and/or DMSO postinfection.

MATERIALS AND METHODS

We used serum with native HCV particles in infecting HepG2 cells in vitro. HCV replication was assessed by reverse transcriptase polymerase chain reaction for detection of HCV RNA and immunofluorescence and flow cytometry for detection of HCV core protein.

RESULTS

HCV 5'UTR and core RNA expression was evident at different time intervals after viral infection, especially after cells were treated with PEG. HCV core protein was also evident at different time intervals using both immunofluorescence and flow cytometry. PEG, not DMSO, has increased the HCV core protein expression in the treated cells, similar to its effect on viral RNA expression.

CONCLUSIONS

These expression profiles suggest that the current model of cultured HepG2 cells allows the study of HCV genotype 4 replication and different stages of the viral life cycle.

Cytotoxicity of dimethyl sulfoxide (DMSO) in direct contact with odontoblast-like cells

OBJECTIVES

To evaluate the cytotoxicity of dimethyl sulfoxide (DMSO) on the repair-related activity of cultured odontoblast-like MDPC-23 cells.

METHODS

Solutions with different concentrations of DMSO (0.05, 0.1, 0.3, 0.5 and 1.0 mM), diluted in culture medium (DMEM), were placed in contact with MDPC-23 cells (5 × 104 cells/cm(2)) for 24 h. Eight replicates (n = 8) were prepared for each solutions for the following methods of analysis: violet crystal dye for cell adhesion (CA), quantification of total protein (TP), alizarin red for mineralization nodules formation (MN) and cell death by necrosis (flow cytometry); while twelve replicates (n = 12) were prepared for viable cell number (Trypan Blue) and cell viability (MTT assay). Data were analyzed by ANOVA and Tukey or Kruskal-Wallis and Mann-Whitney's tests (p < 0.05).

RESULTS

Cell viability, adhesion and percentage of cell death by necrosis were not affected by DMSO at any concentration, with no statistical significant difference among the groups. A significant reduction in total protein production was observed for 0.5 and 1.0 mM of DMSO compared to the control while increased mineralized nodules formation was seen only for 1.0 mM DMSO.

SIGNIFICANCE

DMSO caused no or minor cytotoxic effects on the pulp tissue repair-related activity of odontoblast-like cells.

Toxicity of functional nano-micro zinc oxide tetrapods: impact of cell culture conditions, cellular age and material properties

With increasing production and applications of nanostructured zinc oxide, e.g., for biomedical and consumer products, the question of safety is getting more and more important. Different morphologies of zinc oxide structures have been synthesized and accordingly investigated. In this study, we have particularly focused on nano-micro ZnO tetrapods (ZnO-T), because their large scale fabrication has been made possible by a newly introduced flame transport synthesis approach which will probably lead to several new applications. Moreover, ZnO-T provide a completely different morphology then classical spherical ZnO nanoparticles. To get a better understanding of parameters that affect the interactions between ZnO-T and mammalian cells, and thus their biocompatibility, we have examined the impact of cell culture conditions as well as of material properties on cytotoxicity. Our results demonstrate that the cell density of fibroblasts in culture along with their age, i.e., the number of preceding cell divisions, strongly affect the cytotoxic potency of ZnO-T. Concerning the material properties, the toxic potency of ZnO-T is found to be significantly lower than that of spherical ZnO nanoparticles. Furthermore, the morphology of the ZnO-T influenced cellular toxicity in contrast to surface charges modified by UV illumination or O₂ treatment and to the material age. Finally, we have observed that direct contact between tetrapods and cells increases their toxicity compared to transwell culture models which allow only an indirect effect via released zinc ions. The results reveal several parameters that can be of importance for the assessment of ZnO-T toxicity in cell cultures and for particle development.

A simple tool to improve pluripotent stem cell differentiation

We develop a method to overcome previously documented restrictions on the differentiation propensities of pluripotent stem cells. Culturing pluripotent stem cells in dimethylsulfoxide (DMSO) activates the retinoblastoma protein, increases the proportion of cells in the early G1 phase of the cell cycle, and subsequently improves their competency for directed differentiation into multiple lineages in more than 25 stem cell lines. DMSO treatment also promotes terminal differentiation into functional derivatives.

The threonine protease activity of testes-specific protease 50 (TSP50) is essential for its function in cell proliferation

BACKGROUND

Testes-specific protease 50 (TSP50), a newly discovered threonine enzyme, has similar amino acid sequences and enzymatic structures to those of many serine proteases. It may be an oncogene. TSP50 is up-regulated in breast cancer epithelial cells, and ectopic expression of TSP50 in TSP50-deficient Chinese hamster ovary (CHO) cells has been found to promote cell proliferation. However, the mechanisms by which TSP50 exerts its growth-promoting effects are not yet fully understood.

METHODOLOGY/PRINCIPAL FINDINGS

To delineate whether the threonine protease activity of TSP50 is essential to its function in cell proliferation, we constructed and characterized a mutant TSP50, called TSP50 T310A, which was identified as a protease-dead mutant of TSP50. By a series of proliferation analyses, colony formation assays and apoptosis analyses, we showed that T310A mutation significantly depresses TSP50-induced cell proliferation in vitro. Next, the CHO stable cell line expressing either wild-type or T310A mutant TSP50 was injected subcutaneously into nude mice. We found that the T310A mutation could abolish the tumorigenicity of TSP50 in vivo. A mechanism investigation revealed that the T310A mutation prevented interaction between TSP50 and the NF-κBIκBα complex, which is necessary for TSP50 to perform its function in cell proliferation.

CONCLUSION

Our data highlight the importance of threonine 310, the most critical protease catalytic site in TSP50, to TSP50-induced cell proliferation and tumor formation.

Enhanced expression of recombinant human cyclooxygenase 1 from stably-transfected Drosophila melanogaster S2 cells by dimethyl sulfoxide is mediated by up-regulation of nitric oxide synthase and transcription factor Kr-h1

Recombinant human cyclooxygenase 1 (COX-1) was expressed from stably-transfected Drosophila melanogaster S2 (S2) cells. DMSO improved the expression of recombinant COX-1 by 180 %. DMSO increased the expression of nitric oxide synthase (NOS) at both the RNA and protein levels; NOS expression was closely correlated with the synthesis of recombinant COX-1 mRNA in stably-transfected S2 cells. DMSO also induced the gene encoding Kr-h1 which binds to the CACCC element of the metallothionein promoter to enhance the expression of recombinant COX-1. Therefore, DMSO improves the expression of recombinant COX-1 via NOS and/or the transcription factor Kr-h1.

High cell density attenuates reactive oxygen species: implications for in vitro assays

In vitro cell-based assays are an essential and universally used step in elucidation of biological processes as well as in drug development. However, results obtained depend on the validity of protocols used. This statement certainly pertains to in vitro assays of oxidative stress. The holy grail of in vitro models is reliability and predictability of outcomes that relate to a single variable like addition of hydrogen peroxide or xanthine oxidase. Without such validated outcomes, comparison of results among different laboratories is not possible. Achieving this goal requires a thorough understanding of the complex interplay between the cells, their environment, and the experimental assays. Furthermore, as this knowledge is attained, it must be disseminated and used to update and standardize existing protocols. Here, we confirm and extend the effect of pyruvate and cell density on in vitro oxidative stress assays. Cell viability was assessed using a colorimetric assay measuring the reduction of a tetrazolium salt (XTT) into a colored formazan dye. Extracellular hydrogen peroxide concentrations were measured using the foxp3 assay. We confirmed a previously reported finding that pyruvate, a common ingredient in cell culture media, acts as an extracellular scavenger of reactive oxygen species. We also demonstrated that cell density directly correlates with resistance to oxidative stress in tissue culture. It is theorized that the protective effect due to cell density predominantly relates to intracellular factors such as reduced glutathione and extracellular factors such as catalase.

Development and improvement of a serum-free suspension process for the production of recombinant adenoviral vectors using HEK293 cells

Human Embryonic Kidney 293 (HEK293) cells were adapted into a serum-free suspension medium through steps of gradual serum weaning for the production of adenoviral (AdV) gene therapy vectors. The presence of sodium heparin in the medium formulation reduced cell clumping dramatically in suspension culture. The adapted cells were ready to grow either in serum-containing medium as an attached culture or in serum-free medium in suspension culture. A scalable production process was developed in shake flasks and was then evaluated in stirred tank bioreactors. This process includes a growth phase in batch-mode followed by a production phase involving medium perfusion and supplementation. Fortification with calcium chloride post viral inoculation resulted in an increase in virus production by at least one fold. Addition of stimulating agents such as sodium butyrate, N-acetyl-L-cysteine (NAC), dimethyl sulfoxide(DMSO), or ethyl alcohol post infection was shown to further improve virus production in a dose-dependent manner. The serum-free suspension process described here should be suitable for the manufacturing of other E1-deleted AdV vectors and could potentially be used for the production of recombinant proteins by HEK293 cells.

ATR (ataxia telangiectasia mutated- and Rad3-related kinase) is activated by mild hypothermia in mammalian cells and subsequently activates p53

In vitro cultured mammalian cells respond to mild hypothermia (27-33 °C) by attenuating cellular processes and slowing and arresting the cell cycle. The slowing of the cell cycle at the upper range (31-33 °C) and its complete arrest at the lower range (27-28 °C) of mild hypothermia is effected by the activation of p53 and subsequent expression of p21. However, the mechanism by which cold is perceived in mammalian cells with the subsequent activation of p53 has remained undetermined. In the present paper, we report that the exposure of Chinese-hamster ovary-K1 cells to mildly hypothermic conditions activates the ATR (ataxia telangiectasia mutated- and Rad3-related kinase)-p53-p21 signalling pathway and is thus a key pathway involved in p53 activation upon mild hypothermia. In addition, we show that although p38MAPK (p38 mitogen-activated protein kinase) is also involved in activation of p53 upon mild hypothermia, this is probably the result of activation of p38MAPK by ATR. Furthermore, we show that cold-induced changes in cell membrane lipid composition are correlated with the activation of the ATR-p53-p21 pathway. Therefore we provide the first mechanistic detail of cell sensing and signalling upon mild hypothermia in mammalian cells leading to p53 and p21 activation, which is known to lead to cell cycle arrest.

DMSO modulates the pathway of apoptosis triggering

We demonstrate here that distribution of caspase-9 influences the pathway of apoptosis triggering, since caspase-9 is activated efficiently only when it is distributed solely in the cytosol. Caspase-9 moves to the nuclei in a response to cell stress during isolation of primary hepatocytes; this is called preapoptotic cell stress response. The dimethyl sulfoxide (DMSO) treatment cannot prevent the migration of caspase-9 into the nuclei when it is added to primary hepatocytes immediately after isolation; however, it can trigger redistribution of caspase-9 from the nuclei into the cytosol when added 1 day post-isolation. This redistribution is temporary, since caspase-9 returns to the nuclei within 48 hours of DMSO treatment. Thereafter, some caspase-9 is retained in the nuclei of DMSO-treated hepatocytes for longer than in the nuclei of untreated hepatocytes. By measuring caspase activities, we demonstrate that the addition of DMSO to cell culture medium can temporarily normalize the susceptibility of hepatocytes for apoptosis triggering through the intrinsic pathway. DMSO contributes also to the prolonged pathway inactivation, i.e., by extending preapoptotic cell stress response. We propose that DMSO extends the survival of primary hepatocytes by modulating preapoptotic cell stress response, which could be exploited for extending the lifespan of other primary cell cultures.

An alternative mechanism for radioprotection by dimethyl sulfoxide; possible facilitation of DNA double-strand break repair

The radioprotective effects of dimethyl sulfoxide (DMSO) have been known for many years, and the suppression of hydroxyl (OH) radicals induced by ionizing radiation has been thought to be the main cause of this effect. However, the DMSO concentration used was very high, and might be toxic, in earlier studies. In the present study, we administered a lower, non-toxic concentration (0.5%, i.e., 64 mM) of DMSO before irradiation and examined its radioprotective effects. Colony formation assay and micronucleus assay showed significant radioprotective effects in CHO, but not in xrs5, which is defective in the repair function of DNA double-strand breaks. The levels of phosphorylated H2AX and the formation of 53BP1 foci 15 minutes after irradiation, which might reflect initial DNA double-strand breaks, in DMSO-treated CHO cells were similar to those in non-treated cells, suggesting that the radioprotective effects were not attributable to the suppression of general indirect action in the lower concentration of DMSO. On the other hand, 2 hours after irradiation, the average number of 53BP1 foci, which might reflect residual DNA double-strand breaks, was significantly decreased in DMSO-treated CHO cells compared to non-treated cells. The results indicated that low concentration of DMSO exerts radioprotective effects through the facilitation of DNA double-strand break repair rather than through the suppression of indirect action.

Enhanced Production of Monomeric Interferon-β by CHO Cells through the Control of Culture Conditions

The enhancement of recombinant protein expression of a transfected cell line is essential for the development of an efficient large-scale bioprocess. The effect of various media additives and temperature conditions were studied in an attempt to optimize protein production, stability, and protein glycosylation from a Chinese hamster ovary (CHO) cell line producing human beta-interferon (Hu-beta-IFN). We observed a decrease in the ELISA response of the glycoprotein in the later stages of batch cultures, which was attributed to molecular aggregation. Cells were subjected to various concentrations of glycerol, dimethyl sulfoxide (DMSO), and sodium butyrate (NaBu) in a variety of culture systems and conditions. The addition of both NaBu and DMSO resulted in higher specific productivities but reduced growth rates that resulted in a net reduction of interferon produced. Glycerol appeared to stabilize the secreted beta-IFN, resulting in reduced aggregation, despite a decrease in cell growth rate. Glycosylation analysis of isolated beta-IFN showed a time-dependent decrease in sialylation in batch culture that was ameliorated by the presence of glycerol. Low-temperature conditions (30 degrees C) had the greatest effect on productivity with a significant increase in beta-IFN titer as well as a reduction in the degree of molecular aggregation.

From single cells to tissue architecture-a bottom-up approach to modelling the spatio-temporal organisation of complex multi-cellular systems

Collective phenomena in multi-cellular assemblies can be approached on different levels of complexity. Here, we discuss a number of mathematical models which consider the dynamics of each individual cell, so-called agent-based or individual-based models (IBMs). As a special feature, these models allow to account for intracellular decision processes which are triggered by biomechanical cell-cell or cell-matrix interactions. We discuss their impact on the growth and homeostasis of multi-cellular systems as simulated by lattice-free models. Our results demonstrate that cell polarisation subsequent to cell-cell contact formation can be a source of stability in epithelial monolayers. Stroma contact-dependent regulation of tumour cell proliferation and migration is shown to result in invasion dynamics in accordance with the migrating cancer stem cell hypothesis. However, we demonstrate that different regulation mechanisms can equally well comply with present experimental results. Thus, we suggest a panel of experimental studies for the in-depth validation of the model assumptions.

Enhanced production of recombinant rabies virus glycoprotein (rRVGP) by Drosophila melanogaster S2 cells through control of culture conditions

Culture conditions that affect product quality are important to the successful operation and optimization of recombinant protein production. The objective of this study was to optimize culture conditions for growth of recombinant Drosophila melanogaster S2 cells (S2AcRVGP) in order to enhance the production of rRVGP. The addition of DMSO and glycerol to the medium and growth at a reduced temperature (22 degrees C) were the culture condition variations selected to be tested. Experimental cultures were first performed in serum-free Sf900 II medium in 250 ml Schott flasks. The most promising conditions identified in these experiments were also tested on a higher scale in a 3l bioreactor. In the Schott flasks experiments, all the changes in culture conditions resulted in an increase of rRVGP production. The protein concentration was 3.6-fold higher with addition of 1% DMSO and 1% glycerol and 9.3-fold higher when the cells were cultured at 22 degrees C instead of the standard 28 degrees C. The maximum concentration of rRVGP reached was 591 mug l(-1). In bioreactor experiments, with control of pH at 6.20 and DO at 50%, the reduced culture temperature (22 degrees C) was the strategy that promoted the highest glycoprotein production, 928 mug l(-1).

Proliferation control strategies to improve productivity and survival during CHO based production culture : A summary of recent methods employed and the effects of proliferation control in product secreting CHO cell lines

Chinese Hamster Ovary cells are the primary system for the production of recombinant proteins for therapeutic use. Protein productivity is directly proportional to viable biomass, viability and culture longevity of the producer cells and a number of approaches have been taken to optimise these parameters. Cell cycle arrest, particularly in G1 phase, typically using reduced temperature cultivation and nutritional control have been used to enhance productivity in production cultures by prolonging the production phase, but the mechanism by which these approaches work is still not fully understood. In this article, we analyse the public literature on proliferation control approaches as they apply to production cell lines with particular reference to what is known about the mechanisms behind each approach.

Gene transcription acceleration: main cause of hepatitis B surface antigen production improvement by dimethyl sulfoxide in the culture of Chinese hamster ovary cells

The production and specific productivity of hepatitis B surface antigen (HBsAg) in recombinant Chinese hamster ovary (CHO) cells were increased by 81% and threefold, respectively, when supplemented with 1.5% dimethyl sulfoxide (DMSO) in the culture medium. To investigate the mechanism of DMSO effect on HBsAg production improvement, HBsAg mRNA level was measured by real-time PCR. HBsAg mRNA was increased by about 1.5-fold at 1.5% DMSO. The increase could derive from the increase of HBsAg gene copy number, the improvement of HBsAg mRNA stability, or the acceleration of HBsAg gene transcription. It was found that HBsAg gene copy number was not significantly changed in the cells stimulated with DMSO. HBsAg mRNA stability of cells with DMSO treatment was also not obviously different from control, and the mRNA half-life of 5.58 h in the cells at 1.5% DMSO was comparable to that of 5.36 h in the control culture. DMSO resulted in 80% increase in HBsAg gene transcription activity assessed using a nuclear run-on transcription assay. It could be deduced that the acceleration of HBsAg gene transcription is the main cause of HBsAg production improvement.

Promotion of recombinant macrophage colony stimulating factor production by dimethyl sulfoxide addition in Chinese hamster ovary cells

A Chinese hamster ovary (CHO) cell line is the primary choice for the production of recombinant protein drugs with glycosylation modification. Recombinant protein productivity was enhanced by the addition of dimethyl sulfoxide (DMSO) in CHO cells. However, DMSO induced G0/G1 phase growth arrest and reduced cell growth rate. A two-stage process was developed to utilize the stimulatory effect of DMSO on recombinant protein production and mitigate the problem of growth inhibition in this study. In the first stage, cells are cultured without DMSO for a certain period in order to obtain a high cell density. Sequentially, DMSO is added to achieve a high specific productivity in the second stage. Using this approach, we found that by adding 1% DMSO after 24 h of growth, macrophage colony-stimulating factor (M-CSF) volumetric productivity is increased by 57% compared with the value obtained without the addition of DMSO.

Production of infectious hepatitis C virus by well-differentiated, growth-arrested human hepatoma-derived cells

Dimethyl sulfoxide (DMSO) has been shown to induce the differentiation of primary hepatocytes in vitro. When actively dividing poorly differentiated human hepatoma-derived (Huh7) cells were cultured in the presence of 1% DMSO, cells became cytologically differentiated and transitioned into a nondividing state, characterized by the induction of hepatocyte-specific genes. Moreover, these cells were highly permissive for acute hepatitis C virus (HCV) infection, and persistent long term infection of these cultures could also be achieved. As HCV naturally replicates in highly differentiated nondividing human hepatocytes, this system may more accurately mimic the conditions under which HCV replicates in vivo than previous models using poorly differentiated rapidly dividing hepatoma cells.

Apoptosis in murine lymphoid organs following intraperitoneal administration of dimethyl sulfoxide (DMSO)

A significant increase in lymphocyte apoptosis was detected by the TUNEL method in the thymus, spleen, and Peyer's patches (PP) following intraperitoneal (i.p.) administration of dimethyl sulfoxide (DMSO) (treatment, n = 47; control, n = 8). Interestingly, administration of low doses of DMSO caused apoptosis in only the PP, and suggested that i.p. administration of DMSO induced apoptosis for each lymphoid organ in a dose dependent manner. Moreover, in the early stage during the apoptotic change, a characteristic localization of lymphocytes undergoing apoptosis was observed. Briefly, early apoptosis occurred predominantly in the cortical mid-zone of the thymus, white pulp of the spleen, and germinal centers of PP. With increased time following administration, however, lymphocytes throughout lymphoid tissues, independent of characteristic localization during the early stage, seemed to undergo apoptosis, resulting in the severe loss of lymphocytes. In fact, the relative spleen weight significantly decreased at 24 h following DMSO administration (n = 7; P < 0.001 versus 8 control mice). Taken together, these results showed for the first time that the in vivo administration of DMSO to mice caused apoptosis in lymphoid organs, and also demonstrated that the apoptotic behavior varied between different lymphoid organs.

Evaluation of Proliferation and Functional Differentiation of LLC-PK1 Cells on Porous Polymer Membranes for the Development of a Bioartificial Renal Tubule Device

To develop a bioartificial renal tubule system using renal tubular cells and porous polymer membrane hollow fibers, long-term maintenance of a confluent monolayer and the functionally differentiated condition of cells is essential. We examined the proliferation and functional differentiation of LLC-PK1 (Lewis-lung cancer porcine kidney 1) cells on two types of membranes: polysulfone and cellulose acetate. Cell proliferation was significantly higher on the polysulfone membrane than on the cellulose acetate membrane, and was enhanced by coating the membranes with various extracellular matrices. Confluent monolayer formation of cells was observed on matrix-coated polysulfone membrane but not on matrix-coated cellulose acetate membrane within 1 week. Cell proliferation continued for 3 weeks after confluent monolayer formation. Messenger RNA (mRNA) expression of glucose transporters, indicators of the functional differentiation of the LLC-PK1 cells, was observed in the polysulfone and cellulose acetate membrane groups, but was not observed in the nonporous polystyrene plate group under subconfluent conditions. Expression of glucose transporters mRNA was maintained for 3 weeks after confluent monolayer formation. Polysulfone membrane is more suitable than cellulose acetate membrane for a bioartificial renal tubule system with regard to LLC-PK1 cell proliferation. Extracellular matrix coating of the membrane further improves cell proliferation.

NF-kappaB and NOS may play a role in human RPMI-8402 cell apoptosis

Apoptosis is a fundamental process that is required for the normal development and functioning of the immune system. It can be induced in different ways depending on cell type and acquired signal. Since the NF-kappaB transcription factor complex is believed to be involved in nitric oxide-induced apoptosis, the aim of this study was to investigate NF-kappaB and nitric oxide synthase (NOS) activity during dimethyl sulphoxide (DMSO)-dependent cell death of RPMI-8402 human pre-T cells. Our results show that NF-kappaB activation is associated with a significant up-regulation of NOS activity and induction of apoptosis. Furthermore, the inhibition and reversal of these effects by parthenolide treatment or DMSO removal indicate that these molecules are directly involved in the progression of cell death.

An erythroid differentiation-specific splicing switch in protein 4.1R mediated by the interaction of SF2/ASF with an exonic splicing enhancer

Protein 4.1R is a vital component of the red blood cell membrane cytoskeleton. Promotion of cytoskeletal junctional complex stability requires an erythroid differentiation stage-specific splicing switch promoting inclusion of exon 16 within the spectrin/actin binding domain. We showed earlier that an intricate combination of positive and negative RNA elements controls exon 16 splicing. In this report, we further identified 3 putative exonic splicing enhancers within exon 16 and investigated the function of the sequence CAGACAT in the regulation of exon 16 splicing. Mutation of these sequences leads to increased exclusion of exon 16 in both in vivo and in vitro splicing assays, indicating that CAGACAT is a functional exonic splicing enhancer. UV cross-linking further detects an approximately 33-kDa protein that specifically binds to the CAGACAT-containing transcript. An anti-SF2/ASF antibody specifically immunoprecipitates the approximately 33-kDa protein. Furthermore, SF2/ASF stimulates exon 16 inclusion in both in vitro complementation assays and minigene-transfected mouse erythroleukemia cells (MELCs). Finally, SF2/ASF expression is up-regulated and correlates with exon 16 inclusion in differentiated MELCs. These results suggest that increased splicing factor 2/alternative splicing factor (SF2/ASF) expression in differentiated mouse erythroleukemia mediates a differentiation stage-specific exon 16 splicing switch through its interaction with the exonic splicing enhancer.

Purification and characterization of recombinant murine sulfamidase

Mucopolysaccharidosis type IIIA (MPS IIIA) is a lysosomal storage disorder caused by a deficiency in the lysosomal enzyme sulfamidase, which is required for the degradation of heparan sulfate. The disease is characterized by neurological dysfunction but relatively mild somatic manifestations. A naturally occurring mouse model to MPS IIIA exhibits a similar disease progression to that observed in patients. Disease in the mice results from a base substitution at codon 31 in the sulfamidase gene, altering an aspartic acid to an asparagine (D31N). This aspartic 31 is involved in binding of the divalent metal ion needed for catalytic function, and as such reduces the specific activity of the enzyme to about 3% of that of wild-type. The mutant protein has decreased stability and shows increased degradation over a 24 h chase period when compared to wild-type mouse sulfamidase. Mouse sulfamidase that was purified using a two-step ion exchange procedure was shown to have similar kinetic properties to that of purified human sulfamidase. Recombinant murine sulfamidase was able to correct the storage phenotype of MPS IIIA fibroblasts after endocytosis via the mannose-6-phosphate receptor.

Serofendic acid, a sulfur-containing diterpenoid derived from fetal calf serum, attenuates reactive oxygen species-induced oxidative stress in cultured striatal neurons

We previously identified a novel endogenous substance, serofendic acid, from a lipophilic extract of fetal calf serum. Serofendic acid protects cultured cortical neurons against the cytotoxicity of glutamate and nitric oxide. Here, we reported the protective effect of serofendic acid on reactive oxygen species-induced oxidative stress using primary rat striatal cultures. In addition, we compared the neuroprotective effect and the radical-scavenging activity of serofendic acid with those of dimethyl sulfoxide (DMSO), because serofendic acid possesses a DMSO structure. Paraquat caused neuronal death, which was inhibited by a cell-permeable superoxide dismutase (SOD) mimetic, Mn(III)tetrakis(4-benzoic acid)porphyrin chloride (Mn-TBAP); a cell-permeable SOD/catalase mimetic, EUK-134 [manganese 3-methoxy N,N'-bis(salicylidene)ethylenediamine chloride]; and a ferrous ion chelator, 2,2'-dipyridyl, in rat striatal cultures. Serofendic acid (10-100 microM) suppressed the neurotoxicity of paraquat, whereas DMSO (10-100 microM) did not. By contrast, higher concentrations (30-300 mM) of DMSO ameliorated the paraquat-induced cell death. Furthermore, H(2)O(2) induced neurotoxicity, which was prevented by EUK-134 and 2,2'-dipyridyl. Serofendic acid (10-100 microM) also protected striatal neurons against the H(2)O(2)-induced toxicity. Higher concentrations (30-300 mM) of DMSO ameliorated H(2)O(2)-induced neuronal death, whereas lower concentrations (10-100 microM) did not. Electron spin resonance spectrometry with a spin-trapping technique revealed that serofendic acid and DMSO had approximately the same ability to inhibit the formation of the hydroxyl radical (.OH). These results suggest that the.OH-scavenging activity of serofendic acid is attributable to its DMSO structure and that the remaining components such as the atisane structure play an important role in eliciting neuroprotection at a concentration range of 10 to 100 microM.

Dimethyl Sulfoxide and Oxidative Stress On Cultures of Human Keratinocytes

Objectives:

The aim of the present study was to examine the protective action of the antioxidant dimethyl sulfoxide (DMSO) against the oxidative stress on keratinocyte cultures caused by glucose deprivation and hypoxia, using the concentration of malonyl dialdehyde existing in the cell culture as an indicator of the oxidative stress level.

Methods:

Eighty flasks with cultured human keratinocytes in a confluent layer were divided into eight groups, including the following: culture medium with and without glucose, culture medium with and without the addition of DMSO, culture medium subjected and not subjected to hypoxia, and culture medium with a combination of these factors.

Results and Conclusions:

The statistical analysis of the results showed that DMSO proved to be an effective agent against the oxidative stress on cultures of keratinocytes under the experimental conditions studied.

Wogonin suppresses cellular proliferation and expression of monocyte chemoattractant protein 1 in Peyronie's plaque-derived cells

OBJECTIVE

To test the effect of wogonin on cellular proliferation and expression of monocyte chemoattractant protein 1 (MCP-1) in cells derived from normal and diseased tunica albuginea (TA), as related to Peyronie's disease (PD).

MATERIALS AND METHODS

Cells with characteristics of fibroblasts were isolated from three tissue sources. Those from the plaque of patients with PD were designated as P cells, those from the adjacent, normal-appearing tissue as C cells, and those from the TA of patients without PD as N cells. These cells were treated with wogonin at doses of 0, 10, 20 and 40 micromol/L for 24 h or treated at a fixed dose of 40 micromol/L for 1, 8 and 24 h. Cell proliferation was assayed with a commercial kit, MCP-1 mRNA expression by reverse transcription-polymerase chain reaction, and secreted MCP-1 by enzyme-linked immunosorbent assay.

RESULTS

Wogonin suppressed cell proliferation in a dose-dependent manner; the effect was more pronounced against P cells at 8 and 24 h. Wogonin down-regulated MCP-1 mRNA expression, especially in P cells. Wogonin suppressed the level of secreted MCP-1 by 59-88%. P cells, which secreted far more MCP-1 than N and C cells at 1 h, were suppressed by 88%. C cells were the least suppressed at all three times.

CONCLUSIONS

Wogonin suppressed the proliferation, the expression of MCP-1 mRNA, and the expression of secreted MCP-1 in TA-derived cells. In most cases, the effect of wogonin was greatest against cells derived from the plaque. Wogonin appears to be a worthy candidate for preclinical trials in men with PD.

Simultaneous changes in the function and expression of beta 1 integrins during the growth arrest of poorly differentiated colorectal cells (LISP-1)

Cells usually lose adhesion and increase proliferation and migration during malignant transformation. Here, we studied how proliferation can affect the other two characteristics, which ultimately lead to invasion and metastasis. We determined the expression of beta 1 integrins, as well as adhesion and migration towards laminin-1, fibronectin, collagens type I and type IV presented by LISP-1 colorectal cancer cells exposed to 2.5% dimethyl sulfoxide (DMSO), an agent capable of decreasing proliferation in this poorly differentiated colorectal cell line. Untreated cells (control), as shown by flow cytometry and monoclonal antibodies, expressed alpha 2 (63.8 11.3% positive cells), alpha 3 (93.3 7.0%), alpha 5 (50.4 12.0%) and alpha 6 (34.1 4.9%) integrins but not alpha1, alpha 4, alpha v or 4. Cells adhered well to laminin-1 (73.4 6.0%) and fibronectin (40.0 2.0%) substrates but very little to collagens. By using blocking monoclonal antibodies, we showed that alpha 2, alpha 3 and alpha 6 mediated laminin-1 adhesion, but neither alpha 3 nor alpha 5 contributed to fibronectin adherence. DMSO arrested cells at G0/G1 (control: 55.0 2.4% vs DMSO: 70.7 2.5%) while simultaneously reducing alpha 5 (24.2 19%) and alpha 6 (14.3 10.8%) expression as well as c-myc mRNA (7-fold), the latter shown by Northern blotting. Although the adhesion rate did not change after exposure to DMSO, alpha 3 and alpha 5 played a major role in laminin-1 and fibronectin adhesion, respectively. Migration towards laminin-1, which was clearly increased upon exposure to DMSO (control: 6 2 cells vs DMSO: 64 6 cells), was blocked by an antibody against alpha 6. We conclude that the effects of DMSO on LISP-1 proliferation were accompanied by concurrent changes in the expression and function of integrins, consequently modulating adhesion/migration, and revealing a complex interplay between function/expression and the proliferative state of cells.

Viable Saccharomyces cerevisiae cells at high concentrations cause early growth arrest of non-Saccharomyces yeasts in mixed cultures by a cell-cell contact-mediated mechanism

The growth of Kluyveromyces thermotolerans and Torulaspora delbrueckii was examined in mixed cultures with Saccharomyces cerevisiae in YPD modified for wine fermentations. Although the three yeasts had similar maximum specific growth rates in these fermentations, K. thermotolerans and T. delbrueckii arrested growth earlier than S. cerevisiae, thereby obtaining lower stationary phase cell concentrations than S. cerevisiae. Various single and mixed culture fermentations with the three yeasts were carried out in order to find an explanation for this phenomenon. The early growth arrests of K. thermotolerans and T. delbrueckii were absent in single cultures of the two yeasts, and they seemed to be due neither to nutrient limitations nor to the presence of growth-inhibitory compounds. Rather, they seemed to be due to a cell-cell contact mechanism dependent on the presence of viable S. cerevisiae cells at high concentrations. These results contribute to an increased understanding of why K. thermotolerans and T. delbrueckii arrest growth before S. cerevisiae during wine fermentations.

The use of dimethylsulfoxide as a vehicle in cell culture experiments using ovarian carcinoma cell lines

Dimethylsulfoxide (DMSO) is a well-known solvent that is commonly used in the laboratory. We selected DMSO as the vehicle for an experiment designed to determine if several nonsteroidal anti-inflammatory agents inhibit the growth of Caov-3, OVCAR-3, and SK-OV-3 ovarian carcinoma cell lines. Using the tetrazolium conversion assay, however, we observed some variability in the number of cells present in each ovarian carcinoma cell line with varying concentrations of DMSO (10(-6)-10(-2) M) compared to medium alone. Similarly, when Caov-3, OVCAR-3, and SK-OV-3 cells were treated with 10(-4) M DMSO plus medium (Dulbecco's Modified Eagle Medium with 10% fetal bovine serum) and plated on coverslips, the total number of cells present in 60 random fields increased significantly (P < 0.0001) for each ovarian carcinoma cell line treated with DMSO compared to medium alone. Ethanol did not demonstrate such prominent effects on cellular growth. Our observations are important to consider when selecting an appropriate solvent, especially for growth inhibition studies using Caov-3, OVCAR-3, and SK-OV-3 cell lines.

Caspase activation in equine influenza virus induced apoptotic cell death

Equine influenza virus (EIV) is the leading cause of acute respiratory infection in horses worldwide. In recent years, the precise mechanism by which influenza infection kills host cells is being re-evaluated. In this report, we examined whether caspases, a group of intracellular proteases, are activated following EIV infection and contribute to EIV-mediated cell death. Western blotting analysis indicated that a nuclear target of caspase-3, poly(ADP-ribose) polymerase (PARP) was proteolytically cleaved in EIV-infected MDCK cells, but not in mock-infected cells. In comparison with caspase-3 specific inhibitor Ac-DEVD-CHO, a general caspase inhibitor Boc-D-FMK provided much stronger inhibition of EIV-induced cytopathic effect and apoptosis. Our results suggest that EIV may activate more than one caspase. Caspase activation and cleavage of its cellular targets may play a critical role in EIV-mediated cytotoxicity.

Dimethyl sulfoxide affects the selection of splice sites

Depending on the cell lines and cell types, dimethyl sulfoxide (Me2SO) can induce or block cell differentiation and apoptosis. Although Me2SO treatment alters many levels of gene expression, the molecular processes that are directly affected by Me2SO have not been clearly identified. Here, we report that Me2SO affects splice site selection on model pre-mRNAs incubated in a nuclear extract prepared from HeLa cells. A shift toward the proximal pair of splice sites was observed on pre-mRNAs carrying competing 5'-splice sites or competing 3'-splice sites. Because the activity of recombinant hnRNP A1 protein was similar when added to extracts containing or lacking Me2SO, the activity of endogenous A1 proteins is probably not affected by Me2SO. Notably, in a manner reminiscent of SR proteins, Me2SO activated splicing in a HeLa S100 extract. Moreover, the activity of recombinant SR proteins in splice site selection in vitro was improved by Me2SO. Polar solvents like DMF and formamide similarly modulated splice site selection in vitro but formamide did not activate a HeLa S100 extract. We propose that Me2SO improves ionic interactions between splicing factors that contain RS-domains. The direct impact of Me2SO on alternative splicing may explain, at least in part, the different and sometimes opposite effects of Me2SO on cell differentiation and apoptosis.

Purification and characterization of recombinant human lysosomal alpha-mannosidase

Lysosomal alpha-mannosidase (EC 3.2.1.24) is required in the degradation of the asparagine-linked carbohydrates of glycoproteins. Deficiency of this enzyme leads to the lysosomal storage disorder alpha-mannosidosis. As an initial step toward enzyme replacement therapy for alpha-mannosidosis, the human lysosomal alpha-mannosidase cDNA was cloned into the pcDNA 3.1 vector and expressed in Chinese hamster ovary cells. Dimethyl sulfoxide (DMSO) added to the cell culture media to induce growth arrest led to a 4-fold increase in the enzyme production, with an average yield of 3.2 mg L(-1) day(-1). alpha-Mannosidase was secreted as an active homodimer of a 130-kDa precursor that was proteolyzed into two polypeptides of 55 and 72 kDa during the subsequent purification of the enzyme. N-terminal sequence analysis of the purified enzyme revealed that the proteolysis occurred close to a cleavage site previously identified in the intracellular form of lysosomal alpha-mannosidase. Generation of monoclonal antibodies against the recombinant enzyme made it possible to develop a single-step immunoaffinity purification procedure for alpha-mannosidase. The immunoaffinity-purified enzyme which mainly consisted of the 130-kDa precursor, displayed specific activity and kinetics similar to those of the processed form. Recombinant alpha-mannosidase was taken up by cultured alpha-mannosidosis fibroblasts and was trafficked to the lysosomes via the mannose 6-phosphate pathway where it reduced the amounts of stored mannose-containing oligosaccharides.

Involvement of mitochondrial permeability transition and caspase-9 activation in dimethyl sulfoxide-induced apoptosis of EL-4 lymphoma cells

We observed that dimethyl sulfoxide (DMSO) induced apoptotic changes in the EL-4 murine lymphoma cell line and that effect was dependent on the concentration and time period. Incubating cells over a period of 18 h, 2.5% DMSO was found to induce sub-G1 peak in DNA histograms analyzed by flowcytometer and nucleosomal ladder formation in DNA gel electrophoresis. We also found down-regulation of Bcl-2, collapse of mitochondrial membrane potential (delta psi m) occurred following DMSO treatment, and release of cytochrome c from the mitochondria to cytosol. These observations suggest that DMSO converted its pro-apoptotic signal at the mitochondria. In the involvement of caspases, caspase-9 and -3, but not caspase-8, were found to be activated responding to DMSO treatment. Inhibitory experiments demonstrated that caspase cascade of mitochondrial apoptotic pathway was indispensable for DMSO-induced apoptosis. In the caspase cascade, caspase-9 was an upstream initiator and its primary signal could be transduced and amplified by caspase-3, -6 and -7. Kinetic study of these data showed mitochondrial dysfunction and caspase activation occurred at 12 h and apoptotic change of nuclear DNA at 18 h, providing another support for the transduction of DMSO pro-apoptotic signal via the mitochondrial pathway.