Treatment with certain DNA-damaging agents induce a complex cellular response comprising pertubation of cell cycle progression and/or apoptosis on proliferating mammalian cells. Our studies were focused on the cellular effects of nickel (II) acetate, DNA-damaging agent, on Chinese hamster ovary (CHO) cells. Fragmented DNAs were examined by agarose gel electrophoresis and cell cycle was determined by DNA flow cytometry using propidium iodide fluorescence. Apparent DNA laddering was observed in cells treated with 240 microM nickel (II) and increased with a concentration-dependent manner. Treatment of nickel (II) acetate resulted in apoptosis which was accompanied by G2/M cell accumulation. Proportion of CHO cells in G2/M phase was also significantly increased in cells exposed to at least 480 microM nickel (II) from 57.7% of cells in the G0/G1 phase, 34.7% in the S phase, and 7.6% in the G2/M1 phase for 0 microM nickel (II), to 58.6%, 14.5%, and 26.9% for 640 microM nickel (II). These findings suggest that nickel (II) can modulate cellular response through some common effectors involving in both apoptotic and cell cycle regulatory pathways.
Animal ; Apoptosis/drug effects* ; CHO Cells/drug effects* ; CHO Cells/cytology ; Cell Cycle/drug effects* ; DNA Fragmentation/drug effects ; Flow Cytometry ; G2 Phase/drug effects ; Hamsters ; Mitosis/drug effects ; Nickel/pharmacology*

Iron is an essential element for almost all living organisms. The possible role of iron for growth, adherence and cytotoxicity of Entamoeba histolytica was evaluated in this study. The absence of iron from TYI-S-33 medium stopped amebic growth in vitro. However, iron concentrations in the culture media of 21.4-285.6 microM did not affect the growth of the amebae. Although growth was not retarded at these concentrations, the adhesive abilities of E. histolytica and their cytotoxicities to CHO cell monolayer were correlated with iron concentration. Amebic adhesion to CHO cell monolayers was significantly reduced by low-iron (24.6 +/- 2.1%) compared with 62.7 +/- 2.8 and 63.1 +/- 1.4% of amebae grown in a normal-iron and high-iron media, respectively. E. histolytica cultured in the normal- and high-iron media destroyed 69.1 +/- 4.3% and 72.6 +/- 5.7% of cultured CHO cell monolayers, but amebae grown in the low-iron medium showed a significantly reduced level of cytotoxicity to CHO cells (2.8 +/- 0.2%). Addition of divalent cations other than iron to amebic trophozoites grown in the low-iron medium failed to restore levels of the cytotoxicity. However, when E. histolytica grown in low-iron medium were transferred to normal-iron medium, the amebae showed completely restored cytotoxicity within 7 days. The result suggests that iron is an important factor in the adherence and cytotoxicity of E. histolytica to CHO cell monolayer.
Animals ; CHO Cells ; Cell Adhesion/drug effects ; Cell Survival ; Cricetinae ; Cricetulus ; Entamoeba histolytica/*drug effects/*physiology ; Iron/*pharmacology

Iron is an essential element for almost all living organisms. The possible role of iron for growth, adherence and cytotoxicity of Entamoeba histolytica was evaluated in this study. The absence of iron from TYI-S-33 medium stopped amebic growth in vitro. However, iron concentrations in the culture media of 21.4-285.6 microM did not affect the growth of the amebae. Although growth was not retarded at these concentrations, the adhesive abilities of E. histolytica and their cytotoxicities to CHO cell monolayer were correlated with iron concentration. Amebic adhesion to CHO cell monolayers was significantly reduced by low-iron (24.6 +/- 2.1%) compared with 62.7 +/- 2.8 and 63.1 +/- 1.4% of amebae grown in a normal-iron and high-iron media, respectively. E. histolytica cultured in the normal- and high-iron media destroyed 69.1 +/- 4.3% and 72.6 +/- 5.7% of cultured CHO cell monolayers, but amebae grown in the low-iron medium showed a significantly reduced level of cytotoxicity to CHO cells (2.8 +/- 0.2%). Addition of divalent cations other than iron to amebic trophozoites grown in the low-iron medium failed to restore levels of the cytotoxicity. However, when E. histolytica grown in low-iron medium were transferred to normal-iron medium, the amebae showed completely restored cytotoxicity within 7 days. The result suggests that iron is an important factor in the adherence and cytotoxicity of E. histolytica to CHO cell monolayer.
Animals ; CHO Cells ; Cell Adhesion/drug effects ; Cell Survival ; Cricetinae ; Cricetulus ; Entamoeba histolytica/*drug effects/*physiology ; Iron/*pharmacology

Chinese hamster ovary cells (CHO) are preferable to prokaryotic, yeast or insect cells as hosts for biopharmaceutical production due to the products are more similar to their natural conformation. However, CHO cells confront tremendous difficulties when cultured in large scale such as mal-adaptation to serum-free medium, apoptosis and over-growth without limitation. So in addition to optimizing CHO system in respect of medium, environment and expression vector, modification of CHO cells themselves has drawn more and more attention. Here the main progress in CHO-modification is reviewed.
Animals ; Apoptosis ; genetics ; CHO Cells ; drug effects ; metabolism ; Cell Cycle ; drug effects ; Cell Cycle Proteins ; drug effects ; Cell Division ; drug effects ; Cricetinae ; Genetic Vectors ; genetics ; Transfection

Follicle-stimulating hormone (FSH) is a pituitary glycoprotein hormone that is essential for the development of ovarian follicles and testicular seminiferous tubules. The relatively short half-life of FSH in vivo requires daily injections for more than 10 days that is inconvenient and possibly contribute to the stress perceived by the patients. The goal of the present study was to increase FSH glycosylation, in order to develop a long-acting recombinant FSH. The cDNA of native alpha and beta subunit of human FSH was linked by a sequence with two N-linked glycosylation sites, and the resulted DNA was inserted into pcDNA3.1 vector to generate a recombinant vector of pcDNA3.1-FSH. The pcDNA3.1-FSH was linearized and transfected into CHO-K1, positive transformants were selected by G418 and confirmed by PCR and Western blotting. A single chain recombinant FSH was expressed, with molecular weight of about 49 kDa. The recombinant FSH expression level in CHO-K1 cell strain in serum-free culture was 3 mg/L. Single injection of this recombinant FSH could induce folliculogenesis and ovulation in rats, the efficacy was similar with the commercially available FSH preparation (Folltropin-V) administrated 8 times consecutively. The results suggested a long-acting FSH was produced successfully.
Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Female ; Follicle Stimulating Hormone, Human ; biosynthesis ; Genetic Vectors ; Half-Life ; Humans ; Ovarian Follicle ; drug effects ; Ovulation ; drug effects ; Rats ; Recombinant Proteins ; biosynthesis ; Transfection

Melanocortin is the downstream mediator of leptin signaling and absence of leptin signaling in ob/ob and db/db mice revealed the enhancement of bone formation through the central regulation. While alpha-melanocyte-stimulating hormone (alpha MSH) inhibits the secretion of interleukin-1 alpha and tumor necrosis factor-alpha from the inflammatory cells, alpha MSH can also enhance clonal expansion of pro B cells linked to stimulation of osteoclastogenesis. Therefore, we tested the effect of melanocortin on bones. alpha MSH analogues [6His] alpha MSH-ND and [6Asn] alpha MSH-ND were synthesized and the radio-ligand receptor binding- and cyclic AMP generating activity were analyzed in China Hamster Ovary cell line over- expressing melanocortin receptors. The EC50 of [6His] alpha MSH-ND measured from melanocortin-1, 3, 4 and 5 receptors were 0.008 0.0045, 1.523 0.707, 0.780 0.405, and 250.320 42.234 nM, respectively, and the EC50 of [6Asn] alpha MSH-ND were 16.8 6.94, 271.8 21.95, 8.0 1.21, and 1132.5 635.46 nM, respectively. Four weeks after the subcutaneous injection of the analogues, the body weights in the [6His] alpha MSH-ND and the [6Asn] alpha MSH-ND treated groups (346.0 20.63 g vs. 350.0 13.57 g) were lower than that of the vehicle treated group (375.8 17.31 g, p 0.05). There was no difference in the total femoral BMD measured by dual x-ray absorptiometry among the three groups. Among the three groups, there were no differences in the total numbers of crystal violet positive- or alkaline phosphatase positive colonies, in the expression of Receptor Activator of Nuclear Factor Kappa-B ligand on the tibia and the total number of multinucleated osteoclast-like cells differentiated from primary cultured bone marrow cells. From the above results, no evidence of bone gain or loss was found after treatment of the alpha MSH analogues peripherally.
Animal ; Body Weight/drug effects ; Bone and Bones/*drug effects ; CHO Cells ; Cyclic AMP/biosynthesis ; Eating/drug effects ; Hamsters ; Male ; Osteoblasts/drug effects/physiology ; Osteoclasts/drug effects/physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, Corticotropin/physiology ; alpha-MSH/analogs & derivatives/*pharmacology

Cell transplantation is a promising technology in cancer therapy, however, immunological rejection is the major problem of cell transplantation. Based on the permselective property of microcapsule membrane, encapsulated cells can be immuno-protected. The normal physiological state and function expression of cells can be maintained so as to realize allo- or xenotransplantation. The microencapsulated cells grow in three dimensions, giving a more biologically representative in vivo model, which hints difference in characters of growth and metabolism compared to the monolayer cells. Therefore, characterization of growth and metabolism of microencapsulated recombinant CHO cells is essential for further large-scale culture. In present study, the effect of concentration of glutamine on the growth, metabolism and endostatin production of microencapsulated cells was investigated. In the experimental range of initial glutamine concentrations from 2.69mmol/L to 9.05mmol/L in the culture of microencapsulated recombinant CHO cells, the maximum density of active cells and multiplication ratios almost kept constant. The specific consumption rate of glucose increased with lower initial glutamine concentration (2.69mmol/L). When initial glutamine concentration was much higher (7.91mmol/L to approximately 9.05mmol/L), the specific consumption rates of both glucose and glutamine increased while the efficiencies of glucose and glutamine decreased. The highest efficiencies of glucose and glutamine utilization were observed with initial glutamine concentration of 4.97mmol/L. It was also demonstrated that glutamine had significant effect on the accumulation of endostatin. The accumulative concentration of endostain reached its peak of 546.36 ng/mL with the initial glutamine concentration of 4.97mmol/L.
Animals ; CHO Cells ; Cell Culture Techniques ; Cell Proliferation ; drug effects ; Cells, Immobilized ; Cricetinae ; Cricetulus ; Culture Media ; Endostatins ; biosynthesis ; genetics ; Genetic Engineering ; Glucose ; metabolism ; Glutamine ; pharmacology ; Recombination, Genetic

OBJECTIVETo investigate whether inhalable particulate matters can cause the damage of chromosome or mitotic apparatus to produce micronucleus, and to evaluate genetic toxicology of moxa smoke on chromosome.

METHODSBy MTT method, the 24 h half maximal inhibitory concentration (IC50) of moxa smoke condensation (MSC) on Chinese hamster ovary (CHO) cells was 0.087 mg/mL. CHO cells, which were cultured in vitro, were divided into a solvent control group, a positive control group (cyclophosphamide as solvent), a low concentration group, a moderate concentration group and a high concentration group. The low concentration group, moderate concentration group and high concentration group were set approximately 1/8, 1/4, 1/2 of IC50, respectively. Whether micronucleus had dose-effect response induced by the damage of chromosome or mitotic apparatus was observed after CHO cells were contaminated by MSC in the low concentration group, moderate concentration group and high concentration group.

RESULTSThe rate of micronucleus induced by MSC in the low concentration group, moderate concentration group and high concentration group was higher than that in the solvent control group (all P < 0.05), which presented dosage-effect response. The experiment was repeated 3 times, indicating it was repeatable with statistical significance.

CONCLUSIONHigh concentration of MSC shows toxicity to induce chromosome damage, which disappears at low concentration. The genetic toxicology is also dependent on concentration, and the concentration of moxa smoke is essential. In clinical treatment, it is noted to control the level of moxa smoke, while the clinical safety standard of moxa smoke concentration is in need of further study.

Air Pollutants ; adverse effects ; Animals ; CHO Cells ; Cell Nucleus ; drug effects ; genetics ; Cricetinae ; Cricetulus ; Inhalation Exposure ; adverse effects ; analysis ; Micronucleus Tests ; Moxibustion ; adverse effects ; Particulate Matter ; adverse effects ; Smoke ; adverse effects ; analysis

BACKGROUNDTo study the effect of gene amplification and selection system with DHFR plus GS and DHFR or GS gene on the foreign gene expression.

METHODSUsing the N-terminal truncated hTPO(T184) gene as target gene, two plasmidsre were constructed: pDC- T184 and pGC-T184 where DHFR and GS gene were used respectively as the selective amplification marker. They were cotransfected into CHO dhfr cells to establish dual gene amplification and selection system of DHFR plus GS gen and respectively transfected to establish single gene amplification and selection system of DHFR or GS gene. Three selective methods in dual selective system to compare expression efficiency of hTPO were designed: the first method (DG) was to use drug pressure of MTX, then use MSX; the second method (GD) was reversed; the third method was simultaneously to use MTX and MSX as drug pressure.

RESULTSDHFR+GS dual system had not only higher gene amplification efficiency but also higher level expression. There was no distinct affect in different method of drug pressure.

CONCLUSIONSMTX plus MSX dual drug pressure in dual selection system was an efficient and simple method to increase the expression of foreign gene in mammalian cells.

Animals ; CHO Cells ; Cricetinae ; Gene Amplification ; drug effects ; Gene Expression ; Glutamate-Ammonia Ligase ; genetics ; Methotrexate ; pharmacology ; Plasmids ; genetics ; Tetrahydrofolate Dehydrogenase ; genetics

The present paper is aimed to explore the biological osteoinductive activity of recombinant human bone morphogenetic protein 9 (rhBMP-9) by various biological technologies. In this study, we firstly obtained hBMP-9 cDNA by PCR and inserted it into vector pcDNA4/His Max to reconstruct hBMP-9 eukaryotic expression vector pcDNA4/His Max-BMP-9. Recombinant Chinese hamster ovary (rCHO) cell line expressing high-level rhBMP-9 was reconstructed by co-transfecting the expression vectors pcDNA4/His* Max-hBMP-9 and plasmid pSV2-dhfr into dihydrofolate reductase (dhfr)-deficient CHO cells and the subsequent gene amplification by the methotrexate. We finally obtained a monoclonal cell line expressing the highest level protein. We purified the medium after culturing the highest-producing monoclonal by Ni-NTA His-Bind Resin columns and concentrated to by a Centricon 50 at 4 degrees C and stored at 70 degrees C until it was used. Western blot and SDS-PAGE analyses showed a specific band of about 32kD in pro-region lane and a specific band of about 50kD in pro-region complex lane. Biological activities of rhBMP-9 were tested by colorimetric determination and histochemical staining of Alkaline Phosphatase (ALP) Activity, osteocalcin and oesteopontin for C3H10 T1/2 cells, which were stimulated culture by different concentration (20, 50, 100 microg/mL) of rhBMP-9. The results showed that the rhBMP-9 could induce osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro, and were proportional to the amount. This study can provide experimental data for further tests in vivo and clinical applications.
Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Growth Differentiation Factor 2 ; biosynthesis ; isolation & purification ; pharmacology ; Humans ; Osteogenesis ; drug effects ; Recombinant Proteins ; biosynthesis ; isolation & purification ; pharmacology ; Transfection