Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Bioreactors”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed1996

Production of human natural killer cells for adoptive immunotherapy using a computer-controlled stirred-tank bioreactor.

Large-scale ex vivo expansion of human natural killer (NK) cells for adoptive immunotherapy requires assurance of good manufacturing practices. However, maximal expansion of NK is also desired to facilitate clinical trials with large numbers of IL-2-activated NK (ANK). A closed-system stirred-tank bioreactor is amenable to computer control of culture variables, thereby reducing the risk of contamination. We demonstrate that NK cultured in 250-ml spinner flasks expand 2.5-fold more than NK cultured in stationary tissue culture wells. We further show that during 33 days of culture, it is feasible to control the pH between 7.0 and 7.2 and the dissolved oxygen concentration at 40% of air saturation via direct on-line computer control in a 750-ml stirred-tank bioreactor. On-line measurement of optical density by a laser turbidity sensor, as a measure of cell concentration, correlated well with actual cell count data. NK expansion in the 750-ml bioreactor was 7-fold greater than in stationary tissue culture controls and 3-fold greater than in spinner flask controls. Consumption rates of glucose and oxygen and the production rate of lactate were measured and will be used to develop a nutrient feeding strategy to convert the batch reactor experiment into closed-system fed-batch or continuous flow modes. Computer-controlled stirred-tank bioreactors may facilitate clinical trials with high-purity ANK populations for adoptive immunotherapy.

Cell Culture Techniques↗
PubMed1990

Gas supply across membranes in bioreactors for hepatocyte culture.

The conditions required for hepatocyte cultures is a main topic in the development of bioreactors for hybrid liver support systems. The detoxification of ammonia and the synthesis of urea due to primary isolated hepatocytes was measured in order to compare two different models of gas supply in bioreactors: (a) indirect medium oxygenation and (b) direct membrane-contact oxygenation of the hepatocytes using polypropylene membranes. Increasing oxygen pressure promoted cell function. At day 6 of culture, urea synthesis was 0.8 +/- 0.3 mM in 21% of O2 cultures and 1.5 +/- 0.1 mM in oxygenated cultures. Alkalosis due to CO2 loss decreased ammonia metabolism. The direct membrane-contact oxygenation resulted in enhanced cell metabolism in comparison to medium oxygenation: urea synthesis at day six was 1.42 +/- 0.2 mM in 21% O2 cultures. Polypropylene oxygenation membranes proved to be sufficient for hepatocyte adhesion. Two functions can be integrated in one element in liver support systems using the investigated polypropylene membrane and the direct membrane-contact oxygenation: oxygenation with physiological oxygen pressure in bioreactors due to gas supply across the membrane and adhesion of hepatocytes in bioreactors on the membrane.

Animals↗
PubMed1995

Reconstruction of liver tissue in vitro: geometry of characteristic flat bed, hollow fiber, and spouted bed bioreactors with reference to the in vivo liver.

Bioreactors currently being developed for hybrid artificial livers vary greatly with respect to their microenvironment. The specific architecture modifies the relationship parenchymal and nonparenchymal cells have with the exchange surfaces of the bioreactor. Most designs are either based on hollow fiber, spouted bed, or flat bed devices. This diversity is contrasted by the uniform and unique organization of the in vivo liver. The liver cells are arranged as plates and both sinusoidal surfaces of the hepatocytes are enclosed within the matrix of the space of Disse. In this study we intended to define the in vivo liver tissue characteristics in a manner useful for an organotypical approach to hepatic tissue engineering. Transmission electron microscopy of an in vivo liver was utilized to describe these ratios. The ratios defined in this study are based on the constant hepatocellular expression of two sinusoidal surfaces. A relationship is established between the expression of the sinusoidal surfaces and their use as attachment and exchange surfaces inside a bioreactor. The presence of biliary surfaces and nonparenchymal cell surfaces is compared. The functional relevance of an in vivo like extracellular matrix geometry for oxidative biotransformation of primary hepatocytes in vitro was studied using the two model drugs cyclosporin and rapamycin. The generation of the hydroxylated cyclosporin metabolites AM 9 and AM 1 and four rapamycin metabolites was analyzed by high performance liquid chromatography (HPLC). It is shown that the cell-specific biotransformation rates at 1 week in culture in matrix overlayed hepatocytes was 5-10 times that of hepatocytes without matrix overlay. Bilaminar membrane (BLM) bioreactors were used to reconstruct extracellular matrix geometry, three-dimensional cell plates, and sinusoidal analogs in between cell plates.

Animals↗
PubMed1992

Examination of bacterial characteristics of anaerobic membrane bioreactors in three pilot-scale plants for treating low-strength wastewater by application of the colony-forming-curve analysis method.

Characteristic sludge ecosystems arising in anaerobic membrane bioreactors of three pilot-scale plants treating low-strength (less than 1 g of biological oxygen demand per liter) sewage or soybean-processing wastewater were examined by analysis of the colony-forming-curves (CFC) obtained by counting colonies at suitable intervals. The wastewaters, containing high amounts of suspended solids (SS) (SS/chemical oxygen demand ratio, 0.51 to 0.80), were treated by using two types of bioreactors: (i) a hydrolyzation reactor for solubilization and acidification of SS in wastewater and (ii) a methane fermentation reactor for producing methane. The colony counts for the two sewage treatment plants continued to increase even after 3 weeks of incubation, whereas those for soybean-processing wastewater reached an approximately constant level within 3 weeks of incubation. The CFCs were analyzed by correlating the rate of colony appearance on roll tubes with the physiological types of bacteria present in the bioreactors. It was found that there were large numbers of slow-colony-forming anaerobic bacteria within the bioreactors and that the viable populations consisted of a few groups with different growth rates. It is considered that the slow-growing colonies appearing after 10 days of incubation were the dominant microflora in the sewage treated by hydrolyzation reactors. In particular, highly concentrated sludge (30.0 g of mixed-liquor volatile SS per liter) retained by the membrane separation module contained a large number of such bacteria. Slow-growing colonies of these bacteria could be counted by using a sludge extract medium prepared from only the supernatant of autoclaved sludge. In addition, the highest colony counts were almost always obtained with the sludge extract medium, meaning that most of the anaerobic bacteria in these sludges have complex nutrient requirements for growth. This report also indicates the usefulness of application of the CFC analysis method to the study of bacterial populations of anaerobic treatment systems.

Journal Article↗
PubMedDate not supplied

Expansion of activated lymphocytes obtained from renal cell carcinoma in an automated hollow fiber bioreactor.

Immunotherapy using IL-2 alone or combined with activated lymphocytes has been promising for metastatic renal cell carcinoma. Cytotoxic lymphocytes can be isolated from tumors, expanded in vitro with IL-2, and adoptively transferred back into the tumor-bearing host. These cells can also be transduced with the genes coding for cytokines for local delivery to tumor sites. A major drawback in adoptive immunotherapy is the cumbersome and expensive culture technology associated with the growth of large numbers of cells required for their therapeutic effect. To reduce the cost, resources, and manpower, we have developed the methodology for lymphocyte activation and expansion in the automated hollow fiber bioreactor IMMUNO*STAR Cell Expander (ACT BIOMEDICAL, INC). Tumor Infiltrating Lymphocytes (TIL) isolated from human renal cell carcinoma tumor specimens were inoculated at a number of 10(8) cells in a small bioreactor of 30 ml extracapillary space volume. We have determined the medium flow rates and culture conditions to obtain a significant and repeated expansion of TIL at weekly intervals. The lymphocytes cultured in the bioreactor demonstrated the same phenotype and cytotoxic activity as those expanded in parallel in tissue culture plates. Lymphocyte expansion in the hollow fiber bioreactor required lower volumes of medium, human serum, IL-2 and minimal labor. This technology may facilitate the use of adoptive immunotherapy for the treatment of refractory malignancies.

Biotechnology↗
PubMed2001

Effect of capsule circulation velocity on production of L-lysine by encapsulated Corynebacterium glutamicum in an airlift bioreactor.

The effect of capsule circulation velocity and volumetric oxygen transfer coefficient on the production of L-lysine by encapsulated Corynebacterium glutamicum in an airlift bioreactor has been evaluated. A larger oxygen supply in the airlift bioreactor caused a more than 58% increase in L-lysine productivity compared to that in a shaking flask incubator. The quantity of L-lysine produced during 5 h of cultivation in the airlift bioreactor was suggested to increase with increasing circulation velocity of the capsule in the bioreactor rather than with an increase in volumetric oxygen transfer coefficient.

Journal Article↗
PubMed1996

Novel technology for the preparation of sterile alginate-poly-l-lysine microcapsules in a bioreactor.

The purpose of this study was to develop a method that may be suitable for the commercial manufacture of sterile alginate-polylysine-alginate microcapsules in a bioreactor. A Turbotak atomizing device in conjunction with a Bellco Bioreactor was used to prepare sterile microcapsules. Aseptic procedures were followed using sterilized equipment and materials. Sodium alginate solution was sprayed into calcium chloride solution using the Turbotak, with nitrogen as the atomizing gas. The resultant gelled alginate microcapsules were coated with polylysine and alginate to produce alginate-poly-l-lysine microcapsules. In-process contamination of the atomizing gas and microcapsules was investigated using modified USP sterility tests. Microcapsule size was determined using a light blockage technique (Accusizer) which measures both number and volume weighted mean diameters. The microcapsules prepared passed a modified USP sterility test, and the Bellco Bioreactor was found to minimize the possibilities of environmental contamination and therefore enhanced operator safety. The flow rate of the atomizing gas was determined to significantly alter number and volume weighted mean microcapsule diameters. Statistical analysis indicated that the number weighted mean diameters in conjunction with the volume weighted mean diameters can be used to detect batch-to-batch changes in microcapsule diameters. In conclusion, the modified Bellco Bioreactor offers a novel approach for producing sterile alginate-polylysine microcapsules on a laboratory scale.

Alginates↗
PubMed1990

Large-scale production of monoclonal antibodies in defined serum-free media in airlift bioreactors.

Forty- and ninety-liter airlift bioreactors have been used successfully to grow hybridoma cell lines in chemically defined serum-free media. In the airlift bioreactor, hybridoma cell growth and monoclonal antibody productivity are comparable to that obtained by conventional cell culture. At sparging rates of 0.60-1.20 vvh (volume of sparged gas per bioreactor volume per hour), the airlift bioreactor achieves rapid mixing and adequate oxygen mass transfer. Foaming is minimal and inconsequential for serum-free media and media supplemented with 5%-10% fetal bovine serum. The use of serum-free medium facilitates monoclonal antibody purification and enhances the purity of the final MAb product.

Animals↗
PubMedDate not supplied

A novel bioreactor based on suspended particles of agarose-immobilized species.

Bioreactors often contain porous particles of agarose because these provide an enormous surface area (50 m2/cc gel) onto which enzymes or antibodies can be immobilized. Although many investigators claim that contact with agarose induces significant blood damage, we find that the biocompatibility of immobilized agarose is significantly improved when a novel system is used to fluidize the particles within the bioreactor vessel. We have built a prototype device that is oscillated vigorously about the axis of fluid flow. This action produces secondary flow patterns within the vessel that suspend the particles. In our model system, the bioreactor contains agarose immobilized heparinase. The system is biocompatible for 2 hours in vitro (in human blood at 37 degrees C) as follows: 1) hematocrit, white cell, and platelet counts do not change, 2) levels of plasma hemoglobin increase to 15-34 mg/dl, and 3) levels of complement component C3a increase to 0.64-1.4 micrograms/cc. We hope these studies lead to the development of a heparin removal system that can improve the safety of a variety of extracorporeal procedures. In addition, the techniques and approach used are sufficiently general to permit their extension to any immobilized species bioreactor for blood detoxification.

Biocompatible Materials↗
PubMed1994

[A new liver support system composed of functional human cells and a radial-flow bioreactor].

An artificial liver will be useful for the treatment of acute hepatic failure and a bridge of liver transplantation. The current reports suggest that the hybrid type of artificial liver composed of functional human liver cells and a bioreactor is practical for clinical use. In the present study, we succeeded high density culture on a large-scale of human functional hepatoma (JHH-7) using a newly developed radial flow packed-bed bioreactor. Since the shear stress of this bioreactor is lower than the other type, high density culture without cell damage is possible. JHH-7 cells produced large amounts of human albumin and other liver specific proteins, and then have the function of ammonia metabolism in the system. This study suggests that a radial flow bioreactor will be developed as a new type of artificial liver.

Albumins↗
PubMed1994

Expansion in bioreactors of human progenitor populations from cord blood and mobilized peripheral blood.

Umbilical cord blood (UCB) and mobilized peripheral blood (MPB) provide an alternate source to bone marrow for transplantation. Expansion in vitro of stem/progenitor cell populations from these sources may provide adult-sized grafts otherwise not attainable because of the limited cell numbers available in the case of UCB or because of numerous rounds of apheresis required for sufficient MPB cells. We asked whether continuous perfusion culture could be employed in ex vivo expansion to produce clinically relevant numbers of stem/progenitor cells from these sources. To evaluate MPB, 1-10 million leukocytes, from patients who had received either granulocyte colony-stimulating factor (G-CSF) or cyclophosphamide and granulocyte-macrophage colony-stimulating factor (GM-CSF), were inoculated into bioreactors, with or without irradiated, allogeneic stroma. The growth factor combination in the perfusion medium consisted of interleukin-3 (IL-3), stem cell factor (SCF), GM-CSF and erythropoietin (Epo). Under the best conditions tested, total cell numbers, granulocyte-macrophage colony-forming units (CFU-GM), and long-term culture-initiating cell (LTC-IC) populations were expanded by about 50-, 80-, and 20-fold, respectively, over 14 days. At low cell inocula (1 million), the presence of stroma enhanced the expansion of total cells and CFU-GM but not of LTC-IC. When SCF was not included in the medium, both total cells and CFU-GM expanded to a much lesser extent, but again the expansion of LTC-IC was not affected. At the higher cell inoculum (10 million), expansions of total cells and CFU-GM were equivalent with or without stroma. To evaluate UCB, cells were placed into bioreactors with or without irradiated, allogeneic stroma, and the bioreactors were perfused with medium containing the four standard growth factors. After 6-14 days, in several independent experiments, 20-24 million cells were harvested from bioreactors perfused with SCF-containing medium, irrespective of the presence or absence of preformed stroma. Similarly, in reactors perfused with SCF-containing medium (with or without stroma), an average 40- to 60-fold expansion of CFU-GM was obtained, yielding an average of 1.5-1.8 x 10(5) CFU-GM per reactor. Harvested cells were thus up to 40-fold enriched in CFU-GM in comparison to the inoculum. In the absence of SCF, cell expansions averaged 1.5- to 2-fold, and CFU-GM were expanded only 10- to 14-fold by day 14. As before, the presence of preformed stroma did not affect either cell or CFU-GM yields, provided the cell inoculum was at least 4.5 million cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1998

Serum increases the CD13 receptor expression, reduces the transduction of fluid-mechanical forces, and alters the metabolism of HL60 cells cultured in agitated bioreactors.

The effects of serum medium concentration on the CD13 receptor surface content and mRNA levels of HL60 (human promyelocytic leukemia) cells were examined using flow cytometry and Northern blotting. Increasing the serum concentration from 2.5% to 10% and from 5% to 10% increased the CD13 receptor surface content of HL60 cells by 100% and 25%, respectively, in spinner flasks agitated at 60 rpm. In bioreactors at 80 rpm, increasing the serum concentration from 2.5% to 10% and from 5% to 10% increased the CD13 receptor surface content by 60% and 35%, respectively. This increase in CD13 receptor surface content was correlated with a 30% and a 20% increase in CD13 mRNA levels. Increasing serum concentrations also increased the average HL60 cell size under non-damaging conditions (60 rpm in spinner flasks, 80 rpm in bioreactors). Under conditions of agitation at 300 rpm in 2 L bioreactors, increasing serum concentrations (2.5% vs. 10%, 5% vs. 10%) allowed for higher HL60 apparent growth rates, but decreased the CD13 receptor surface content and mRNA levels. In view of our earlier findings on the effects of agitation on the CD13 antigen, these data suggest that serum reduces the transduction of mechanical forces that affect CD13 expression. At 300 rpm, HL60 cells cultured in 10% serum exhibited glucose consumption and lactate production rates that were approximately 50% and 60% lower than the values of cells cultured in 5% and 2.5% serum, respectively.

Bioreactors↗
PubMed1999

Solid-state fermentation in rotating drum bioreactors: operating variables affect performance through their effects on transport phenomena.

Aspergillus oryzae ACM 4996 was grown on an artificial gel-based substrate and on steamed wheat bran during solid-state fermentations in 18.7 L rotating drum bioreactors. For gel fermentations fungal growth decreased as rotational speed increased, presumably due to increased shear. For wheat bran fermentations fungal growth improved under agitated compared to static culture conditions, due to superior heat and mass transfer. We conclude that the effects of operational variables on the performance of SSF bioreactors are mediated by their effects on transport phenomena such as mixing, shear, heat transfer, and mass transfer within the substrate bed. In addition, the substrate characteristics affect the need for and the rates of these transport processes. Different transport phenomena may be rate limiting with different substrates. This work improves understanding of the effects of bioreactor operation on SSF performance.

Aspergillus oryzae↗
PubMed1999

Effect of harvesting protocol on performance of a hollow fiber bioreactor.

In this study, a bioreactor subject to Starling flow in closed shell batch harvest mode was compared to two forms of additional forced extracapillary (EC) space convection including EC circulation and EC cycling. Despite the presence of Starling flow as the dominant EC convection mechanism in the batch harvest system, the bioreactor start up was fairly good. However, the antibody productivity of the batch harvest system fell off rapidly after day 20 resulting in only 4.5 g of antibody produced. EC circulation with flow parallel to the fibers had a slightly better start up than the batch harvest. However, the antibody productivity also dropped after day 20 with EC circulation, resulting in only 7.5 g of antibody produced. EC cycling with flow both parallel and perpendicular to the fibers resulted in a start up similar to that of EC circulation. However, in contrast to the other two systems, antibody productivity in the EC cycling system was stable over the 60-day experiment resulting in the production of 23 g of antibody. These results demonstrate the importance of inducing the proper flow distribution in the EC space to allow consistent and stable production in hollow fiber bioreactors.

Animals↗
PubMed2000

A hollow-fiber membrane bioreactor for the removal of trichloroethylene from the vapor phase.

A hollow-fiber membrane bioreactor was used to separate trichloroethylene (TCE) from a gaseous waste stream with subsequent cometabolic biodegradation by a pure culture of Methylosinus trichosporium OB3b PP358. The two-stage bioreactor system was successfully operated for 20 days. PP358 was grown in a continuous-flow chemostat and circulated through the fiber lumen of a hollow-fiber membrane module (HFMM), while TCE contaminated air (141 to 191 microg/L) was pumped through the HFMM shell. Between 54% -84% TCE transfer and 92%-96% TCE cometabolism were obtained in the HFMM reactor loop. Short shell-residence times, 1.6 to 5.0 minutes, demonstrated quick throughput of TCE contaminated air. Best-fit computer modeling of the biological experiments estimated mass transfer coefficients between 2.0 x 10(-3) cm/min and 5.6 x 10(-3) cm/min. The average pseudo-first-order biodegradation rate constant for the biological experiments was 0.46 L/mg TSS/d. These results demonstrate that the hollow-fiber membrane bioreactor represents an attractive technology for the bioremediation of gaseous waste streams.

Biodegradation, Environmental↗
PubMed2000

Inhibitory role of root hairs on transport within root culture bioreactors.

An experimental system was developed to produce root cultures of Hyoscyamus muticus with and without the profuse root hairs. Growth in the presence of 7.6 microM pyrene butyric acid (PBA) and 2.2 mM phosphate virtually eliminated root hairs, whereas growth rate, general morphology and nutrient yields remained unchanged in well-mixed flask culture. These root cultures were used to demonstrate decreased flow resistance in a tubular reactor as a result of root hair removal. To assess the impact on bioreactor performance, hairy and hairless root cultures were grown in a highly characterized 15-L bubble column bioreactor. In the absence of root hairs, the mixing was greatly enhanced; mixing times became shorter for the hairless culture at roughly 100 g (fresh weight)/L. By the end of the 3-week culture period, the mixing time of the hairy culture was 29 times longer than that of the hairless culture. The growth rate of the hairless culture in the bioreactor was as much as 2.4 times greater than growth of the hairy culture under the same conditions. The improved reactor performance was reflected in greater biomass accumulation and respiratory activity. These results show that the root hairs-which facilitate nutrient uptake in a static soil environment-are detrimental to growth in a liquid environment as an effect of their stagnating fluid flow and limiting oxygen availability.

Biological Transport↗
PubMed2000

Microbial dynamics in an extractive membrane bioreactor exposed to an alternating sequence of organic compounds.

Wastewaters containing organic compounds have been treated using extractive membrane bioreactors (EMBs). During treatment, a biofilm normally develops on the surface of the membrane, on the biological side. This study investigates the dynamics of biofilm growth in an EMB exposed to an alternating sequence of organic compounds. Microbial dynamics of both suspended and attached cultures were investigated experimentally in a single-tube extractive membrane bioreactor (STEMB), which comprised a continuous stirred-tank bioreactor (CSTB) coupled to eight single-tube extractive membrane modules (STEMMs) via a recirculating biomedium. A model microbial culture consisting of a Burkholderia sp. strain JS150 (ATCC No. 51283), able to degrade monochlorobenzene, and a Xanthobacter autotrophicus sp. strain GJ10 (ATCC No. 43050), able to degrade 1, 2-dichloroethane, was used. Both microbial strains exhibited exclusive degradative capabilities. The CSTB was monitored by quantification of individual strains and by product and organic compound evolution. To investigate the biofilm growth dynamics, eight STEMMs were run in parallel with the same operating conditions. Every week, STEMMs were stopped for biofilm analysis and the organic compound in the wastewater was changed. Biofilm growth was investigated by quantification of individual strains, by evaluation of the overall biofilm growth, and by microscopic analysis. A biofilm composed of both strains was developed and maintained during the whole experiment in the STEMMs. The biofilm that developed on the membrane improved the response of the system to changes in the wastewater.

Biodegradation, Environmental↗
PubMed2001

Effect of airflow rate on yields of Steinernema carpocapse Az 20 in liquid culture in an external-loop airlift bioreactor.

Maximization of the contact between males and females is a key factor in the production of the nematode Steinernema carpocapsae in a bioreactor.%The influence of the airflow rate in male and female distribution and mass production in an external-loop bioreactor with a deceleration zone was studied. When operating at an airflow rate of 0.05 vvm, a high retention of females in the deceleration zone of the bioreactor was observed and a larger nematode productivity was obtained. At this aeration rate there was a higher proportion of males in that zone, which together with the lower circulation rate, increases the probability of encounters, thereby explaining the increase in productivity.

Air Movements↗