Production of monoclonal antibodies for breast cancer by HB8696 hybridoma cells using novel perfusion system

Perfusion culture using spinfilters have been used for the production of health-care products using mammalian cells culture. However, available spinfilters are either highly prone to clog and/or are disposable and hence affects product formation. To address these problems, a novel non-woven Bombyx mori silk screen based spinfilter module for clog-free extended perfusion culture of hybridoma cells has been designed. The module is versatile in nature and reusable, after autoclaving and replacement of used polymeric membrane. Its application for clog-free extended perfusion culture was demonstrated by comparative perfusion experiments of HB8696 cells with stainless-steel spinfilter. HB8696 cells produce monoclonal antibodies (MAbs) 520C9 active against breast cancer oncoprotein. Silk spinfilter was found to be less prone to clog with cells and debris owing to its negatively charged hydrophobic screen compared to the positively charged hydrophilic stainless-steel spinfilter. Therefore, it provides extended cell growth phase and production phase of up to 56 h and 40 h respectively and 57.4% increase in MAb productivity compared to the stainless-steel spinfilter. The effect of different perfusion rates on MAb production was studied and an optimal MAb productivity of 1.6 g L(-1) day(-1) was achieved.

Amino acid supplementation enhances urokinase production by HT-1080 cells

Medium optimization is an important strategy that can lead to several fold increase in the production of proteins in cell culture. However, the usual methods of medium optimization are complex and time consuming. Urokinase is a widely employed thrombolytic drug for the treatment of stroke. We describe here medium optimization for maximizing urokinase production by HT-1080 cells using supplementation of specific amino acids. The new specifically designed method resulted in 240 % increase in urokinase productivity.

Development of optimal medium for production of commercially important monoclonal antibody 520C9 by hybridoma cell

Hybridoma HB-8696 produces monoclonal antibody (mAb) 520C9 (mouse IgG(1)), which recognizes breast cancer oncoprotein c-erbB2. The objective of this study was to optimize the medium recipe of HB 8696 cell for production of mAb 520C9. The optimization consisted of two steps: (1) screening of significant nutrients to make subsequent experiments more efficient with less runs and (2) locating their optimal concentrations. 29 variables including essential and non-essential amino acids, glucose, serum and 6 salts, namely NaCl, KCl, CaCl(2), NaH(2)PO(4), MgSO(4) and Na-pyruvate were chosen in screening phase. The Plackett-Burman method was used to screen the variables influencing mAb production. Seven factors namely glucose, serum, asparagine, threonine, serine, NaCl and NaH(2)PO(4) were identified to have a positive influencing role on mAb production with a confidence level >90 % (p < 0.1). Finally, Response surface methodology revealed the optimal level of the variables. The mAb production and average specific mAb production rate were enhanced by 111.05 and 105 %, respectively, compared to control medium.

External modulation of HT-1080 human fibrosarcoma cells improves urokinase production

Urokinase was produced in a hollow fiber reactor using HT-1080 human fibrosarcoma cells. External modulation comprised replenishing of the medium in the extracapillary space, reducing the serum concentration in the extracapillary space from 10% to 2% and increasing flow rate of the circulating medium in the intracapillary space from 20 to 80 mL/min, each according to a specific protocol. More than sixfold increase was observed in the cumulative urokinase production for two and three medium replenishing modulations of the extracapillary space. After 15 days of continuous operation, the highest cumulative urokinase obtained was 1.63 x 10(6) PU/mL. SDS-PAGE and zymogram study established that the urokinase obtained was in the high molecular weight range of 54 kDa. The effect of external modulation on cumulative urokinase production was visualized as trajectories with respect to the ratio of lactic acid production rate (LPR) to the glucose uptake rate (GUR). The collective external modulation data showed two separate physiological regions in the cumulative urokinase vs. LPR/GUR plane. The HT-1080 cells exhibited two distinct morphologies in these regions that may be related to acidosis and metastasis. These regions also correspond to low and high urokinase productivity.

Purification of dibenzothiophene monooxygenase from a recombinant Escherichia coli

Dibenzothiophene monooxygenase is the first enzyme involved in the degradation of dibenzothiophene. This gene was expressed via the pET28a vector in E. coli and was purified in a single step using affinity chromatography. The protein was purified 39-fold with a specific activity of 38 U/mg.

Urokinase separation from cell culture broth of a human kidney cell line

A single step ion-exchange chromatography on a sulfo-propyl (SP)- Sepharose column was performed to separate both the high molecular weight (HMW)- and low molecular weight (LMW)- forms of enzymatically active urokinase type plasminogen activator from human kidney (HT1080) cell culture media. The level of urokinase secreted by the cell line reached to about 145 Plough units/ml culture broth within 48 h of cultivation. The conditioned cell culture media was applied directly to the column without any prior concentration steps. Polyacrylamide gel electrophoresis of the column eluates in the presence of sodium dodecyl sulphate showed that the cell line secretes three forms of two-chain high molecular weight (HMW) urokinase of molecular weights (M(r)) 64,000, 60,900 and 55,000. In addition, two low molecular weight (LMW) forms of M(r) 22,000 and 20,000; proteolytic cleavage products of HMW, were also found. The HMW and LMW forms had intrinsic plasminogen dependent proteolytic activity as judged by zymographic analysis. The specific activity of the pooled peak fractions increased (approximately 93-fold) to values as high as 1481 Plough units/ mg protein. Both HMW as well as LMW forms were obtained in significantly high yields.

Recovery of urokinase from integrated mammalian cell culture cryogel bioreactor and purification of the enzyme using p-aminobenzamidine affinity chromatography

An integrated product recovery system was developed to separate urokinase from the cell culture broth of human kidney cells HT1080. Supermacroporous monolithic cryogels provided ideal matrices with respect to surface and flow properties for use as cell culture scaffold as well as for affinity chromatographic capture step of the enzyme in the integrated system. The urokinase was produced continuously in the reactor running for 4 weeks with continuous circulation of 500 ml of culture medium. The enzyme activity in the culture medium reached to 280 Plough units (PU)/mg protein. Cu(II)-iminodiacetic acid (IDA)-polyacrylamide (pAAm) cryogel column was used to capture urokinase by integrating with the gelatin-coupled pAAm-cryogel bioreactor for HT1080 cell culture. After removing the urokinase capture column from the integrated system the bound protein was eluted. The metal affinity capture step gave 4.5-fold purification of the enzyme thus achieving a specific activity of 1300 PU/mg protein. The enzyme eluate from Cu(II)-IDA-pAAm cryogel capture column was further purified on benzamidine-Sepharose affinity column. This step finally led to a homogeneous preparation of different forms of urokinase in two different elution peaks with a best urokinase activity of 13 550 PU/mg of protein. As compared to initial activity in the cell culture broth, about 26.2- and 48.4-fold increase in specific activity was achieved with enzyme yields corresponding to 32% and 35% in two different peak fractions, respectively. Native electrophoresis and SDS-PAGE showed multiple protein bands corresponding to different forms of the urokinase, which were confirmed by Western blotting and zymography.

Synthesis, regulation and production of urokinase using mammalian cell culture: a comprehensive review

Urokinase, a serine protease, catalyzes the conversion of plasminogen to plasmin, which is responsible for dissolution of clots in blood vessels. It is an important drug for treatment of thromboembolic disease. Production of urokinase by mammalian cell culture has the following important steps: synthesis, regulation and secretion. Production and accumulation of this product in a bioreactor is a real challenge for biochemical engineers. Considerable information at molecular level needs to be understood for production of urokinase in order to correlate different parameters, which in turn can maximize the productivity. This information will be highlighted in this review. Moreover, urokinase production is a product-inhibited process. Therefore, in situ urokinase separation strategy is required to operate a bioreactor at its maximum urokinase formation rate. Integrated urokinase production and isolation processes developed recently will also be discussed briefly in this review.

Production and purification of urokinase: A comprehensive review

An increased emphasis on prevention of fatalities due to thrombovascular disorders is broadening opportunities for several cardiovascular agents, especially plasminogen activators, for preventing strokes and heart attacks. Hence, urokinase, as one of the most potent plasminogen activators is attracting a great deal of attention. Developments in cell lines and bioprocess technology have made it possible to produce urokinase from in vitro cell culture. Attempts are now underway to enhance urokinase production from cell culture through media manipulation, bioreactor cultivation, and innovative purification techniques. Downstream processing also poses an intricate problem due to the complexity of cell culture extracts, susceptibility of urokinase to autocatalytic and proteolytic degradation and due to the presence of plasminogen activator inhibitors in the culture media. Hence, enhancing cellular productivity and downstream product recovery continue to be major challenges as discussed in this review. Furthermore, an approach for integrated upstream and downstream processing is needed to develop an economically viable technology. In the present review the emerging trends in urokinase production and purification have been discussed in detail.

Integrated bioprocess for the production and isolation of urokinase from animal cell culture using supermacroporous cryogel matrices

An integrated cell cultivation and protein product separation process was developed using a new type of supermacroporous polyacrylamide gel, called cryogel (pAAm-cryogel) support matrix. Human fibrosarcoma HT1080 and human colon cancer HCT116 cell lines were used to secrete urokinase (an enzyme of immense therapeutic utility) into the culture medium. The secreted protein was isolated from the circulating medium using a chromatographic capture column. A pAAm cryogel support with covalently coupled gelatin (gelatin-pAAm cryogel) was used for the cultivation of anchorage dependent cells in the continuous cell culture mode in 5% carbon dioxide atmosphere. The cells were attached to the matrix within 4-6 h of inoculation and grew as a tissue sheet inside the cryogel matrix. Continuous urokinase secretion into the circulating medium was monitored as a parameter of growth and viability of cells inside the bioreactor. No morphological changes were observed in the cells eluted from the gelatin-cryogel support and re-cultured in T-flask. The gelatin-pAAm cryogel bioreactor was further connected to a pAAm cryogel column carrying Cu(II)-iminodiacetic acid (Cu(II)-IDA)-ligands (Cu(II)-IDA-pAAm cryogel), which had been optimized for the capture of urokinase from the conditioned medium of the cell lines. Thus an automated system was built, which integrated the features of a hollow fiber reactor with a chromatographic protein separation system. The urokinase was continuously captured by the Cu(II)-IDA-pAAm cryogel column and periodically recovered through elution cycles. The urokinase activity increased from 250 PU/mg in the culture fluid to 2,310 PU/mg after recovery from the capture column which gave about ninefold purification of the enzyme. Increased productivity was achieved by operating integrated bioreactor system continuously for 32 days under product inhibition free conditions during which no backpressure or culture contamination was observed. A total 152,600 Plough units of urokinase activity was recovered from 500 mL culture medium using 38 capture columns over a period of 32 days.

Supermacroporous cryogel matrix for integrated protein isolation

A new type of supermacroporous, monolithic, cryogel affinity adsorbent was developed, allowing the specific capture of urokinase from conditioned media of human fibrosarcoma cell line HT1080. The affinity adsorbent was designed with the objective of using it as a capture column in an integrated perfusion/protein separation bioreactor setup. A comparative study between the utility of this novel cryogel based matrix and the conventional Sepharose based affinity matrix for the continuous capture of urokinase in an integrated bioreactor system was performed. Cu(II)-ion was coupled to epoxy activated polyacrylamide cryogel and Sepharose using iminodiacetic acid (IDA) as the chelating ligand. About 27-fold purification of urokinase from the conditioned culture media was achieved with Cu(II)-IDA-polyacrylamide cryogel column giving specific activity of about 814 Plough units (PU)/mg protein and enzyme yields of about 80%. High yields (95%) were obtained with Cu(II)-IDA-Sepharose column by virtue of its high binding capacity. However, the adsorbent showed lower selectivity as compared to cryogel matrix giving specific activity of 161 PU/mg protein and purification factor of 5.3. The high porosity, selectivity and reasonably good binding capacity of Cu(II)-IDA-polyacrylamide cryogel column make it a promising option for use as a protein capture column in integrated perfusion/separation processes. The urokinase peak pool from Cu(II)-IDA-polyacrylamide cryogel column could be further resolved into separate fractions for high and low molecular weight forms of urokinase by gel filtration chromatography on Sephacryl S-200. The selectivity of the cryogel based IMAC matrix for urokinase was found to be higher as compared to that of Cu(II)-IDA-Sepharose column.

Biotechnology of desulfurization of diesel: prospects and challenges

To meet stringent emission standards stipulated by regulatory agencies, the oil industry is required to make a huge investment to bring down the sulfur content in diesel to the desired level, using conventional hydrodesulfurization (HDS) technology, by which sulfur is catalytically converted to hydrogen sulfide in the presence of hydrogen. These reactions proceed rapidly only at high temperature and pressure and therefore the capital cost as well as the operating cost associated with HDS very high. Biological desulfurization has the potential of being developed as a viable technology downstream of classical HDS. Various attempts have been made to develop biotechnological processes based on microbiological desulfurization employing aerobic and anaerobic bacteria. However, there are several bottlenecks limiting commercialization of the process. This review discusses various aspects of microbial desulfurization and the progress made towards its commercialization.

A potential resource for bioconversion of domestic wastewater sludge

Twenty seven filamentous fungal strains representing five genera; Aspergillus, Penicillium, Trichoderma, Myriodontium and Pleurotus were isolated from four sources; domestic wastewater sludge cake (SC) from IWK (Indah Water Konsortium) wastewater treatment plant, palm oil mill effluent compost from Sri Ulu palm Oil Processing Mill, compost of plant debris, and fungal fruiting bodies from a rotten wood stump. Thirty-three strains/isolates were tested for their ability to convert domestic wastewater sludge into compost by assessing biomass production and growth rate on sludge enriched media. The strains/isolates Aspergillus niger, SS-T2008, WW-P1003 and RW-P1 512 produced the highest dry biomass at higher sludge supplemented culture media from their respective group (Aspergillus, Trichoderma, Penicillium and Basidiomycetes, respectively). This implied these strains are better adapted for growth at higher sludge rich substances, and subsequently may be efficient in bioconversion/biodegradation of sludge. The fungi isolated from ecological closely related sources were more amendable to adaptation in a sludge rich culture media.

Treatment of wastewater sludge by liquid state bioconversion process

This study was conducted to evaluate the effect of an eminent decay fungus, Phanerocheate chrysosporium of organic residues on wastewater sludge for its improvement through decomposition and separation of waste particles by Liquid State Bioconversion (LSB). The effect of fungal treatment was compared to uninoculated (Control) at three different harvests 7, 14 and 21 days after inoculation (DAI). The observed results showed that the weight loss and solid content of wastewater sludge were significantly influenced by Phanerocheate chrysosporium. Both parameters were highly influenced at 7 DAI. The COD and pH of wastewater sludge were also highly influenced by fungal treatment.

Biodesulphurization of coal: mechanism and rate limiting factors

The pyrite sulphur removal from coal by Thiobacillus ferrooxidans was studied in batch reactor. A combination of SEM, IR and XRD was used to study the presence of superficial phases and the changes in solid surface during biodesulphurization. Biodesulphurization was found to be a three-step process. In the first step (0-4 days), direct oxidation of pyrite by bacteria brought about 28% pyritic sulphur removal. Both direct and indirect oxidation contributed to the second step (4-10 days) resulting in 51% pyrite removal. The deposition of elemental sulphur, jarosite and ferric sulphate precipitates in the third step reduced the pyrite availability and ferric iron concentration in the leachate and brought the process of biodesulphurization to an end.

Biphasic biomethanation of wood-hydrolysate effluent

The dissolving pulp industry, spread throughout the world, is the principal source of wood-hydrolysate effluent rich in hemicelluloses. This effluent is the major source of pollution in the industry. COD and BOD5 values of the effluent range from 60,000 to 103,000 and 42,000 to 78,000 mg/l respectively. Biomethanation of this effluent is the best possible treatment option for reducing the COD load and recovering the bioenergy embedded in the effluent. This paper deals with the study on the biphasic biomethanation of the wood-hydrolysate in upflow acidogenic reactor coupled with anaerobic filter methanogenic reactor. The two reactors were operated at organic loading rates of 69.6 and 30.1 g COD/l/d respectively. The overall COD, hemicelluloses and lignin reductions, and methane generation were observed to be 88%, 92%, 82% and 6.5 l/l reactor volume/d respectively. The relative size of the biphasic, anaerobic filter (mono-phasic) and upflow anaerobic sludge blanket (mono-phasic) reactors is found to be 1:1.6:2.03 respectively.

An empirical model on extractive lactic acid bioconversion

The commercial production of lactic acid through fermentation process has always been in competition with its chemical synthesis process (Kirk Othmer, 1995). Lactic acid produced through the fermentation process has to cope with the problems of purification to meet the required quality standards. An attempt to improve the fermentative production is possible by proper design of an industrial process involving low capital cost for the plant. Also, the low energy costs both in its fermentation and purification, are required. In the commercial interest, the investment cost should be minimised, which is possible only when the cell density in fermenter is high. It means that the inhibitory effect of the product on process kinetics must be minimised. Based on these requirements, the extractive bioconversion technique is one of the approaches to achieve the commercially viable lactic acid production. Extractive lactic acid bioconversion using ion-exchange resin process has already been described in our earlier publications (Srivastava e al., 1992: Roychoudhury et al., 1995) It is always an advantage to develop a process model, thus opening an area of biotechnological improvements to the process. In the present paper, an empirical mathematical model has been described to explain this extractive bioconversion using ion-exchange resin process. It was based on generalised Monod's growth model and Leudeking and Piret equation. The system was defined with the assumption that the microbial growth can be represented as a single reaction; only a very little part of the substrate is utilised for the maintenance of the cells. The effect of end product inhibition on growth and product formation kinetics has also been considered in this model. A non-linear regression technique was used for evaluation of bioconversion kinetic parameters. The fourth order Runge Kutta method was used for solving the differential equations. The results of this process simulation are also discussed in the present paper. It indicates that the use of present technique has minimised the effect of lactic acid inhibition on process kinetics and hence higher productivity and least substrate utilisation for maintenance of cells. A statistical F-test has been performed for determining the validity of the model for a given set of experimental data with a level of significance alpha = 0.05 selected for this extractive batch recycle bioconversion process using ion-exchange resin.

Production of urokinase by HT 1080 human kidney cell line

Studies were carried out in T-flasks and bioreactor to produce urokinase enzyme using HT 1080 human kidney cell line. While growing the cell line it has been observed that the lag phase is reduced considerably in the bioreactor as compared to T-flask culture. The HT 1080 cell adhesion rate and urokinase production were observed to be the function of serum concentration in the medium. The maximum urokinase activity of 3.1 x 10(-4) unit ml(-1) was achieved in the bioreactor at around 65 h of batch culture. Since HT 1080 is an anchorage dependent cell line, therefore, the hydrodynamic effects on the cell line were investigated.