Modular Bioreactor Research Articles

Fed-batch strategies for intensified rVSV vector production in high cell density cultures of suspension HEK293 cells.

Vesicular stomatitis virus (VSV) has been increasingly demonstrated as a promising viral vector platform. As the interest over this modality for vaccine and gene therapy applications increases, the need for intensified processes to produce these vectors emerge. In this study, we develop fed-batch-based operations to intensify the production of a recombinant VSV-based vaccine candidate (rVSV-SARS-CoV-2) in suspension cultures of HEK293 cells. A feeding strategy, in which a commercial concentrated medium was added to cultures based on cell growth through a fixed cell specific feeding rate (CSFR), was applied for the development of two different processes using Ambr250 modular bioreactors. Cultures operated in hybrid fed-batch/perfusion (FB/P) or fed-batch (FB) were able to sustain infections performed at 8.0 × 106 cells/mL, respectively resulting in 3.9 and 5.0-fold increase in total yield (YT) and 1.7 and 5.6-fold increase in volumetric productivity (VP) when compared with a batch reference. A maximum viral titer of 4.5 × 1010 TCID50/mL was reached, which is comparable or higher than other processes for VSV production in different cell lines. Overall, our study reports efficient fed-batch options to intensify the production of a rVSV-based vaccine candidate in suspension HEK293 cells.

Development of a bioreactor for in-vitro compression cycling of tissue engineered meniscal implants

Injuries to the meniscus are common and can impair physical activities. Bioprinted meniscal tissue offers an attractive alternative to donor tissue for meniscal repair but achieving the strength of native tissue is a challenge. Here we report the development of a tissue engineering bioreactor designed to apply repetitive force which may lead to an increase in the compressive modulus and durability of bioprinted meniscal tissues. The modular bioreactor system is composed of a sterilizable tissue culture vessel together with a dock that applies and measures mechanical force. The culture vessel allows for simultaneous compression cycling of two anatomically sized menisci. Using a hybrid linear actuator with a stepper motor, the dock can apply up to 300 N of force at speeds up to 20 mm/s, corresponding to the upper limits of anatomical force and motion in the knee. An interchangeable 22 N load cell was mated between the culture vessel and the dock to log changes in force. Both the culture vessel and dock are maintained in a standard cell culture incubator to provide heat and CO2, while the dock is powered and controlled externally using a step motor drive and customized software.

Titelbild Chem. Ing. Tech. 12/2022

Chemie Ingenieur TechnikVolume 94, Issue 12 p. 1869-1869 Cover PictureFree Access Titelbild Chem. Ing. Tech. 12/2022 First published: 22 November 2022 https://doi.org/10.1002/cite.202271201AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Fed-batch production of mRNA in single-use bioreactor with at-line HPLC reaction monitoring Copyright: Sartorius Production of mRNA is traditionally performed in batch mode by in vitro transcription reaction. We employ single-use bioreactor traditionally used for cell-based production of biopharmaceuticals to increase the yield of the in vitro transcription reaction by applying fed-batch mode. A controlled and automated feed addition functionality of a 250-mL single use modular bioreactor is used for continuous addition of mRNA building blocks, coupled with rapid at-line HPLC analytical monitoring, to design a feeding strategy to achieve a yield of 12 g L−1. This approach significantly decreases reagent costs and paves the way towards continuous manufacturing of mRNA. J. Skok, P. Megušar, T. Vodopivec, D. Pregeljc, N. Mencin, M. Korenč, A. Krušič, A. Martinčič Celjar, N. Pavlin, J. Krušič, M. Mueller, K. McHugh, A. Štrancar, R. Sekirnik, Chem. Ing. Tech. 2022, 94 (12), 1928–1935. DOI: https://doi.org/10.1002/cite.202200133 Volume94, Issue12Special Issue: Single-Use TechnologyDecember 2022Pages 1869-1869 RelatedInformation

Gram‐Scale mRNA Production Using a 250‐mL Single‐Use Bioreactor

AbstractThe COVID‐19 pandemic triggered an unprecedented surge in development of mRNA‐based vaccines. Despite the need to increase process productivity and thus decrease the cost of mRNA vaccines, limited scientific literature is available on strategies to increase the yield of in vitro transcription (IVT) reaction, the unit operation with highest cost of goods, which has traditionally been performed as a batch reaction. Single‐use bioreactors are traditionally used for cell‐based production of biopharmaceuticals, but some core functionalities, such as controlled and automated feed addition, are potentially useful for cell‐free mRNA processes. We report the production of 2 g mRNA in an Ambr® 250 Modular bioreactor system with a starting volume of 100 mL, reaching a maximum mRNA concentration of 12 g L−1 by a fed‐batch IVT approach, and demonstrate the feasibility of continuous fed‐batch production, paving the way towards continuous manufacturing of mRNA.

Modular Bioreactor Design for Directed Tendon/Ligament Tissue Engineering.

Functional tissue-engineered tendons and ligaments remain to be prepared in a reproducible and scalable manner. This study evaluates an acellular 3D extracellular matrix (ECM) scaffold for tendon/ligament tissue engineering and their ability to support strain-induced gene regulation associated with the tenogenesis of cultured mesenchymal stromal cells. Preliminary data demonstrate unique gene regulation patterns compared to other scaffold forms, in particular in Wnt signaling. However, the need for a robust bioreactor system that minimizes process variation was also evident. A design control process was used to design and verify the functionality of a novel bioreactor. The system accommodates 3D scaffolds with clinically-relevant sizes, is capable of long-term culture with customizable mechanical strain regimens, incorporates in-line load measurement for continuous monitoring and feedback control, and allows a variety of scaffold configurations through a unique modular grip system. All critical functional specifications were met, including verification of physiological strain levels from 1–10%, frequency levels from 0.2–0.5 Hz, and accurate load measurement up to 50 N, which can be expanded on the basis of load cell capability. The design process serves as a model for establishing statistical functionality and reliability of investigative systems. This work sets the stage for detailed analyses of ECM scaffolds to identify critical differentiation signaling responses and essential matrix composition and cell–matrix interactions.

Enzymes immobilized in wood-derived cellulose scaffold for constructing a novel modular bioreactor

Modular bioreactors can provide a flexible platform for constructing complex multi-step pathways, which may be a solution for maximizing reactions and overcoming the complexity of multi-enzyme systems. Here, we selected wood-derived cellulose scaffold as a support for enzyme immobilization and constructed the modular bioreactor. Cellulose scaffold was prepared after removing lignin from wood, followed by citric acid functionalization and the addition of glutaraldehyde finally allowed the cross-linking of enzymes. Three enzymes, horseradish peroxidase (HRP), glucose oxidase (GOD), and catalase (CAT), were separately immobilized, resulting in the immobilized enzyme amount to over 40 mg/g. The introduction of carboxyl groups from citric acid facilitated the rapid enzyme adsorption on the support surface and immobilized enzymes possess ∼65% expressed activity. Modular bioreactors were constructed by using the immobilized enzymes. With the immobilized HRP module, reactor showed desired catalytic performance with the phenol degradation rate of > 90%. Also, a pH regulation can occur in the bioreactors for preserving enzyme activities and neutralizing acid products. In the GOD/CAT modular bioreactor, the cascade reaction with adjusting pH values can achieve a 95% yield of sodium gluconate and exhibit a favorable reusability of 5 operation cycles.

A novel, scalable, and modular bioreactor design for dynamic simulation of the digestive tract.

In vitro gut model systems permit the growth of gut microbes outside their natural habitat and are essential to the study of gut microbiota. Systems available today are limited by a lack of scalability and flexibility in the mode of operation. Here, we describe the development of a versatile bioreactor module that can be easily adjusted for culture size and capable of sensing and controlling of environmental parameters such as pH control of culture medium, rate of influx and efflux of the culture medium, and aerobic/anaerobic atmosphere. Bioreactor modules can be operated as single units or linked in series to construct a model of a digestive tract with multiple compartments to allow the growth of microbiota in vitro. We tested the growth of synthetic and natural bacterial communities in a multicompartment continuous dynamic culture model simulation of the mammalian gut. The distal compartments of a sterile system inoculated with the synthetic bacterial community at the proximal module attained a stable bacterial density by 24 h, and all the genera present in the inoculum were firmly established in the distal modules simulating the large intestine at 5 days of continuous culture. A natural bacterial community simultaneously inoculated into the distal modules attained a stable bacterial composition at the phylum level by Day 7 of continuous culture. The findings illustrate the utility of the system to culture mixed bacterial communities which can be used to study the collective biological activities of the cultured microbiota in the absence of host influence.

A feasibility study of the installation of a modular bioreactor inside a chemical scrubber at a wastewater treatment plant

Chemical scrubbing and biofiltration are well-established technologies for treating contaminated pollutants generated at wastewater treatment plants (WWTPs). Nevertheless, the growing need to reduce the ecological footprint of abatement technologies without affecting process efficiency is prioritizing biological alternatives. This study deals with the challenge of designing a structure for converting a chemical scrubber currently operating at a WWTP with a capacity of 6400 population equivalent (PE) into a modular bioreactor without any actual modification of the scrubber´s structure. The inside of the reactor was divided into three levels or platforms for holding the biomaterial, and the corresponding parts were manufactured in PVC, with the exceptions of the screws and cross bracing. The study of the parts’ stress and strain limits revealed that the slats and half-rings should be reinforced with ribs, and the optimal rib height was studied on a case-by-case basis. It was also concluded that the base legs could hold the weight of 80 cm height biomaterial bed onto each of the three platforms. Based on previous studies, the converted biofilter with an inlet flow rate of 1150 m3/h could render simultaneous removal efficiencies greater than 90 % for H2S and NH3. Regarding the viability study, the annual savings from the elimination of chemical consumption were around 9.7 % of the total investment cost. One of the main strengths of replacing the scrubber with a biofilter was the improvement in sustainable performance and health and safety, reducing both risk and the budget for prevention.

A novel bioreactor system to purify contaminated runoff water

Water scarcity has become a global crisis and an economic burden. Environmental challenges in climate change, population growth, and urbanization have raised serious concerns for safe drinking water, food security, social stability, and public health. Current physicochemical purification techniques are costly, chemically-invasive, or ineffective. The aim of this study was to engineer an eco-friendly and cost-effective water purification system using an ex-situ bioremediation approach. The main objective was to use limestone, denitrifying bacteria, and sulfate-reducing bacteria present in the soil as natural resources. Organic compost was added as a carbon source to enhance activities of intrinsic soil bacteria. All samples were collected from mining and industrial sites in Eastern Pennsylvania. We evaluated and verified the feasibility of a novel modular bioreactor system for the effective removal of nitrate, sulfate, and heavy metals from runoff water while increasing its alkalinity. The impacts of pH and temperature on the bioremediation efficiency were evaluated, revealing ideal temperatures to be above 16°C and pH above 7. Nitrate levels dropped from 80 ppm to 0 ppm, and pH increased from 4 to above 7 consistently. Combining neutralization with bacterial bioremediation proved to have synergistic benefits within 30 minutes of treatment. Results showed a successful removal of nitrate (NO3-), sulfate (SO42-), sulfite (SO32-), Zinc (Zn), Copper (Cu), Aluminum (Al), and Lead (Pb) from contaminated wastewater. This system is a cost-effective, energy-efficient, and practical tool that opens numerous avenues for generating sustainable, portable, and fast water purification options for low-income communities. A large-scale system could be adapted for commercial or industrial purposes.

Oxygenation Profiles of Human Blood, Cell Culture Medium, and Water for Perfusion of 3D-Bioprinted Tissues using the FABRICA Bioreactor Platform

Persistent and saturated oxygen distribution from perfusion media (i.e., blood, or cell culture media) to cells within cell-dense, metabolically-active biofabricated tissues is required to keep them viable. Improper or poor oxygen supply to cells within the tissue bulk severely limits the tissue culturing potential of many bioreactors. We added an oxygenator module to our modular FABRICA bioreactor in order to provide stable oxygenation to biofabricated tissues during culture. In this proof of concept study of an oxygenated and perfused bioreactor, we characterized the oxygenation of water, cell culture medium, and human blood in the FABRICA as functions of augmenting vacuum (air inlet) pressure, perfusion (volumetric flow) rate, and tubing/oxygenator components. The mean oxygen levels for water and cell culture media were 27.7 ± 2.1% and 27.6 ± 4.1%, respectively. The mean oxygen level for human blood was 197.0 ± 90.0 mmHg, with near-physiologic levels achieved with low-permeability PharMed tubing alone (128.0 ± 14.0 mmHg). Hematologic values pre- and post-oxygenation, respectively were (median ± IQR): Red blood cell: 6.0 ± 0.5 (106/μL) and 6.5 ± 0.4 (106/μL); Hemoglobin: 17.5 ± 1.2 g/dL and 19.2 ± 3.0 g/dL; and Hematocrit: 56.7 ± 2.4% and 61.4 ± 7.5%. The relative stability of the hematologic parameters indicates that blood function and thus blood cell integrity were maintained throughout oxygenation. Already a versatile research tool, the now oxygenated FABRICA provides easy-to-implement, in vivo-like perfusion and stable oxygenation culture conditions in vitro semi-independently of one another, which means the bioreactor has the potential to serve as a platform for investigating the behavior of 3D tissue models (regardless of biofabrication method), performing drug toxicity-testing, and testing pharmaceutical efficacy/safety.

Microbial Engineering Community (mce): Selecting Key Players in Microbiomes

Microbial Community Engineering (MCE) is an emerging paradigm in biotechnology, which focuses the attention on microbial consortia or communities, sometimes addressed as microbiomes. Microbial communities are ubiquitous in nature and useful in many areas. Earth’s microbial ecosystems are important in the production of foods, nitrogen fixation and carbon cycles, recycling of micronutrients, bioremediation and in maintaining the health of humans, animals, and plants, among many others. MCE is a growing field that can be exploited to produce bulk and fine chemicals, bioenergy as well as pharmaceuticals by enhancing the effect of natural microbiomes. Adapted/selected microbial consortia have the potential to advance specialized tasks by resorting to high-order communities’ mechanisms, which are difficult to accomplish with monocultures. Notwithstanding the interest in MCE, biotechnological applications remain rudimentary; mixed cultures of partially known composition govern the processes of wastewater treatment and the anaerobic digestion of organic refuses, yet the vast potential of “microbial ecological power”, observed in most natural environments, remains largely underemployed. After a brief overview of key mechanisms that govern microbiomes, this work is aimed to suggest experimental approaches for the separation of constituents of complex microbiomes and to use MCE to reproduce the natural biological order by designing interlinked modular bioreactors where MCE would overcome limitations of natural systems.

Engineering a dynamic model of the alveolar interface for the study of aerosol deposition

Nano and micro particles are widely used in industrial, household and medicinal applications. To understand the interaction between particles and epithelial cells, we developed a dynamic model of the alveolar interface. This system, named DALI (Dynamic Model for the ALveolar Interface), is a modular bioreactor composed of two chambers divided by a porous membrane where epithelial lung cells are seeded. The membrane is the support of the alveolar barrier that separates the two compartments of the alveolus: the air and blood side. The system integrates the following elements: i) Air/Liquid interface, thanks to the two chambers divided by the membrane: ii) Cell culture media flow, thanks to the presence of a peristaltic pump; iii) Lung breathing motion, thanks to an airflow that allows the stretching of the membrane; iv) Aerosol deposition system, to study the effects of drug efficacy or particle toxicity on the epithelial layer; v) Quartz Crystal Microbalance, to quantify the amount of aerosolized particles.

Study of the Operation of a Continuous Modular Bioreactor Used for Treatment of Wastewater from a Recycling Industry of by-Products from Slaughterhouses

The objective of this paper was to present the operational performance of a bioreactor’s technology for treating wastewater from a recycling industry of by-products from slaughterhouses. In addition, it contributes to overcome the main disadvantages of treatment using Australian pond systems. The modular bioreactor described in this work consists of an alternative and innovative equipment that operates continuously on an industrial scale, which enables the treatment of liquid waste. The modular bioreactor was constructed of reinforced concrete with dimensions 70 m in length, 1.2 m in width, and 0.6 m in height, with an internal volume of 35,000 L, the process of wastewater degradation alternating between aerobic and anoxic conditions, being predominantly anoxic. The bioreactor was tested in two stages, by using this industrial wastewater. In the first stage, totaling 243 days, a primary effluent was added, consisting of high concentration of pollutants; and in a second stage, totaling 288 days, it was added a biologically pretreated effluent (after an anaerobic post-digestion process). The input-output parameters pH, turbidity, conductivity, temperature, and dissolved oxygen were monitored weekly, while total phosphorus, orthophosphate, total nitrogen, ammonium, nitrite, nitrate, total suspended solids, sedimented solids, oils and greases, COD, BOD, and alkalinity parameters were determined monthly. The bioreactor was promising in terms of pollutant removal efficiency, and partial nitrification may have occurred on a continuous scale in the first stage of the tests.

A new millifluidic-based gastrointestinal platform to evaluate the effect of simulated dietary methylglyoxal intakes.

The search for new in vitro modular bioreactors to simulate flow-mediated transport and absorption of chemical substances is a very important issue in toxicology and in drug and bioactive delivery research. The possibility of setting up a dynamic microenvironment leads to experimental conditions that may more closely resemble the in vivo model, especially to measure acute or chronic intake of compounds. We propose a novel millifluidic-based gastrointestinal model as an evolution of the common in vitro methods, to evaluate the exposure to exogenous methylglyoxal (MGO), a highly reactive α-oxoaldehyde responsible for the formation of advanced glycation end products involved in a number of chronic diseases. Gastric and intestinal cells were seeded into two different chambers, creating a multi-compartmental system where fluids dynamically interact with human gastric stromal and intestinal cells. MGO was tested at concentrations simulating different MGO food intakes (meal, daily, and hypothetically weekly). Cell viability was measured over time, and simultaneously, extracellular MGO was quantified by a validated RP-HPLC-DAD method to evaluate its absorption/metabolization. This new platform gives the opportunity to connect different compartments, allowing studying kinetic and metabolic profiles of different substances and representing a very promising alternative to animal models, at least in preliminary investigations.

A versatile modular bioreactor platform for Tissue Engineering.

Tissue Engineering (TE) bears potential to overcome the persistent shortage of donor organs in transplantation medicine. Additionally, TE products are applied as human test systems in pharmaceutical research to close the gap between animal testing and the administration of drugs to human subjects in clinical trials. However, generating a tissue requires complex culture conditions provided by bioreactors. Currently, the translation of TE technologies into clinical and industrial applications is limited due to a wide range of different tissue‐specific, non‐disposable bioreactor systems. To ensure a high level of standardization, a suitable cost‐effectiveness, and a safe graft production, a generic modular bioreactor platform was developed. Functional modules provide robust control of culture processes, e.g. medium transport, gas exchange, heating, or trapping of floating air bubbles. Characterization revealed improved performance of the modules in comparison to traditional cell culture equipment such as incubators, or peristaltic pumps. By combining the modules, a broad range of culture conditions can be achieved. The novel bioreactor platform allows using disposable components and facilitates tissue culture in closed fluidic systems. By sustaining native carotid arteries, engineering a blood vessel, and generating intestinal tissue models according to a previously published protocol the feasibility and performance of the bioreactor platform was demonstrated.

Alginate/porous silica matrices for the encapsulation of living organisms: tunable properties for biosensors, modular bioreactors, and bioremediation devices

Abstract:The encapsulation of living cells within inorganic silica hydrogels is a promising strategy for the design of biosensors, modular bioreactors, and bioremediation devices, among other interesting applications, attracting scientific and technological interest. These hostguest multifunctional materials (HGFM) combine synergistically specific biologic functions of their guest with those of the host matrix enhancing their performance. Although inorganic immobilization hosts present several advantages over their (bio)polymer-based counterparts in terms of chemical and physical stability, the direct contact of cells with silica precursors during synthesis and the constraints imposed by the inorganic host during operating conditions have proved to influence their biological response. Recently, we proposed an alternative two-step procedure including a pre-encapsulation in biocompatible polymers such as alginates in order to confer protection to the biological guest during the inorganic and more cytotoxic synthesis. By means of this procedure, whole cultures of microorganisms remain confined in small liquid volumes generated inside the inorganic host, providing near conventional liquid culture conditions.Moreover, the fact of protecting the biological guest during the synthesis of the host, allows extending the synthesis parameters beyond biocompatible conditions, tuning the microstructure of the matrix. In turn, the microstructure (porosity at the nanoscale, radius of gyration of particles composing the structure, and fractal dimension of particle clusters) is determinant of macroscopic parameters, such as optical quality and transport properties that govern the encapsulation material’s performance. Here, we review the most interesting applications of the two-step procedure, making special emphasis on the optimization of optical, transport and mechanical properties of the host as well as in the interaction with the guest during operation conditions.

Mimicking biophysical stimuli within bone tumor microenvironment.

In vivo, cells reside in a complex environment regulating their fate and function. Most of this complexity is lacking in standard in vitro models, leading to readouts falling short of predicting the actual in vivo situation. The use of engineering tools, combined with deep biological knowledge, leads to the development and use of bioreactors providing biologically sound niches. Such bioreactors offer new tools for biological research, and are now also entering the field of cancer research. Here we present the development and validation of a modular bioreactor system providing: (i) high throughput analyses, (ii) a range of biological conditions, (iii) high degree of control, and (iv) application of physiological stimuli to the cultured samples. The bioreactor was used to engineer a three-dimensional (3D) tissue model of cancer, where the effects of mechanical stimulation on the tumor phenotype were evaluated. Mechanical stimuli applied to the engineered tumor model activated the mechanotransduction machinery and resulted in measurable changes of mRNA levels towards a more aggressive tumor phenotype.

Isolation and Expansion of Hepatic Stem-like Cells from a Healthy Rat Liver and their Efficient Hepatic Differentiation of under Well-defined Vivo Hepatic like Microenvironment in a Multiwell Bioreactor

BackgroundCurrently, undifferentiated cells are found in all tissue and term as local stem cells which are quiescent in nature and less in number under normal healthy conditions but activate upon injury and repair the tissue or organs via automated activating mechanism. Due to very scanty presence of local resident somatic local stem cells in healthy organs, isolation and expansion of these adult stems is an immense challenge for medical research and cell based therapy. Particularly organ like liver, there is an ongoing controversy about existence of liver stem cells. MethodsHerein, Hepatic stem cells population was identified during culture of primary hepatocyte cells upon immediate isolation of primary hepatocyte cells. These liver stem cells has been expanded extensively and differentiated into primary hepatocytes under defined culture conditions in a nanostructured self assembling peptides modular bioreactor that mimic the state of art of liver microenvironment and compared with Matrigel as a positive control. Nanostructured self assembling peptides were used a defined extracellular matrix and Matrigel was used for undefined extracellular matrix. Proliferation of hepatic stem cells was investigated by two strategies. First strategy is to provide high concentration of hepatocyte growth factor (HGF) and second strategy is to evaluate the role of recombinant human erythropoietin (rHuEPO) in presence of trauma/ischemia cytokines (IL-6, TNF-α). Expansion to hepatic differentiation is observed by morphological analysis and was evaluated for the expression of hepatocyte-specific genes using RT-PCR and biochemical methods. ResultsHepatocyte-specific genes are well expressed at final stage (day 21) of differentiation period. The differentiated hepatocytes exhibited functional hepatic characteristics such as albumin secretion, urea secretion and cytochrome P450 expression. Additionally, immunofluorescence analysis revealed that hepatic stem cells derived hepatocytes exhibited mature hepatocyte markers (albumin, CK-19, CPY3A1, alpha 1-antitrypsin). Expansion and hepatic differentiation was efficiently in nanostructured self assembling peptides without such batch to batch variation while there was much variation in Matrigel coated bioreactor. In conclusion, the results of the study suggest that the nanostructured self assembling peptides coated bioreactor supports expansion as well as hepatic differentiation of liver stem cells which is superior than Matrigel. ConclusionThis defined microenvironment conditions in bioreactor module can be useful for research involving bioartificial liver system, stem cell research and engineered liver tissue which could contribute to regenerative cell therapies or drug discovery and development.

A novel modular bioreactor to in vitro study the hepatic sinusoid.

We describe a unique, versatile bioreactor consisting of two plates and a modified commercial porous membrane suitable for in vitro analysis of the liver sinusoid. The modular bioreactor allows i) excellent control of the cell seeding process; ii) cell culture under controlled shear stress stimulus, and; iii) individual analysis of each cell type upon completion of the experiment. The advantages of the bioreactor detailed here are derived from the modification of a commercial porous membrane with an elastomeric wall specifically moulded in order to define the cell culture area, to act as a gasket that will fit into the bioreactor, and to provide improved mechanical robustness. The device presented herein has been designed to simulate the in vivo organization of a liver sinusoid and tested by co-culturing endothelial cells (EC) and hepatic stellate cells (HSC). The results show both an optimal morphology of the endothelial cells as well as an improvement in the phenotype of stellate cells, most probably due to paracrine factors released from endothelial cells. This device is proposed as a versatile, easy-to-use co-culture system that can be applied to biomedical research of vascular systems, including the liver.

Remediation and selective recovery of metals from acidic mine waters using novel modular bioreactors.

Mine waters are widely regarded as environmental pollutants, but are also potential sources of valuable metals. Water draining the Maurliden mine (Sweden) is highly acidic (pH 2.3) and rich in zinc (∼ 460 mg L(-1)) and iron (∼ 400 mg L(-1)), and contains smaller concentrations (0.3-49 mg L(-1)) of other transition metals and arsenic. We have developed novel techniques that promote the concurrent amelioration of acidic waste waters and selective recovery of metals, and have used these systems to treat synthetic Maurliden mine water in the laboratory. The two major metals present were removed via controlled biomineralization: zinc as ZnS in a sulfidogenic bioreactor, and iron as schwertmannite by microbial iron oxidation and precipitation of ferric iron. A small proportion (∼ 11%) of the schwertmannite produced was used to remove arsenic as the initial step in the process, and other chalcophilic metals (copper, cadmium and cobalt) were removed (as sulfides) in the stage 1 metal sulfide precipitation reactor. Results from this work have demonstrated that modular biomineralization units can be effective at processing complex mine waters and generating metal products that may be recycled. The economic and environmental benefits of using an integrated biological approach for treating metal-rich mine waters is discussed.