Guidance on good cell culture practice. a report of the second ECVAM task force on good cell culture practice

Glucose sensitivity of mouse olfactory bulb neurons is conveyed by a voltage-gated potassium channel

The olfactory bulb has recently been proposed to serve as a metabolic sensor of internal chemistry, particularly that modified by metabolism. Because the voltage-dependent potassium channel Kv1.3 regulates a large proportion of the outward current in olfactory bulb neurons and gene-targeted deletion of the protein produces a phenotype of resistance to diet-induced obesity in mice, we hypothesized that this channel may play a role in translating energy availability into a metabolic signal. Here we explored the ability of extracellular glucose concentration to modify evoked excitability of the mitral neurons that principally regulate olfactory coding and processing of olfactory information. Using voltage-clamp electrophysiology of heterologously expressed Kv1.3 channels in HEK 293 cells, we found that Kv1.3 macroscopic currents responded to metabolically active (d-) rather than inactive (l-) glucose with a response profile that followed a bell-shaped curve. Olfactory bulb slices stimulated with varying glucose concentrations showed glucose-dependent mitral cell excitability as evaluated by current-clamp electrophysiology. While glucose could be either excitatory or inhibitory, the majority of the sampled neurons displayed a decreased firing frequency in response to elevated glucose concentration that was linked to increased latency to first spike and decreased action potential cluster length. Unlike modulation attributed to phosphorylation, glucose modulation of mitral cells was rapid, less than one minute, and was reversible within the time course of a patch recording. Moreover, we report that modulation targets properties of spike firing rather than action potential shape, involves synaptic activity of glutamate or GABA signalling circuits, and is dependent upon Kv1.3 expression. Given the rising incidence of metabolic disorders attributed to weight gain, changes in neuronal excitability in brain regions regulating sensory perception of food are of consequence.

The ToxBank Data Warehouse: Supporting the Replacement of In Vivo Repeated Dose Systemic Toxicity Testing

The aim of the SEURAT-1 (Safety Evaluation Ultimately Replacing Animal Testing-1) research cluster, comprised of seven EU FP7 Health projects co-financed by Cosmetics Europe, is to generate a proof-of-concept to show how the latest technologies, systems toxicology and toxicogenomics can be combined to deliver a test replacement for repeated dose systemic toxicity testing on animals. The SEURAT-1 strategy is to adopt a mode-of-action framework to describe repeated dose toxicity, combining in vitro and in silico methods to derive predictions of in vivo toxicity responses. ToxBank is the cross-cluster infrastructure project whose activities include the development of a data warehouse to provide a web-accessible shared repository of research data and protocols, a physical compounds repository, reference or "gold compounds" for use across the cluster (available via wiki.toxbank.net), and a reference resource for biomaterials. Core technologies used in the data warehouse include the ISA-Tab universal data exchange format, REpresentational State Transfer (REST) web services, the W3C Resource Description Framework (RDF) and the OpenTox standards. We describe the design of the data warehouse based on cluster requirements, the implementation based on open standards, and finally the underlying concepts and initial results of a data analysis utilizing public data related to the gold compounds.

Endothelial cells derived from nuclear reprogramming

The endothelium plays a pivotal role in vascular homeostasis, regulating the tone of the vascular wall, and its interaction with circulating blood elements. Alterations in endothelial functions facilitate the infiltration of inflammatory cells and permit vascular smooth muscle proliferation and platelet aggregation. Therefore, endothelial dysfunction is an early event in disease processes including atherosclerosis, and because of its critical role in vascular health, the endothelium is worthy of the intense focus it has received. However, there are limitations to studying human endothelial function in vivo, or human vascular segments ex vivo. Thus, methods for endothelial cell (EC) culture have been developed and refined. Recently, methods to derive ECs from pluripotent cells have extended the scientific range of human EC studies. Pluripotent stem cells may be generated, expanded, and then differentiated into ECs for in vitro studies. Constructs for molecular imaging can also be employed to facilitate tracking these cells in vivo. Furthermore, one can generate patient-specific ECs to study the effects of genetic or epigenetic alterations on endothelial behavior. Finally, there is the opportunity to apply these cells for vascular therapy. This review focuses on the generation of ECs from stem cells; their characterization by genetic, histological, and functional studies; and their translational applications.

Look back in anger - what clinical studies tell us about preclinical work

Misled by animal studies and basic research? Whenever we take a closer look at the outcome of clinical trials in a field such as, most recently, stroke or septic shock, we see how limited the value of our preclinical models was. For all indications, 95% of drugs that enter clinical trials do not make it to the market, despite all promise of the (animal) models used to develop them. Drug development has started already to decrease its reliance on animal models: In Europe, for example, despite increasing R&D expenditure, animal use by pharmaceutical companies dropped by more than 25% from 2005 to 2008. In vitro studies are likewise limited: questionable cell authenticity, over-passaging, mycoplasma infections, and lack of differentiation as well as non-homeostatic and non-physiologic culture conditions endanger the relevance of these models. The standards of statistics and reporting often are poor, further impairing reliability. Alarming studies from industry show miserable reproducibility of landmark studies. This paper discusses factors contributing to the lack of reproducibility and relevance of pre-clinical research.

THE CONCLUSION

Publish less but of better quality and do not rely on the face value of animal studies.

Isolation and characterization of the environmental bacterial and fungi contamination in a pharmaceutical unit of mesenchymal stem cell for clinical use

Design and implementation of an environmental monitoring program is vital to assure the maintenance of acceptable quality conditions in a pharmaceutical manufacturing unit of human mesenchymal stem cells. Since sterility testing methods require 14 days and these cells are only viable for several hours, they are currently administered without the result of this test. Consequently environmental monitoring is a key element in stem cell banks for assuring low levels of potential introduction of contaminants into the cell products. The aim of this study was to qualitatively and quantitatively analyze the environmental microbiological quality in a pharmaceutical manufacturing unit of human mesenchymal stem cells production for use in advanced therapies. Two hundred and sixty one points were tested monthly during one year, 156 from air and 105 from surfaces. Among the 6264 samples tested, 231 showed contamination, 76.6% for bacteria and 23.4% for fungi. Microbial genuses isolated were Staphylococcus (89.7%), Microccocus (4.5%), Kocuria (3.2%) and Bacillus (2.6%). In the identification of fungi, three genuses were detected: Aspergillus (56%), Penicillium (26%) and Cladosporium (18%). The origin of the contamination was found to be due to personnel manipulation and air microbiota. For all sampling methods, alert limits were set and corrective measures suggested.

Derivation of xeno-free and GMP-grade human embryonic stem cells--platforms for future clinical applications

Clinically compliant human embryonic stem cells (hESCs) should be developed in adherence to ethical standards, without risk of contamination by adventitious agents. Here we developed for the first time animal-component free and good manufacturing practice (GMP)-compliant hESCs. After vendor and raw material qualification, we derived xeno-free, GMP-grade feeders from umbilical cord tissue, and utilized them within a novel, xeno-free hESC culture system. We derived and characterized three hESC lines in adherence to regulations for embryo procurement, and good tissue, manufacturing and laboratory practices. To minimize freezing and thawing, we continuously expanded the lines from initial outgrowths and samples were cryopreserved as early stocks and banks. Batch release criteria included DNA-fingerprinting and HLA-typing for identity, characterization of pluripotency-associated marker expression, proliferation, karyotyping and differentiation in-vitro and in-vivo. These hESCs may be valuable for regenerative therapy. The ethical, scientific and regulatory methodology presented here may serve for development of additional clinical-grade hESCs.

Validation and quality control of replacement alternatives – current status and future challenges

Alternatives to animal testing have been developed mainly in the fields of toxicology and vaccine testing. Typical examples are the evaluation of phototoxicity, eye irritation or skin corrosion/irritation of cosmetics and industrial chemicals. However, examples can also be found in other biomedical areas, such the control of the quality of drug preparations for pyrogens or for the control of the production process of biologics, such as botulinum neurotoxin. For regulatory purposes, the quality, transferability and predictivity of an alternative method needs to be evaluated. This procedure is called the “validation process” of a new method. It follows defined rules, and several governmental institutions have been established to perform, supervise or advise on this process. As this often results in a delay of method implementation, different alternatives for the evaluation of a method's suitability and quality are under discussion. We describe here the principles of model development and quality control. We also give an overview on methods that have undergone validation. Strengths and shortcomings of traditional approaches are discussed, and new developments and challenges are outlined.

Quantifying processes determining the free concentration of phenanthrene in Basal cytotoxicity assays

Difficulties may arise when extrapolating in vitro derived toxicity data to in vivo toxicity data because of the high variability and occasional low sensitivity of in vitro results. Differences in the free concentration of a test compound between in vitro and in vivo systems and between different in vitro systems may in part explain this variability and sensitivity difference. The aim of this study was to determine what assay components influence the free concentration of phenanthrene in a Balb/c 3T3 and RTgill-W1 MTT assay. Partition coefficients of phenanthrene to serum, well plate plastic, cells, and headspace were measured and subsequently used to model the free concentration of the compound in vitro. The estimated free concentration was compared to the free concentration measured in the assays using solid phase microextraction (SPME). Results indicate that the free concentration of phenanthrene, a relatively volatile and hydrophobic compound, is significantly reduced in a typical in vitro setup as it binds to matrices such as serum protein and well plate plastic. A reduction in free concentration due to increasing serum protein levels is accompanied by an increase in the median effect concentration (EC(50)) and can be modeled, with the exception of evaporation, using the partition coefficients of the compound to assay components.

Standardization of pluripotent stem cell cultures for toxicity testing

INTRODUCTION

Pluripotent stem cell (PSC) lines offer a unique opportunity to derive various human cell types that can be exploited for human safety assessments in vitro and as such contribute to modern mechanistically oriented toxicity testing.

AREAS COVERED

This article reviews the two major types of PSC cultures that are currently most promising for toxicological applications: human embryonic stem cell lines and human induced PSC lines. Through the review, the article explains how these cell types will improve the current safety evaluations of chemicals and will allow a more efficient selection of drug candidates. Additionally, the article discusses the important issues of maintaining PSCs as well as their differentiation efficiency.

EXPERT OPINION

The demonstration of the reliability and relevance of in vitro toxicity tests for a given purpose is mandatory for their use in regulatory toxicity testing. Given the peculiar nature of PSCs, a high level of standardization of undifferentiated cell cultures as well as of the differentiation process is required in order to ensure the establishment of robust test systems. It is, therefore, of pivotal importance to define and internationally agree on crucial parameters to judge the quality of the cellular models before enrolling them for toxicity testing.

Embryonic stem cells in safety pharmacology and toxicology

Embryonic stem (ES) cells undergo self-renewal and are pluripotent, i.e., they can give rise to all the types of specialised cells in the body. Scientific knowledge on ES cells is increasing rapidly, leading to opportunities for establishment of ES cell-based in vitro tests for drug discovery, preclinical safety pharmacology and toxicology. The main properties of ES cells making them useful in in vitro assays are that they have a normal diploid karyotype and can provide a large number of cells for high-throughput assays. Human ES cells additionally have the potential to provide solutions to problems related to interspecies differences and methods for screening for human polymorphisms, thus supporting robust human hazard identification and optimised drug discovery strategies. Importantly, ES cell based assays could be potential tools to reduce and perhaps replace, animal experiments. This chapter will describe ongoing research in the use of ES cells in toxicology and safety pharmacology, focusing on the major areas of progress, namely, embryotoxicology, cardiotoxicology and hepatoxicology.

Banking stem cells for research and clinical applications

Standardization in stem cell research is a challenging aspect of the field although progress is being made to improve reliability and reproducibility of culture methods and differentiation protocols. A vital element in enabling valid comparisons of research data based on cell lines is to be able to assure the scientific quality of the cells used. Stem cell resource centers or "stem cell banks" can play an important role in stem cell research by focussing on delivery of pluripotent stem cell (PSC) lines that are fit for researchers needs, have not been switched or cross-contaminated by other cells, and are free of microbial contaminants. These fundamental elements of good scientific practice will help to promote good quality and comparable research publications. Stem cell banks can also provide advice on selection from the PSC lines they hold and best practice in culture, preservation, and quality control of stem cell lines. This chapter explores the value of stem cell banks and the various issues to address in delivering PSC lines for both research and as seed stocks for clinical development.

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

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

A call for standardized naming and reporting of human ESC and iPSC lines

Human embryonic and induced pluripotent stem cell lines are being generated at a rapid pace and now number in the thousands. We propose a standard nomenclature and suggest the use of a centralized database for all cell line names and a minimum set of information for reporting new derivations.

Alternative in vitro assays in nanomaterial toxicology

Nanomaterials are acclaimed for their novel properties, for which broad new uses are being discovered with increasing frequency. It is obvious that, as the properties change, unwanted properties (toxicity) are to be expected as well. Current toxicology, however, is already overwhelmed with the challenge of addressing new chemicals, not to mention the enormous number of old chemicals never properly assessed. Limitations of traditional approaches range from animal welfare issues, which were a strong driving force for alternative approaches (the 3Rs concept) over the last two decades, to aspects of throughput and accuracy of the predicted toxicities. The latter has prompted discussion about a revolutionary change in chemical safety assessment, now known as Toxicology for the 21st Century (Tox-21c). The multitude of possible formulations of nanomaterials to be assessed for novel toxic properties makes these alternative approaches especially attractive, given the well recognized limitations of traditional animal-based approaches--limitations that might be even more pronounced for nanomaterials, which have notably altered biokinetics.

Defined culture medium for stem cell differentiation: applicability of serum-free conditions in the mouse embryonic stem cell test

The embryonic stem cell test (EST) is a validated method to assess the developmental toxicity potency of chemicals. It was developed to reduce animal use and allow faster testing for hazard assessment. The cells used in this method are maintained and differentiated in media containing foetal calf serum. This animal product is of considerable variation in quality, and individual batches require extensive testing for their applicability in the EST. Moreover, its production involves a large number of foetuses and possible animal suffering. We demonstrate the serum-free medium and feeder cell-free maintenance of the mouse embryonic stem cell line D3 and investigate the use of specific growth factors for induction of cardiac differentiation. Using a combination of bone morphogenetic protein-2, bone morphogenetic protein-4, activin A and ascorbic acid, embryoid bodies efficiently differentiated into contracting myocardium. Additionally, examining levels of intracellular marker proteins by flow cytometry not only confirmed differentiation into cardiomyocytes, but demonstrated significant differentiation into neuronal cells in the same time frame. Thus, this approach might allow for simultaneous detection of developmental effects on both early mesodermal and neuroectodermal differentiation. The serum-free conditions for maintenance and differentiation of D3 cells described here enhance the transferability and standardisation and hence the performance of the EST.

Optimization of chemically defined cell culture media--replacing fetal bovine serum in mammalian in vitro methods

Quality assurance is becoming increasingly important. Good laboratory practice (GLP) and good manufacturing practice (GMP) are now established standards. The biomedical field aims at an increasing reliance on the use of in vitro methods. Cell and tissue culture methods are generally fast, cheap, reproducible and reduce the use of experimental animals. Good cell culture practice (GCCP) is an attempt to develop a common standard for in vitro methods. The implementation of the use of chemically defined media is part of the GCCP. This will decrease the dependence on animal serum, a supplement with an undefined and variable composition. Defined media supplements are commercially available for some cell types. However, information on the formulation by the companies is often limited and such supplements can therefore not be regarded as completely defined. The development of defined media is difficult and often takes place in isolation. A workshop was organised in 2009 in Copenhagen to discuss strategies to improve the development and use of serum-free defined media. In this report, the results from the meeting are discussed and the formulation of a basic serum-free medium is suggested. Furthermore, recommendations are provided to improve information exchange on newly developed serum-free media.

Human cell culture process capability: a comparison of manual and automated production

Cell culture is one of the critical bioprocessing steps required to generate sufficient human-derived cellular material for most cell-based therapeutic applications in regenerative medicine. Automated cell expansion is fundamental to the development of scaled, robust and cost effective commercial production processes for cell-based therapeutic products. This paper describes the first application of process capability analysis to establish and compare the short-term process capability of manual and automated processes for the in vitro expansion of a selected anchorage-dependent cell line. Estimates of the process capability indices (Cp, Cpk) have been used to assess the ability of both processes to consistently meet the requirements for a selected productivity output and to direct process improvement activities. Point estimates of Cp and Cpk show that the manual process has poor capability (Cp = 0.55, Cpk = 0.26) compared to the automated process (Cp = 1.32, Cpk = 0.25), resulting from excess variability. Comparison of point estimates, which shows that Cpk < Cp, indicates that the automated process mean was off-centre and that intervention is required to adjust the location of the process mean. A process improvement strategy involving an adjustment to the automated process settings has demonstrated in principle that the process mean can be shifted closer to the centre of the specification to achieve an estimated seven-fold improvement in process performance. In practice, the 90% confidence bound estimate of Cp (Cp = 0.90) indicates that that once the process is centred within the specification, a further reduction of process variation is required to attain an automated process with the desired minimum capability requirement.

Lessons learned from alternative methods and their validation for a new toxicology in the 21st century

Europe and the United States further the development of new toxicological tools in different ways. While the replacement of animal tests has been promoted strongly in Europe over the last decades (following the 3Rs principles--reduce, replace, refine), in the United States the vision for a toxicology in the 21st century (Tox-21c), which was prompted by the National Research Council document only 3 years ago, dominates the discussion. In both cases, there is significant political support. However, while in Europe the horizontal animal welfare legislation from 1986 (which urges the use of 3Rs methods wherever possible) currently under revision and cosmetics and chemical legislation are the primary drivers, in the United States it is mainly federal agencies, most prominently the U.S. Environmental Protection Agency (EPA), that made the implementation of the NRC report their toxicity testing strategy only in 2009. This preempts such likely legislative measures as the reauthorization of the Toxic Substances Control Act (TSCA) in the United States. The European implementation is characterized by substantial broad funding programs to develop 3Rs methods and can be termed a "bottom-up" approach; in contrast, the Tox-21 program represents a "top-down" approach, where programmed research is carried out and commissioned. It is postulated that the two approaches are two sides of the same coin, and instruct and complement each other. However, more importantly, if brought together they can result in a Human Toxicology Project and a real revolution in regulatory toxicology.

Identification of cross-contaminated animal cells by PCR and isoenzyme analysis

Animal cell lines have become very popular substrates for the production of vaccines and biopharmaceuticals. Characterization of candidate production cell lines is central to ensure product safety and maintenance of consistency in the manufacture of biologicals. Nested PCR and isoenzyme analysis have been used widely to prove the identity and purity of various cell lines and primary cells individually and also after deliberate cross-contamination. The nested PCR based on the Cytochrome b (Cyt b) gene of mitochondrial DNA (Mt DNA) was found to be more sensitive than isoenzyme analysis in detecting low levels of contaminants (as low as 1%). Interestingly, competition between different co-cultured cell lines has shown in one case that cross-contamination need not always results in a mixed cell population. The nested PCR technique for the Cyt b gene described in this study appears to be a potential replacement for isoenzyme analysis and here we demonstrate the PCR method used is sensitive and reliable for cell line authentication in a simple, rapid and reliable format to help assure the authenticity of cell substrates for the production of safe vaccines and biopharmaceuticals.

Cryopreservation of dissociated human embryonic stem cells in the presence of ROCK inhibitor

Two different methods have been adopted for the cryopreservation of human embryonic stem cells (hESCs): vitrification and conventional slow freezing/rapid thawing. However, these methods present poor viability and high differentiation rates. Therefore, the development of an efficient cryopreservation protocol for hESCs is one of the major challenges for the application of these cells in clinical therapy and regenerative medicine. A novel method for the cryopreservation of dissociated hESCs in the presence of a selective Rho-associated kinase (ROCK) inhibitor that increases cell survival and the efficiency of colony formation of cryopreserved hESCs has been developed. Moreover, this protocol improves the existing methods presenting short recovery times and hardly any differentiation rates. Thus, an easy handling protocol that allows the cryopreservation of large amounts of hESCs is described.

A toxicology for the 21st century--mapping the road ahead

The landmark publication by the National Research Council putting forward a vision of a toxicology for the 21st century in 2007 has created an atmosphere of departure in our field. The alliances formed, symposia and meetings held and the articles following are remarkable, indicating that this is an idea whose time has come. Most of the discussion centers on the technical opportunities to map pathways of toxicity and the financing of the program. Here, the other part of the work ahead shall be discussed, that is, the focus is on regulatory implementation once the technological challenges are managed, but we are well aware that the technical aspects of what the National Academy of Science report suggests still need to be addressed: A series of challenges are put forward which we will face in addition to finding a technical solution (and its funding) to set this vision into practice. This includes the standardization and quality assurance of novel methodologies, their formal validation, their integration into test strategies including threshold setting and finally a global acceptance and implementation. This will require intense conceptual steering to have all pieces of the puzzle come together.

Banks, repositories and registries of stem cell lines in Europe: regulatory and ethical aspects

To overview banks, repositories and registries of stem cell lines in Europe excluding bone marrow and cord blood banks; to concisely discuss the most important scientific, regulatory and ethical aspects of stem cell banking in a manner understandable to a layperson, but remain detailed enough not to compromise thoroughness of information. Review of scientific publications, laws and ethical guidelines in this field up through September 2008; hearing the opinions of key persons working in stem cell banking. The article discusses the procedure of stem cell banking and related safety issues and reviews the regulation of stem cell banking at the regional (European) and the national level. Stem cell banking can help meet scientific and certain ethical imperatives, but is complicated in the context of heterogeneous laws, guidelines, and ethical standards. In the pluralistic European society with cultural diversity leading to heterogeneous laws, harmonisation of international guidelines and national laws regulating stem cell banking is needed, as well as mapping of implementation at the national level.

Acutoxbase, an innovative database for in vitro acute toxicity studies

Acutoxbase is as an internet-based database developed for coherent management of all information relevant to the EU integrated project 'A-Cute-Tox' (www.acutetox.org), which aims to optimise and prevalidate an in vitro testing strategy for predicting acute human toxicity. The database consists of two principal parts for archiving in vitro and in vivo data, respectively. The in vitro part, designed following the principles of Good Cell Culture Practice (GCCP), provides a standard format for collection of in vitro data, together with detailed descriptions of methodologies (Standard Operating Procedures, SOPs), generated by research laboratories participating in the project. In the course of the study 97 reference chemicals were tested in approximately 100 in vitro assays, including models for general acute cytotoxicity, metabolism-mediated toxicity, biokinetics, haemato-, immuno-, neuro-, nephro-, and hepatotoxicity. The in vivo part compiles mammalian acute toxicity studies derived from published literature and human acute poisoning cases available from clinical reports. The database has proven to be a useful tool for a quality controlled transfer and organisation of large in vitro and in vivo toxicological data sets. At present time, Acutoxbase is under continuous development, and it will be available for the broad circles of toxicologists and physicians in a near future.

Derivation of human skin fibroblast lines for feeder cells of human embryonic stem cells

After the first derivations of human embryonic stem cell (hESC) lines on fetal mouse feeder cell layers, the idea of using human cells instead of mouse cells as feeder cells soon arouse. Mouse cells bear a risk of microbial contamination, and nonhuman immunogenic proteins are absorbed from the feeders to hESCs. Human skin fibroblasts can be effectively used as feeder cells for hESCs. The same primary cell line, which can be safely used for up to 15 passages after stock preparations, can be expanded and used for large numbers of hESC derivations and cultures. These cells are relatively easy to handle and maintain. No animal facilities or animal work is needed. Here, we describe the derivation, culture, and cryopreservation procedures of research grade human skin fibroblast lines. We also describe how to make feeder layers for hESC using these fibroblasts.

Biobanking

Biobanks, more formally known as biological resource centers (BRCs), form an "unsung" yet critical component of the infrastructures for scientific research, industry and conservation, without which much of the current scientific activity involving microbial cultures and cell-lines would be effectively impossible. BRCs are de facto depositories of "biological standards" holding taxonomic and other reference strains on which much of the associated published science and industrial standards are built and upon which some significant international commercial and ethical issues rely. The establishment and maintenance of BRCs is a knowledge- and skill-rich activity that in particular requires careful attention to the implementation of reliable preservation technologies and appropriate quality assurance to ensure that recovered cultures and other biological materials perform in the same way as the originally isolated culture or material. There are many types of BRC, which vary both in the kinds of material they hold and in their functional role. All BRCs are expected to provide materials and information of an appropriate quality for their intended use and work to standards relevant to those applications. There are important industrial, biomedical, and conservation issues that can only be addressed through effective and efficient operation of BRCs in the long term. This requires a high degree of expertise in the maintenance and management of collections of biological materials at ultra-low temperatures, or as freeze-dried material, to secure their long-term integrity and relevance for future research, development, and conservation.

Replacement of in vivo acute oral toxicity studies by in vitro cytotoxicity methods: opportunities, limits and regulatory status

The development of a new medicinal product is a long and costly process in particular due to the regulatory requirements for quality, safety and efficacy. There is a common interest to increase the efficiency of drug development and to provide new, better quality medicinal products much faster to the public. One possible way to economize time and costs, as well as to consider animal protection issues, is to introduce new alternative methods into non-clinical toxicity testing. Currently, animal tests are mandatory for the evaluation of acute toxicity of chemicals and new drugs. The replacement of the in vivo tests by alternative in vitro assays would offer the opportunity to screen and assess numerous compounds at the same time, to predict acute oral toxicity and thus accelerate drug development. Moreover, the substitution of in vivo tests by in vitro methods shows a proactive pursuit of ethical and animal welfare issues. Importantly, the implementation of in vitro assays for acute oral toxicity would require the establishment of common test guidelines across the EU, USA and Japan, i.e., the regions of ICH (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use). Presently, alternative in vitro tests are being investigated internationally. Yet, in order to achieve regulatory acceptance and implementation of in vitro assays, convincing results from validation studies are required. In this review, we discuss the current regulatory status of acute oral toxicity testing and point out achievements of alternative methods. We describe the application of in vitro tests, correlating in vitro with in vivo data. The use of in vitro data to predict in vivo acute oral toxicity is analyzed using the Registry of Cytotoxicity, an official independent database. We have then analyzed opportunities and drawbacks for future implementation of in vitro test methods, with particular focus on industrial use.

Alternative Methods for Eye and Skin Irritation Tests: An Overview

The evaluation of eye and skin irritation potential is essential to ensuring the safety of individuals in contact with a wide variety of substances designed for industrial, pharmaceutical or cosmetic use. The Draize rabbit eye and skin irritancy tests have been used for 60 years to attempt to predict the human ocular and dermal irritation of such products. The Draize test has been the standard for ocular and dermal safety assessments for decades. However, several aspects of the test have been criticised. These include: the subjectivity of the method; the overestimation of human responses; and the method's cruelty. The inadequacies of the Draize test have led to several laboratories over the last 20 years making efforts to develop in vitro assays to replace it. Protocols that use different types of cell cultures and other methods have been devised to study eye and skin irritation. Different commercial kits have also been developed to study eye and skin irritation, based on the action of chemicals on these tissues. This article presents a review of the main alternatives developed to replace the use of animals in the study of chemical irritation. Particular attention is paid to the reproducibility of each method.

Changing medium and passaging cell lines

Cell lines are widely used in biomedical research. This protocol describes the methods used routinely to change the medium and passage the cells. Medium changes keep the cells healthy by providing fresh nutrients, while cell passage or splitting is required to maintain cells in exponential growth. Despite the simplicity of the methods used, each cell line has idiosyncracies. Whether working with one or several cell lines, there is no substitute for knowledge of their needs, including the range of phenotypes and growth patterns under different physical and nutrient conditions. Given the necessary care and attention, most cell lines are easy to maintain and grow.

Development of a mechanistically-based genetically engineered PC12 cell system to detect p53-mediated cytotoxicity

The human wild type p53 gene, key for apoptosis, was introduced into the pheochromocytoma (PC12) cell line, to create a mechanistically-based in vitro test model for the detection of p53-mediated toxicity. Expression of the wt p53 gene was regulated by a system, which allowed or blocked expression p53 by absence or presence of tetracycline in the culture media. Western blot analyses confirmed an inducible and tetracycline-dependent expression of the wt p53 protein. Functionality of the p53 protein was verified by camptothecin treatment, known to induce p53-dependent apoptosis. Results showed that p53-expressing cells were significantly more sensitive to camptothecin induced cytotoxicity compared to non-expressing cells, and presented a significantly higher incidence of apoptosis. A screening study on 31 metal compounds, showed that the classified human carcinogens (NaAsO2, CdSO4 .8H2O, Na2CrO4 .4H2O, MnCl2, (NH4)2PtCl6) significantly increased cytotoxicity in p53-expressing cells compared to non-expressing cells, suggesting that their cytotoxicity was p53-mediated. Finally, acute and subchronic treatment with methyl mercury showed no significant differences in cytotoxicity and the percentage of apoptosis or necrosis between p53-expressing and non-expressing differentiated cells, suggesting that methyl mercury cytotoxicity was p53-independent.

Toward an evidence-based toxicology

The increasing demands on toxicology of large-scale risk assessment programmes for chemicals and emerging or expanding areas of chemical use suggest it is timely to review the toxicological toolbox. Like in clinical medicine, where an evidence-based medicine (EBM) is critically reviewing traditional approaches, toxicology has the opportunity to reshape and enlarge its methodology and approaches on the basis of compounded scientific knowledge. Such revision would have to be based on structured reviews of current practice, ie, assessment of test performance characteristics, mechanistic understanding, extended quality assurance, formal validation and the use of integrated testing strategies. This form of revision could optimize the balance between safety, costs and animal welfare, explicitly stating and, where possible, quantifying uncertainties. After a self-critical reassessment of current practices and evaluation of the thus generated information, such an evidence-based toxicology (EBT) promises to make better use of resources and to increase the quality of results, facilitating their interpretation. It shall open up hazard and also risk assessments to new technologies, flexibly accommodating current and future mechanistic understanding. An EBT will be better prepared to answer the continuously growing safety demands of modern societies.

A refined in vitro model to study inflammatory responses in organotypic membrane culture of postnatal rat hippocampal slices

Background

Propagated tissue degeneration, especially during aging, has been shown to be enhanced through potentiation of innate immune responses. Neurodegenerative diseases and a wide variety of inflammatory conditions are linked together and several anti-inflammatory compounds considered as having therapeutic potential for example in Alzheimer's disease (AD). In vitro brain slice techniques have been widely used to unravel the complexity of neuroinflammation, but rarely, has the power of the model itself been reported. Our aim was to gain a more detailed insight and understanding of the behaviour of hippocampus tissue slices in serum-free, interface culture per se and after exposure to different pro- and anti-inflammatory compounds.

Methods

The responses of the slices to pro- and anti-inflammatory stimuli were monitored at various time points by measuring the leakage of lactate dehydrogenase (LDH) and the release of cytokines interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-α) and nitric oxide (NO) from the culture media. Histological methods were applied to reveal the morphological status after exposure to stimuli and during the time course of the culture period. Statistical power analysis were made with nQuery Advisor^®, version 5.0, (Statistical Solutions, Saugus, MA) computer program for Wilcoxon (Mann-Whitney) rank-sum test.

Results

By using the interface membrane culture technique, the hippocampal slices largely recover from the trauma caused by cutting after 4–5 days in vitro. Furthermore, the cultures remain stable and retain their responsiveness to inflammatory stimuli for at least 3 weeks. During this time period, cultures are susceptible to modification by inflammatory stimuli as assessed by quantitative biochemical assays and morphological characterizations.

Conclusion

The present report outlines the techniques for studying immune responses using a serum-free slice culture model. Statistically powerful data under controlled culture conditions and with ethically justified use of animals can be obtained as soon as after 4–5 DIV. The model is most probably suitable also for studies of chronic inflammation.