The role of ECVAM in promoting the regulatory acceptance of alternative methods in the European Union. European Centre for the Validation of Alternative Methods

A Cytotoxicity Assay as an Alternative to the Murine Model for the Potency Testing of Bothrops jararaca Venom and Antivenom: An Intralaboratory Pre-validation Study

Antivenom therapy is the only specific treatment for snakebite envenomation, and antivenom potency determination is key in the efficacy assurance quality control process. Nowadays, this process relies on the in vivo murine model - thus, the development of alternative in vitro methods is imperative. In the current study, the principle of the proposed method is the ability of Bothrops venom to induce cytotoxic effects in Vero cells, and the capacity to evaluate the inhibition of this cytotoxicity by the respective antivenom. After exposure to the venom/antivenom, the relative proportions of adherent (viable) cells were evaluated by direct staining with Coomassie Blue. The optical density (OD) of the lysed cell eluate was directly proportional to the number of adherent cells. This cytotoxicity-based alternative method could represent a potential candidate for validation as a replacement for the current in vivo test. The in vitro-determined cytotoxicity of the Brazilian Bothrops reference venom (expressed as the 50% effective concentration; EC50) was 3.61 μg/ml; the in vitro-determined 50% inhibitory concentration (IC50) of the Brazilian Bothrops reference antivenom was 0.133 μl/ml. From these two values, it was possible to calculate the potency of the reference antivenom. The results from the assays exhibited a good linear response, indicating that the method could be a potential candidate replacement method for use in antivenom quality control prior to lot release, subject to further validation.

RE-Place: A Unique Project Collecting Expertise on New Approach Methodologies

By applying “New Approach Methodologies (NAMs)” based on innovative technologies such as computer modeling, high throughput testing, omics, and sophisticated cell cultures, the use of experimental animals in the life sciences can be reduced or sometimes even completely avoided. Stimulating NAMs may benefit from a bottom-up approach, i.e., local initiatives mapping the available NAMs and promoting their use. An example of such an initiative in Belgium is the RE-Place project, which collects the available NAMs in one central database, and links this knowledge with the names of experts and research centers. To this extent, a template was created to collect the information of interest in a fast and consistent manner. Based on this template, a web-based application was developed to facilitate the entry of information, which was evaluated in a pilot study by experts in the field of NAMs. After integration of their feedback, a revised version of the RE-Place online tool was launched to the public. Aspects such as user-friendliness, quality of submitted information, protection of personal data and Intellectual Property (IP) rights were all considered in the development process. Hurdles like incentives for collaboration were also taken into account. Information submitted with the online tool is directly integrated in the RE-Place open access database. By consulting the database, scientists from various disciplines can easily identify the different types of NAMs and the experts using them in Belgium. As such, the RE-Place database contributes to building trust in the use of NAMs and stimulating their use and regulatory uptake.

Overview of alternative methodologies in toxicology

In vitro toxicology generally refers to the study of toxicological phenomena in non-whole-animal models. This broader connotation includes studies utilizing isolated organs, tissue slices, explants cultures, and isolated primary cells, as well as cell lines and subcellular fractions (e.g., microsomes). These model systems have made major contributions to toxicological sciences, particularly in our understanding of the mechanisms of toxicity, xenobiotic metabolism, and species differences in expressions of toxicity. This unit reviews the use of in vitro models and their value in toxicology testing.