Replacement

The term Replacement refers to all methods which avoid or replace animal use in preclinical research. Particularly in this principle of the 3Rs, great progress has been made in recent years, sometimes supported by other scientific developments such as CRISPR-Cas9, Next-Generation-Sequencing and modern 3D-printing. Promising techniques such as organs-on-a-chip, in silico models, i.e. the computer-aided modeling of biological processes, as well as 3D cell cultures thus received not only scientific recognition but also broad media interest. These alternative methods are usually referred to as “replacement,” although they only represent one aspect of the field. Replacement can be further subdivided into: Absolute replacement: This means that the use of animals is completely replaced by an alternative method. Examples include in vitro methods such as animal-free cell cultures, organoids, and organs-on-a-chip, as well as in silico methods, for example for the development of modern pharmacological agents. Partial replacement: involves the use of invertebrates that, according to current scientific knowledge, have no or only limited pain perception, such as Drosophila melanogaster (fruit flies), immature or early forms (e.g., embryos of mammals, birds, and reptiles), or bacteria. Relative replacement: involves the use of animals exclusively for the extraction of cells, tissue, or organs that are subsequently required for in vitro methods.

Nowadays, the 3R principle of replacement is understood to mean more than just replacing animal testing with alternative methods. The term replacement also encompasses the use of animal-free products in laboratories.

However, before any animal testing takes place, the availability of alternative methods must be checked in accordance with the implementation of the 3R principle in Austrian animal testing legislation. If the specific question can be answered using these alternative methods, then they must be used. Ultimately, the complete replacement of animal testing is the highest goal of current research in the field of alternative methods. However, this goal should be approached realistically, as there are currently no alternatives to animal testing, especially for more complex phenomena such as neurodegenerative diseases like Alzheimer's or Parkinson's. Future alternative methods for more complex disease models will nevertheless bring this goal within reach.

In areas where alternative methods are not currently available, refinement and reduction are two further approaches to optimizing animal welfare. For the latest news in the field of 3Rs, click here.

Due to the constant growth in alternative methods, the search for adequate and validated replacement methods can be very time-consuming without the appropriate resources. For this reason, various organizations have focused specifically on the problem of research and offer the following resources:

• EURL-ECVAM DataBase service on Alternative Methods to animal experimentation (DB-ALM): The DB-ALM is a publicly accessible collection of alternative methods and associated protocols that have been submitted to the European Centre for the Validation of Alternative Methods (ECVAM) for validation. Link to the database: DB-ALM
   
• ALTEX - Alternatives to Animal Experimentation: The open-access journal ALTEX is a specialist journal that has been in existence since 1984 and is dedicated to the quarterly publication of scientific articles on the development and promotion of alternative methods to animal testing. ALTEX is the official journal of the Center for Alternatives to Animal Testing (CAAT). Link to the official website of the journal: ALTEX - Alternatives to Animal Experimentation.