32 TESTING
In vivo
Live animal testing
In vitro
involve animal suffering
Components
In vitro
involve ‘humane’ animal sacrifice
Components
from meat industry not involving additional animal suffering
Draize test OECD TG 404
Foetal bovine serum (FBS); MatrigelTM
Tissue extracts, e.g rat liver for genotoxicity studies; rat tail collagen
Bovine cornea; gelatin
Components are waste products
In vitro
exposed to animal products
Components have previously been
In vitro
Animal product- free components are ethically human-derived
In vitro
Animal-product- free fully defined
In vitro
Human cell lines
previously cultured in FBS; tissue models exposed to animal products during manufacturing
Human serum; human platelet lysate (hPL); human liver extract
Chemically defined media, e.g X-VivoTM
Figure 2: XCellR8’s scale for animal-free testing. Using the scale, we can define just how close to ‘animal-free’ any given test is, helping to provide an ethical & scientific judgement on testing strategies
Is 100% animal-product-free testing achievable? The short answer is yes, it is achievable, and awareness of this issue is increasing. Alternatives to animal-derived components already exist and are commercially available. Human serum can be used as an ethical and human-relevant alternative to FBS, with completely chemically defined synthetic alternatives being the ideal replacement. Animal-derived antibodies can be replaced
by those produced by non-animal derived alternatives - a move strongly recommended in 2020 by EURL ECVAM, the European Union Network of Laboratories for the Validation of Alternative Methods - and human recombinant enzymes and proteins used in place of those extracted from animals. Making an informed choice about your test
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systems can be difficult since getting clarity on what, if any, animal products are present in any given test can be convoluted for those not familiar with the scientific methods. In response to this, and to help the
adoption of 100% animal-product-free testing, XCellR8 has developed a reference scale for test methods, ranging from level 1 (in vivo live animal testing) to level 7 (in vitro tests using completely defined animal-product-free conditions). Using this scale, it is possible to make an ethical choice on the technologies available for a given test method.
What is preventing us from moving all tests to being completely animal- product-free?
When discussing this, it is important to consider that the use of animal-derived
SENSITISER
Figure 3: Developments into fully-defined and synthetic reagents as a replacement to animal components is ongoing, and a growing area of interest
components such as FBS have been the standard across industry and academia, having been used in research and test development for decades. Moving towards the use of non-animal
reagents will require both increased education of availability, and a reduction in the price of what are currently relatively specialised products. In addition, many tests have been validated using existing animal-derived products. Changing these components has the potential
to significantly alter any test system, providing results that no longer match the predictivity obtained during validation. When the tests in question may be used to ensure the safety of consumers, it is of paramount importance that any change to the system is properly investigated for its potential impact. With tests that have been internationally
KERATINOCYTES
DENDRITIC CELLS
Inflammatory Cytokine Release MIGRATION TO LOCAL LYMPH NODE LYMPHOCYTE PROLIFERATION T-CELL
Figure 4: The adverse outcome pathway (AOP) for skin sensitisation. In vitro tests have been developed to model Key Events 1-3, and are used in combination to assess the potential of an ingredient or chemical to cause skin sensitisation
PERSONAL CARE June 2022
validated and accepted for use in regulatory submissions and associated legislation, the task of revalidating an altered method can be extensive. An example of validating such a change is XCellR8’s adaptation of the OECD (Organisation for Economic Co-operation and Development) TG442d KeratinoSens™ - an in vitro test for skin sensitisation - to xeno-free conditions.
Adapting regulatory guidelines to animal-product-free A skin sensitiser is a substance inducing an allergic response upon contact to the skin, ranging from minor to severe reactions. Skin sensitisation to a substance such as a cosmetic ingredient is a permanent condition, making the accurate identification of skin sensitisers an important safety test. Preservatives and fragrances are the
most common cause of sensitisation in a cosmetic product, and the use of in vitro tests provides an ethical alternative to human trials, which risk permanently sensitising a human volunteer.
The most used regulatory strategy for
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EXAMPLES
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