In vitro (meaning in glass) describes an alternative method to animal testing and clinical testing on live subjects, in which samples are tested on cultured skin models and skin like tissue with characteristics of human skin. This method of using cell culture models has revolutionised the way products are evaluated for safety and efficacy, providing an alternative method to in vivo methods using live subjects. The approach uses a controlled environment such as petri dishes or test tubes and is an indispensable method in the cosmetics and personal care industry, where understanding how products interact with biological systems is crucial. In vitro methods can also be used to enhance other test strategies, complementing ex vivo and in vivo tests, and cosmetogenomics.
In vitro methods are commonly used for their controlled, reproducible, and ethically favourable testing procedures. A primary reason in vitro methods are becoming increasingly popular is the elimination of the need for animal testing. These methods align with ethical standards and regulatory requirements, particularly in regions like the European Union, where animal testing for cosmetics is prohibited. The cultured cells can simulate some biological processes that occur in animals, providing an alternative way to see how products interact with these living organisms.
Testing on live subjects using in vivo testing methods can be expensive and logistically challenging, requiring extensive recruitment and multiple appointments. Relying on human subjects presents many risks, such as recruitment difficulties such as person-to-person infection risks highlighted by COVID-19, to personal circumstances meaning recruitment numbers are not always met. In vitro methods do not rely on live subjects and therefore provide a quicker, more streamlined process making these testing methods cost-effective and time-efficient. Variables in in vitro testing environments can also be precisely manipulated allowing reproducible results. This is essential for validating product claims and understanding mechanisms of action of active ingredients, raw materials, and cosmetics products.
Many cosmetics markets have strict regulatory standards, such as those set by OECD and Good Laboratory Practices (GLP) that set high standards for safety and product efficacy. In vitro testing encompasses a wide range of assays, each designed to evaluate specific aspects of safety and efficacy. Some common types of in vitro tests include:
Safety Tests
A range of safety tests can be performed using in vitro testing methods. Cytotoxicity tests assess the potential toxicity of substances on isolated cells. They are crucial for determining the safety of cosmetic ingredients and other products. Advanced models, like 3D reconstructed epithelial models, provide deeper insights into cytotoxicity for tissues such as oral, gingival, and vaginal epithelium. Irritation tests are also commonly used safety tests that evaluate the potential of a substance to cause irritation. Ocular irritation tests, guided by OECD standards (e.g., OECD 491, 492), assess the irritant potential on eye tissues, while cutaneous irritation tests (e.g., OECD 439) focus on skin irritation. Eurofins offers a comprehensive range of in vitro tests, including cutaneous irritation tests (OECD 439, OECD 431), and can determine the irritant potential of various substances.
Phototoxicity tests conducted under guidelines like OECD 432 or OECD 498, determine whether a substance becomes toxic when exposed to light, an essential consideration for products like sunscreens and photo-sensitive formulations. Sensitisation methods are also a common in vitro testing method. These assays, including methods like Keratinosens and h-CLAT, evaluate whether a substance could cause allergic reactions. They are vital for ensuring that cosmetic and personal care products do not induce sensitisation in consumers. Recently, in vitro tests are commonly being used for micronucleus and AMES tests (used for detecting chromosomal aberrations) which are pivotal for assessing genetic toxicity and ensuring products do not cause harmful mutations.
Efficacy Tests
In vitro efficacy tests assess the functional benefits of a product. For instance, barrier function tests evaluate protection against environmental stressors such as pollutants. Eurofins can run microbiome tests, and test for associated pathologies of anti-acne. These tests can assess scalp and skin inflammation and measure the anti-aging and regenerative properties of cosmetics products. Trans-Epidermal Water Loss (TEWL) measurements provide insights into skin barrier integrity and hydration. TEWL is often used to support claims of barrier-restoring and -strengthening properties of skincare products.
In vitro Sun Care Studies
In vitro testing methods are also commonly used for sun care products. These methods can measure SPF, UVAPF, or Critical Wavelength to support broad-spectrum protection claims. Other associated factors such as HEV and IR can also be measured in vitro.
By leveraging various in vitro assays, companies can better understand how their products interact with biological systems, ultimately delivering safer and more effective solutions to consumers. Eurofins Cosmetics and Personal Care goes above and beyond providing these tests to ensure your products meet regulatory requirements, also offering the option to choose fully vegan versions of selected safety tests.
