What is the Difference Between Ex Vivo and In Vitro Testing Methods?
Modern science offers a variety of methods for safety and efficacy testing of cosmetic products. Some of the commonly used methods for cosmetics testing include in vitro and ex vivo. While both types of experiments take place outside of a living organism, there are important differences between the two.
In this article, we will take a closer look at the similarities and differences of in vitro vs. ex vivo, and what role these methods play in the safety and efficacy testing of cosmetics.
What Are In Vitro and Ex Vivo Testing Methods?
Today, many testing methods are available to cosmetics brands that want to test their products for safety, characterize their efficacy and active ingredients, or guide research and development of new formulations.
Testing methods in science are traditionally called by their Latin names, such as in vivo, ex vivo, in vitro, in silico, and more. Each name broadly describes the test environment: for instance, in vivo and ex vivo mean, respectively, experiments conducted inside and outside a living body.
Let’s examine in vitro and ex vivo testing methods in more detail.
In vitro translates from Latin as “in glass.” This testing method involves experiments on biological matter (cells or tissues) outside of a living organism. The reference to glass is quite literal: in vitro experiments were historically conducted in a Petri dish.
One of the features of in vitro testing is that a specific lineage of cells (e.g., keratinocytes, fibroblastes or melanocytes) are isolated, separated and purified from their usual biological surroundings. This allows more detailed cellular and molecular analysis and characterization compared to using a whole organism. Moreover, isolated cells can usually be, under the right conditions, amplified in culture to generate stock and batches for future reuse.
In vitro experiments can be conducted on a wide range of test subjects, from bacteria to cells derived from living organisms. Thanks to modern science, increasingly complex in vitro models are now available. Anything from modified bacteria to reconstructed tissues can be created, modified and reproduced many times, specifically for the needs of the experiment.
By contrast, ex vivo means “outside of a living body.” In this type of experiment, the living tissues are not created artificially but directly taken from a living organism. The experiment is then immediately conducted in a laboratory environment, with minimal alteration of the organism’s natural conditions.
In Vitro and Ex Vivo in Cosmetics Testing
Both in vitro and ex vivo play an important role in cosmetics testing. These methods can be used for mandatory safety testing and efficacy assessment, as well as during new product research.
Some of the tests using in vitro and ex vivo methods for cosmetics include:
- Toxicity (cytotoxicity)
- Substantiation of claims on:
- Skin barrier properties
- Epidermal regeneration
- Skin hydration and protection
- Skin pigmentation
Another key aspect of in vitro and ex vivo methods is that they offer a great alternative to animal testing. Once animal testing in cosmetics was fully banned in the EU in 2013, more cosmetics brands have turned to these methods for safety and efficacy testing, spurring exciting technological advances.
In Vitro vs. Ex Vivo: Differences and Similarities
On the surface, in vitro and ex vivo appear very similar, as both testing methods involve experiments on biological matter, conducted outside of a living organism and in an artificial environment. The cells and tissues for ex vivo experiments are taken from a living organism, whether donated or harvested (e.g., hair follicles, skin explants). Meanwhile, for in vitro tests, cells are obtained from repositories and cultured to create the necessary model (e.g., reconstructed human epidermis).
Nevertheless, the most important difference between the two methods lies in their complexity and responsiveness.
For instance, ex vivo models are:
- on the one hand, much more complex in terms of cell diversity, and therefore closer to in vivo conditions;
- on the other hand, less reactive in terms of biological response to a treatment or a stress.
Meanwhile, in vitro models are:
- essentially, simplified versions of ex vivo models in terms of biological complexity;
- but more reactive in terms of biological response.
So how does in vitro vs. ex vivo compare in terms of cosmetics testing? Is either of the two methods better than the other? It depends entirely on the experiment.
In some cases, ex vivo models can be more accurate in representing human skin, particularly when researchers want to study the transdermal delivery of an ingredient after topical application or investigate the effect of product on skin integrity and tissue morphology. On the other hand, in vitro models offer a lot of versatility, especially when a product must simultaneously be tested on different types of skin or specific demographics (age, ethnicity, etc.) or when a deeper mechanism of action study is required.
Find an In Vitro or Ex Vivo Testing Program to Suit Your Needs
At Bioalternatives, we are committed to developing effective in vitro & ex vivo alternative options to animal experimentation methods, by offering a full range of solutions for the development of active ingredients and cosmetic formulations.
We offer customized technical solutions to guide your product research and support the claims of your cosmetic products. Our selection of in vitro and ex vivo testing solutions can be used to characterize your cosmetic products’ active ingredients, demonstrate the efficacy of your formulations, and test the safety of your cosmetic products at an early stage (for R&D purposes only).
With extensive experience in cosmetic product testing and state-of-the-art facilities, we are pleased to offer you dedicated project management support and consulting for your R&D process.
Ready to discuss a testing and research program that will suit your business’s needs?