Dropper pipette with clear cosmetic serum on petri dish

Today’s consumers of beauty products don’t take anything for granted. Now more than ever, they care where ingredients come from, how it has been sourced, what is its impact on the planet, and above all, whether or not they do what they say they do. Marketing claims that sound “too good to be true” or are based on pseudoscience, ring alarm bells, which can lead to widespread rejection in the marketplace.

To adapt to this new landscape, cosmetics and personal care manufacturers—from global corporations to boutique brands—have changed their approach to product development. Clean beauty is now a mainstay, sustainably-sourced ingredients rule, and solid scientific evidence is highly coveted, replacing “snake oil” remedies with well-validated ingredients.

Coordinated with the rise of science in skincare, consumers are beginning to take matters into their own hands, using genetic testing to direct their personalized skincare, beauty routines, and product selection. Consumer-focused, genetics-based skincare services have become more widespread, driven by the availability of low-cost sequencing platforms and bioinformatics, enabling consumers to educate themselves about how their beauty products can better fit with their unique genetic profile.

These changes, on both the corporate and consumer sides, would not be possible without a broad portfolio of in vitro testing technologies, such as molecular diagnostics, precision bioassays, and a variety of state-of-the-art “-omics” technologies, including genomics and others. In vitro testing for cosmetics and personal care research can provide data on the effectiveness and safety of beauty ingredients and their effect on users based on their genetic background.

To better understand these tidal shifts in beauty industry, let's look at the rising industry trends and the importance of the modern assays and technologies behind them.


Bioactive ingredients and their biological effects

There has been a rise in immune-, microbiome-, and other biology-related claims in the personal care and cosmetics industry [1,2]. These research areas have been major areas of focus for academic, industrial, and governmental labs for years, leading to a robust collection of scientific data on which to base these claims. With this foundation, compounds that exert distinct biological effects—known as bioactive ingredients—on the immune system, skin microbiome, or other biological systems have become easier to incorporate into a plethora of different beauty formulations.

Consider the increasing use of cannabinoids, such as cannabidiol (CBD) and cannabigerol (CBG), in cosmetics and personal care products. Due to their sourcing from the Cannabis sativa plant, these compounds have a long, checkered past and a lot of unfounded or confusing claims attached to it [3,4]. But the cannabinoids are going through a re-birth, driven by rigorous testing of their biological activity. As a result, several attractive discoveries, including antioxidant, anti-inflammatory, and antimicrobial activities have emerged [5,6].

These and other bioactivities are revealed using in vitro assays. While in vivo animal testing has long been used as a model for testing bioactive ingredients, it is now largely frowned upon, particularly in the EU, where it is prohibited by regulatory bodies [7]. In vitro testing for cosmetics and personal care ingredients has emerged as the favored alternative to animal testing, as they provide biological insights, are low-cost, and relatively easy to perform at large scales.

In vitro assays can be classified as cell-based (i.e., testing ingredient effects on the release of a biomarker from a relevant cell type) or cell-free (i.e., testing ingredient effects on enzymatic/chemical reactions or receptor binding). In skincare research, many cell-based assays use normal human epidermal keratinocytes (NHEK) or human dermal fibroblasts (HDF) as these are cell types that make up the various layers of the skin.

For example, if a bioactive anti-inflammatory ingredient is investigated, NHEKs may be stimulated with various test compounds to measure its effect on the release of pro-inflammatory biomarkers. This can be done by measuring the concentration of cytokines, such as IL-1β, IL-6, TNFɑ, and IL-8, or lipid mediators such as PGE2 or LTB4, released in culture media by enzyme-linked immunoassay (ELISA) or by measuring the expression of cytokine genes using methods such as quantitative real-time PCR (qPCR). These types of assays have been useful for the analysis of complex ingredients, such as probiotics like Bifidobacterium longum lysate, which reduces inflammatory biomarkers, such as vasodilation, edema, mast cell degranulation, and TNFɑ release [8].


In vitro toxicology and product safety

In vitro assays are also used to assess product safety and toxicity of beauty ingredients on biological systems. These assays may be required to prove to regulatory agencies that the formulations and ingredients in question are safe for human use.

Cell-based toxicology assays are used to measure many different factors. For instance, genotoxicity can be assessed by treating mammalian cells with test compounds and assessing chromosomal aberrations or mutations. Cytotoxicity, another important characteristic, can be assessed by measuring cell viability following treatment with a test compound in assays, such as a methyl thiazolyl tetrazolium (MMT) assay. Many common mammalian cell lines are used for such assays, but various organ models of skin, eye, lung, liver, brain, heart, kidneys, and muscle can be used to mimic the metabolism, activity, and ultimately, predict the effect of test compounds on specific organs.

Bacterial assays are also commonly used for assessing cell-based toxicity. The Microtox test is popular amongst cosmetics and personal care developers and relies on the bioluminescent bacteria Vibrio fischeri, which expresses reduced luminescence in response to bacteriostatic (inhibits bacterial growth) or bacteriocidal (disrupts the bacteria membrane, leading to lysis) compounds [9]. Bacterial toxicology testing has increased due to increasing awareness about the skin microbiome and the concomitant increase in “microbiome-friendly” claims applied to cosmetics and personal care products. While there is no defined test for measuring this, viability testing can be done using single bacterial strains or bacterial communities that are commonly found to be a part of the skin microbiome. 3D skin models, such as reconstructed human epidermis, can also be used to assess the adhesion of certain bacterial species to the skin and the effect of test compounds on adhesion [10].

Product and ingredient safety is measured using cell-free toxicology assays as well. The US Environmental Protection Agency (EPA) has established a collection of validated assays, called ToxCast, which uses enzyme inhibition assays to assess toxicity. ToxCast focuses primarily on the detection of nervous system effects and endocrine-disrupting activities. Receptor-binding assays can be used similarly, by measuring the binding affinity of test compounds to specific hormone receptors.

Genetic assays such as PCR are also useful for the verification of ingredients and the detection of low levels of microbial contaminants—bacteria, fungi, and viruses. In contrast to other types of assays, PCR-based assays can be performed rapidly, in hours, using limited thermal cycling or qPCR instruments and simple consumables.


Accessing personalized skincare through genomics

Access to low-cost, high-throughput, next-generation sequencing (NGS), genotyping microarrays, and qPCR platforms have jettisoned genomics into nearly every facet of biological research, including cosmetics and personal care. As described above, the beauty industry is gaining a better appreciation for the biological activities of their ingredients, yet the underlying genetics of the individual and its effect on their skin can have an important impact on the efficacy of a given ingredient.

This fact has given rise to personalized skincare, where beauty formulations are tailored to a person’s genetic or environmental characteristics. In same-sex twin studies, 60% of the variation in “perceived age”, which includes skin phenotypes such as the presence, depth, and the number of wrinkles, had to do with genetics, while 40% had to do with environmental factors such as smoking, sun exposure, and more [11,12].

Skin aging is one of the best-studied phenotypes related to the cosmetics and personal care industry and several genome-wide association studies have been published identifying single nucleotide polymorphism (SNPs) and their influence on skin aging [13,14]. For instance, SNPs in a family of proteins called the matrix metalloproteinases (MMP) are associated with skin aging phenotypes and linked functionally to skin hydration, skin elasticity, and antioxidant capacity [15,16]. Direct-to-consumer sequencing companies are using these and many other validated SNPs to provide access to genetic reports that provide insights into an individuals’ skin type and sell complementary, tailored beauty products.

The identification of these SNPs enables lower cost genotyping assays that can be performed at higher throughput, making personalized skincare affordable to broader audiences.


Getting up close and personal: Where beauty is headed

While personalized skincare and bespoke beauty have mass appeal, the science behind genetics-based beauty products is still evolving. Genetics only tells a part of the story; other protein or metabolic biomarkers may shed additional light on just what type of beauty formulation may be required for an individuals’ skin type. Global beauty brands are investing in protein biomarker platforms that can push the personalized, precision skincare, and beauty movements to the next level [16]. As in vitro testing continues to provide in-depth data on the biological effects of bioactive ingredients alongside consumer genetic testing, the industry will continue to close in on products that are better customized to each user.

Explore how Thermo Fisher Scientific can support your in vitro testing and genomics needs with our Molecular Diagnostics Custom Solutions for Commercial Supply. Check out the broad range of custom molecular test development capabilities, including reverse transcriptase enzymes, DNA polymerases, oligonucleotide probes, and custom manufacturing services.


References
  1. Microbiome Claims: Should Pre-, Pro- and Postbiotic Skin Care Be Regulated? Cosmetics & Toiletries. Accessed March 5, 2022. Published April 30, 2021. 
  2. Trend Alert: beauty consumers are ready for immunity-boosting skin care. Cosmetics Design USA. Accessed March 5, 2022. Published February 24, 2021. 
  3. Warning Letters and Test Results for Cannabidiol-Related Products. US Food & Drug Administration. Published August 5, 2021. Accessed February 23, 2022 
  4. Hussain SA, Zhou R, Jacobson C, et al. (2015) Perceived efficacy of cannabidiol-enriched cannabis extracts for treatment of pediatric epilepsy: A potential role for infantile spasms and Lennox-Gastaut syndrome. Epilepsy Behav 47:138–141. doi:10.1016/j.yebeh.2015.04.009 
  5. Sampson PB. (2021) Phytocannabinoid pharmacology: Medicinal properties of Cannabis sativa constituents aside from the "Big Two". J Nat Prod 84(1):142–160. doi:10.1021/acs.jnatprod.0c00965 
  6. REGULATION (EC) No 1223/2009 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL. European Commission. Published December 18, 2009. Accessed March 5, 2022. 
  7. Guéniche A, Bastien P, Ovigne JM, et al. (2010) Bifidobacterium longum lysate, a new ingredient for reactive skin. Exp Dermatol 19(8):e1-e8. doi:10.1111/j.1600-0625.2009.00932.x 
  8. De Zwart D, Sloof W. (1983) The Microtox as an alternative assay in the acute toxicity assessment of water pollutants. Aquat Toxicol 4(2):129–138. doi:10.1016/0166-445X(83)90050-4 
  9. Lerebour G, Cupferman S, Bellon-Fontaine MN. (2004) Adhesion of Staphylococcus aureus and Staphylococcus epidermidis to the Episkin reconstructed epidermis model and to an inert 304 stainless steel substrate. J Appl Microbiol 97(1):7–16. doi:10.1111/j.1365-2672.2004.02181.x 
  10. Christensen K, Thinggaard M, McGue M, et al. (2009) Perceived age as clinically useful biomarker of ageing: cohort study. BMJ 339:b5262. doi:10.1136/bmj.b5262  
  11. Shekar SN, Luciano M, Duffy DL, et al. (2015) Genetic and environmental influences on skin pattern deterioration. J Invest Dermatol 125(6):1119–1129. doi:10.1111/j.0022-202X.2005.23961.x 
  12. Law MH, Medland SE, Zhu G, et al. (2017) Genome-Wide Association Shows that Pigmentation Genes Play a Role in Skin Aging. J Invest Dermatol 137(9):1887–1894. doi:10.1016/j.jid.2017.04.026 
  13. Chang ALS, Atzmon G, Bergman A, et al. (2014) Identification of genes promoting skin youthfulness by genome-wide association study. J Invest Dermatol 134(3):651–657. doi:10.1038/jid.2013.381 
  14. Naval J, Alonso V, Herranz MA. (2014) Genetic polymorphisms and skin aging: the identification of population genotypic groups holds potential for personalized treatments. Clin Cosmet Investig Dermatol 7:207–214. doi:10.2147/CCID.S55669 
  15. Vierkötter A, Schikowski T, Sugiri D, et al. (2015) MMP-1 and -3 promoter variants are indicative of a common susceptibility for skin and lung aging: results from a cohort of elderly women (SALIA). J Invest Dermatol 135(5):1268–1274. doi:10.1038/jid.2015.7 
  16. Skin trend predictions: L’Oréal files patent on protein biomarker analysis, skin diagnosis system. Cosmetics Design Europe. July 22, 2021. Accessed March 9, 2022. 
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