The sample preparation of a cosmetic specimen in Cosmetic Science for the purpose of determining the analytical composition of heavy and toxic metals such as lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As) is of particular importance due to the difficulty of handling the sample. There are two main methods of sample preparation. The first method is the wet digestion of the sample with strong acids such as H₂SO₄, HNO₃, HF, and HNO₃/HCl (1:3) and the combination of a strong acid with H₂O₂. Liquid digestion of the sample under the influence of strong acids damages the organic material of the sample and converts the carbon into carbon dioxide. The contained metals are oxidized to the highest oxidizing step and converted to soluble salts. A problem with this method is the loss of metals during digestion because it occurs at high temperatures as well as the decrease in the concentration of the residual acid. The second method of preparation is the wet liquid digestion of the sample with strong acids in a microwave oven in a closed vessel. The acids that are used are mainly HNO₃ or mixtures of acids such as HNO₃–HCl and HNO₃–H₂SO₄. When the sample in the acid’s solvent is exposed to microwave energy, it can reach temperatures substantially above the boiling temperature of the acid solution. The result is the decomposition of the organic material, the oxidation of the metals, and their conversion to soluble nitrates. The advantages of using microwaves are the ability to control the temperature, pressure, and loss of metals and, thus, avoid erroneous measurement results. Simultaneously with the above, extraction methods have been, for almost a decade, very effective complementary processes that we can use to enrich a sample of a cosmetic product. Liquid–liquid dispersion micro-extraction (DLLME) and solid phase extraction (SPE) are the two main methods used in sample preparation and are usually applied after the digestion process.

It is interesting to note that some of the most lucrative commercial products available today are derived from plant cell cultures. Apple, grape, ginger, rice, and other plant stem cells have been successfully and extensively utilized in cosmetic preparations all over the world. The advantages of plant cell suspensions over field-grown complete plants, which exhibit developmental stages of growth, plant age, and organ-specific differences, include sustainability, lack of pesticide residues, and independence from climate fluctuations. The procedure of extracting and purifying physiologically active compounds from plant cell cultures is significantly streamlined because of the possibility that these chemicals may be released into the intercellular gaps or wasted media through the cell walls and membrane. Upon downstream processing from the cells, the released chemicals exhibit minimal losses and a high degree of purity. Overall, the practical interest is in creating high-quality, sustainable, and innovative skincare solutions that meet both consumer needs and environmental concerns while driving the cosmetic industry toward more advanced biotechnological approaches. Our review intends to show the advantages of plant stem cells in cosmetic preparations.

The European Society for Laser Dermatology (ELSD) has established recommendations for safe and effective photo epilation; however, short-term common adverse effects occur as a result of laser treatment, such as edema and perifollicular erythema. Post-inflammatory hyperpigmentation also appears in certain skin types. Very few clinical studies have been conducted on the topical application of cosmetic skin care products aimed at decreasing the adverse effects on the skin epidermis following laser-assisted epilation procedures. Stem cells are found in plant and animal organisms and are responsible for the growth and restoration of damaged tissues. Plant stem cells divide throughout the life of the plant, creating new plant parts. Our aim was to develop a new cosmetic cream to decrease the intensity of some of the side effects of laser epilation and thus reduce the administration of topical medication. We developed a formulation with the active substance Olea europaea (Olive) Callus Culture Lysate (OLEA VITAE™ 02), which is derived from plant stem cells of the Mediterranean wild variety of Olea europaea, for application following laser epilation with an Nd:YAG 1064 nm laser. The new skin care cream was tested for its physicochemical and microbiological stability, according to the European Pharmacopoeia. The impacts of this substance on the potential side effects of Nd:YAG 1064 nm application, i.e., trans-epidermal water loss, keratin hydration, melanin, erythema, and skin elasticity, in comparison with the appropriate placebo, were investigated using biophysical measurements and a self-assessment questionnaire. Skin biopsies were also performed to evaluate the influence of the procedure and the application of the products on the epidermis and papillary dermis thickness. According to our findings, the incorporation of the plant stem cell extract of Olea europaea into our cream resulted in a stable cream with an appealing texture. Furthermore, the activity of erythema and hyperpigmentation was decreased when the cream was applied after Nd:YAG 1064 nm laser epilation.