Márcio Lorencini

Active ingredients against human epidermal aging

The decisive role of the epidermis in maintaining body homeostasis prompted studies to evaluate the changes in epidermal structure and functionality over the lifetime. This development, along with the identification of molecular mechanisms of epidermal signaling, maintenance, and differentiation, points to a need for new therapeutic alternatives to treat and prevent skin aging. In addition to recovering age- and sun-compromised functions, proper treatment of the epidermis has important esthetic implications. This study reviews active ingredients capable of counteracting symptoms of epidermal aging, organized according to the regulation of specific age-affected epidermal functions: (1) several compounds, other than retinoids and derivatives, act on the proliferation and differentiation of keratinocytes, supporting the protective barrier against mechanical and chemical insults; (2) natural lipidic compounds, as well as glycerol and urea, are described as agents for maintaining water-ion balance; (3) regulation of immunological pathogen defense can be reinforced by natural extracts and compounds, such as resveratrol; and (4) antioxidant exogenous sources enriched with flavonoids and vitamin C, for example, improve solar radiation protection and epidermal antioxidant activity. The main objective is to provide a functional classification of active ingredients as regulatory elements of epidermal homeostasis, with potential cosmetic and/or dermatological applications.

Comparison between fibroblasts and mesenchymal stem cells derived from dermal and adipose tissue.

Stem cells have the ability to renew themselves and differentiate into various cell types. For this reason, numerous research groups have been studying these cells for their therapeutic potential. Some of the therapies, however, are not producing the expected results because of contamination by other cell types, especially by fibroblasts. In the cosmetic industry, stem cells are used to test the efficacy of anti‐ageing and rejuvenation products. The purpose of this work was to gain a better understanding of the differences in phenotype, in gene expression associated with stem cells, in the pattern of cell surface proteins and in the differentiation capacity of adipose‐derived stem cells, of skin‐derived stem cells and of commercially available fibroblasts.

In vitro induction of apoptosis, necrosis and genotoxicity by cosmetic preservatives: application of flow cytometry as a complementary analysis by NRU

Preservatives are used in cosmetics to prevent microbial contamination; however, some preservatives are not free of allergenic and cytotoxic potential. Allergenicity and cytotoxicity potential values are major aspects of preservative safety, which determine limitations and maximum concentration dose in a cosmetic product. The purpose of this study was to investigate and compare the in vitro apoptosis, necrosis and genotoxicity‐inducing potential of five different types of preservatives: Phenoxyethanol (PE), Propylparaben (PP), Methylparaben (MP), Benzyl Alcohol (BA) and Ethylhexyl Glycerine (EG). In vitro experiments were carried out on human dermal fibroblasts by a quantitative flow cytometry method, using specific cell markers (Annexin V, Propidium Iodide and H2AX). We compared the resulting cell viability by means of neutral red uptake (NRU) and established the IC50. Our results showed that PE, PP, MP and BA have similar cytotoxic mechanisms (high apoptosis and necrosis levels only at the test concentration of 1%), whereas EG showed only an apoptosis pathway. For genotoxicity, both parabens yielded the highest values. Results obtained by flow cytometry for necrosis were comparable to those produced by NRU; however, NRU does not distinguish apoptosis from necrosis. We propose that flow cytometry is a more sophisticated methodology for understanding the cytotoxic mechanisms of cosmetic preservatives and can be used to complement the NRU.

Triple nanoemulsion potentiates the effects of topical treatments with microencapsulated retinol and modulates biological processes related to skin aging

BACKGROUND The sum of environmental and genetic factors affects the appearance and function of the skin as it ages. The identification of molecular changes that take place during skin aging provides biomarkers and possible targets for therapeutic intervention. Retinoic acid in different formulations has emerged as an alternative to prevent and repair age-related skin damage. OBJECTIVES To understand the effects of different retinoid formulations on the expression of genes associated with biological processes that undergo changes during skin aging. METHODS Ex-vivo skin samples were treated topically with different retinoid formulations. The modulation of biological processes associated with skin aging was measured by Reverse Transcription quantitative PCR (RT-qPCR). RESULTS A formulation containing microencapsulated retinol and a blend of active ingredients prepared as a triple nanoemulsion provided the best results for the modulation of biological, process-related genes that are usually affected during skin aging. CONCLUSION This association proved to be therapeutically more effective than tretinoin or microencapsulated retinol used singly.

Elastin structure and its involvement in skin photoageing.

Skin aging is a complex process that may be caused by factors that are intrinsic and extrinsic to the body. Ultraviolet (UV) radiation represents one of the main sources of skin damage over the years and characterizes a process known as photoaging. Among the changes that affect cutaneous tissue with age, the loss of elastic properties caused by changes in elastin production, increased degradation and/or processing produces a substantial impact on tissue esthetics and health. The occurrence of solar elastosis is one of the main markers of cutaneous photoaging and is characterized by disorganized and non‐functional deposition of elastic fibers. The occurrence of UV radiation‐induced alternative splicing of the elastin gene, which leads to inadequate synthesis of the proteins required for the correct assembly of elastic fibers, is a potential explanation for this phenomenon. Innovative studies have been fundamental for the elucidation of rarely explored photoaging mechanisms and have enabled the identification of effective therapeutic alternatives such as cosmetic products. This review addresses cutaneous photoaging and the changes that affect elastin in this process.

In vivo study of dermal collagen of striae distensae by confocal Raman spectroscopy

This research work mainly deals with studying qualitatively the changes in the dermal collagen of two forms of striae distensae (SD) namely striae rubrae (SR) and striae albae (SA) when compared to normal skin (NS) using confocal Raman spectroscopy. The methodology includes an in vivo human skin study for the comparison of confocal Raman spectra of dermis region of SR, SA, and NS by supervised multivariate analysis using partial least squares discriminant analysis (PLS-DA) to determine qualitatively the changes in dermal collagen. These groups are further analyzed for the extent of hydration of dermal collagen by studying the changes in the water content bound to it. PLS-DA score plot showed good separation of the confocal Raman spectra of dermis region into SR, SA, and NS data groups. Further analysis using loading plot and S-plot indicated the participation of various components of dermal collagen in the separation of these groups. Bound water content analysis showed that the extent of hydration of collagen is more in SD when compared to NS. Based on the results obtained, this study confirms the active involvement of dermal collagen in the formation of SD. It also emphasizes the need to study quantitatively the role of these various biochemical changes in the dermal collagen responsible for the variance between SR, SA, and NS.

Parameters for assessing the aquatic environmental impact of cosmetic products

The cosmetic industrys growing concern about the impact of its supply chain on the environment, sustainability of raw materials, and biodiversity increases the need to ensure that the final product has a lower environmental impact. The objective of this review is to summarize and compare the information available from international organizations and legislation regarding the main criteria used to assess raw materials for aquatic toxicity, as well as the most suitable alternative methods for obtaining assessment parameters. Using the literature available in databases, a review of the scientific literature and international legislation, this work discusses and compares the parameters established by international organizations such as the Environmental Protection Agency (EPA) and Cradle to Cradle (C2C), as well as European legislation, namely, European Regulation 1272/2008, for assessing environmental impact. Defining the ecotoxicity parameters of the main classes of raw materials in rinse-off cosmetic products can enable the development of products that are more environmentally sustainable, prioritizing substances with less environmental impact.

Integrated Safety Strategy for the Development of Children’s Cosmetic Products Using In Vitro and Clinical Methodologies

Brazil is one of the largest cosmetic markets and represents great opportunities for several beauty niches, including children’s products. Regarding safety assessment and considering the particular needs of the target market, children’s products must be specifically formulated and require special attention to avoid inappropriate use and adverse reactions. Because animal tests are no longer accepted for cosmetic evaluation in Europe, the major challenge in this field is to ensure reliable products using alternative methods and other available data such as those found in the literature. The objective of this study was to define an integrated theoretical and technical rationale for the suitable development of children’s makeup products (lipstick, gloss, blush, and nail polish). Without applying animal methods, formulation safety analyses, toxicological in vitro tests (cytotoxicity, phototoxicity, and skin irritation), and clinical trials were considered. First, a systematic study was performed for selection of the intended ingredients that could be used in each formulation. In vitro methods were applied for the evaluation of cytotoxicity, phototoxicity (following the internationally adopted and validated Organization for Economic Cooperation and Development [OECD] guidance document [GD] OECD GD 129 and test guidelines [TG] OECD TG 432, respectively), and acute skin irritation (using a reconstituted human skin model based on OECD TG 439). Complimentary clinical trials were conducted on adults and children, under pediatrician supervision, for the assessment of skin irritability, sensibility, photoallergy, phototoxicity, and tolerability in real usage conditions. The theoretical components of the rationale for the evaluation of children’s products were based on the following: (1) simple formulations with fewer ingredients in comparison to products for adults; (2) raw materials properly analyzed according to their chemical structures, levels of exposure, and toxicological profiles, including available literature; and (3) fragrances within International Fragrance Association (IFRA) recommendations. Concerning in vitro results, none of the children’s products was identified as phototoxic, as skin irritant, or as significantly cytotoxic in the tested concentrations. Clinical trials also showed negative results for all the toxicological endpoints analyzed, considering adult and children’s panels. The safety rationale developed in the present work, using specific formulation criteria and in vitro alternative methods to animal use, was assertive and well correlated to the results of clinical trials. This rationale represents a practical, integrated, and valuable tool for the development of appropriate formulations and the safety assessment of children’s cosmetic products.