Determination of the effect of infrared-A radiation on gene modulation in human skin culture to develop an alternative method for assessment of preclinical efficacy

Abstract

The Brazil currently ranks third in the consumer ranking of cosmetic. Considering the growth rate, the Brazilian market surpassed that of winners - US and Japan. Having reference to this economic context, we can consider that the trajectory of cosmetic market has established itself as the most dynamic on international scene. It is known that 30% of the annual total of this market, which reached 101 billion reais in Brazil in 2014 (Brazilian Association of Toiletries, Perfumery and Cosmetics - ABIHPEC) are conducted for research and development of new products and releases. In this way, the search for safest and more effective ingredients and products reinforces the need to elaborate refined methodologies that better translates its effects. The advent of the 3R policy (Replace, Reduce and Refine) that supports the use of alternative tests to replace, refine and reduce the use of animals in research, safety assessment and cosmetic efficacy was restricted to in vitro and clinical models. In vitro assays can predict possible toxic effects and determine the likely biological mechanisms of action responsible for the clinical benefit of cosmetic, complementing the results in vivo, although the direct inference from these results requires caution, because not always the mechanisms observed in cell cultures can be extrapolated to the real condition of use. Similarly, clinical outcomes, although providing a strong contribution to the assessment of safety and efficacy cosmetic, do not provide data related to the mechanisms of action, such as those obtained by in vitro techniques. Thus, a plausible and sustainable alternative to fill this gap between in vitro and clinician is using skin equivalent or skin fragments from elective surgeries, which are characterized as ex vivo model to approach the real responsible purpose by clinical benefits of a product applied topically. Clinical signs of photoaging skin such as wrinkles and hyperpigmentation, are among the main aesthetic concerns that affect humans. Proven ultraviolet radiation is the main factor that contributes to tissue damage and skin aging, however, the infrared radiation A (IVA) has been identified as an aggravating of this process, corroborating the physiological skin changes. In view of these considerations, the objective of this study is to evaluate the effects of IVA radiation on modulation of large-scale gene expression using as substrate the spare human skin fragments of elective plastic surgery in order to develop and make available an alternative assessment methodology of preclinical efficacy. (AU)