Joseph Robert Kaczvinsky

Measuring the effects of topical moisturizers on changes in stratum corneum thickness, water gradients and hydration in vivo

Background  Moisturizers are the most commonly used topically applied product for the treatment of dry skin conditions. They affect many properties and functions of the stratum corneum but some moisturizers have been reported to be detrimental to barrier function. Stratum corneum barrier function is a composite of its total structure and thickness but few studies have taken this into account. As a biosensor, the stratum corneum (SC) will change its structure in response to treatment and a swelling effect has been clearly demonstrated by skin hydration. Recently several moisturizing agents have been shown to have an effect on SC swelling behaviour with conflicting results. However, there is a paucity of data reported for measuring the effects of long‐term usage of moisturizers on SC thickness in vivo as, until recently, traditional techniques did not have the resolution to measure the effects of moisturizers on nonpalmoplantar body sites. The development of confocal Raman spectroscopy for use in human subjects provides noninvasive, real‐time, in vivo measurement of SC water concentration profiles and we have also used this state of the art equipment to measure the effect of the long‐term use of moisturizers on SC thickness for the first time.

Reduction in the appearance of facial hyperpigmentation after use of moisturizers with a combination of topical niacinamide and N‐acetyl glucosamine: results of a randomized, double‐blind, vehicle‐controlled trial

Background  Topical niacinamide and N‐acetyl glucosamine (NAG) each individually inhibit epidermal pigmentation in cell culture. In small clinical studies, niacinamide‐containing and NAG‐containing formulations reduced the appearance of hyperpigmentation.

A randomized, controlled comparative study of the wrinkle reduction benefits of a cosmetic niacinamide/peptide/retinyl propionate product regimen vs. a prescription 0·02% tretinoin product regimen

Summary Background  Tretinoin is considered the benchmark prescription topical therapy for improving fine facial wrinkles, but skin tolerance issues can affect patient compliance. In contrast, cosmetic antiwrinkle products are well tolerated but are generally presumed to be less efficacious than tretinoin.

Efficacy of anti‐aging products for periorbital wrinkles as measured by 3‐D imaging

Background  The periorbital area is a key wrinkle‐prone region, where the first signs of aging usually appear.

Understanding age-induced alterations to the biomechanical barrier function of human stratum corneum

BACKGROUND The appearance and function of human skin are dramatically altered with aging, resulting in higher rates of severe xerosis and other skin complaints. The outermost layer of the epidermis, the stratum corneum (SC), is responsible for the biomechanical barrier function of skin and is also adversely transformed with age. With age the keratin filaments within the corneocytes are prone to crosslinking, the amount of intercellular lipids decreases resulting in fewer lipid bilayers, and the rate of corneocyte turnover decreases. OBJECTIVES The effect of these structural changes on the mechanical properties of the SC has not been determined. Here we determine how several aspects of the SCs mechanical properties are dramatically degraded with age. METHODS We performed a range of biomechanical experiments, including micro-tension, bulge, double cantilever beam, and substrate curvature testing on abdominal stratum corneum from cadaveric female donors ranging in age from 29 to 93 years old. RESULTS We found that the SC stiffens with age, indicating that the keratin fibers stiffen, similarly to collagen fibers in the dermis. The cellular cohesion also increases with age, a result of the altered intercellular lipid structure. The kinetics of water movement through the SC is also decreased. CONCLUSIONS Our results indicate that the combination of structural and mechanical property changes that occur with age are quite significant and may contribute to the prevalence of skin disorders among the elderly.

Transcriptional profiling of epidermal barrier formation in vitro

BACKGROUND Barrier function is integral to the health of epithelial tissues. Currently, there is a broad need to develop and improve our knowledge with regard to barrier function for reversal of mild skin irritation and dryness. However, there are few in vitro models that incorporate modulations of both lipids and epidermal differentiation programs for pre-clinical testing to aid in the understanding of barrier health. OBJECTIVE We have generated a reconstituted epidermis on a decellularized dermis (DED) and characterized its barrier properties relative to human epidermis in order to determine its utility for modeling barrier formation and repair. METHODS We followed the process of epidermal differentiation and barrier formation through immunocytochemistry and transcriptional profiling. We examined barrier functionality through measurements of surface pH, lipid composition, stratum corneum water content, and the ability to demonstrate topical dose-dependent exclusion of surfactant. RESULTS Transcriptional profiling of the epidermal model during its formation reveals temporal patterns of gene expression associated with processes regulating barrier function. The profiling is supported by gradual formation and maturation of a stratum corneum and expression of appropriate markers of epidermis development. The model displays a functional barrier and a water gradient between the stratum corneum and viable layers, as determined by confocal Raman spectroscopy. The stratum corneum layer displays a normal acidic pH and an appropriate composition of barrier lipids. CONCLUSION The epidermal model demonstrates its utility as an investigative tool for barrier health and provides a window into the transcriptional regulation of multiple aspects of barrier formation.

Changes in Stratum Corneum Thickness, Water Gradients and Hydration by Moisturizers

As the outermost layer of skin, the stratum corneum (SC), plays the pivotal role in protecting our bodies. It is the first line of defense against the outside world, providing both mechanical and chemical protection and regulating the movement of water and other materials in and out, enabling the bodies’ equilibrium to be maintained. Despite the relatively small dimensions of the SC over most of the body (its thickness is of the order of only 20 μm over a large portion of the body), it has a very complicated chemical and physical structure. Chemical concentrations and cellular structure change across its thickness, and these changes are responsible for the properties it possesses and for regulating the processes occurring within it. To better understand the role all of these components play within the SC, therefore, is not only necessary to ask ‘how much is there?’, but also ‘where is it located?’ and ‘how is it distributed?’ While a number of techniques have been developed previously to analyze concentration gradients within the SC, until recently no single technique has been able to quantitatively assess different chemical components as a function of depth, rapidly and in vivo. Furthermore, as the use of topical cosmetic products has become more popular and widespread, especially in the anti-aging market, the ability to accurately monitor ingredients which are capable of penetrating into the skin is now a necessity. Also, it is becoming more and more important to demonstrate how topically applied products can improve the skin in clinical tests; therefore, new methods to assess the skin in greater and greater detail are constantly being explored.