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Vernix Caseosa: The Ultimate Natural Cosmetic?
By: Johann W. Wiechers, PhD, JW Solutions; and Bernard Gabard, PhD, Iderma
Posted: August 31, 2009, from the September 2009 issue of Cosmetics & Toiletries.
- Figure 1. Vernix caseosa covers newborn infants
- Figure 2. Lipid, free lipid extract and ceramide analyses
- Figure 3. Water loss profiles
- Figure 4. Water loss profiles of vernix caseosa films as a function of relative humidity
- Figure 5. Equilibrium water sorption-desorption curves
- Figure 6. Percent barrier recovery after tape stripping versus film permeability
- Figure 7. Moisture accumulation assessment
- Figure 8. Water release profiles
- Figure 9. Microgels and coating lipids
- Figure 10. Water release profiles of native VC and various biofilms
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This data was combined with the SC barrier recovery following tape stripping assessed previously,31 and the resulting graph is shown in Figure 6. This shows that optimal barrier recovery is obtained when the water vapor transport rate is in the range of 25–65 g.m-2.h-1. In this experiment vernix caseosa has a water vapor transport rate of 25 g.m-2.h-1 and 70 g.m-2.h-1, depending on the thickness of the layer of vernix caseosa applied, avoiding both total occlusion of the skin surface and total free transport of water, where the barrier recovery rate is significantly lower.33
These findings make vernix caseosa a perfect candidate as a therapeutic to be applied topically to impaired and/or damaged human skin, but because it is a biological material of human origin, and because of its less favorable cosmetic properties—e.g., cheesy appearance, odor, consistency, potential presence of blood and skin cells—its use is not widespread. The scientific literature references a limited number of research papers where vernix caseosa has been tested on human skin. In one Russian study, for example, vernix caseosa exhibited wound healing properties in adults treated for trophic ulcers of the lower extremities.34 In another, Moraille et al.6 investigated the skin cleansing properties of vernix caseosa on the volar forearm of human subjects. A study by Bautista et al. measured baseline surface hydration, moisture accumulation and TEWL, concluding that vernix caseosa treated skin had a significantly higher water-holding capacity, which was provisionally attributed to the absorption of water by the fetal corneocytes;23 similar work was conducted by Gunt.25
A fifth study by Barai using vernix caseosa on human skin in vivo measured the speed of barrier repair of tape stripped volar forearm skin that showed an intermediate water vapor permeability, resulting in a rapid increase in barrier recovery between days 3 and 5, following tape stripping.35 Interestingly, the vernix caseosa samples were sterilized by gamma radiation after collection6, 23, 35 and before application to the skin of the newborn’s mother.35
The biological origin of vernix caseosa has led to two types of current research. First, it is being used in cultured skin substitutes that serve as wound healing models to study fundamental skin biology.36 In addition, synthetic analogues of vernix caseosa are being developed in an attempt to obtain its beneficial properties from a non-biological origin; after all, this is where great potential is, as Haubrich states: “Application of the fetal/neonatal skin science findings (of vernix caseosa) to the adult burn population offers the potential for a clinically relevant homologous substitute for impaired integrity.”37 Therefore, the last section of this review will evaluate current attempts to mimic vernix caseosa and identify the criteria for success, to give cosmetic formulators some guidance as to how to make a perfect skin repair cream.
How to Mimic Vernix caseosa
Understanding the physical chemistry and biology of vernix caseosa poses a significant challenge to the cosmetic scientist. Hoath et al.38 list the functions and characteristics that should be fulfilled by a synthetic analogue of vernix caseosa. These include considerations such as being: “structurally similar to the stratum corneum, which it intimately covers; vernix caseosa lacks lipid lamellae [although Rissmann et al. recently did find some18] and desmosomal contact. Uniquely human, vernix caseosa is multifunctional: a skin cleanser, moisturizer, anti-infective and antioxidant, which works in both aqueous and non-aqueous environments.