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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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Vernix caseosa is characterized by an initial rapid water loss prior to a sustained, steady dehydration at room temperature. Of all the synthetic analogues developed, the one labeled B2c (see Figure 10) was closest to native vernix caseosa; this sample included coated particles and had an initial water content of 80%; the particle/lipid ratio was 2:1. With these modifications, the researchers were able to extend the water release from 24 hr to 140 hr.28 This of course raised the question of whether or not the synthetic vernix caseosa also had a superb barrier repair mechanism, which was the subject of later papers.
First, a tape-stripping model on mouse skin was developed in which skin was stripped to a specific level (79 ± 6 g/m2/hr), where a crust was formed and almost complete recovery (~90%) was obtained within only 8 days. The topical application of vernix caseosa considerably increased initial and long-term recovery, promoted a rapid formation of the SC, and prevented epidermal thickening.42
Second, this model was treated with the same synthetic biofilms as well as oil-based ointments and the skin barrier recovery was compared to native vernix caseosa. Application of all tested formulations improved the skin barrier recovery and reduced crust formation and hyperproliferation but remarkably, the best-performing biofilm was the one containing uncoated particles with 50% (w/w) initial water content and a particle/lipid ratio of 2:1. The fact that the water profile experiments depicted in Figure 10 were the most similar to vernix caseosa, in which the initial water content was 80%, indicated that the amount of lipids might play an important role in the skin barrier recovery.
This raised the question of how important water-handling properties, as well as the presence of corneocytes, are for barrier recovery. Synthetic lipid mixtures with and without barrier lipids were therefore included in the study. The skin barrier repair results for a water and particle-free formulation with barrier lipids were very similar to those observed for native vernix caseosa. This demonstrated that the lipids, including barrier lipids, play a more prominent role in barrier recovery than the water content and presence of corneocytes. The latter, however, may be beneficial for increasing skin hydration and act as a drug delivery reservoir.43
Vernix caseosa: The Ultimate Natural Cosmetic?
Scientific research of the last decade has provided sufficient evidence for the beneficial properties of vernix caseosa as a barrier cream that not only corrects moisturization levels within the skin, but also improves skin barrier recovery by creating and maintaining a water activity level that allows all enzymes to function properly. However, its availability is insufficient to address the needs of the world of products that can restore skin barrier function and moisturization. Synthetic analogues have therefore been created and tested, and such vernix caseosa substitutes must meet only one criterion to be successful. While the necessity of water in such a formulation is still debated (for instance, see Reference 43), the semi-permeable nature of the product is absolutely essential, since both fully occlusive and non-occlusive products function far less well; and indeed there are already a few cosmetic ingredients44 as well as formulated products on the market that meet this requirement.