Characterization of vernix caseosa as a natural biofilm: Comparison to standard oil-based ointments

The application of occlusive films and oil-in-oil ointments has been report ed to improve epidermal barrier function in very low birthweight, preterm i nfants. Such infants have a structurally immature stratum corneum and lack a surface coating of vernix caseosa, In this study we examined the short-te rm effects of topical application of vernix caseosa to human skin and contr asted these effects with commonly used ointments and water-in-oil emulsions . Specifically, vernix, Eucerin(R), Aquaphor(R), and petrolatum were applie d to the volar skin surface of adult volunteers. Surface electrical capacit ance (SEC) and transepidermal water loss (TEWL) were measured as indices of surface hydration. Sorption-desorption profiles were performed to determin e skin surface hydrophobicity, Particular attention was given to monitoring the acute (0-120 minutes) changes following vernix treatment in order to c ompare these effects with earlier reports on the rate of skin surface dryin g in newborn infants following birth. Immediately after vernix application there was an increase in the rate of water loss from the skin surface. Rela tive to control skin and skin treated with the ointments and water-in-oil e mulsions, the application of vernix to freshly bathed human skin resulted i n a unique profile of temporal change in baseline surface hydration, moistu re accumulation, and water-holding capacity. These results demonstrate majo r differences between human vernix and standard oil-based topical ointments . The results provide a framework for discussing the various properties of topical barriers applied to the very low birthweight infant.