The Effect of in Vivo Occlusion on Human Stratum Corneum Hydration-Dehydration in Vitro

Five male subjects with dry skin treated one leg for 6 or 14 nights by plastic film occlusion. The treatment resulted in a marked improvement in the appearance of the skin in four out of five subjects. Following the treatment period, dermatome sections of the treated and control skin were prepared and the stratum corneum was isolated and examined lot its vapor-phase hydration and dehydration kinetics as well as its composition. Occlusion treatment resulted in an increased mass of tissue/cm2 without a change in either the tissue thickness or number of cell layers. This increased mass was associated with an increase in both the water-extractable material and the cellular residue (keratin) and a decrease in the either-extractable materials. The occlusion-treated samples showed an increased capacity to absorb water when hydrated at 95% RH for several days. The increased mass of water was lost more slowly during dehydration at 0% RH and 30°C. The results are discussed in terms of their significance to dry skin formation in vivo.