Isolation of corneocyte envelopes from porcine epidermis.

Sheets of porcine stratum corneum were dispersed into individual corneocytes after 4 h in a solution consisting of 8 mM N,N-dimethyldodecylamine oxide and 2 mM sodium dodecylsulfate in phosphate-buffered isotonic saline, at 45 degrees C. With continued detergent treatment and moderate sonication, most of the cells lost their keratin contents and were then separated from the remaining intact cells by centrifugation in cesium chloride solution of density 1.280. Electron microscopy showed that the cell envelopes retained both the crosslinked protein envelope and its attached lipid envelope. The dry weight of envelopes was approximately 7% of the estimated dry weight of the original stratum corneum, while the corneocytes surviving intact also amounted to 7% of the starting weight. Mild alkaline hydrolysis of the corneocyte envelopes allowed the extraction of hydroxyceramides amounting to 10% of the dry weight of the envelopes. The procedure therefore provides isolated corneocyte envelopes suitable for studying both the protein and lipid components of this compound sheath.