In vitro reconstitution of stratum corneum lipid lamellae.

In the final stages of differentiation in the epidermis of terrestrial mammals, lipids are extruded into the intercellular spaces. The initially extruded lipid becomes transformed into broad, multilamellar sheets that are found in the intercellular spaces throughout the stratum corneum. These lamellae display an unusual alternating broad-narrow-broad pattern of lucent bands as revealed by transmission electron microscopy (TEM). This arrangement results in two periodicities that can be measured from electron micrographs and are also evident in X-ray diffraction-5 nm (broad) and 13 nm (broad-narrow-broad). The goal of the present study was to reconstitute these lamellae in vitro. Porcine stratum corneum lipids were applied to Millipore filters. The disks were placed in water and heated to 80 degrees C for 1 h. After cooling, the disks were stored over desiccant. At each stage, the disks were prepared for TEM. TEM revealed that the application of the lipid solutions onto the disks resulted to deposition of mostly amorphous material. Heating in water resulted in the formation of many lamellae. The width of the lamellae was uniform and in the range of 5 to 6 nm with no broad-narrow-broad pattern; however, after storage under desiccating conditions, the broad-narrow-broad pattern was reproduced.

The effects of scaling procedures on epithelial cell growth on titanium surfaces.

This study examined in vitro epithelial cell growth on titanium surfaces which had been instrumented by 3 types of periodontal curets. Commercially pure titanium discs were uniformly scaled using plastic, stainless steel, or gold-coated curets and then seeded with a microdot (50,000 cells per 10 microliters) of rat gingival epithelial cells. After 5 days of growth, epithelial cell surface area (mm2) coverage was measured on photographed specimens using a computer digitizing system. Scanning electron microscopic evaluation showed a denser central core of cellular growth on the stainless steel-treated surfaces as compared to the other surface treatments. Epithelial surface area coverage on the stainless steel, plastic, and control groups did not vary significantly among groups. However the gold-coated curet exposed surfaces supported significantly less epithelial growth than the stainless steel and control surfaces. A better understanding of in vitro epithelial cell responses to different titanium surface characteristics will assist in designing implant scaling procedures which allow maintenance of the implant perimucosal seal.