Changes of the basement membrane and type IV collagen in human skin during aging

To determine the relationship between skin collagen IV and basement membrane changes during aging, a total of 35 women who had been admitted for surgery, were studied.

Subjects were arranged into six age-groups (from 35 to 60 years). Skin biopsies were performed in all patients and the samples were taken from a site 6 cm above the pubic symphysis. The collagen IV content and the epithelial basement membrane were analyzed by using immunohistochemical, transmission electron microscopy and computer-assisted image analysis methods. The skin collagen IV content was measured by an image analysis program and expressed in arbitrary units of integrate optical density, and, the basement membrane thickness was expressed in nanometers.

Type IV collagen content decreased with age after 35 years (r = -0.9561). The epithelial basement membrane thickness increased significantly with age (r = 0.98192; P < 0.01) and there is an inverse correlation between these two parameters (r = -0.990502).

Although type IV collagen is a basement membrane component and declines with aging, the total thickness of this membrane increases, which suggests a reduction in tissue turnover.