Relationship of sebaceous cell stage to growth in culture.

The maturational stage at which sebaceous epithelial cells are irreversibly committed to autolysis has not been determined in a biologic system. The purpose of these experiments was to determine the relationship of sebocyte maturation to their ability to grow in culture. Single cell suspensions from adult rat preputial glands were prepared, and sebocyte stages were classified using lipid staining as one criterion of maturation. Cells were subjected to one-step, isokinetic discontinuous density gradient centrifugation in Percoll. Cells were cultured on 3T3 feeder layers in an epithelial cell medium containing 20% fetal calf serum, growth factors, and antibiotics. Growth in culture occurred from sebocytes in all gradient fractions. The least growth was found from cells in the lightest density fraction (1.020), which contained sebocytes with the most lipid, i.e., the most mature. Over fivefold more growth occurred from cells in the most dense fraction (1.080), which contained undifferentiated and immature sebocytes. Cell growth in culture was then correlated with the type of sebocyte in each fraction plated. Although cell growth in culture correlated significantly with the number of undifferentiated cells (r2 = 0.460), epithelial colonies were found in the absence of discernible undifferentiated cells in most fractions. Growth in culture correlated much better with the number of early plus mid-differentiated sebocytes (r2 = 0.702). These data suggest that, whereas mature sebocytes are not capable of attachment/proliferation, early differentiation of sebocytes is compatible with retention of the capacity to proliferate. If this property is shared by human sebocytes, it would contribute to the intransigence and diversity of acne-form lesions.