Human Sebocytes Research Articles

Human biliary metabolites of isotretinoin: identification, quantification, synthesis, and biological activity

1. The metabolites of isotretinoin (13-cis-retinoic acid, Accutane) were investigated in the bile of two patients with biliary T-tube drainage after administration of a single, oral, 80-mg dose of 14C-isotretinoin. Radioactivity measurements showed that the two patients excreted 22.7 and 17.1% of the dose in their bile in 4 days. 2. The two major drug-related components in the bile were identified as the glucuronide conjugates of 4-oxo-isotretinoin and 16-hydroxy-isotretinoin. Two minor components were identified as the glucuronide conjugates of isotretinoin and 18-hydroxy-isotretinoin. 3. H.p.l.c. analyses of Glusulase-treated bile samples indicated that the glucuronides of isotretinoin and the two major metabolites accounted for about 48% and 44% of the total radioactivity in the bile of the two patients. 4. Racemic 16-hydroxy-isotretinoin was synthesized and evaluated for its effect on human sebocytes in vitro. This metabolite and the other major metabolites of isotretinoin were less active than isotretinoin in inhibiting the proliferation of the sebocytes.

Organ maintenance of human sebaceous glands: in vitro effects of 13-cis retinoic acid and testosterone

Human sebaceous glands were isolated by shearing, and maintained for 7 days either on defined medium, on medium supplemented with 3 microM-testosterone or on medium supplemented with both 3 microM-testosterone and 1 microM-13-cis retinoic acid. Freshly isolated glands retained their in vivo morphology. On maintenance, the glands retained their freshly isolated rates of cell division, but the sebocytes showed increased keratinization and there was multilayering of the peripheral undifferentiated cells. However, glands maintained in the presence of 1 microM-13-cis retinoic acid showed very little luminal keratinization and only a small degree of multilayering. On autoradiography, freshly isolated glands retained their in vivo pattern of [methyl-3H]thymidine incorporation. Similar patterns were seen when glands were maintained for 7 days with or without testosterone. However, in the presence of both testosterone and 13-cis retinoic acid there was only slight graining. Following 7 days maintenance the rate of lipogenesis fell significantly. This was partially reversed by testosterone, but further inhibited by 13-cis retinoic acid. The patterns of lipids that are synthesised after a week's maintenance are very similar to those seen in freshly isolated glands, except that the squalene:cholesterol ratio is reversibly regulated by 3 microM-testosterone and 1 microM-retinoic acid. Protein synthesis was maintained at the same rates as for freshly isolated glands under all conditions of maintenance. Whereas DNA synthetic rates were maintained in the presence of testosterone, they were significantly inhibited by 13-cis retinoic acid. Glandular wet weights were retained under all conditions of maintenance, except that they were significantly reduced by 13-cis retinoic acid. This study shows that human sebocytes continue to divide on organ maintenance, but that they do not differentiate fully. However, this provides the first demonstration that 13-cis retinoic acid acts on human sebaceous glands directly, reducing the rate of cell division and the rate of lipogenesis, which shows that the maintained human sebaceous gland might provide a useful model for studying the effect of 13-cis retinoic acid on human sebocytes.

Isolation of human sebaceous glands and cultivation of sebaceous gland-derived cells as an in vitro model

An experimental technique is presented as an in vitro model for the study of human sebaceous gland-derived cells. Intact sebaceous glands were isolated from full-thickness human skin after incubation in dispase (2.4 U/ml) and in deoxyribonuclease (0.02%) by using microsurgical instruments under microscopical observation of the epidermal underface. Subsequently, the ducts of the glands were removed, the isolated gland lobules were seeded on a 3T3-cell feeder layer in Dulbecco's modified Eagle's medium and Ham's F 12 medium (3:1)supplemented with fetal calf serum (10%), L-glutamine, antibiotics, epidermal growth factor (10 ng/ ml), hydrocortisone (0.4μg/ml), and cholera toxin (10−9 M), and were then cultivated in a CO2-incubator at 37°C. After 2–3 wk cell outgrowths resulting from the periphery of the gland lobules were obtained and dispersed cells were passaged for three subcultures with or without 3T3-cell feeder layer. The cultured cells preserved in vitro morphologic characteristics and differentiation patterns comparable to those described for normal human sebocytes in vivo, with a high rate of viable cells. Their labeling pattern with MoAb showed close similarities to the pattern reported for sebocytes in vivo but differences to the pattern of keratinocytes in vivo and in vitro. In their cytoplasm oil red and nile red stained droplets were detected, and the observed density and distribution evidenced in vitro lipogenesis. The technique presented here may provide a promising model for further experimental studies on sebaceous gland cell development and function.

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.

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.