In VitroCell.Dev.Biol.28A:699.November-December1992 © 1992TissueCultureAssociation 0883-8364/92 $01.50+0.00
Letter to the Editor SEBACEOUS CELLS IN MONOLAYER CULTURE wax esters while keratinocytes do not. However, lipogenesis in the sebaceous gland is remarkably species specific (3). It would be, therefore, interesting to examine the amount and quality of lipids contained in rat preputial gland cells in culture in order to evaluate the model of cultured rat preputial gland cells as an alternative to human sebocyte cultures for investigating the effects of hormones and of synthetic compounds, i.e. androgens and retinoids, on sebaceous cell growth and differentiation (1,9,10).
Dear Editor: In an interesting recent article Laurent et al. (2) presented a partial characterization of rat preputial gland cells in culture which seem to possess some of the properties found in cultured human sebocytes (Table 1). Like human sebocyte cultures, rat preputial gland cells grew slower than epidermal keratinoeytes, expressed the acinar keratin 4, and formed only a small number of cornified envelopes. The authors claim that the expression of keratin 4 by rat preputial gland cells in culture identifies them being of sebocytic origin. However, the expression of keratin 4, although has been indicative for cells originating from the sebaceous gland, does not alone prove a preservation of sebaceous properties in vitro. Epidermal keratinocytes in monolayer culture also express occasionally keratin 4 (5). It is likely, therefore, that cultured keratinocytes expressed partially, indeed, keratin 4, as found by the authors (3 out of 11 samples) and this was probably not due to contamination of the keratinocyte cultures tested with rat preputial gland cells. On the other hand, the major parameter of sebocytic differentiation is the amount and the quality of fipids synthesized in the sebaceous cells (4). We could show that cultured human sebocytes (6) contain in primary culture 4 times more intracellular lipids than epidermal keratinocytes of the same subjects, a ratio increasing after comparing the first subcultures (8,9). Moreover, human sebocytes in culture synthesize the scbum-specific lipids squalene and
REFERENCES
1. Akamatsu, H.; Zouboulis, Ch.C.; Orfanos, C. E. Control of human sebocyte proliferation in vitro by testosterone and 5-alpha-dihydrotestosterone is dependent on the localization of the sebaceous glands. J. Invest. Dermatol. In press. 2. Laurent, S. J.; Mednieks, M. J.; Rosenfield, R. L. Growth of sebaceous cells in mono|ayer culture. In Vitro Cell. Dev. Biol. 28A:83-89; 1992. 3. Nikkari, T. Comparative chemistry of sebum. J. Invest. Dermatol. 62:257-267; 1974. 4. Thody, A. J.; Shuster, S. Control and function of sebaceous glands. Physiol. Rev. 69:383-416; 1989. 5. Van Muijen, G. N. P.; Warnaar, S. O.; Ponec, M. Differentiation-related changes of cytokeratin expression in cultured keratinocytes and in fetal, newborn, and adult epidermis. Exp. Cell Res. 171:331-345; 1987. 6. Xia, L.; Zouboulis, Ch.; Detmar, M., et al. Isolation of human sebaceous glands and cultivation of sebaceous gland-derived cells as an in vitro model. J. Invest. Dermatol. 93:315-321; 1989. 7. Zouboulis, Ch.C. Sebocyte cultures: how they can improve our understanding of diseases of the sebaceous glands. Retinoids Today and Tomorrow 26(suppl.):6-12; 1992. 8. Zouboulis, Ch.C.; Xia, L.; Detmar, M., et al. Cultivation of human sebocytes and markers of sebocytic differentiation in vitro. Skin Pharmacol. 4:74-83; 1991. 9. Zouboulis, Ch.C.; Xia, L.; Korge, B., et at. Cultivationof human sebocytes in vitro: cell characterization and influence of synthetic retinoids. In: Saurat, J.-H., ed. Retinoids: 10 years on. Basel: Karger; 1991:254-273. 10. Zouboulis, Ch.C.; Korge, B.; Akamatsu, H., et at. Effects of 13-cis-retinoic acid, all-trans-retinoic acid and acitretin on the proliferation, lipid synthesis and keratin expression of cultured human sebocytes in vitro. J. Invest. Dermatol. 96:792-797; 1991.
TABLE 1 CHARACTERISTICS OF SEBOCYTIC DIFFERENTIATION IN VITRO (MODIFIED FROM REF. 7) Morphology Polymorphicepithelial appearance not resembling a cobble-stone pattern Presence of cells in several stages of sebocytic differentiation Abundant cytoplasmic lipid droplets Missing of desmosomes in intercellular contacts Lipid synthesis during cell proliferation Proliferation Slower .growth than epidermal keratinocytes of the same subjects Decreasing number of proliferating cells after subcuhivation Cellular Lipids 4 times higher lipid content than keratinocytes Synthesis of squalene, wax esters and free fatty acids Keratin Pattern Expression of keratins 4, 7 and 13 Enhanced expression of keratin 19 No expression of keratins 1 and 2 Phenotype Positive labeling with the monoclonal antibody OM-1, recognizing a sebaceous cell antigen Formation of small numbers of cornified envelopes
Chrisms C. Zouboulis Department of Dermatology
University Medical Center Steglitz The Free University of Berlin Hindenburgdamm 30 W-1000 Berlin 45 Germany
(Received 13 July 1992)
699
Letter to the Editor SEBACEOUS CELLS IN MONOLAYER CULTURE wax esters while keratinocytes do not. However, lipogenesis in the sebaceous gland is remarkably species specific (3). It would be, therefore, interesting to examine the amount and quality of lipids contained in rat preputial gland cells in culture in order to evaluate the model of cultured rat preputial gland cells as an alternative to human sebocyte cultures for investigating the effects of hormones and of synthetic compounds, i.e. androgens and retinoids, on sebaceous cell growth and differentiation (1,9,10).
Dear Editor: In an interesting recent article Laurent et al. (2) presented a partial characterization of rat preputial gland cells in culture which seem to possess some of the properties found in cultured human sebocytes (Table 1). Like human sebocyte cultures, rat preputial gland cells grew slower than epidermal keratinoeytes, expressed the acinar keratin 4, and formed only a small number of cornified envelopes. The authors claim that the expression of keratin 4 by rat preputial gland cells in culture identifies them being of sebocytic origin. However, the expression of keratin 4, although has been indicative for cells originating from the sebaceous gland, does not alone prove a preservation of sebaceous properties in vitro. Epidermal keratinocytes in monolayer culture also express occasionally keratin 4 (5). It is likely, therefore, that cultured keratinocytes expressed partially, indeed, keratin 4, as found by the authors (3 out of 11 samples) and this was probably not due to contamination of the keratinocyte cultures tested with rat preputial gland cells. On the other hand, the major parameter of sebocytic differentiation is the amount and the quality of fipids synthesized in the sebaceous cells (4). We could show that cultured human sebocytes (6) contain in primary culture 4 times more intracellular lipids than epidermal keratinocytes of the same subjects, a ratio increasing after comparing the first subcultures (8,9). Moreover, human sebocytes in culture synthesize the scbum-specific lipids squalene and
REFERENCES
1. Akamatsu, H.; Zouboulis, Ch.C.; Orfanos, C. E. Control of human sebocyte proliferation in vitro by testosterone and 5-alpha-dihydrotestosterone is dependent on the localization of the sebaceous glands. J. Invest. Dermatol. In press. 2. Laurent, S. J.; Mednieks, M. J.; Rosenfield, R. L. Growth of sebaceous cells in mono|ayer culture. In Vitro Cell. Dev. Biol. 28A:83-89; 1992. 3. Nikkari, T. Comparative chemistry of sebum. J. Invest. Dermatol. 62:257-267; 1974. 4. Thody, A. J.; Shuster, S. Control and function of sebaceous glands. Physiol. Rev. 69:383-416; 1989. 5. Van Muijen, G. N. P.; Warnaar, S. O.; Ponec, M. Differentiation-related changes of cytokeratin expression in cultured keratinocytes and in fetal, newborn, and adult epidermis. Exp. Cell Res. 171:331-345; 1987. 6. Xia, L.; Zouboulis, Ch.; Detmar, M., et al. Isolation of human sebaceous glands and cultivation of sebaceous gland-derived cells as an in vitro model. J. Invest. Dermatol. 93:315-321; 1989. 7. Zouboulis, Ch.C. Sebocyte cultures: how they can improve our understanding of diseases of the sebaceous glands. Retinoids Today and Tomorrow 26(suppl.):6-12; 1992. 8. Zouboulis, Ch.C.; Xia, L.; Detmar, M., et al. Cultivation of human sebocytes and markers of sebocytic differentiation in vitro. Skin Pharmacol. 4:74-83; 1991. 9. Zouboulis, Ch.C.; Xia, L.; Korge, B., et at. Cultivationof human sebocytes in vitro: cell characterization and influence of synthetic retinoids. In: Saurat, J.-H., ed. Retinoids: 10 years on. Basel: Karger; 1991:254-273. 10. Zouboulis, Ch.C.; Korge, B.; Akamatsu, H., et at. Effects of 13-cis-retinoic acid, all-trans-retinoic acid and acitretin on the proliferation, lipid synthesis and keratin expression of cultured human sebocytes in vitro. J. Invest. Dermatol. 96:792-797; 1991.
TABLE 1 CHARACTERISTICS OF SEBOCYTIC DIFFERENTIATION IN VITRO (MODIFIED FROM REF. 7) Morphology Polymorphicepithelial appearance not resembling a cobble-stone pattern Presence of cells in several stages of sebocytic differentiation Abundant cytoplasmic lipid droplets Missing of desmosomes in intercellular contacts Lipid synthesis during cell proliferation Proliferation Slower .growth than epidermal keratinocytes of the same subjects Decreasing number of proliferating cells after subcuhivation Cellular Lipids 4 times higher lipid content than keratinocytes Synthesis of squalene, wax esters and free fatty acids Keratin Pattern Expression of keratins 4, 7 and 13 Enhanced expression of keratin 19 No expression of keratins 1 and 2 Phenotype Positive labeling with the monoclonal antibody OM-1, recognizing a sebaceous cell antigen Formation of small numbers of cornified envelopes
Chrisms C. Zouboulis Department of Dermatology
University Medical Center Steglitz The Free University of Berlin Hindenburgdamm 30 W-1000 Berlin 45 Germany
(Received 13 July 1992)
699
