Androgen Induces Differentiation Of Hair Follicle Stem Cells Into Sebocytes In Vitro

Each hair follicle contains a reservoir of stem cells mainly locating to bulge. Recent Experiments demonstrated that bulge-located stem cells not only can migrate to the upper part of the hair follicle to generate sebaceous glands and epidermis, but also can migrate to the lower part of the hair follicle to give rise to many compartments of the lower hair follicle.The growth and differentiation of sebocytes were regulated by retinoids, hormones, and cytokines. Androgen plays an important role in stimulating sebocytes'development and lipogenesis. The androgen receptor (AR) is a ligand-dependent transcription regulator that mediates the diverse biological actions of androgen. It is reported that AR has been localized to the base layer of the sebaceous gland and the outer root sheath keratinocytes of the hair follicle in human skin.To explore the possibility that the androgen may facilitate differentiation of hair follicle stem cells (HFSC) into sebocytes, we carried out experiments to test this hypothesis. The concrete steps to carry out this research were as follow:Firstly, observed the expression of AR and examined the expression of AR mRNA of rat vibrissa follicle stem cells in vivo in three defined phases of a hair follicle cycle, including anagen, catagen and telogen.Secondly, cultured HFSC deprived from vibrissa follicle bulge region in culture flasks and observed the expression of AR, ketertin 15 (K15), cluster of differentiation 34 (CD34) andβ1-integrin of those cells.Thirdly, Divided culture flasks into two groups. Media plus testosterone propionate (TP) has been added to one group of culture flasks to induce differentiation of HFSC into sebocytes in vitro. The media without TP still has been added to the other group of culture flasks as conctrol. Then observed the expression of epithelial membrane antigen (EMA) and lipid droplets of cells induced in vitro and that of cells as control. Methods:AR, K15, CD34,β1-integrin and EMA were observed by immunohistochemistry. Lipid droplets were observed by rathonum red staining. The expression of AR mRNA was examined by RT-PCR. Media plus TP was used to induce differentiation of HFSC into sebocytes in vitro.Results:1. In vivo HFSC expressed AR in three different phases of a hair follicle cycle, including anagen, catagen and telogen.2. AR was strongly expressed in anagen, while weakly in catagen and telogen. AR mRNA was strongly expressed in anagen, while weakly in catagen and telogen. The expression pattern of AR is consistent with that of AR mRNA. The density of AR of HFSC is in accordance with the capability of differentiation of those cells.3. In vitro HFSC expressed AR, K15, CD34 andβ1-integrin.4. Cells induced in vitro expressed EMA and Lipid droplets were observed by rathonum red staining, while those as control didn't.Conclusion:1. In vivo vibrissa follicle bulge region is the target tissue of androgen. HFSC in vitro are also target cells of androgen and the characteristic of stemness of HFSC in vitro is well maintained.2. The expression of AR and AR mRNA of rat vibrissa follicle stem cells in vivo was altered regularly throughout a hair follicle cycle. The expression pattern of AR is consistent with that of AR mRNA. The density of AR of HFSC is consistent with the capability of differentiation of those cells.3. Cells induced in vitro expressed EMA and Lipid droplets were observed by rathonum red staining, while those as control didn't, which confirmed that androgen can facilitate the differentiation of vibrissa follicle stem cells into sebocytes.