Immunohistochemical Expression of Sox9 and CD34 in Androgenetic Alopecia Patients

Androgenetic alopecia (AGA) is the most prevalent type of hair loss. Hair follicle stem cells (HFSCs) and their progeny play a pivotal role in hair regeneration. Pathologic modifications of those stem cells are responsible for dysregulation of hair growth and subsequently hair loss. So we aimed to study the immunohistochemical expression of sex determining region Y-box 9 (Sox9) and cluster of differentiation 34 (CD34) in androgenetic alopecia patients. This case-control study included 40 subjects: 14 males with androgenetic alopecia (AGA) and 6 females with female pattern hair loss (FPHL), in addition to 20 age, sex and site-matched healthy volunteers as a control group. All subjects were subjected to history taking followed by examination. Scalp biopsies were taken from all subjects, followed by immunohistochemical analysis to detect Sox9 and CD34 expression. It was found that CD34 was expressed in all control scalp biopsies in comparison to 60% of frontal bald skin samples of AGA patients. Similar decline in CD34 staining was observed in frontal biopsies when compared with hairy occipital skin of the same AGA patient. Sox9 was expressed with the highest intensities and percentage in all samples of frontal bald, occipital hairy together with control scalp biopsies. We concluded that the diminish in expression of CD34+ progenitor cells in the studied AGA frontal bald biopsies in addition to preserved expression of Sox9 + HFSCs could suggest that dysregulated conversion of HFSCs to progenitors may play a significant role in the pathogenesis of AGA.