Mapping the Expression of Epithelial Hair Follicle Stem Cell-Related Transcription Factors LHX2 and SOX9 in the Human Hair Follicle

The study investigated the expression patterns of transcription factors LHX2 and SOX9 in human hair follicles, particularly in relation to known epithelial hair follicle stem cell markers K15 and K19. It was found that K15 and K19 marked distinct progenitor cell populations in different regions of the outer root sheath (ORS), with K19 expression stronger in the proximal bulb ORS and K15 stronger in the bulge. LHX2 and SOX9 were distributed throughout the ORS, not limited to the bulge, with SOX9 most prominent below the bulge and LHX2 between the sub-bulge and proximal bulb ORS. During catagen, LHX2 and SOX9 expression increased in the proximal HF epithelium. The study concluded that LHX2 and SOX9 identify distinct progenitor cell populations, separate from K15 and K19, potentially playing a crucial role in maintaining the human hair follicle epithelium.