TOWARDS THE GENERATION OF A LASER CAPTURE MICRODISSECTION-BASED HUMAN ANAGEN HAIR FOLLICLE TRANSCRIPTOME ATLAS

While this is available for murine HFs, systematic characterization of the transcriptome of specific human hair follicle (HF) compartments remains a major unmet challenge in human hair research. Here, we have aimed to initiate the generation of such an atlas to reveal HF compartment-specific transcriptome. We performed laser capture microdissection (LCM) on 8 selected compartments, i.e. bulge outer root sheath (ORS), suprabulbar ORS, inner root sheath (IRS), precortical hair matrix (HM), germinative HM, dermal papilla (DP), the lower dermal cup (DC), and the connective tissue sheath (CTS), of human anagen VI scalp HFs, and analysed these by RNA-seq. Principal component analysis (PCA) was used to validate the distinctness of the microdissected compartments. Biological replicates were clearly separated by HF compartments and a high degree of similarity of the distinct transcriptional profiles of each examined compartment was seen. Afterwards, we matched well-known signature genes to the correct HF compartments. For example, VCAN (versican) and ALPL (alkaline phosphatase) were correctly expressed in the DP, the lower DC, and suprabulbar CTS, while TCHH (trichohyalin) was solely found in the proximal IRS, and KRT85 (Keratin 85) and KRT31 (Keratin 31) were almost exclusively expressed in the precortical HM. These transcriptomic data were used to generate an easily accessible database for identifying and defining compartment-specific gene expression profiles, which can be ultimately made publicly accessible (“hair follicle MONasterium InteraCtive atlas – hairMONic”). This human HF transcriptomic map and the associated interactive database will support the identification of HF compartment-specific signature genes, and facilitates the development of compartment-specific, therapeutic interventions for the management of human HF disorders. Overall design: We utilized laser capture microdissection (LCM)-based RNA-Seq from 8 defined HF compartments - bulge outer root sheath (bORS), suprabulbar ORS (sbORS), inner root sheath (IRS), germinative hair matrix (gHM), precortical HM (pcHM), dermal papilla (DP), lower dermal cup (DC), and connective tissue sheath (CTS) – of occipital scalp terminal anagen VI HFs from 7-10 male and female donors undergoing hair transplantation, followed by RNA-Seq analysis of 3-5 HFs per donor.