Integrating Single-Cell and Spatial Transcriptomics of Human Hair Follicles to Define Transcriptional Signature of Follicular Dermal Papilla

The study focused on the follicular dermal papilla (DP), a crucial cell in hair follicle development. Due to the limited number of DP cells, previous single-cell level studies have been unsatisfactory. In this study, anagen hair follicles and DPs were manually isolated from three human scalp specimens for single-cell RNA sequencing (scRNA-seq). Additionally, Digital Spatial Profiling (DSP) was used to provide spatial information on human DP expression profiles. The integration of scRNA-seq and DSP data estimated cell abundance in hair-specific regions and identified molecular markers of the specialized hair mesenchyme. The study found that RSPO4, WNT5A, TRPS1, CRABP1, APCDD1, EDN3, RSPO3, LEF1, BMP4, BMP7, and NRG2 are specifically expressed in DP cells, while MME, LGR4, LGR5, FZD1, CXCL14, and TAGLN were mainly expressed in the dermal sheath. These findings were confirmed through in situ RNA hybridization (RNA-ISH). This research lays the groundwork for understanding the molecular characteristics of DP.