• Dermal adipose tissue secretes HGF to promote human hair growth and pigmentation

      Nicu, C.; O'Sullivan, J.D.B.; Ramos, R.; Timperi, L.; Lai, T.; Farjo, N.; Farjo, B.; Pople, J.; Bhogal, R.; Hardman, J.A.; et al. (2021-07-01)
      Hair follicles (HFs) are immersed within dermal white adipose tissue (dWAT), yet human adipocyte-HF communication remains unexplored. Therefore, we investigated how perifollicular adipocytes affect the physiology of organ-cultured human anagen scalp HFs. Quantitative (immuno-)histomorphometry, microCT and transmission electron microscopy showed that the number and size of perifollicular adipocytes declined during anagen-catagen transition, whilst fluorescence lifetime imaging revealed increased lipid oxidation in adipocytes surrounding the bulge/sub-bulge region. Ex vivo, dWAT significantly stimulated hair matrix keratinocyte proliferation and HF pigmentation. Both dWAT pericytes and PREF1/DLK1+ adipocyte progenitors secreted hepatocyte growth factor (HGF) during human HF-dWAT co-culture, for which the c-Met receptor is expressed in the hair matrix and dermal papilla. These effects were abrogated by an HGF-neutralising antibody, and reproduced using recombinant HGF. Laser capture microdissection-based microarray analysis of the hair matrix showed that dWAT-derived HGF up-regulated KRT27, KRT73, KRT75, KRT84, KRT86 and TCHH. Mechanistically, HGF stimulated Wnt/β-catenin activity in the HM by inhibiting SFRP1 in the dermal papilla, up-regulating matrix AXIN2, LEF1, WNT6 and WNT10B expression. Our study demonstrates that dWAT regulates human hair growth and pigmentation via HGF secretion, and thus identifies important, molecular and cellular targets for therapeutic intervention in disorders of human hair growth and pigmentation.