Pre-aggregation of scalp progenitor dermal and epidermal stem cells activates the WNT pathway and promotes hair follicle formation in in vitro and in vivo systems

Abstract

BackgroundBillions of dollars are invested annually by pharmaceutical companies in search of new options for treating hair loss conditions; nevertheless, the challenge remains. One major limitation to hair follicle research is the lack of effective and efficient drug screening systems using human cells. Organoids, three-dimensional in vitro structures derived from stem cells, provide new opportunities for studying organ development, tissue regeneration, and disease pathogenesis. The present study focuses on the formation of human hair follicle organoids.MethodsScalp-derived dermal progenitor cells mixed with foreskin-derived epidermal stem cells at a 2:1 ratio aggregated in suspension to form hair follicle-like organoids, which were confirmed by immunostaining of hair follicle markers and by molecular dye labeling assays to analyze dermal and epidermal cell organization in those organoids. The hair-forming potential of organoids was examined using an in vivo transplantation assay.ResultsPre-aggregation of dermal and epidermal cells enhanced hair follicle formation in vivo. In vitro pre-aggregation initiated the interactions of epidermal and dermal progenitor cells resulting in activation of the WNT pathway and the formation of pear-shape structures, named type I aggregates. Cell-tracing analysis showed that the dermal and epidermal cells self-assembled into distinct epidermal and dermal compartments. Histologically, the type I aggregates expressed early hair follicle markers, suggesting the hair peg-like phase of hair follicle morphogenesis. The addition of recombinant WNT3a protein to the medium enhanced the formation of these aggregates, and the Wnt effect could be blocked by the WNT inhibitor, IWP2.ConclusionsIn summary, our system supports the rapid formation of a large number of hair follicle organoids (type I aggregates). This system provides a platform for studying epithelial-mesenchymal interactions, for assessing inductive hair stem cells and for screening compounds that support hair follicle regeneration.

The potential role of hsa_circ_0001079 in androgenetic alopecia via sponging hsa‐miR‐136‐5p

“… 21 , 22 Wnt5a is a representative Wnt family protein in the non‐classical Wnt pathway and plays important roles in cell proliferation, differentiation, migration and movement. 23 The non‐classical Wnt5a‐Cdc42 axis antagonizes classical Wnt signaling and ultimately induces a phenotype in young hair follicle stem cells similar to premature aging. 24 , 25 To understand the role of the Wnt signaling pathway in hair follicle growth, when locating Wnt marker proteins, it was found that Wnt10b and TCF3 were highly expressed in dermal papilla cells during the growth period, while Wnt5a and Wnt10a were weakly expressed.…”

Early-stage bilayer tissue-engineered skin substitute formed by adult skin progenitor cells produces an improved skin structure in vivo

“…Epidermal and dermal cells used were previously frozen cells at passage 1, and after thawing, the cells were cultured for two more passages (passage 3) to obtain sufficient numbers of cells for all experiments. These dermal and epidermal progenitor cells have been proven to be multipotent after culture expansion [ 22 , 25 ].…”

Functional hair follicle regeneration: an updated review

“…The addition of recombinant WNT3a protein to the medium enhanced the formation of these aggregates, and the transplantation of these organoids in vivo achieved HF formation. 115 Finally, a 3D integumentary organ system (IOS) obtained by the self-assembly of mesenchymal and Epi-SCs from iPSCs using the clustering-dependent embryoid body transplantation method also regenerated fully functional HF organoids. 116 After transplantation into nude mice, the HF organoid in that system could form proper connections to the surrounding host tissues, such as the epidermis, arrector pili muscles and nerve fibres, without tumorigenesis, and show appropriate hair eruption and hair cycles, including the rearrangement of follicular stem cells and their niches.…”