Follicular dermal papilla structures by organization of epithelial and mesenchymal cells in interfacial polyelectrolyte complex fibers.

The hair follicle is a regenerating organ that produces a new hair shaft during each growth cycle. Development and cycling of the hair follicle is governed by interactions between the epithelial and mesenchymal components. Therefore, development of an engineered 3D hair follicle would be useful for studying these interactions to identify strategies for treatment of hair loss. We have developed a technique suitable for assembly of different cell types in close proximity in fibrous hydrogel scaffolds with resolutions of ∼50 μm. By assembly of dermal papilla (DP) and keratinocytes, structures similar to the native hair bulb arrangement are formed. Gene expression of these constructs showed up-regulation of molecules involved in epithelial-mesenchymal interactions of the hair follicle. Implantation of the follicular structures in SCID mice led to the formation of hair follicle-like structures, thus demonstrating their hair inductive ability. The transparency of the fiber matrix and the small dimensions of the follicular structures allowed the direct quantitation of DP cell proliferation by confocal microscopy, clearly illustrating the promoting or inhibitory effects of hair growth regulating agents. Collectively, our results suggested a promising application of these 3D engineered follicular structures for in vitro screening and testing of drugs for hair growth therapy.