Hair follicle induction by cultured human hair follicle dermal stem cells

Hair follicles are remarkable mini-organs that are made from skin but that contain unique stem cell populations. Using animal models we have previously demonstrated that we can remove a small group of cells, called dermal papilla cells, from the base of the adult hair follicle and multiply them in the laboratory. When we put these cells back into the skin they interact with the overlying skin epidermal cells and direct them to become completely new hair follicles. Up to now, however, other researchers have not been able to do the same thing with human dermal papilla cells. We have recently identified two things that change when the human dermal papilla cells are grown outside the body. It appears that they rapidly lose much of the signalling information that allows them to influence other cells, and they also become less sticky so that, when they go back into skin, instead of staying together and making a hair, the move off. This project will address these problems in two ways. We will use modern gene manipulation technology to restore the missing signalling molecules to the cells. We will also use grow the cells in the laboratory inside different materials and manipulate their environment such that their stickiness is restored and they remain together when returned to the skin. If successful this bioengineering of hair follicles will lead to so called ?hair cloning? and be a major advance for the treatment of different forms of baldness. It would also be a key step towards the aim of creating an engineered skin incorporating skin appendages for use in skin grafting after burns or other skin loss.

To a considerable extent, our laboratory has pioneered the concept of hair follicle neogenesis using hair follicle dermal cells as the inductive source. This project provides a key enabling technological step that advances the concept of hair follicle induction towards translational use in humans. The hair follicle dermal papilla is a unique component of the hair follicle, which has been shown to be fundamental for hair follicle cycling, and when isolated from the hair follicle is capable of inducing de novo hair follicle formation (neogenesis). Nevertheless, when human dermal papilla cells are propagated in culture, the hair inductive capability of these cells is lost. By carrying out molecular profiling of dermal papilla cells after they are isolated from the hair follicle and at stages during their subsequent culture, we have established a molecular signature of these cells in relation to their inductive status. We have also demonstrated that manipulating the cultured cells to create three-dimensional structures partially restores their original molecular profile. Our hypothesis is that restoration of genes that are essential for hair follicle induction through a combination of methods will fully restore the ability of dermal papilla cells to induce de novo hair follicles. 1) From our profiling we will introduce key missing transcription factors by transduction ? we will also introduce dermal papilla signature reporter genes into the cells 2) We will manipulate culture conditions by adding secreted factors elucidated from epithelial cells; 3) By spatially restricting three dimensional dermal cell cultures either in a bioengineered matrix or by surrounding them with epidermal cells we will alter the interaction between cells in such a way that we promote a functional in vivo dermal papilla profile. The inductive status of the cells will be tested throughout, using different in vivo functional studies, the most stringent of which assesses follicle neogenesis directly in human skin pre-grafted to immunocompromised mice. The use of these functional assays will be governed in part by reporter readouts. A successful outcome at the end of this project will firmly establish the proof-of-principle for procedures required to achieve hair follicle induction in the clinical setting, thereby providing the opportunity for rapid translational development. Moreover, while bioengineering of hair follicles is an innovative alternative in the hair follicle transplantation field, it is also a key step towards the ultimate aim of creating an engineered skin incorporating skin appendages for skin grafting and replacement.