

To answer your questions it might be best first to lay out our current aims/understanding:
1) Rat whisker dermal papilla (DP) can be isolated, cultured and re-implanted into the skin to induce new follicles.
2) Fresh, whole human DP can be re-implanted to induce a follicle.
3) 2D cultured human DP lose this ability to induce follicle.
4) Dr Higgins in her paper demonstrated this nicely by by performing a micro-array, (a technique which compares, in bulk, gene expression between two or more samples). She showed that there was significant variation in several thousand genes between in vivo DP and 2D cultured DP (Fig 2A of her paper). http://www.pnas.org/content/early/2013/10/16/1309970110
5) She also demonstrated that 3D culture of human DP restored ~40% of the in vivo DP genetic character that was lost in 2D culture (Fig. 4C)
6) These 3D spheres were able to induce the formation of follicle structures from 5 of 7 donors with an efficiency ranging from 10-60% (i.e 10 spheres - 1 follicle structure = 10% efficiency).
So we want to take this further and there are several areas that we want to look at:
7) Improve efficiency, use more accessible cells, use only adult human tissues and develop a "quick" non-animal model assay.
8) Efficiency - Further restore in vivo DP character to 3D DP cultures, we are attempting to do this by coating the DP spheres with epithelial cells, to mimic the interactions that are occurring in vivo (Dr Higgins explained this really well in her talk). These dermal-epidermal interactions are key in follicle development and subsequent hair cycling. See also: http://www.hairtx.com/files/2014/03/peg.gif this is the interaction that we're attempting to mimic in our cultures.
9) Accessible cells - Attempt to restore DP character to non DP cultures. We are looking at the dermal sheath (DS) as we think they are more similar in character to the DP than dermal fibroblasts (DF). But this is a stepping stone to using DF as the Rendl group are attempting. See "P202 (SY10) REPROGRAMMING REGULAR SKIN FIBROBLASTS INTO HAIR INDUCING DERMAL PAPILLA CELLS Carlos CLAVEL" from WCHR2014. We are doing this by adding genes that Dr Higgins identified in her paper, into DS and seeing if we can make them DP like.
10) Adult tissues - The majority of studies which demonstrate inductivity either use mouse or neonatal human epithelial cells/tissue. This obviously wont apply in patient so we need to demonstrate inductivity in a less "competent" tissue.
11) Quick assay - we need to screen for a lot of things, we need a quick, easy and cheap assay to achieve this. None of the current assays tick these boxes.
So what do I show?:
12) Efficiency - Epithelial coating restores markers of inductivity that are not seen in dermal only spheres, the populations are interacting, this is great and we hope to repeat Dr Higgins microarray experiment and see if we further restore character. When this works, it works really well. BUT the efficiency of coating is poor, a lot of the time the epithelial cells don't stick to the dermal model, so no improvement in inductivity, we're not sure why this is but we are trying other methods of coating, isolation epithelial cells and epithelial cell populations.
13) Accessible cells - A better option than above, but currently none of the factors we have screened have restored DP character. We have lots more factors and will move onto multiple factor screens as well.
14) Adult tissues - All our work is progressing using adult tissues, but we have yet to try our new cultures in a mouse model, we will do so shortly when we have our ideal double-sphere and any promising DS-DP .
15) Quick model - This has worked out really nicely, we have a new model we can use in the lab to see if our spheres induce the epithelium to grow down into the dermis of our gels, which is reminiscent of initial follicle formation.
Sorry for the wall of text, but I think it shows our thinking nicely. Other groups have differing ideas and it was great to see them at the WCHR and to see what it is that the other groups are up to. We can then apply the nice bits of their thinking to our models (and hopefully they might use some of our ideas

To answer the other key question of "when". To be honest I don't know, every year we make progress as do all the other groups. I don't really believe in this "5 years" time thing, as I honestly think one group will crack it, and it will appear very rapidly after that. Look out for papers using adult only human tissues, non follicle derived dermal cells and with high reproducibility those are the ones that are going to have the widest applications.
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