» I was just speculating about the cancer protection part. That was just a
» shot in the dark.
» However, let's look at what we DO know. We know that when cultured human
» DSC cells are injected into a mouse, there is substantial hair growth.
» Maybe I wasn't being clear. I am not talking about mouse DSC cells
» injected into a mouse. I am talking about HUMAN DSC cells injected into a
» I think that was already done multiple times by RepliCel, indeed they
» didn't have to get approval from any country's regulatory authority to do
» it. Isn't RepliCel's famous photo of the mouse with the thick tuft of hair
» on the base of its neck a result of human DSC cells injected into a mouse?
Hey roger, I just looked up their 2003 paper (which I think you're referring to.) It seems they used the mices' own DSC cells from the vibrissae: http://www.nature.com/jid/journal/v121/n6/full/5602058a.html
Your idea about loss of trichogenic ability being related to some cancer protection mechanism isn't bad, though. It makes me think of folliculomas, which are hamartomas of the hair follicle. Perhaps this mechanism is lost in these kinds of tumors. Just as an example, human fibroblasts, which are closely related to DS cells, are known to reach senescence after some 50 generations due to telomere shortening (the Hayflick limit.) So, in either case, such a mechanism would set an upper limit for how much a cell culture can be expanded. The Hayflick limit can be circumvented, though, so I'm sure the Replicel guys have taken that into account already, but there might also be other, less known mechanisms at work.
That being said, the fact that we know that inductivity can be maintained for longer when co-culturing HF mesenchymal cells with skin keratinocytes points to that much of the trichogenicity is upheld by signals from other cell lines, just as KO pointed out. When the DSC cells are pulled out from their natural surroundings, these signals are lost, and so the expression profile of the DSCs changes and their identity is lost. As an analogy, docs rely on the concept of donor dominance. The fact is that this state is - in my belief - always transitory, as the recipient environment slowly will change cell identity to one that more closely resembles what would have been native to the recipient tissue. That's why eyebrow transplants with time will grow shorter and acquire a shorter anagen phase (same thing goes for grafts that grow longer when transplanted to the scalp.)
kekeke is located in [NA] and he is available to meet: NO