Maher,
That's the problem with injecting growth factors; once they are in the body, it is very difficult for them to make "good" things grow without also making "bad" things grow. For example, they may support DP cell growth and proliferation, but they could also support growth and proliferation of other, non-targeted cells (ie a tumor). The problem, as well, is that it wouldn't really take a pre-formed malignancy for these cells to cause a problem. We experience inappropriate cell growth, improper genetic coding, incorrect division, etc, on a daily basis, but our body contains mechanisms to compensate and stop the problem before it really becomes bad. If we shift the body into a permanent anabolic state, however, with growth factors, issues could occur. Like Ben said too, it's difficult to interpret the safety trials - in my opinion - because these types of issues often happen over a longer period (not just during the 12 months its evaluated during a safety trial). Now, absolutely no one knows if this would happen for sure, but there will always be concern with injecting growth factors.
In my opinion, I think it's difficult to say that the cells will or will not be DHT resistant. In the video, David Hall states that the cells are taken from a DHT resistant region of the scalp. However, I was under the impression that the androgen receptors on the DP cells, not the DSC cells were the issue. If new DSC cells are implanted and support existing DP cells without creating new ones, the same androgenic receptors will exist (and they will still be prone to DHT). Maybe I'm interpreting it wrong and someone can clarify?