@JohnAdams, You manage to gain access to that PRP paper?
I am looking through the MSC paper you posted, I haven't finished it yet, but it looks very interesting. They are finding that the MSCs can differentiate in to neurons, which is contrary to what most believe.
"By a combination of growth factor stimulation and expression of the transcription factor, Math1, that is required for hair cell formation in the inner ear, we show here that MSCs derived from bone marrow can be induced to differentiate into hair cells."
Utilizing growth factors as well, the same as PRP. This is seeming very similar to Shim.