I had a hair transplant in 2007. 3 months later I suffered badly from Shock loss.
I strated to take large doses of MSM.
Without 3 months I noticed that I did not have to use as much toppik. Both my natural hairs and the transplanted hairs had started to grow back. My surgeon told me that it would take from 12 to 18 months. After 6 months my hair looked great. My surgeon said I was very lucky and it was unusual for this to happen. I attribute the growth to MSM as this is the only thing that I took (other than aldactone -which i had been taking anyway).
I now regularly take MSM. I believe that it does accelerate hair growth.