Can subcision damaged hair follicles? It can damage beard growth?

When performed by an expert, subcision has a very rare chance of damaging hair follicles. Experienced physicians will avoid the hair follicles. I suggest consulting with a board certified cosmetic dermatologist or facial plastic surgeon in order to determine a treatment plan that is customized to your specific needs. Best, Dr. Emer. 

Theoretically, if one transects a hair follicle in certain locations it is possible to affect hair regrowth on the face.  Most of the time that follicle will regrow. An experienced doctor will usually enter the skin in an area that avoids the hair follicles and therefore does not produce permanent alopecia. In my opinion, it is rare to see hair loss after subcision.