The basic concept has to do with extracting the patient’s blood and spinning it through a centrifuge to create different layers: red blood cells, platelet rich plasma and platelet poor plasma. Platelets are cells that travel in the blood which help with the clotting process.
Thrombin and calcium chloride are added to the platelets to release growth factors and cytokines which are supposed to help revive hair follicles. Again, there is no real form of support for this.
PRP procedures involve wounding the skin before applying the plasma. New follicles are produced after the skin heals from wounding, although growth is very minimal. It is not clear if wounding or the PRP helps create new hair.