Does PRP treatments for preventing hair loss really work?

Platelet-rich plasma has been utilized for years in wound healing and orthopedic conditions, but more recently it has gained traction in aesthetic medicine, especially with respect to hair loss. Several clinicians have had some success in treating alopecia of various etiologies (lichen planopilaris, alopecia areata, etc), but most of the limited data have been focused on PRP use for male- and female-pattern hair loss.
The mechanism of action involves platelets’ ability to aggregate together, activate, and release alpha-granules containing various growth factors, such as platelet derived growth factor, transforming growth factor beta, vascular endothelial growth factor, epidermal growth factor, fibroblast growth factor, and insulin like growth factor-1 (IGF-1). Their release increases angiogenesis and vascularization, providing resting telogen hairs the signal that they need to enter the anagen phase. This increased vascularization and mix of growth factors also fosters the proliferation of dermal papilla cells and inhibits apoptosis, helping to prolong the anagen phase.More specific to androgenetic alopecia, PRP may help to counteract certain effects of dihydrotestosterone (DHT). In a mouse model of androgenetic alopecia, DHT was shown to block IGF-1 contributing to hair loss and PRP is a known source of IGF-1.
Platelet-rich plasma is fully autologous and thus provides patients a more “natural” treatment, with side effects limited to procedural discomfort and bruising.
There is no standard system, quantity, or interval of treatment regarding PRP for hair loss, which is why we currently utilize a proprietary hyperconcentrated platelet rich plasma concentration and treat patients monthly 4 times, then reevaluate after 8 to 12 months. If a patient has a response, then retreatment at follow-up may result in continued efficacy if performed at a 6- to 12-month basis.

PRP for hair loss works well for patients who have hair thinning or recently have lost hair in an area.  It slows down hair loss so it's a long term strategy to maintain as much as hair as possible before losing it.  It increases the active growth phase of the follicle and provides increased density by making the hair longer and thicker.  

 Studies have shown that there is a significant role inflammation due to oxidative stress and free radicals resulting in chronic perifollicular fibrosis which can lead to  hair loss. 
Platelet rich plasma offers a strong anti-inflammatory effect, angiogenesis effect, prevents apoptosis and up regulates the signaling proteins which are associated with trichostimulation.
The initial PRP program should be combined with other treatments such as Topical therapy, LLLT, Nutrafol/ Viviscal for better outcome and one should have a maintenance PRP program for continuous trichostimulatory effect.