Positive results in the PRP group can be attributed to increased angiogenesis which supports hair growth in the anagen phase. Angiogenesis provides necessary blood flow to support hair follicle development. The healing power of PRP depends on preparation techniques that delivery viable platelets in adequate numbers. Platelet viability and activation is vital for effective PRP injections. Once activated, platelets release a wide variety of growth factors, tiny bioactive proteins that bolster tissue repair by increasing cell mitosis and chemotaxis. Specifically, angiogenesis is increased by fibroblast growth factor 7, transforming growth factor (alpha-beta), vascular endothelial growth factor, epidermal growth factor, and connective tissue growth factor.⁵ Additionally, the authors note the anti-inflammatory effects of PRP benefit patients with alopecia areata which is characterized by an increase in inflammatory cytokines.