PF4 and Hermansky-Pudlak syndrome: In this regard, higher levels of (lymph-)angiogenesis inhibitors (TSP-1, PF-4) in HPS have previously been demonstrated not to cause inferior lymph vessel generation in comparison to Hypoxic Preconditioned Plasma (HPP), a product that lacks platelet activation through the addition of heparin anti-coagulation, resulting in lower TSP-1 and PF-4 concentration than in HPS [24].