Fig. 4. Description of procedure for two-step centrifugation preparation and heterogeneity of PRP preparations from two different patients. Blood separation and manipulation under a laminar flow hood. Following first centrifugation (280 g at 15 min) in a centrifugation tube (50 ml), the three phases can be readily attained with a visible buffy coat (circled) which includes the platelet phase. This phase is isolated (5 ml sterile pipette), placed in a second sterile centrifugation tube, and centrifuged (280 g for 15 min) to obtain a platelet concentrate. Platelet pellet is suspended in a minimum quantity of plasma (2-4 ml).