The long-term objectives and specific aims of this project are directed towards the research and development of a new platelet harvesting device for separating plateletrich plasma from 450 ml units of whole human blood from random donors for clinical use. Methodology to accomplish these goals in Phase I are: (a) to scale-up the small model (21 ml) platelet separator which is based on a principle of counter-flow displacement and depth filtration; (b) to design the scaled-up system using sterile, closed and disposable bai?s; and (c) to evaluate systematically each of the two devices (Prototype I and IiYin terms of the efficiency and quality of the collected platelet-rich plasma.National Heart, Lung and Blood Institute