Blood is composed of red blood cells, white blood cells, plasma and platelets. If a vial of blood were left out on a table, the blood would eventually stratify into three distinct layers with the heaviest components sinking to the bottom and the lightest rising to the top. Eventually three distinct layers would become visible; red blood cells (RBCs) at the base, white blood cells and platelets in a thin layer above the RBCs (also known as the ‘buffy coat’), and finally platelet poor plasma on top.
Centrifugation accelerates this innate sedimentation process and allows practitioners to isolate and re-inject platelets in a timely manner. Under centrifugation, the particles in suspension experience radial force which moves them away from the axis of rotation. Particles of a higher density travel at a faster rate and become separated out from less dense and smaller particles.