Platelet-rich plasma (PRP) centrifugation is a clinical process that separates whole blood into distinct layers based on density to concentrate healing factors. The final “composition” refers to both the chemical additives in the preparation tube and the resulting cellular layers of the processed blood.

• Anticoagulants: Essential to prevent clotting before the platelets can be isolated and injected. Common choices include Sodium Citrate or Acid Citrate Dextrose-A (ACD-A), with ACD-A often preferred for preserving platelet morphology.
• Separation Gel: Many modern tubes include a chemically inert gel that acts as a physical barrier between red blood cells and plasma during the spin.
• Activators (Optional): After processing, substances like 10% Calcium Chloride may be added to trigger the release of growth factors. 

1. Platelet-Poor Plasma (PPP): The top, straw-colored layer consisting mostly of liquid plasma with very few platelets (approx. 55% of total volume).
2. Buffy Coat: A thin, intermediate layer containing a high concentration of platelets and white blood cells (leukocytes). This is the primary source of growth factors such as VEGF, PDGF, and TGF-B.
3. Red Blood Cell (RBC) Layer: The dense bottom layer, typically discarded for “Pure PRP” or partially included for “Leukocyte-Rich PRP”. 

• Leukocyte-Poor (LP-PRP): Contains fewer than 0.1 million leukocytes per microliter; preferred for reducing post-injection pain and swelling.
• Leukocyte-Rich (LR-PRP): Contains more than 1 million leukocytes per microliter; may offer superior anti-inflammatory and infection-fighting properties.