Blood contains red cells, white cells and platelets. Platelets contain hundreds of proteins called growth factors which are important in the healing of injuries. Platelets also have an important role in the clotting of blood. Platelet Rich Plasma (PRP) is where you have a high concentration of platelets and therefore growth factors, being up to 5 to 10 times greater than in normal blood. PRP is then injected by a Radiologist into the requested body region under ultrasound guidance. Read more here