BLOOD SAMPLING AND MEASUREMENT OF SDF-1Α A blood sample of about 5 ml will be sampled by peripheral venepuncture and anticoagulated with heparin. Blood samples will be spun for 15 minutes at 1000g within 30 minutes of collection. The resulting plasma will be stored at -80°C until analysis. Levels of SDF-1α in the plasma will be determined using a commercially available ELISA kit according to the manufacturer's instructions.