Method for identifying a non-anticoagulant sulfated polysaccharide which enhances blood coagulation dependence on FXI

A method of identifying a non-anticoagulant sulfated polysaccharide (NASP) which is capable of enhancing blood coagulation in FXI dependent manner, the method comprising:

• a) combining a blood or plasma sample comprising activation competent FXI with a composition comprising a sulfated polysaccharide and measuring the clotting or thrombin generation parameters of the blood or plasma sample;
• b) combining a corresponding blood or plasma sample deficient in activation competent FXI with a composition comprising the sulfated polysaccharide and activated Factor XI (FXIa) and measuring the clotting or thrombin generation parameters of the blood or plasma sample;
• and
• c) comparing the clotting or thrombin generation parameters of the blood or plasma samples as determined in steps (a) and (b) with each other, wherein a result of no decrease in the clotting time of the blood sample or no increase in peak thrombin or no decrease in peak time of the plasma sample comprising activation competent FXI compared to the clotting time of the blood sample or peak thrombin or peak time of the plasma sample deficient in activation competent FXI is indicative that the NASP is an activator of Factor XI.