Mitigation of coagulation by removing clotting factors part 1: in vitro feasibility study

Heparin is associated with adverse effects in some patients during extracorporeal circulation. A potential alternate anticoagulation strategy explored in this investigation involved mitigation of coagulation by removing clotting factors from blood by adsorption on a protamine-immobilized Sepharose matrix (PSM). Human or porcine plasmas treated with PSM in vitro were tested for clotting factors I (fibrinogen), II (prothrombin), VIII, and X, and proteins C and S, and for prothrombin time (PT), activated partial thromboplastin time (APTT), and total protein concentration. Bovine blood treated with PSM was also perfused through a hollow-fiber cartridge to assess thrombogenic potential in a shear flow system. PT increased with increasing protamine-Sepharose-to-plasma ratios and with increasing mixing time. When the PT and APTT of treated plasma were prolonged three to six times the baseline, Factors II and X were significantly removed (>90%), Factors I and VIII were partly removed (<35%), and total protein concentration remained >80% of the initial value. When blood depleted of clotting factors was perfused through hollow-fiber cartridges without an anticoagulant, cartridge patency was prolonged compared with cartridges perfused with untreated blood. This investigation demonstrated that inhibition of blood coagulation by removal of key clotting proteins is feasible.