A Method for Extracorporeal Heparin Removal from Blood by Affinity Chromatography

A high level of heparin, infused into blood, often causes severe complications such as hemorrhage, especially when a drug is administered over a long period. The most common way of preventing a patient from bleeding after transfusion is by administering a heparin antagonist such as protamine. The complex molecules formed between heparin and protamine, if left in the bloodstream, may cause hypotension and other side effects. Protamine was immobilized as a bioligand on the affinity matrix formed by grafting an acrylic polymer on cellulose backbone. By flowing blood tangentially along the matrix surface immobilized with protamine, 70-90% heparin reduction was achieved from 1 L of blood containing 10 IU/ml of heparin studied in vitro. The acrylic gel surface avoids lysis of blood, the cellulose support sustains the flow of viscous blood at 50 ml/min, and the tangential flow design permits direct processing of blood without pressure buildup in the system. The example demonstrates the feasibility of applying such a device as a means of immunoadsorptive filter for the selective removal of disease-causing factors from blood.