A novel bioreactor based on suspended particles of agarose-immobilized species

Bioreactors often contain porous particles of agarose because these provide an enormous surface area (50 m2/cc gel) onto which enzymes or antibodies can be immobilized. Although many investigators claim that contact with agarose induces significant blood damage, we find that the biocompatibility of immobilized agarose is significantly improved when a novel system is used to fluidize the particles within the bioreactor vessel. We have built a prototype device that is oscillated vigorously about the axis of fluid flow. This action produces secondary flow patterns within the vessel that suspend the particles. In our model system, the bioreactor contains agarose immobilized heparinase. The system is biocompatible for 2 hours in vitro (in human blood at 37 degrees C) as follows: 1) hematocrit, white cell, and platelet counts do not change, 2) levels of plasma hemoglobin increase to 15-34 mg/dl, and 3) levels of complement component C3a increase to 0.64-1.4 micrograms/cc. We hope these studies lead to the development of a heparin removal system that can improve the safety of a variety of extracorporeal procedures. In addition, the techniques and approach used are sufficiently general to permit their extension to any immobilized species bioreactor for blood detoxification.