Specific hemoperfusion through agarose acrobeads.

Abstract

Agarose acrobeads were produced by encapsulating polyacrolein microspheres (acrobeads) of 0.2 micron average diameter within an agarose matrix. Crosslinked agarose acrobeads of diameters ranging from 0.5 to 0.8 mm were found to be optimal spheres for specific hemoperfusion purposes. Agarose provides the biocompatibility and mechanical strength of the agarose acrobeads. Acrobeads contain a high aldehyde-group content through which various amino ligands, i.e., proteins, antigens, antibodies, enzymes, and so on, can be covalently bound in a single step under physiological pH (or other pH). Thus, antibodies, antigens, or toxic materials may be directly removed from whole blood by hemoperfusion. During in vitro and in vivo hemoperfusion trials, the content of erythrocytes, leukocytes, and thrombocytes was essentially unaltered. Likewise, a battery of the soluble blood components (Cl-, K+, Na+, Ca2+, PO3/4-), total proteins, albumin, and C'4 component of the complement cascade, as well as the enzymes SGOT, LDH, and alkaline phosphatase, remained constant within narrow limits during the hemoperfusion procedure. The chemical and physical structure of the beads is stable; neither acrolein nor bead fragments were detected in hemoperfusion trials. Similarly, leakage of antibody bound to the agarose acrobeads into the blood is insignificant. Thus far, we have demonstrated the efficacy of the crosslinked agarose acrobeads for extracorporeal removal of "unwanted" substances from whole blood in the following systems: (a) removal of specific antigens (digoxin or paraquat removal with antidigoxin or antiparaquat antibodies bound to the acrobeads, respectively), (b) removal of specific antibody (antiBSA) removal with BSA bound to the beads), (c) removal of immune complexes (BSA-antiBSA complex removal with C1q bound to acrobeads), and (d) removal of specific metals (removal of iron with deferoxamine bound to the agarose acrobeads).