A fluidized immunoadsorption device for removing beta-2-microglobulin from whole blood : a potential treatment for dialysis-related amyloidosis

Abstract

Dialysis-related amyloidosis (DRA) is a frequent complication of end-stage renal disease that has been associated with the accumulation of 2-microglobulin (2m). Excluding transplantation, existing kidney replacement technologies are believed to remove insufficient quantities of P2m for the prevention of DRA, as they are non-specific and based on size-exclusion. A proposed DRA therapy is to use immunoadsorptive particles within an extracorporeal Vortex Flow Plasmapheretic Reactor (VFPR) to specifically remove 2m from blood. The compartmental design of the VFPR allows for the use of small adsorbent particles (100 m) that possess inherent mass-transfer advantages over the larger ones (>400 gIm) that are required for safe contact with whole blood for this application. Demonstrating the efficacy of this technology as a therapy for DRA would support its tailored application for treating other pathologies that are caused by circulating compounds such as sepsis, liver failure, autoimmune disease, drug overdoses, and genetic disorders. Whole anti-P2m antibodies (BBM.1) were immobilized onto agarose beads and used within a VFPR to remove donor baseline and defined quantities of recombinant 32m from whole human blood, in vitro. A dynamic immunoadsorption model was developed for the VFPR that was based upon the independent characterization of the mass-transfer processes within the VFPR and the thermodynamics of the immunoadsorbent. The experimentally-observed and model-predicted dynamics of 32m clearance from the blood indicate that the process controlling the rate of P2m removal was the hemofiltration rate (50 mL-plasma/min), which was on the order of the reported supply rate of 2m into the vasculature (70 mL-plasma/min).

(cont.) Single-chain variable region (scFv) antibody fragments offer several potential advantages over whole antibodies due to their size and genetic definition, as well as their amenability for microbial expression and in vitro evolution. Hence, a BBM.1 scFv was expressed by a yeast display vector and its affinity was quantified with a fluorescence-activated cell sorter (KD = 0.008 +/-proposed therapy to treat and/or prevent DRA.