Membrane plasma protein fractionation for low-density lipoprotein apheresis: comparison of two hollow fiber modules and two filtration systems

Abstract

Human plasma was separated by plasmapheresis from patients with familial hypercholesterolemia and fractionated using two different hollow fiber membrane modules and two different filtration techniques. The goal of the membrane plasma protein fractionation process was to eliminate excess low-density lipoproteins (LDL) from the separated plasma and to return the LDL-purified plasma (with all other physiological proteins) to the patient. The major obstacles encountered in the filtration of macromolecular solutions are concentration polarization, membrane fouling and pore plugging. The loss of inherent membrane characteristics due to these secondary filtration effects results in a drastically reduced filtration flux and decreased protein sieving. This study shows that the desired fractionation into graded protein size classes can be accomplished when appropriate membranes and controlled filtration conditions are used. In a total of 273 LDL apheresis treatments in 9 patients, the improved filtration technique, the FU system, demonstrates that ultrafiltration is a suitable fractionation process and therapeutic substitution-free LDL plasmapheresis is possible.