MCO Membranes: Enhanced Selectivity in High-Flux Class

Abstract

Novel MCO high-flux membranes for hemodialysis have been developed with optimized permeability, allowing for filtration close to that of the natural kidney. A comprehensive in vitro characterization of the membrane properties by dextran filtration is presented. The sieving profile of pristine membranes, as well as that of membranes exposed to blood for 40 minutes, are described. The effective pore size (Stokes-Einstein radius) was estimated from filtration experiments before and after blood exposure, and results were compared to hydrodynamic radii of middle and large uremic toxins and essential proteins. The results indicate that the tailored pore sizes of the MCO membranes promote removal of large toxins while ensuring the retention of albumin.

Effects of Hemodialysis Therapy Using Dialyzers with Medium Cut-Off Membranes on Middle Molecules

“…Dialyzers containing MCO membranes have been developed to achieve filtration properties with a very steep filtration curve and thus maximal removal of larger middle molecules, while retaining albumin. To this end, the pore size distribution has been narrowed, which allows molecular weight cut-off in the proximity of but still lower than the molecular weight of albumin [7] . Their approval and introduction into maintenance HD brings a therapeutic tool that targets the larger middle molecules in patients with end-stage renal disease for the first time, without excessive loss of albumin, which was in the mean 2.8 and 3.0 g per treatment in the studies presented [9] .…”

“…Recent advances in membrane design have produced membranes with very tight pore size distribution, which results in a steep filtration curve. This allows placing the molecular weight cut-off relatively close to albumin, thus enabling the clearance of larger middle molecules while retaining albumin [7] . These medium cut-off (MCO) membranes may allow improvement of solute clearance beyond what is currently possible with HDF and extend the benefits of more adequate uremic toxin removal to more patients [8] .…”

The Evolving Patterns of Uremia: Unmet Clinical Needs in Dialysis

“…Theoretically, the HDx using HRO/MCO membrane would improve the clinical prognosis of dialysis by promoting the removal of more toxin solutes retained in the blood of ESRD patients, while ensuring the retention of albumin [20] . The advantages of these novel membranes are more evident when compared to conventional high-flux membranes.…”

“…The development of high retention onset (HRO) membrane [18] , originally defined as medium cut-off (MCO) membrane [19,20] , represents one of the most recent advances in membrane technology for renal replacement therapy. It is characterized by enhanced selectivity and permeability with a very high molecular weight retention onset and high molecular weight cut-off close to the molecular weight of albumin [18] .…”

“…First, HRO/MCO permits the filtration of medium-and macromolecular solutes (including toxin and pro-inflammation factors), with the unchanging schedule of HD, negligible loss of albumin, and good safety property. The removal of large toxins involves β2M, complement factor D, myoglo-bin, and phosphorus [19,20] . Compared to high-flux dialysis, HDx also enhances the removal of chronic inflammation factors in a controlled duration of 4 weeks each, plus 8 weeks extension phase among 48 patients [21] .…”