Oxidative stress and anemia in chronic hemodialysis: The promise of bioreactive membranes

Patients with advanced chronic kidney disease are characterized by an imbalance between pro- and antioxidant factors, and increased oxidative stress has been associated with complications of end-stage renal disease such as atherosclerosis, beta(2)-Microglobulin amyloidosis and anemia. Antioxidants such as vitamin E work by inhibiting LDL oxidation by oxidants and by limiting cellular response to oxidized LDL, and are potentially useful adjuncts to the usual medical therapy provided to such patients. In chronic hemodialysis (HD) patients, vitamin E therapy may be administered in the form of dietary supplementation, or as an integral part of the HD procedure in the form of bioreactive dialysis membranes, in which the blood surface has been modified with a-tocopherol. Since blood membrane interaction plays a key role in generating oxidative stress, direct free radical scavenging at the membrane site is a logical approach. Dialysis with vitamin E-coated membranes (VECM) is associated with an improvement in circulating biomarkers of lipid peroxidation. Other than antioxidant activity, the modified surface appears to render these dialyzers more biocompatible, in that cellulose-based membranes behave similar to synthetic dialyzers in terms of cytokine induction. In small studies in chromic HD patients, both dietary vitamin E supplementation as well as use of VECM have been associated with reduced RBC fragility, prolonged RBC lifespan, and improvements in hemoglobin and rHuEpo requirements. Newer VECM based on polysulfone bring us further down the road towards complete biocompatibility, and represent a promising therapy against oxidative stress in chronic HD patients. Copyright (c) 2008 S. Karger AG, Basel.