Vitamin E as a functional and biocompatibility modifier of synthetic hemodialyzer membranes: an overview of the literature on vitamin E-modified hemodialyzer membranes.

Along with one century of history, research has provided many solutions for hemodialysis (HD) biomaterials, encompassing several generations of copolymers that have found wide application in the development of hollow-fiber dialyzer membranes. Polysulfone-based biomaterials have gained increasing consideration and are now the gold standard in the production of biocompatible hemodialyzers. However, even the highest biocompatibility now available cannot exclude that dialyzer membranes and the overall extracorporeal circulation may produce at the subclinical level immunoinflammatory reactions and thus an increased cardiovascular risk of patients on regular HD therapy. The lipophilic antioxidant and radical scavenger vitamin E has been used (as α-tocopherol) to modify cellulosic and synthetic hollow-fiber membranes with the ultimate goal to neutralize harmful reactive species and to mimic lipid structures of blood cell plasmalemma and lipoprotein particles. Besides filtration and biocompatibility, this modifier has introduced a third function of dialyzer membranes, namely 'antioxidant bioactivity'. Vitamin E can also serve as a template molecule to produce synthetic redox-active and -silent (non-antioxidant) modifiers for future generations of dialyzer membranes. This mini-review article describes the evolution of vitamin E-derived copolymers as a generation of biomaterials that has offered a clinical challenge and still represents a chance to further improving the quality of HD therapy.