Hemodialysis membrane biocompatibility: the case of erythropoietin.

Protein adsorption occurs upon blood exposure to hemodialysis membranes. While adsorption of certain proteins may be beneficial, adsorption of others may be undesirable. In the present study, we investigated the binding of recombinant human erythropoietin (rHuEPO) to different types of hemodialysis membranes in vitro. The amount of rHuEPO bound was dependent on the time of incubation, the concentration of the protein offered and the membrane material. Membranes made from the copolymer of polyacrylonitrile and methallyl sulfonate (AN69) bound the greatest quantity of rHuEPO. The dose-response curve of the binding to this type of membrane was linear. At the highest concentration examined, AN69 membranes bound 30 times more rHuEPO than did Cuprophan. This amount bound to AN69 was also greater than that which is expected to be present in a monolayer covering the nominal membrane surface area. We conclude that, under certain conditions, the binding of rHuEPO can be substantial and represents an example in which protein binding to hemodialysis membrane may be disadvantageous.