Proteomic investigations on the effect of different membrane materials on blood protein adsorption during haemodialysis

Background. During haemodialysis procedure, the contact of blood with the membrane material contained in the hemodialyser results in protein deposition and adsorption, and surfaceadsorbed proteins may trigger a variety of biological pathways with potential pathophysiologic consequences. The present work was undertaken to examine for protein adsorption capacity of two membranes used for clinical haemodialysis, namely cellulose triacetate (a derivatized cellulosic membrane) and the synthetic polymer polysulfone-based helixone. Materials and methods. We performed a prospective cross-over study in chronic haemodialysis patients, routinely treated with a cellulose triacetate dialyser (n=3) or with a helixone dialyser (n=3). Dialysers from each patient were obtained after dialysis session, and flushed with a litre of saline to remove residual blood. Adsorbed proteins were then eluted by a strong chaotropic buffer. Patients were next switched to the other membrane dialyser for four weeks, at the end of this period protein adsorption being evaluated again. After silver staining, expression profile protein of the two groups was analyzed by 2-DE gels, analyzed and identified by Peptide Mass-finger printing and MALDI-TOF-MS/MS sequency. Moreover nanoLC-MS/ MS shotgun profiling was pursued using a semi-quantitative label free approach by emPAI data analysis. Results. A total of 54 differentially expressed proteins were identified: 22 proteins more concentrated in helixone membrane (predominantly low abundant plasma proteins) and 32 in cellulose triacetate (most represented by high abundant plasma proteins). The difference proved to be related to membrane material and not to patient's characteristics. Discussion. Proteomic techniques represent a useful approach for the investigation of proteins surface-adsorbed onto a haemodialysis membrane, and can also be applied for critical assessment to compare efficiencies of different dialyser membrane materials in the adsorption of plasma proteins.