Influence of clinical hemodialysis membrane morphology and chemistry on protein adsorption and inflammatory biomarkers released: In-situ synchrotron imaging, clinical and computational studies

Abstract

Hemodialysis (HD) is often accompanied with activation of biochemical cascade reactions, caused by undesirable protein adsorption, which results in severe consequences for HD patients. Present research aims to study three hemodialysis membranes currently available in the Canadian hospitals of polyacrylonitrile (PAN), polyethersulfone (PES) and polyvinylidene fluoride (PVDF) and their interaction with three main human serum proteins: Human Serum Ablumin (HSA), Human Serum Fibrinogen (FB) and Human Serum Transferrin (TRF). In-situ synchrotron-based X-ray tomography (SR-μCT) was used to evaluate main membranes characteristics such as fiber diameter, pore size and their distribution, as well as to study the process of protein adsorption on the membranes surface and along membrane matrices. Scanning Electron Microscopy (SEM) was also used to investigate the morphology of proteins deposited on the membrane surface. Furthermore, interaction of membranes with inflammatory biomarkers was studied. Collected blood samples from HD patients were analyzed using Luminex assay for the inflammatory biomarkers of Serpin/Antitrombin-III, Properdin, C5a, 1L-1α, 1L-1β, IL-6 and TNF-α. Our results indicate the difference in the interaction of membranes with proteins is mainly attributed to a membrane surface charge and membrane chemistry. PAN and PES membranes, which are possessing high negative charge (-41.5mV and -68mV) and polar surface groups, would alter the morphology of adsorbed HAS and FB, while PVDF surface does not affect protein crystals growth. Furthermore, the molecular docking results showed that the highest interaction energy of human serum proteins was with PES membrane. The increased interaction of PES membrane with human serum proteins has triggered inflammation reactions. The release of C5a, IL-6 and Serpin cytokines for PES membrane was drastically higher compared to PAN and PVDF. The relative increase in those cytokine concentrations was 400-2000% for PES membrane, while it decreased by 10-40% for PAN and PVDF. It is worth noted that PVDF membrane had the lowest charge of -2.5 mV among investigated membranes, and it possessed the lowest interaction with human serum proteins and the least inflammation response.