Uremic Toxins and Blood Purification: A Review of Current Evidence and Future Perspectives

Abstract

Accumulation of uremic toxins represents one of the major contributors to the rapid progression of chronic kidney disease (CKD), especially in patients with end-stage renal disease that are undergoing dialysis treatment. In particular, protein-bound uremic toxins (PBUTs) seem to have an important key pathophysiologic role in CKD, inducing various cardiovascular complications. The removal of uremic toxins from the blood with dialytic techniques represents a proved approach to limit the CKD-related complications. However, conventional dialysis mainly focuses on the removal of water-soluble compounds of low and middle molecular weight, whereas PBTUs are strongly protein-bound, thus not efficiently eliminated. Therefore, over the years, dialysis techniques have been adapted by improving membranes structures or using combined strategies to maximize PBTUs removal and eventually prevent CKD-related complications. Recent findings showed that adsorption-based extracorporeal techniques, in addition to conventional dialysis treatment, may effectively adsorb a significant amount of PBTUs during the course of the sessions. This review is focused on the analysis of the current state of the art for blood purification strategies in order to highlight their potentialities and limits and identify the most feasible solution to improve toxins removal effectiveness, exploring possible future strategies and applications, such as the study of a synergic approach by reducing PBTUs production and increasing their blood clearance.

Keywords: adsorption; blood purification; hemoperfusion; protein-bound toxins; uremic toxins.

Figure 1

Mechanism of a semipermeable membrane (left) and porous surface of a hollow fiber membrane (right).

Figure 2

Mechanism of adsorption (left), polymeric beads (center) and structure of the porous polymeric resin surface (right).

Figure 3

Evolution of the adsorption-based techniques for PBTUs removal during the years. HFR: hemodiafiltration with endogenous infusion; SUPRA HFR: hemodiafiltration with ultrafiltrate regeneration by resin adsorption; HP: hemoperfusion; HD: conventional dialysis; UF: ultrafiltrate.