Influence of Dialysis Membranes on Clinical Outcomes: From History to Innovation

Abstract

Dialysis membranes were traditionally classified according to their material compositions (i.e., as cellulosic or synthetic) and on the basis of the new concept of the sieving coefficient (determined by the molecular weight retention onset and molecular weight cut-off). The advantages of synthetic polymer membranes over cellulose membranes are also described on the basis of their physical, chemical, and structural properties. Innovations of dialysis membrane in recent years include the development of medium cutoff membranes; graphene oxide membranes; mixed-matrix membranes; bioartificial kidneys; and membranes modified with vitamin E, lipoic acid, and neutrophil elastase inhibitors. The current state of research on these membranes, their effects on clinical outcomes, the advantages and disadvantages of their use, and their potential for clinical use are outlined and described.

Keywords: cellulose membranes; dialysis membranes; graphene oxide membranes; mixed-matrix membranes; synthetic polymer membranes.

Figure 1

The procedure of hemodialysis. A patient is connected to a dialysis machine and their blood is pumped out via vascular access and filtered using a dialyzer (an artificial kidney containing up to 15,000 hollow fiber membranes). The blood is then pumped back into the patient’s body.

Figure 2

Mixed-matrix membrane (MMM) is made of an inner layer of polyethersulfone (PES)/polyvinylpyrrolidone (PVP) blend and an outer layer of activated carbon (AC) microparticles. It is characterized by the removal of protein-bound toxins from the blood as well as the removal of endotoxins from the dialysate. The endotoxins are adsorbed by activated carbon particles. (A) A illustration of gross equipment of mixed-matrix membrane. (B) The detail structure of mixed-matrix membrane and we can find endotoxin binded on mixed-matrix membrane (C) In molecular level, activated carbon in mixed-matrix membrane grabbed endotoxins and protein-bound toxins.

Figure 3

Bioartificial kidneys (BAKs) are membranes that mimic native kidney processes by engaging a monolayer of conditionally immortalized proximal tubule epithelial cells (ciPTECs) cultured on polymeric membranes and collagen IV. Polyethersulfone (PES) membrane layers help ciPTECs avoid direct contact with blood and improve the membrane’s hemocompatibility.