Innovation in dialysis care is fundamental to improve well-being and outcomes of patients with end-stage kidney disease. The dialyzer is the core element of dialysis treatments, as it largely defines which substances are removed from the patient’s body. Moreover, its large surface size is the major place of interaction of the patient’s blood with artificial surfaces and thus may lead to undesired effects such as inflammation or coagulation. In the present article we summarize the development path for a new dialyzer, including in vitro and clinical evidence generation. We use the example of the novel FX CorAL dialyzer, which has recently entered European and US markets, to show which steps are needed to develop and characterize a new dialyzer. The FX CorAL dialyzer includes a new hydrophilic membrane, which features reduced protein adsorption, sustained performance, and an improved hemocompatibility profile, characterized in numerous in vitro and clinical studies. Safety evaluations revealed a favorable profile, with low incidences of adverse device effects. Insights gained from both in vitro and clinical studies contribute to the advancement of dialyzer development, ultimately leading to improved patient care.

Investigation of dialyzer thrombogenicity is a critical step during the development of a new dialyzer. Novel dialyzer membranes aim to reduce the inherent thrombogenic potential of artificial surfaces by, e.g., increasing membrane hydrophilicity. Reliable in vitro testing is fundamental during dialyzer development and must be in line with the current standards. Using the novel FX CorAL dialyzer with its increased membrane hydrophilicity as an example, this study characterizes dialyzer thrombogenicity in an in vitro test setup in line with ISO 10993-4 and identifies factors which influence dialyzer thrombogenicity. In a recirculation setup with human blood, platelet activation (platelet counts, β-thromboglobulin, platelet adsorption), coagulation (thrombin–antithrombin III complex) and complement activation (sC5b-9) were investigated among polysulfone- (FX CorAL, FX CorDiax, Optiflux, xevonta), polyethersulfone- (ELISIO, Revaclear, Theranova) and AN69 ST-based (Nephral) dialyzers. Additionally, the impact of dialysate and electrolyte composition on thrombogenicity was investigated. The FX CorAL showed the lowest platelet activation compared to all poly(ether)sulfone-based dialyzers and lower complement activation compared to most poly(ether)sulfone-based dialyzers and to the Nephral dialyzer. No significant differences were observed between the investigated dialyzers with regard to plasmatic coagulation. Among the tested parameters, the dialyzer showed the strongest impact on the thrombogenicity results. This study proposes guidance on in vitro testing of dialyzer thrombogenicity in line with current standards and may contribute to reducing the current heterogeneity among in vitro hemocompatibility testing.

Performance and hemocompatibility are the main focus areas in the development of new hemofilters for continuous kidney replacement therapy. The novel multiFlux hemofilter features a polysulfone membrane with increased hydrophilicity to improve performance stability and hemocompatibility. In the present in vitro study, we compared the multiFlux hemofilter to established hemofilters on the market, i.e., Ultraflux AV (polysulfone-based), Prismaflex HF (polyarylethersulfone-based) and Prismaflex ST (AN69 ST-based). For the characterization of performance, dialysate-side plasma clearance of urea, creatinine and β2-microglobulin (β2M) were investigated over 24 h. Hemocompatibility was characterized in a blood recirculation setup by determining activation of platelets, plasmatic coagulation, the complement system and leukocytes. For urea and creatinine clearance, all hemofilters reached or approached the effluent limit across all time points. For β2M, the multiFlux hemofilter showed significantly higher clearance values at each time point vs. all comparators (p < 0.001) and the most stable performance over 24 h. The multiFlux hemofilter also showed a favorable hemocompatibility profile, especially in terms of platelet activation (vs. Ultraflux AV and Prismaflex HF) and complement activation (vs. all comparators). This in vitro study supports previous findings that increased membrane hydrophilicity improves performance stability and hemocompatibility of synthetic membranes.