Determination of the number of times for reuse of hemodialysis dialyzer through macrophage responses against dialyzer-eluted protein, a proposed method.

Background: Although the number of times dialyzer-reuse in hemodialysis is currently determined by the total volume of the dialyzer, the determination by macrophage activation using dialyzer-eluted protein might predict systemic inflammation.

Objective: The pro-inflammatory activities of the proteins from 5- and 15-times reused dialyzers were tested as a proof of concept experiment.

Methods: Accumulated proteins in dialyzers were eluted by the roller pump (the recirculation of 100 mL of buffer in a dialyzer with a roller pump at 15 mL/min for 2 h) or infusion procedures (infusion of 100 mL buffer in a dialyzer for 2 h) using chaotropic or potassium phosphate buffers (KPB) before the activation on macrophages cell lines (THP-1-derived human macrophages or RAW264.7 murine macrophages).

Results: The concentrations of dialyzer-eluted protein from both methods were not different and the infusion procedure was further used. The eluted proteins (by both buffers) from 15-times-reused dialyzers reduced cell viability, increased supernatant cytokines (TNF-α and IL-6), and upregulated pro-inflammatory genes (IL-1β and iNOS) in either THP-1-derived or RAW264.7 macrophages (higher responses in RAW264.7 cells) compared with the new dialyzer. Meanwhile, the 5-times-reused dialyzer protein did not reduce cell viability but enhanced some of these pro-inflammatory macrophage markers.

Conclusions: Due to the simpler preparation of KPB over chaotropic buffer with an easier protocol of RAW264.7 over THP-1-derived macrophages, the responses of RAW264.7 against dialyzer-eluted protein with infusion method using KPB buffer were proposed for determination of the number of times dialyzer reuse in hemodialysis.