Comparison of biocompatibility in polysulfone dialysis membranes with different sterilization.

INTRODUCTION: Polysulfone (PSf) membrane has been widely used for hemodialysis. A few studies have been reported in which a method of sterilization may affect biocompatibility. In this study, the comparison was made between two PSf membranes in order to evaluate the effect of sterilization from the biocompatibility point of view.

METHODS: We investigated the biocompatibility of the following two dialyzers, that is, APS-11SA (Asahi Kasei medical Co., Tokyo, Japan), sterilized by gamma-ray irradiation, and RENAK PS-1.0 (Kawasumi laboratories, Tokyo, Japan), sterilized by autoclave. Heparin of 40 units/mL was put in a syringe, and test blood was collected from healthy volunteers. Then, the dialyzer and blood circuit were filled with the test blood. Subsequently, the blood was circulated by a roller pump at the rate of 200 mL/min. We measured the platelet counts, CD41 and CD42b platelet surface markers, beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) at 30, 120, and 240 minutes, respectively.

FINDINGS: The platelet counts at 30, 120, and 240 minutes decreased significantly from the initiation of blood circulation in both dialyzers. The average beta-TG and PF4 increased from 61.3 ± 22.1 and 17.0 ± 6.4 ng/mL to 680.7 ± 217.1 and 550.7 ± 116.7 ng/mL with APS-11SA and to 454.3 ± 85.6 and 402.0 ± 58.0 ng/mL with RENAK PS-1.0, respectively. The average expression of CD41 and CD42b in APS-11SA and RENAK PS-1.0 was similar.

DISCUSSION: There are some reports that the gamma-ray irradiation changes the membrane structure of the PSf membrane, crosslinking the polyvinylpyrrolidone (PVP), a hydrophilic agent, on to the membrane. On the other hand, excess amount of PVP may have been eluted during the rinsing procedure in RENAK PS-1.0 because it was sterilized with autoclave. Because both these factors influenced on our results, APS-11SA and RENAK PS-1.0 dialyzers showed excellent blood compatibility.