Intra- and post-dialytic platelet activation and PDGF-AB release:: cellulose diacetate vs polysulfone membranes

Background, During haemodialysis the blood-membrane contact causes a release of platelet granule content, which contains platelet-derived growth factor AB (PDCF-AB). In view of the potential role of this in altering biocompatibility during haemodialysis, we evaluated the intra- and post-dialytic changes in PDGF-AB serum levels during haemodialysis sessions performed with cellulose diacetate (CDA) and polysulfone (PS) membranes respectively. Methods. PDGF-ABI platelet factor 4 (PF4), beta thromboglobulin (beta TG), and mean platelet volume (MPV) levels were determined in 30 patients, each of whom underwent six dialysis sessions: three with a CDA and three with a PS membrane. Blood samples were taken at times 0, 15, 30, 120, 180, and 240 min during dialysis and at 1, 4, and 20 h after the end of the session. Statistical analysis was performed using a one-way ANOVA and Student's t test. Results. PDGF-AB at 15 min was increased to +41 +/- 9% with CDA vs + 20 +/- 5% with PS (P< 0.001) from the TO values, and at 120 min it was + 19 +/- 8'%, with CDA vs -25 +/- 9% with PS (P < 0.001) from TO levels. At 240 min it was +95+/-14% with CDA vs +49+/-15% with PS (P<0.001) from the TO values, returning to basal only 20 h after the end of the session. <beta>TG at 15 min was + 60 +/- 8% for CDA vs + 24 +/- 7.5% for PS (P < 0.001) from the T0 values. PF4 showed a similar trend to <beta>TG. MPV at 30 min from the start of dialysis was 7.4 +/- 0.3 fl with CDA and 8 +/- 0.3 fl with PS (P<0.001), and at 240 min MPV was 7.9+/-0.3 fl with CDA and 8.4+/-0.3 fl with PS (P < 0.001). Conclusions. Platelet activation and platelet release reactions are lower with PS than with CDA membranes. PDGF-AB, released during and after dialysis, represents a clear biocompatibility marker. Its slow return to basal values and its action on vascular cells make it a potential risk factor for atherosclerosis in uraemic patients.