Albumin treatment reduces in vitro platelet deposition to PMMA dialysis membrane

We investigated in an in vitro system the effect of albumin on the interaction between circulating platelets and artificial membranes used for hemodialysers. Using a recently described method we evaluated platelet adhesion to polymethylmethacrylate (PMMA) and cuprophan (CU) hollow-fibers. Deposition of washed radiolabelled platelets on these two membranes was measured in small dialysis filters with or without previous perfusion with an albumin solution. Also measured was the amount of albumin that adhered to the membranes after perfusion of the filters with radiolabelled albumin. Platelet deposition to PMMA was significantly reduced by albumin treatment (from 1070 ± 498 to 296 ± 174 plt/mm2, P < 0.01). Platelet deposition on the CU membrane was comparable with and without albumin pre-perfusion (141 ± 70 vs. 152 ± 100 plt/mm2). Deposition of radiolabelled albumin was higher on PMMA than on CU membrane. Thus, higher adborption of this protein, observed in our in vitro system, might explain the lower platelet deposition found on the PMMA rather than on the CU membrane. These results suggest that platelet interactions with PMMA during dialysis could be improved by treating the dialyser with albumin before blood contact. However, before this treatment is used clinically further experimental studies are required to confirm that our in vitro observation also applies to in vivo conditions.