Nephrology Dialysis Transplantation, Vol 12, Issue 9 1968-1973, Copyright © 1997 by Oxford University Press
J Mulvihill, T Crost, J Renaux and J Cazenave
Background. Precise evaluation of the
haemocompatibility of prototype membranes, flow configurations and
anticoagulant regimens is an essential step in the development of dialysis
systems minimizing blood activation. An ex vivo model
in humans currently employed in our laboratory has recently been adapted to
allow the parallel evaluation of two minimodule dialysers with blood from a
single donor, thus eliminating differences due to donor variability in the
comparison of test and control dialysis modules.
Methods. The ex vivo flow system
is designed to reproduce the haemodynamic conditions of clinical dialysis
on a 1/50 scale. A blood line from the forearm vein of the volunteer donor
is divided at a Y-shaped junction, two roller pumps assure equivalent blood
flow (5 ml/min) in the branches leading to two minimodule dialysers and
heparin (0.1 IU/ml final concentration) is injected into each branch
immediately after the Y junction. Samples for analysis of blood activation
markers are collected at the exits of the two minimodules over a test
period of 27 min In the present series of tests, a new polyacrylonitirile
membrane (PAN) was evaluated relative to standard commercial polysulphone
(PS), acrylonitrile copolymer (AN 69) and cuprophan (CUP) membranes.
Results. A steady minimal level of anticoagulation
corresponding to a slightly less than two-fold prolongation of APTT
(activated partial thromboplastin time) was maintained throughout testing
in both branches of the ex vivo flow system. Time
curves for the accumulation of activation markers (thrombin-antithrombin II
complexes, prothrombin fragment 1+2, platelet {beta}-thromboglobulin,
and complement fragment C3a) showed all four types of minimodule dialyser
to induce comparable low levels of activation of coagulation parameters and
platelets, together with similar mild activation of complement for AN 69,
PAN, and PS dialysers as compared to stronger activation for CUP modules.
Overall results thus confirmed the acceptable haemocompatibility of the
prototype polyacrylonitrile (PAN) membrane.
Conclusions. Among current methods for evaluation of
the biocompatibility of haemodialysis systems, ex vivo
flow models in humans avoid problems arising from species differences and
may be designed to closely reproduce the conditions of clinical dialysis. A
parallel configuration eliminates artefacts due to individual variations in
donor response. This not only facilitates the direct comparison of test and
control membranes under close to identical experimental conditions, but
also provides a model particularly well adapted to studies of the effects
of different anticoagulation regimens, flow configurations and dialysates,
or alternative methods of sterilization, rinsing and priming of the
dialysers. Keywords: biocompatibilty; haemodialysis;
ex vivo model; polyacrylonitrile; hollow-fibre
membrane; parallel flow system
TECHNICAL REPORT
Evaluation of haemodialysis membrane biocompatibility by parallel assessment in an ex vivo model in health y volunteers
INSERM U.211, Laboratoire de Biologie et Pharmacologie des Interactions du Sang avec les Vaisseaux et les Biomateriaux, Etablissement de Transfusion Sanguine, Strasbourg, France; Hospal R & D Int. Meyzieu, France; Corresponding author at: Etablissement de Transfusion Sanguine, BP No. 36, 10 rue Spielmann, 67065 Strasbourg Cedex, France
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