Examination of particulate macroporous hydrogels in an extracorporeal rat haemoperfusion model

A series of macroporous hydrogels has been synthesized, selected from a range of such materials in which the presence of functional groups has been shown to produce sorbent properties with respect to molecules having clinical significance in the field of liver support. The use of freeze thaw polymerization, together with inverse suspension polymerization in hexane, or in brine, enables macroporous beads ranging in size from 150 to 2000 microm, to be prepared from functional monomers exhibiting a range of chemical functionalities and aqueous solubilities. In order to investigate the behaviour of these rigid porous hydrophilic substrates in haemoperfusion, a rat model was used to explore various aspects of whole blood response. The materials were incorporated into an extracorporeal circuit linking the right carotid artery and left jugular vein of male Sprague-Dawley rats. Erythrocyte, leucocyte and platelet levels were monitored over a 240 min haemoperfusion period. The most significant observation is that, apart from the strongly acidic polyacrylic acid substrate. matrix chemistry has relatively little effect on leucocyte or platelet response. The most important factors appear to be surface area, pore size and surface rugosity, which do produce measurable, but not dramatic differences. This is encouraging for future work, since these variables may be manipulated by polymerization conditions.