The microscopic characterization of multinucleated giant cells formed on polymeric surfaces perfused with blood.

Multinucleated, foreign body giant cells were formed by the fusion of blood monocytes on polymeric membranes perfused with blood during extended extracorporeal circulation. In the current study, heparinized blood, flowing in an arteriovenous shunt in a sheep, perfused polycarbonate, polypropylene and silicone rubber membranes of a recently developed bioartificial tissue culture system. The multinucleated giant cells were studied by light, scanning electron, and transmission electron microscopy, after membrane perfusion for periods of one to two weeks. The giant cells, which were the predominant cellular components of the blood-polymer interface layer, contained from a few to more that one hundred nuclei and varied in diameter up to 400 microns. The cellular interaction with the three membrane types was similar, although fewer mononuclear cells were observed adhering to the silicone rubber membrane. The presence or absence of micropores in the membranes had no effect on the formation of giant cells, nor did the presence of foreign tissue in culture behind the microporous membranes. High blood flow rates and chronic anticoagulation with heparin permitted observation of this foreign body reaction of blood independent of thrombosis.