Prestorage leukocyte reduction prevents the formation of microaggregates that occlude artificial capillary vessels

PURPOSE: The passage behavior of stored blood through an artificial microchannel system, as a model of capillary vessels, was examined. MATERIALS AND METHODS: Using blood obtained from a total of 17 healthy volunteers, untreated and prestorage leukocyte reduced blood, or untreated and prestorage microfiltered (35 microm-pore size) blood were stored, and then the passage behavior through the microchannels was evaluated. Also, using blood from 16 patients stored for about 2 weeks, the effect of a leukocyte reduction filter, microfilter or mesh filter (175-210 microm-pore size) on the passage through the microchannels was examined. RESULTS: Untreated blood passed through the microchannels immediately after blood collection, but after 1 week occlusion of the microchannels occurred. Prestorage leukocyte reduced blood, however, passed through the microchannels for up to 6 weeks. Occlusion of the microchannels occurred with both the untreated and prestorage microfiltered blood. Although filtration through a leukocyte reduction filter provided blood that can pass through the microchannels, occlusion occurred with blood filtered in other way. CONCLUSIONS: The present results show that stored blood produces abundant microaggregates, potentially occluding capillary vessels. These microaggregates are not formed after prestorage leukocyte reduction or can be removed by use of a leukocyte reduction filter.