Effects of polyethylene glycol and hydroxyethyl starch in University of Wisconsin preservation solution on human red blood cell aggregation and viscosity.

University of Wisconsin (UW) preservation solution is considered an effective flush and cold storage liquid. However, recent studies have provided evidence of the hyperaggregating effect on human red blood cells (RBC) of hydroxyethyl starch (HES), one of the components of the UW solution. In contrast, preservation solutions containing polyethylene glycol (PEG) have been found to be effective for organ preservation. The aim of this study was to compare the effects of HES (50 g/L); PEG 20 kDa (50 and 30 g/L), and PEG35 kDa (1.05 g/L) added to UW on the rheologic parameters of human RBC at 4 degrees C. Sedimentation rate was measured by the Westergren procedure and blood viscosity evaluated at high shear rates using a cone/plate viscometer. Alterations in RBC morphology and aggregation were evaluated by light microscopy. RBC sedimentation and viscosity were not affected by the inversion of Na+ and K+ concentrations in UW, but were increased by HES. PEGs appeared to reduce RBC deformability with concomitant inhibition of RBC aggregation. These results were consistent with reduced viscosity for PEG-containing solutions. In conclusion, the use of PEG did not change the physiologic function of human RBCs and thus may be an alternative to HES in UW liquids.