C-1017: Stabilizing effect of liposomes on rat red blood cell membrane quality is treatment-time dependent

Abstract

Liposome treatment minimizes red blood cell (RBC) membrane damage occurring during 42 day hypothermic storage (HS) in additive solutions. The aim of this study was to examine the effect of time of the liposome treatment on the in vitro RBC quality parameters. Leukoreduced, packed rat RBCs were incubated for 30 min at 37 °C in AS3 solution with either HEPES-NaCl solution or unilamellar liposomes (1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC):cholesterol, 7:3 mol%, 2 mM lipid). RBC membrane quality was evaluated by % hemolysis (Drabkins), deformability (ektacytometry), aggregation (syllectometry), hematological indices (Coulter) and microvesiculation (flow cytometry) immediately following RBC-liposome treatment and following 6 weeks of HS. DOPC liposome treatment resulted in decreased in percent hemolysis (1.4 ± 0.2% vs. 2.1 ± 0.3%, p = 0.03), increased in deformability (0.58 ± 0.01 vs. 0.57 ± 0.00, p = 0.03) and aggregation amplitude (15.4 ± 0.9 au vs. 12.5 ± 1.6 au, p = 0.03). After 6 weeks of HS, liposome-treated RBCs continued to differ from control RBCs by exhibiting increased aggregation amplitude (15.9 ± 3.2 au vs. 14.1 ± 0.7 au, p = 0.04). Flow cytometry analysis also showed increased microparticle (MPs) concentration in liposome-treated RBCs (812,113 ± 322,762 MPs/μL vs. 598,073 ± 132,869 MPs/μL, p = 0.03) and increased phosphatidylserine (PS) exposure in both RBCs (1.7 ± 0.6 vs. 1.5 ± 0.4, p = 0.05) and MPs (55.8 ± 6.5 vs. 34.8 ± 8.5, p = 0.03). The stabilizing effect of liposome treatment on rat RBCs is evident immediately after the incubation for parameters such as hemolysis. However, the presence of liposomes throughout the 6 week storage period induces MPs formation and PS exposure. Considering that most storage-induced membrane lesions start to appear after 2 weeks of HS, future research will examine the time-point when the liposome treatment would be most beneficial.