Background: The study aimed to investigate the influence of in vitro storage on erythrocyte complement receptor one (E-CR1), cell shrinkage and eryptosis of human red blood cells (RBCs), and to assess the possible effects of ulinastatin (UTI) on them.
Methods: After collection, RBCs were treated with saline (control group) and different concentrations of UTI (5,000 U/mL, 10,000 U/mL, and 50,000 U/mL in Group C1, Group C2, and Group C3, respectively). E-CR1, cell size, and phosphatidylserine (PS) exposure and intracellular Ca2+ concentration were analyzed by flow cytometer every 7 days up to Day 35.
Results: E-CR1 level and cell size of all groups decreased during storage. In the control group, E-CR1 began to decrease on Day 28 and cells shrank on Day 21. The E-CR1 level of Group C2 was significantly higher than that of the control group beginning on Day 21. The cells of Group C1 and Group C2 began to shrink remarkably on Day 21, and those of Group C3 on Day 35. PS-exposure levels of 4 groups started to increase on Day 7 (p < 0.05), while from Day 14 to 35 those of Group C3 were significantly lower than the control group (p < 0.05). The intracellular Ca2+ levels of the control group started to increase significantly on Day 7, one week earlier than the experimental groups. From Day 21 to 35, the intracellular Ca2+ levels of Group C2 and C3 were significantly lower than those of the control group (p < 0.05).
Conclusions: RBCs underwent E-CR1 loss, cell shrinkage, and eryptosis during in vitro storage, which could be attenuated by UTI.