Effects of blood donor characteristics and storage on red blood cell haemoglobin β S-nitrosylation.

Background and objectives: In the setting of tissue hypoxia, S-nitrosylated haemoglobin (SNO-Hb) plays crucial roles in the control of blood flow. This is associated with decreased oxygen affinity to haemoglobin and increase in tissue oxygenation. Red blood cell (RBC) transfusion is primarily performed to improve tissue oxygenation in anaemic patients. RBCs after storage undergo a variety of biochemical and functional alterations, including deficiency of nitric oxide (NO) bioactivity. However, how donor characteristics affect NO levels during RBC storage is unclear. We sought to investigate the association of blood donor age, gender and storage duration with NO and SNO-Hb levels in blood units.

Materials and methods: Blood samples from 42 healthy younger (≤30 years) and older (≥45 years) donors were collected and stored for up to 42 days. Total NO kits were used to detect total nitrite and nitrate levels in blood storage solution. SNO-Hb levels in RBCs were detected and analysed by quantitative mass spectrometry.

Results: Total NO levels in the blood storage solution significantly increased with donor age and storage duration. Proteomic analysis revealed that RBCs from older donors, particularly older females, significantly lost SNO-Hb during storage. Our findings indicate that RBCs from older donors are associated with reduced SNO-Hb levels and increased NO metabolites in storage solution after ≥35 days storage.

Conclusion: The findings suggest stored RBCs from older donors may have reduced capacity to deliver oxygen to tissues under hypoxia. A shorter shelf life may be required for storing RBCs from older donors, particularly older females.