  The functionality and viability of stored human red blood cells (RBCs) is an
important clinical issue in transfusion. To systematically investigate changes
in stored whole blood, the hematological properties of individual RBCs were
quantified in blood samples stored for various periods with and without a
preservation solution called CPDA-1. With 3-D quantitative phase imaging
techniques, the optical measurements of the 3-D refractive index (RI)
distributions and membrane fluctuations were done at the individual cell level.
From the optical measurements, the morphological (volume, surface area and
sphericity), biochemical (hemoglobin content and concentration), and mechanical
parameters (dynamic membrane fluctuation) were simultaneously quantified to
investigate the functionalities and their progressive alterations in stored
RBCs. Our results show that the stored RBCs without CPDA-1 had a dramatic
morphological transformation from discocytes to spherocytes within 2 weeks
which was accompanied with significant decreases in cell deformability and cell
surface area, and increases in sphericity. However, the stored RBCs with CPDA-1
maintained their morphology and deformability for up to 6 weeks.
