Background/Case Studies: Red blood cell concentrates (RCCs), vital to transfusion therapy, consist of a heterogeneous population of red blood cells (RBCs) with varying biological ages. Older (O-) RBCs contribute to increased storage lesions, while younger (Y-) RBCs have enhanced post-transfusion survival. This study examined how whole blood filtration (WBF) and red-cell filtration (RCF) manufacturing methods, affect the density-based distribution of Y- and O-RBCs in a final RCC. We hypothesized that in the RCF method, Y-RBCs may be lost during buffy coat removal, leading to a lower Y-to-O-RBC ratio in RCF-derived RCCs than in WBF-derived RCCs.
Study
Design/Methods: To eliminate the impacts of donor factors on the density distribution of RBCs, 12 whole blood units were split into two halves, each undergoing either RCF or WBF methods. Density profiling of each RCC was performed using the Percoll separation method. Using the mean corpuscular hemoglobin concentration (MCHC) and mean cell volume (MCV), the Percoll densities required to create a density panel for each RCC were estimated. RBCs were layered onto the density gradient of Percoll solutions. Tubes were centrifuged, isolating Y- and O-RBCs from the top and bottom of tubs, respectively. RBC indices and volume of each fraction were measured using a hematology analyzer and a calibrated adjustable-volume pipette to estimate the proportion of each subpopulation. The estimated median density (EMD) was calculated for each RCCs.
Results/Findings: WBF-derived RCCs demonstrated significantly higher hemoglobin (Hb) levels, RBC count, hematocrit (HCT), and MCHC compared to RCF-derived RCCs (p< 0.0001). Red cell distribution width (RDW) was higher in WBF-derived RCCs, indicating greater variability in cell size (p< 0.0001). WBF-derived RCCs had higher final volume than RCF-derived RCCs (p< 0.0001). No significant difference was observed in the EMD of RCCs between the two methods. Analysis of RBC subpopulations showed variations between some identical units processed using different methods, however, the ratio of Y- to O-RBCs remained consistent across all units. Conclusions: Although WBF-derived RCCs had higher levels of HCT, Hb, RBC counts, and volume, the distribution of Y- and O-RBCs in RCCs was not significantly influenced by manufacturing methods, suggesting that the centrifugation conditions employed during manufacturing may not have effectively separated Y- and O-RBCs. Variations in RBC subpopulation distribution in some RCCs may stem from donor-related factors rather than the manufacturing method, emphasizing the need to consider donor factors when evaluating RBC distribution. Future studies may benefit from utilizing biotin-labeled RBCs to trace subpopulations throughout manufacturing, providing valuable insights into how manufacturing affects RBC distribution.
